oxymorphone and noroxycodone

The pharmacokinetics of oxycodone in patients with end-stage renal disease (ESRD) requiring haemodialysis are largely unknown. Therefore, we investigated the pharmacokinetics of oxycodone/naloxone prolonged release and their metabolites in patients with ESRD during and between haemodialysis sessions.. Single doses of oxycodone/naloxone (5/2.5 or 10/5 mg) were administered in nine patients with ESRD using a cross-over design on the day of dialysis and on a day between dialysis sessions. Plasma, dialysate and urine concentrations of oxycodone, naloxone and their metabolites were determined up to 48 h post-dosing using a liquid chromatography-tandem mass spectrometry system.. Haemodialysis performed 6-10 h after dosing removed ∼10% of the administered dose of oxycodone predominantly as unconjugated oxycodone and noroxycodone or conjugated oxymorphone and noroxymorphone. The haemodialysis clearance of oxycodone based on its recovery in dialysate was (mean ± SD) 8.4 ± 2.1 L/h. The geometric mean (coefficient of variation) plasma elimination half-life of oxycodone during the 4-h haemodialysis period was 3.9 h (39%) which was significantly shorter than the 5.7 h (22%) without haemodialysis. Plasma levels of the active metabolite oxymorphone in its unconjugated form were very low.. Oxycodone is removed during haemodialysis. The pharmacokinetics including the relatively short half-life of oxycodone in patients with ESRD with or without haemodialysis and the absence of unconjugated active metabolites indicate that oxycodone can be used at usual doses in patients requiring dialysis.

Topics: Adult; Aged; Analgesics, Opioid; Cross-Over Studies; Female; Humans; Kidney Failure, Chronic; Kidney Function Tests; Male; Middle Aged; Morphinans; Naloxone; Narcotic Antagonists; Oxycodone; Oxymorphone; Prognosis; Renal Dialysis; Tissue Distribution

Oxycodone is a µ-opioid receptor agonist widely used in the treatment of cancer pain. The predominant metabolic pathway of oxycodone is CYP3A4-mediated N-demethylation to noroxycodone, while a minor proportion undergoes 3-O-demethylation to oxymorphone by CYP2D6. The aim of this study was to investigate the effects of the mild CYP3A4 inhibitor aprepitant on the pharmacokinetics of orally administered controlled-release (CR) oxycodone.. This study design was an open-label, single-sequence with two phases in cancer patients with pain who continued to be administered orally with multiple doses of CR oxycodone every 8 or 12 hours. Plasma concentration of oxycodone and its metabolites were measured up to 8 hours after administration as follows: on day 1, CR oxycodone was administered alone; on day 2, CR oxycodone was administered with aprepitant (125 mg, at the same time of oxycodone dosing in the morning). The steady-state trough concentrations (Css) were measured from day 1 to day 3.. Aprepitant increased the area under the plasma concentration-time curve (AUC0-8) of oxycodone by 25% (p<0.001) and of oxymorphone by 34% (p<0.001), as well as decreased the AUC0-8 of noroxycodone by 14% (p<0.001). Moreover, aprepitant increased Css of oxycodone by 57% (p = 0.001) and of oxymorphone by 36% (p<0.001) and decreased Css of noroxycodone by 24% (p = 0.02) at day 3 compared to day 1.. The clinical use of aprepitant in patients receiving multiple doses of CR oxycodone for cancer pain significantly altered plasma concentration levels, but would not appear to need modification of the CR oxycodone dose.. UMIN.ac.jp UMIN000003580.

Topics: Adult; Aged; Analgesics, Opioid; Aprepitant; Area Under Curve; Delayed-Action Preparations; Female; Humans; Male; Middle Aged; Morphinans; Morpholines; Neoplasms; Oxycodone; Oxymorphone; Pain

This study evaluated the plasma concentrations of oxycodone and its demethylates and opioid-induced adverse effects based on cachexia stage in cancer patients receiving oxycodone. Seventy patients receiving oxycodone for cancer pain were enrolled. Cachexia was evaluated using the Glasgow Prognostic Score (GPS). Predose plasma concentrations of oxycodone, oxymorphone, and noroxycodone were determined at the titration dose. Opioid-induced adverse effects were monitored for 2 weeks after the titration. Plasma concentrations of oxycodone and oxymorphone but not noroxycodone in patients with a GPS of 2 were significantly higher than that with a GPS of 0. The metabolic ratios of noroxycodone but not oxymorphone to oxycodone in patients with a GPS of 1 and 2 were significantly lower than in those with a GPS of 0. A higher GPS was associated with a higher incidence of somnolence, while the GPS did not affect the incidence of vomiting. Plasma concentrations of oxycodone and oxymorphone were not associated with the incidence of adverse effects. In conclusion, cancer cachexia raised the plasma exposures of oxycodone and oxymorphone through the reduction of CYP3A but not CYP2D6. Although the cachexia elevated the incidence of somnolence, alterations in their pharmacokinetics were not associated with the incidence.

Topics: Aged; Analgesics, Opioid; Cachexia; Cytochrome P-450 CYP2D6; Cytochrome P-450 CYP3A; Female; Humans; Male; Middle Aged; Morphinans; Neoplasms; Oxycodone; Oxymorphone; Pain

The main metabolic pathways of oxycodone, a potent opioid analgetic, are N-demethylation (CYP3A4) to inactive noroxycodone and O-demethylation (CYP2D6) to active oxymorphone. We performed a three-way, placebo-controlled, double-blind cross-over study to assess the pharmacokinetic and pharmacodynamic consequences of drug interactions with oxycodone.. The 12 participants (CYP2D6 extensive metabolizers) were pre-treated with placebo, ketoconazole or paroxetine before oral oxycodone ingestion (0.2 mg/kg).. Pre-treatment with ketoconazole increased the AUC for oxycodone 2- to 3-fold compared with placebo or paroxetine. In combination with placebo, oxycodone induced the expected decrease in pupil diameter. This decrease was accentuated in the presence of ketoconazole, but blunted by paroxetine. In comparison to pre-treatment with placebo, ketoconazole increased nausea, drowsiness, and pruritus associated with oxycodone. In contrast, the effect of pre-treatment with paroxetine on the above-mentioned adverse events was not different from that of placebo. Ketoconazole increased the analgetic effect of oxycodone, whereas paroxetine was not different from placebo.. Inhibition of CYP3A4 by ketoconazole increases the exposure and some pharmacodynamic effects of oxycodone. Paroxetine pretreatment inhibits CYP2D6 without inducing relevant changes in oxycodone exposure, and partially blunts the pharmacodynamic effects of oxycodone due to intrinsic pharmacological activities. Pharmacodynamic changes associated with CYP3A4 inhibition may be clinically important in patients treated with oxycodone.

Topics: Adult; Analgesics, Opioid; Cross-Over Studies; Cytochrome P-450 CYP2D6 Inhibitors; Cytochrome P-450 CYP3A; Cytochrome P-450 CYP3A Inhibitors; Double-Blind Method; Drug Interactions; Genotype; Humans; Ketoconazole; Miosis; Morphinans; Oxycodone; Oxymorphone; Pain Measurement; Paroxetine; Placebos; Young Adult

Oxycodone is widely used for the treatment of cancer pain, but little is known of its pharmacokinetics in cancer pain patients. The aim of this study was to explore the relationships between ordinary patient characteristics and serum concentrations of oxycodone and the ratios noroxycodone or oxymorphone/oxycodone in cancer patients.. Four hundred and thirty-nine patients using oral oxycodone for cancer pain were included. The patients' characteristics (sex, age, body mass index [BMI], Karnofsky performance status, "time since starting opioids", "oxycodone total daily dose", "time from last oxycodone dose", use of CYP3A4 inducer/inhibitor, "use of systemic steroids", "number of medications taken in the last 24 h", glomerular filtration rate (GFR) and albumin serum concentrations) influence on oxycodone serum concentrations or metabolite/oxycodone ratios were explored by multiple regression analyses.. Sex, CYP3A4 inducers/inhibitors, total daily dose, and "time from last oxycodone dose" predicted oxycodone concentrations. CYP3A4 inducers, total daily dose, and "number of medications taken in the last 24 h" predicted the oxymorphone/oxycodone ratio. Total daily dose, "time from last dose to blood sample", albumin, sex, CYP3A4 inducers/inhibitors, steroids, BMI and GFR predicted the noroxycodone/oxycodone ratio.. Women had lower oxycodone serum concentrations than men. CYP3A4 inducers/inhibitors should be used with caution as these are predicted to have a significant impact on oxycodone pharmacokinetics. Other characteristics explained only minor parts of the variability of the outcomes.

Topics: Analgesics, Opioid; Cross-Sectional Studies; Cytochrome P-450 CYP3A; Cytochrome P-450 CYP3A Inhibitors; Dose-Response Relationship, Drug; Female; Humans; Linear Models; Male; Middle Aged; Morphinans; Neoplasms; Oxycodone; Oxymorphone; Pain; Sex Factors

Oxycodone is a widely used opioid analgesic, the global use of which has increased several-fold during the last decade. This study was designed to determine the effect of age on the pharmacokinetics of intravenous oxycodone, with special reference to renal function in elderly patients.. We compared the pharmacokinetics of 5 mg of intravenous oxycodone in four groups of 10-11 patients, aged 20-40, 60-70, 70-90 years, undergoing orthopaedic surgery. Plasma concentrations of oxycodone and its noroxycodone, oxymorphone and noroxymorphone metabolites were measured for 24 hours with a liquid chromatography-tandem mass spectrometric method. The cytochrome P450 (CYP) 2D6 genotype of the patients was determined. Glomerular filtration rate (GFR) was estimated on the basis of the age, sex and serum creatinine concentration of the patient.. The pharmacokinetics of oxycodone showed age dependency. In the oldest group, the mean area under the plasma concentration-time curve from time zero to infinity (AUC(∞)) of oxycodone was 80% greater (p < 0.001) and the apparent total body clearance of the drug from plasma (CL) was 34% lower (p < 0.05) than in the youngest group. The mean AUC(∞) of oxycodone was also 30-41% greater in the oldest group than in the age groups of 60-70 and 70-80 years (p < 0.05). Oxycodone plasma concentrations from 8 hours post-dose were >2-fold higher (p < 0.01) in patients aged >80 years than in patients aged 20-40 years. Noroxycodone AUC(∞) was increased in the oldest group compared with patients aged 20-40 and 60-70 years (p < 0.05). There were no significant sex-related differences in any of the pharmacokinetic parameters. Because 37 of the 41 patients were extensive metabolizers through CYP2D6, the effect of the CYP2D6 genotype on oxycodone pharmacokinetics could not be properly assessed. There was a linear correlation between GFR and CL (p < 0.01, coefficient of determination [r(2)] = 0.26), volume of distribution at steady state (p < 0.05, r(2) = 0.19) and AUC(∞) (p < 0.01, r(2) = 0.29) of oxycodone.. Age is an important factor affecting the pharmacokinetics of oxycodone. Following intravenous administration of oxycodone, patients aged >70 years are expected to have, on average, 40-80% higher exposure to oxycodone than young adult patients. Because oxycodone pharmacokinetics are greatly dependent on the age of the patient, it is important to titrate the analgesic dose individually, particularly in the elderly.

Topics: Adult; Age Factors; Aged; Aged, 80 and over; Analgesics, Opioid; Area Under Curve; Chromatography, Liquid; Creatinine; Cytochrome P-450 CYP2D6; Female; Genotype; Glomerular Filtration Rate; Humans; Injections, Intravenous; Male; Middle Aged; Morphinans; Orthopedic Procedures; Oxycodone; Oxymorphone; Pain, Postoperative; Tandem Mass Spectrometry; Tissue Distribution; Young Adult

The aim of this study was to evaluate the plasma dispositions of oxycodone and its demethylates and dose escalation based on genetic polymorphisms of CYP2D6, CYP3A5, ABCB1, and OPRM1 in cancer patients receiving oxycodone. Sixty-two Japanese cancer patients receiving oxycodone extended-release tablets were enrolled. Predose plasma concentrations (C(12)) of oxycodone, noroxycodone, and oxymorphone were determined at the titrated dose. Daily oxycodone escalation rate was evaluated as the opioid escalation index (OEI). Genetic variants did not significantly alter oxycodone C(12). Oxymorphone C(12) and its ratio to oxycodone C(12) were significantly higher in CYP2D6 extensive metabolizers than in intermediate metabolizers but did not affect dose escalation. In contrast, noroxycodone C(12) and its ratio to oxycodone C(12) were significantly higher in the CYP3A5*1 carrier group than in the *3/*3 group. The OEI was significantly higher in the CYP3A5*3/*3 group than in the *1 carrier group. No significant difference was observed in the OEI in the other genetic variants. Noroxycodone C(12) was higher in the dose escalation group as compared to the nonescalation group and significantly affected the incidence of dose escalation. In conclusion, CYP3A5*3 altered the plasma disposition of noroxycodone, which was inversely affecting the dose escalation in cancer patients receiving oxycodone.

Topics: Aged; Asian People; ATP Binding Cassette Transporter, Subfamily B; ATP Binding Cassette Transporter, Subfamily B, Member 1; Cytochrome P-450 CYP2D6; Cytochrome P-450 CYP3A; Delayed-Action Preparations; Female; Humans; Male; Middle Aged; Morphinans; Neoplasms; Oxycodone; Oxymorphone; Polymorphism, Genetic; Receptors, Opioid, mu

We evaluated and compared the pharmacokinetics of two oral administration routes of oxycodone parenteral liquid (10 mg/mL)--single buccal and sublingual administration--in 30 generally healthy awake children, aged 6-91 months.. Two groups of children undergoing inpatient surgery were enrolled. In a randomised fashion, children received a single dose of oxycodone 0.2 mg/kg buccally (n = 15) or sublingually (n = 15). Regular blood samples were collected for up to 12 hours, and plasma was analysed for oxycodone, oxymorphone and noroxycodone using gas chromatography-mass spectrometry.. Bioavailability was similar after administration at the two instillation sites. The area under the plasma concentration-time curve from time zero extrapolated to infinity (AUCinfinity) was 2400-8000 ng x min/mL (median 4200 ng x min/mL) in the buccal group and 2700-7900 ng x min/mL (median 5500 ng x min/mL) in the sublingual group. After buccal administration, maximum plasma concentration (Cmax) was 5.4-39 ng/mL (16 ng/mL) after buccal and 5.5-42 ng/mL (22 ng/mL) after sublingual administration. Twelve of the 15 children in both groups reached the oxycodone analgesic concentration of 12 ng/mL, which was sustained for 43-209 minutes (median 160 minutes) in the children with buccal oxycodone and for 32-262 minutes (median 175 minutes) in the children with sublingual oxycodone. The terminal elimination half-lives were closely similar in the two groups: 104-251 minutes (median 140 minutes) in the buccal group and 110-190 minutes (150 minutes) in the sublingual group.. The results of this study show that in young children the absorption of oxycodone is similar after buccal and sublingual instillation.

Topics: Administration, Buccal; Administration, Sublingual; Analgesics, Opioid; Area Under Curve; Child; Child, Preschool; Female; Gas Chromatography-Mass Spectrometry; Half-Life; Humans; Indicators and Reagents; Infant; Male; Morphinans; Oxycodone; Oxymorphone

Thirty patients with cancer pain completed a double-blind crossover study comparing controlled-release (CR) and immediate-release (IR) oxycodone. In open-label titration (2 to 21 days), these patients were stabilized on IR oxycodone qid. They were then randomized to double-blind treatment with CR oxycodone q12h or IR oxycodone qid for 3 to 7 days followed by crossover at the same daily dose. Mean (+/- SD) pain intensity (0 = none to 10 = severe) decreased from a baseline of 6.0 +/- 2.2 to 2.7 +/- 1.1 after titration with IR oxycodone dosed qid. Pain intensity remained stable throughout double-blind treatment: 2.7 +/- 1.9 with CR oxycodone and 2.8 +/- 1.9 with IR oxycodone. Acceptability of therapy and pain scores correlated with plasma oxycodone concentrations for each interval and were similar for both medications (IR and CR oxycodone). Adverse events were similar for both formulations. Following repeat dosing under double-blind conditions, oral CR oxycodone administered q12h provided analgesia comparable to IR oxycodone given qid.

Topics: Administration, Oral; Adult; Aged; Aged, 80 and over; Analgesics, Opioid; Biological Availability; Chronic Disease; Cross-Over Studies; Delayed-Action Preparations; Dose-Response Relationship, Drug; Double-Blind Method; Drug Administration Schedule; Female; Humans; Male; Middle Aged; Morphinans; Neoplasms; Oxycodone; Oxymorphone; Pain; Pain Measurement; Therapeutic Equivalency; Vomiting

To determine the pharmacokinetics of oxycodone and the excretion of oxycodone and its metabolites noroxycodone and oxymorphone in uremic patients undergoing renal transplantation.. Open study of the pharmacokinetics and excretion of oxycodone.. IV Department of Surgery, Helsinki University Central Hospital.. 10 uremic patients undergoing renal transplantation and 10 ASA status I patients undergoing general surgery.. Intravenous (IV) oxycodone chloride 0.07 mg/kg was administered 30 minutes before induction of standardized anesthesia. Sampling of blood and urine was conducted for 24 hours.. The concentrations of oxycodone and noroxycodone in plasma and the 24 hour urine recoveries of the conjugated and unconjugated forms of oxycodone, noroxycodone, and oxymorphone were measured. Mean elimination half-life was prolonged in uremic patients due to increased volume of distribution and reduced clearance. Interindividual variation was very great. Plasma concentrations of noroxycodone were higher in uremic patients. Significantly smaller quantities of free oxycodone and noroxycodone and both free and conjugated oxymorphone were excreted in the urine in the uremic than in the control patients.. Elimination of oxycodone is impaired in end-stage renal failure.

Topics: Adult; Analgesics, Opioid; Biotransformation; Female; Half-Life; Humans; Injections, Intravenous; Kidney Transplantation; Male; Morphinans; Oxycodone; Oxymorphone; Uremia

1. The pharmacokinetics and metabolism of oxycodone were studied in nine healthy young volunteers in a cross-over study. Each subject received oxycodone chloride once intramuscularly (0.14 mg kg-1) and twice orally (0.28 mg kg-1) at intervals of 2 weeks. A double-blind randomized pretreatment with amitriptyline (10-50 mg a day) or placebo was given prior to oral oxycodone. 2. The concentrations of oxycodone, noroxycodone and oxymorphone in plasma and the 24 h urine recoveries of their conjugated and unconjugated forms were measured by gas chromatography. 3. No differences were found between treatments in mean Cmax and AUC values of oxycodone which varied from 34 to 38 ng ml-1 and from 208 to 245 ng ml-1 h, respectively. The median tmax of oxycodone was 1 h in all groups. The bioavailability of oral relative to i.m. oxycodone was 60%. The mean renal clearance of oxycodone was 0.07-0.08 l min-1. The kinetics of oxycodone were unaffected by amitriptyline. 4. The mean ratio of the AUC(0.24 h) values of unconjugated noroxycodone to oxycodone was 0.45 after i.m. oxycodone and 0.6-0.8 after oral oxycodone. Plasma oxymorphone concentrations were below the limit of the assay. Eight to 14% of the dose of oxycodone was excreted in the urine as unconjugated and conjugated oxycodone over 24 h. Oxymorphone was excreted mainly as a conjugate whereas noroxycodone was recovered mostly in an unconjugated form.

Topics: Administration, Oral; Adult; Amitriptyline; Chromatography, Gas; Double-Blind Method; Female; Humans; Injections, Intramuscular; Male; Morphinans; Oxycodone; Oxymorphone; Placebos; Reference Values

A range of opioids are commonly prescribed to manage chronic pain, but individual patient responses vary greatly, especially in older populations. One source of that variability are differences in absorption, metabolism and excretion, i.e. pharmacokinetics. Blood, plasma and serum concentrations of opioids allow that variability to be quantified and may be used to optimise opioid dosing. As an aid to that process, there is an unmet need to rapidly quantify several opioids and their metabolites in a single analytical method.. To develop a liquid chromatography-tandem mass spectrometry (LC-MS/MS) method for simultaneous quantification of tramadol, oxycodone, fentanyl and their major metabolites in various human matrices.. Sample preparation involved adding three deuterated internal standards followed by protein precipitation with 100 % acetonitrile, evaporation and reconstitution. Separation of analytes via LC was achieved on a reversed phase column via binary gradient elution using 0.005 % formic acid in water and 100 % acetonitrile as mobile phases. Analytes were detected via MS/MS with multiple reaction monitoring (MRM).. The method was accurate with the inter-day and intra-day accuracy of quality control samples (QCs) below 15 %. It was also precise with inter-day and intra-day coefficient of variation below 15 %. The lower limit of quantification (LLOQ) was 0.2 ng/mL for all analytes except tramadol and its metabolites, where the LLOQ was 10 ng/mL. Recovery was greater than 88 % for all analytes, except for O-desmethyltramadol (81 %). Analytes were stable over four freeze-thaw cycles, for 24 h on the bench top and for 24 h post-preparation. The inter- and intra-day variability of concentrations determined in blood and plasma were within 84-124%, whereas the inter- and intra-day variability for blood samples prepared using volumetric absorptive micro-sampling (VAMS) compared to those prepared from whole blood ranged between 83-122%.. A LC-MS/MS method is described that is able to accurately and precisely quantify a number of commonly prescribed opioids and their major metabolites in plasma and whole blood, including whole blood collected using VAMS.

Topics: Aged; Chromatography, Liquid; Fentanyl; Humans; Morphinans; Oxycodone; Oxymorphone; Reproducibility of Results; Tandem Mass Spectrometry; Tramadol

Oxycodone is used as a potent analgesic medication. Oxycodone is extensively metabolized. To fully describe its metabolism, the oxygenation of oxycodone to oxycodone N-oxide was investigated in hepatic preparations. The hypothesis tested was that oxycodone

Topics: Analgesics, Opioid; Animals; Cytochrome P-450 Enzyme System; Female; Hemoglobins; Humans; Male; Mixed Function Oxygenases; Morphinans; NADP; Oxides; Oxycodone; Oxymorphone; Rats

Oxycodone is a widely prescribed, full agonist opioid analgesic. As such, it is used clinically to treat different kinds of painful conditions, with a relatively high potential for doping practices in athletes. In this paper, different classic and innovative miniaturised matrices from blood and urine have been studied and compared, to evaluate their relative merits and drawbacks within therapeutic drug monitoring (TDM) and to implement new protocols for anti-doping analysis. Plasma, dried blood spots (DBS) and dried plasma spots (DPS) have been studied for TDM purposes, while urine, dried urine spots (DUS) and volumetric absorptive microsamples (VAMS) from urine for anti-doping. These sampling techniques were coupled to an original bioanalytical method based on liquid chromatography-tandem mass spectrometry (LC-MS/MS) for the evaluation and monitoring of the levels of oxycodone and its major metabolites (noroxycodone and oxymorphone) in patients under pain management and in athletes. The method was validated according to international guidelines, with good results in terms of precision, extraction yield and accuracy for all considered micromatrices. Thus, the proposed sampling, pre-treatment and analysis are attractive strategies for oxycodone determination in human blood and urine, with advanced options for application to derived micromatrices. Microsampling procedures have significant advantages over classic biological matrices like simplified sampling, storage and processing, but also in terms of precision (<9.0% for DBS, <7.7% for DPS, <7.1% for DUS, <5.3% for VAMS) and accuracy (>73% for DBS, >78% for DPS, >74% for DUS, >78% for VAMS). As regards extraction yield, traditional and miniaturised sampling approaches are comparable (>67% for DBS, >74% for DPS, >75% for DUS, >75% for VAMS). All dried matrices have very low volumes, leading to a significant advantage in terms of analysis feasibility. On the other hand, this also leads to a corresponding decrease in the overall sensitivity.

Topics: Blood Specimen Collection; Body Fluids; Chromatography, Liquid; Doping in Sports; Dried Blood Spot Testing; Drug Monitoring; Humans; Miniaturization; Morphinans; Oxycodone; Oxymorphone; Plasma; Specimen Handling; Tandem Mass Spectrometry; Urine

Opioids are the preferred analgesic drugs to treat severe chronic pain conditions among dialysis patients; however, knowledge about their dialyzability features is limited. Oxycodone is increasingly used for the treatment of chronic pain conditions as oral controlled release (CR) tablets; however, evidence about this drug and its metabolites' dialyzability is lacking.. We assessed, during 4-hour dialysis sessions, the effect of standard hemodialysis (HD) and online hemodiafiltration (HDF) methods on the plasma concentration of oxycodone and its metabolites in n = 20 chronic pain patients with end-stage renal disease who were stably treated with oral CR oxycodone. Chromatographic techniques were used to evaluate the studied compounds' plasma concentrations at three different time points during dialysis.. Mean plasma concentrations of oxycodone and noroxycodone in the sample showed an overall reduction trend over time, but it was less enhanced for noroxycodone. Mean reduction in oxycodone and noroxycodone arterial concentrations was significant and higher with HDF (54% and 27%, respectively) than with HD (22% and 17%, respectively). Analysis of the regression of these compounds' clearance on their increasing arterial concentration showed a more stable and linear clearance prediction with HDF (roughly 85 mL/min); with HD, for increasing arterial concentration, clearance of oxycodone decreased while noroxycodone clearance increased.. While no oxymorphone or noroxymorphone metabolites were detected, limited dialyzability of oxycodone and noroxycodone was documented along with insignificant postdialysis pain increment. This evidence will contribute toward considerations as to the safety of the use of oxycodone in dialysis patients in the future.

Topics: Adult; Analgesics, Opioid; Chronic Disease; Chronic Pain; Female; Humans; Kidney Failure, Chronic; Male; Middle Aged; Morphinans; Oxycodone; Oxymorphone; Renal Dialysis

Oxycodone is a narcotic drug widely used to alleviate moderate and severe acute and chronic pain. Variability in analgesic efficacy could be explained by inter-subject variations in plasma concentrations of parent drug and its active metabolite, oxymorphone. To evaluate patient compliance and to set up therapeutic drug monitoring (TDM), an ultra-high-performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS) assay was developed and validated for the parent drug and its major metabolites noroxycodone and oxymorphone.. Extraction of analytes from plasma and urine samples was obtained by simple liquid-liquid extraction. The chromatographic separation was achieved with a reversed phase column using a linear gradient elution with two solvents: acetic acid 1% in water and methanol. The separated analytes were detected with a triple quadrupole mass spectrometer operated in multiple reaction monitoring (MRM) mode via positive electrospray ionization (ESI).. Separation of analytes was obtained in less than 5 min. Linear calibration curves for all the analytes under investigation in urine and plasma samples showed determination coefficients (r2) equal or higher than 0.990. Mean absolute analytical recoveries were always above 86%. Intra- and inter-assay precision (measured as coefficient of variation, CV%) and accuracy (measured as % error) values were always better than 13%. Limit of detection at 0.06 and 0.15 ng/mL and limit of quantification at 0.2 and 0.5 ng/mL for plasma and urine samples, respectively, were adequate for the purpose of the present study.. Rapid extraction, identification and quantification of oxycodone and its metabolites both in urine and plasma by UHPLC-MS/MS assay was tested for its feasibility in clinical samples and provided excellent results for rapid and effective drug testing in patients under oxycodone treatment.

Topics: Aged; Aged, 80 and over; Chromatography, High Pressure Liquid; Female; Humans; Male; Middle Aged; Morphinans; Oxycodone; Oxymorphone; Tandem Mass Spectrometry

Oxycodone is an opioid agonist largely prescribed for the treatment of moderate to severe pain. Variability in analgesic efficacy could be explained by inter-subject variations in plasma levels of parent drug and its active metabolite, oxymorphone. For this purpose it is necessary to develop and validate a sensitive and selective analytical method for the quantification of oxycodone and its major metabolites, noroxycodone and oxymorphone, in human plasma. The analytical method consisted of a liquid-liquid extraction procedure followed by a high performance liquid chromatography with heated assisted electrospray ionization mass spectrometry (HPLC-HESI-MS/MS). The chromatographic separation was achieved using gradient elution with a mobile phase consisting of ethanol and 10mM ammonium acetate on a Synergi MAX-RP analytical column (150×2mm, 4μm) protected by a security guard cartridge (C12 4×2mm) at a flow rate of 300μL/min.The calibration functions are linear in the range of 300-50,000pg/mL for oxycodone and noroxycodone and 50 to 10 000pg/mL for oxymorphone. Intra- and inter-day relative standard deviations are less than 5.5% and 6.4%, respectively for all analytes. The limit of detection was 30pg/mL for all analytes. We introduce a new HPLC-HESI-MS/MS sensitive and specific analytical method capable to simultaneously quantify oxycodone, noroxycodone and oxymorphone, in human plasma, and suitable for the conduct of pharmacokinetic studies after a single dose administration of the parent compound.

Topics: Chromatography, Liquid; Humans; Limit of Detection; Morphinans; Oxycodone; Oxymorphone; Reproducibility of Results; Tandem Mass Spectrometry

Oxycodone is an opioid analgesic metabolized to oxymorphone and noroxycodone by cytochrome P450 (CYP) 2D6 and 3A4/5, respectively. This was a retrospective study to evaluate sex, age, urinary pH and concurrent medication use on oxycodone, oxymorphone and noroxycodone distributions. Urine specimens obtained from patients on chronic opioid therapy were analyzed by LC-MS-MS. There were 108,923 specimens from a subject's first or single visit, who were at least 18 years of age, and had documented physician-reported oxycodone use. The majority of specimens had detectable oxycodone urine concentrations (n = 106,852) resulting in oxycodone mole fractions (arithmetic mean ± SD) of 0.44 ± 0.27. Ninety-eight percent (n = 106,229) and 49% (n = 53,394) had detectable oxymorphone and noroxycodone, respectively. Oxycodone and oxymorphone mole fractions were lower in women compared with men (P < 0.0001). Mean ± SD age was 49.1 ± 12.9 years. Noroxycodone mole fractions were highest in the 65 years and older age group. Concurrent use of a CYP2D6 inhibitor, but not a CYP3A4/5 inhibitor, altered oxycodone and oxymorphone mole fractions. Dual inhibition of CYP2D6 and CYP3A4/5 did not result in a statistical difference upon comparison with CYP2D6 inhibitor or CYP3A4/5 inhibitor use. Patient factors affect oxycodone and metabolite mole fractions and suggest increased awareness of each contribution when attempting to monitor therapy with urine drug testing.

Topics: Adolescent; Adult; Age Factors; Aged; Analgesics, Opioid; Chromatography, Liquid; Cytochrome P-450 CYP2D6; Cytochrome P-450 CYP2D6 Inhibitors; Cytochrome P-450 CYP3A; Cytochrome P-450 CYP3A Inhibitors; Drug Interactions; Female; Humans; Hydrogen-Ion Concentration; Male; Middle Aged; Morphinans; Oxycodone; Oxymorphone; Pain; Retrospective Studies; Sex Factors; Specimen Handling; Tandem Mass Spectrometry; Young Adult

The aim of this study is to evaluate the pharmacokinetic profile of oxycodone and three of its metabolites, noroxycodone, oxymorphone and noroxymorphone after intravenous administration in Chinese patients with pain.. Forty-two subjects were assigned to receive intravenous administration of oxycodone hydrochloride of 2.5, 5 or 10 mg. Plasma and urine samples were collected for up to 24 h after intravenous administration of oxycodone hydrochloride.. Pharmacokinetic parameters showed that mean values of C(max), AUC(0-t) and AUC(0-∞) of oxycodone were dose dependent, whereas Tmax and t(1/2) were not. The mean AUC(0-t) ratio of noroxycodone to oxycodone ranged from 0.35 to 0.42 over three doses, and those of noroxymorphone, or oxymorphone, to oxycodone were ranging of 0.06-0.08 and 0.007-0.008, respectively. Oxycodone and its three metabolites were excreted from urine. Approximately 10% of unchanged oxycodone was recovered in 24 h. Most adverse events (AEs) reported were mild to moderate. The frequently occurred AEs were dizziness, nausea, vomiting, drowsiness and fatigue. No dose-related AEs were found.. Our pharmacokinetics of oxycodone injection in Chinese patients with pain strongly support continued development of oxycodone as an effective analgesic drug in China.

Topics: Adult; Analgesics, Opioid; Area Under Curve; Female; Humans; Injections, Intravenous; Male; Middle Aged; Morphinans; Oxycodone; Oxymorphone; Pain

The impact of polymorphic cytochrome P450 CYP2D6 enzyme on oxycodone's metabolism and clinical efficacy is currently being discussed. However, there are only spare data from postoperative settings. The hypothesis of this study is that genotype dependent CYP2D6 activity influences plasma concentrations of oxycodone and its metabolites and impacts analgesic consumption.. Patients received oxycodone 0.05 mg/kg before emerging from anesthesia and patient-controlled analgesia (PCA) for the subsequent 48 postoperative hours. Blood samples were drawn at 30, 90 and 180 minutes after the initial oxycodone dose. Plasma concentrations of oxycodone and its metabolites oxymorphone, noroxycodone and noroxymorphone were analyzed by liquid chromatography-mass spectrometry with electrospray ionization. CYP2D6 genotyping was performed and 121 patients were allocated to the following genotype groups: PM (poor metabolizer: no functionally active CYP2D6 allele), HZ/IM (heterozygous subjects, intermediate metabolizers with decreased CYP2D6 activity), EM (extensive metabolizers, normal CYP2D6 activity) and UM (ultrarapid metabolizers, increased CYP2D6 activity). Primary endpoint was the genotype dependent metabolite ratio of plasma concentrations oxymorphone/oxycodone. Secondary endpoint was the genotype dependent analgesic consumption with calculation of equianalgesic doses compared to the standard non-CYP dependent opioid piritramide.. Metabolism differed between CYP2D6 genotypes. Mean (95%-CI) oxymophone/oxycodone ratios were 0.10 (0.02/0.19), 0.13 (0.11/0.16), 0.18 (0.16/0.20) and 0.28 (0.07/0.49) in PM, HZ/IM, EM and UM, respectively (p = 0.005). Oxycodone consumption up to the 12(th) hour was highest in PM (p = 0.005), resulting in lowest equianalgesic doses of piritramide versus oxycodone for PM (1.6 (1.4/1.8); EM and UM 2.2 (2.1/2.3); p<0.001). Pain scores did not differ between genotypes.. In this postoperative setting, the number of functionally active CYP2D6 alleles had an impact on oxycodone metabolism. The genotype also impacted analgesic consumption, thereby causing variation of equianalgesic doses piritramide : oxycodone. Different analgesic needs by genotypes were met by PCA technology in this postoperative cohort.

Topics: Aged; Analgesics, Opioid; Cytochrome P-450 CYP2D6; Cytochrome P-450 CYP3A; Female; Genotype; Humans; Male; Middle Aged; Morphinans; Oxycodone; Oxymorphone; Spectrometry, Mass, Electrospray Ionization

The ongoing epidemic of prescription opioid abuse in the United States has prompted interest in semi-synthetic opioids in the federal workplace drug testing program. This study characterized the metabolism and disposition of oxycodone (OC) in human urine. Twelve healthy adults were administered a single oral 20 mg dose of OC in a controlled clinical setting. Urine specimens were collected at timed intervals up to 52 h and analyzed by liquid chromatography-tandem mass spectrometry (limit of quantitation: 50 ng/mL) for OC, oxymorphone (OM), noroxycodone (NOC) and noroxymorphone (NOM) with and without enzymatic hydrolysis. OC and NOC appeared in urine within 2 h, followed by OM and NOM. Peak concentrations of OC and metabolites occurred between 3 and 19 h. Mean peak concentrations in hydrolyzed urine were in the following order: NOC > OC > OM > NOM. Only OM appeared to be excreted extensively as a conjugated metabolite. OC concentrations declined more quickly than NOC and OM. At a cutoff concentration of 50 ng/mL, detection times were approximately 30 h for OC and 40 h for NOC and OM. Some specimens did not contain OC, but most contained NOC, thereby facilitating interpretation that OC was the administered drug; however, five specimens contained only OM. These data provide information that should facilitate the selection of appropriate test parameters for OC in urine and assist in the interpretation of test results.

Topics: Adult; Analgesics, Opioid; Chromatography, High Pressure Liquid; Employment; Female; Humans; Male; Morphinans; Oxycodone; Oxymorphone; Substance Abuse Detection; Tandem Mass Spectrometry; Time Factors; Workplace; Young Adult

Urine drug testing of pain patients provides objective information to health specialists regarding patient compliance, diversion, and concurrent illicit drug use. Interpretation of urine test results for semi-synthetic opiates can be difficult because of complex biotransformations of parent drug to metabolites that are also available commercially and may be abused. Normetabolites such as norcodeine, norhydrocodone and noroxycodone are unique metabolites that are not available commercially. Consequently, detection of normetabolite in specimens not containing parent drug, provides conclusive evidence that the parent drug was consumed. The goal of this study was to evaluate the prevalence and patterns of the three normetabolites, norcodeine, norhydrocodone and noroxycodone, in urine specimens of pain patients treated with opiates. Urine specimens were hydrolyzed with beta-glucuronidase and analyzed by a validated liquid chromatography tandem mass spectrometry (LC/MS/MS) assay for the presence of codeine, norcodeine, morphine, hydrocodone, norhydrocodone, hydromorphone, dihydrocodeine, oxycodone, noroxycodone, and oxymorphone. The limit of quantitation (LOQ) for these analytes was 50ng/mL. The study was approved by an Institutional Review Board. Of the total specimens (N=2654) tested, 71.4% (N=1895) were positive (>or=LOQ) for one or more of the analytes. The prevalence (%) of positive results for codeine, hydrocodone and oxycodone was 1.2%, 26.1%, and 36.2%, respectively, and the prevalence of norcodeine, norhydrocodone and noroxycodone was 0.5%, 22.1%, and 31.3%, respectively. For specimens containing normetabolite, the prevalence of norcodeine, norhydrocodone and noroxycodone in the absence of parent drug was 8.6%, 7.8% and 9.4%, respectively. From one-third to two-thirds of these specimens also did not contain other metabolites that could have originated from the parent drug. Consequently, the authors conclude that inclusion of norcodeine, norhydrocodone and noroxycodone is useful in interpretation of opiate drug source and reduces potential false negatives that would occur without tests for these unique metabolites.

Topics: Analgesics, Opioid; Chromatography, Liquid; Codeine; False Negative Reactions; Forensic Toxicology; Humans; Hydrocodone; Medication Adherence; Morphinans; Oxycodone; Oxymorphone; Pain; Tandem Mass Spectrometry

The aim of this study was to investigate the effects of the cytochrome P450 3A4 (CYP34A) inhibitor itraconazole on the pharmacokinetics and pharmacodynamics of orally and intravenously administered oxycodone.. Twelve healthy subjects were administered 200 mg itraconazole or placebo orally for 5 days in a four-session paired cross-over study. On day 4, oxycodone was administered intravenously (0.1 mg/kg) in the first part of the study and orally (10 mg) in the second part. Plasma concentrations of oxycodone and its oxidative metabolites were measured for 48 h, and pharmacodynamic effects were evaluated.. Itraconazole decreased plasma clearance (Cl) and increased the area under the plasma concentration-time curve (AUC0-infinity) of intravenous oxycodone by 32 and 51%, respectively (P<0.001) and increased the AUC(0-infinity) of orally administrated oxycodone by 144% (P<0.001). Most of the pharmacokinetic changes in oral oxycodone were seen in the elimination phase, with modest effects by itraconazole on its peak concentration, which was increased by 45% (P=0.009). The AUC(0-48) of noroxycodone was decreased by 49% (P<0.001) and that of oxymorphone was increased by 359% (P<0.001) after the administration of oral oxycodone. The pharmacologic effects of oxycodone were enhanced by itraconazole only modestly.. Itraconazole increased the exposure to oxycodone by inhibiting its CYP3A4-mediated N-demethylation. The clinical use of itraconazole in patients receiving multiple doses of oxycodone for pain relief may increase the risk of opioid-associated adverse effects.

Topics: Analgesics, Opioid; Area Under Curve; Cross-Over Studies; Cytochrome P-450 CYP3A; Cytochrome P-450 CYP3A Inhibitors; Humans; Injections, Intravenous; Itraconazole; Morphinans; Oxidation-Reduction; Oxycodone; Oxymorphone

We present herein a sensitive and selective assay for the determination of oxycodone and its main metabolites, oxymorphone, noroxycodone and noroxymorphone in human plasma, using column-switching and liquid chromatography coupled to tandem mass spectrometry (LC-MS/MS). Sample preparation comprised protein precipitation with perchloric acid. After neutralization, the supernatant was injected without any evaporation step onto a polymeric, pH-resistant cartridge (HySphere Resin GP 10-12 microm) for sample clean-up (Prospekt II). The latter operation was achieved by using alkaline conditions to ensure retention of analytes and methanol for matrix interference removal. More than two hundred plasma samples could be analyzed with a single cartridge. Analytes were desorbed in the backflush mode and were separated on a conventional reversed phase column (XTerra MS 4.6 x 50 mm, 3.5 microm), using an acidic mobile phase (i.e. containing 0.1% of formic acid). Mass spectrometric detection was achieved with a 4000 Q TRAP equipped with an atmospheric pressure chemical ionization (APCI) source, in positive ionization mode, operated in the selected reaction monitoring mode (SRM). Starting from a plasma volume of 250 microl, quantification ranges were 25-10,000 pg/ml for OXM and NOXM and 50-10,000 pg/ml for OXC and NOXC. Accuracy was found to be within 98% and 108% and precision better than 7%. Replicate determination of incurred or study samples ensured the method to be reproducible and usable for clinical studies.

Topics: Chromatography, Liquid; Humans; Hydrogen-Ion Concentration; Least-Squares Analysis; Morphinans; Oxycodone; Oxymorphone; Perchlorates; Reproducibility of Results; Sensitivity and Specificity

A sensitive and specific liquid chromatography-tandem mass spectrometry (LC-MS/MS) method was developed and validated for the quantification of oxycodone, noroxycodone, oxymorphone, and noroxymorphone. Following solid-phase extraction, the analytes were separated on a reverse-phase column by gradient elution and analyzed by MS/MS. The analytes were found to be stable in plasma for at least three freeze-thaw cycles and 5 hours at room temperature, and also in the reconstitution solution at 8 degrees C for at least 48 hours. The lower limits of quantification were 0.1 ng/mL for oxycodone and oxymorphone and 0.25 ng/mL for noroxycodone and noroxymorphone. All calibration curves were linear up to 100 ng/mL. The extraction recoveries were more than 85%, the intraday and interday coefficients of variation were <15%, and the accuracy was >90% for all analytes at relevant plasma concentrations. The method has been used in the therapeutic drug monitoring of more than 1000 clinical plasma samples. About 50 concomitantly used drugs were tested for possible ion suppression and found not to interfere with the method. In conclusion, this method is suitable for pharmacokinetic studies in patients and healthy volunteers, and it can be applied to therapeutic monitoring of oxycodone.

Topics: Analgesics, Opioid; Chromatography, High Pressure Liquid; Humans; Indicators and Reagents; Morphinans; Oxycodone; Oxymorphone; Reference Standards; Reproducibility of Results; Spectrometry, Mass, Electrospray Ionization; Spectrophotometry, Ultraviolet

1. The pharmacokinetics and oxidative metabolism of oxycodone were investigated following intravenous and oral administration in male and female Sprague-Dawley (SD) rats. 2. High-performance liquid chromatography (HPLC)-electrospray ionization (ESI)-tandem mass spectrometry (MS-MS) was used to quantify plasma concentrations of oxycodone and its oxidative metabolites noroxycodone and oxymorphone following administration of single bolus intravenous (5 mg/kg) and oral (10 mg/kg) doses of oxycodone. 3. The mean (+/-SEM) clearance of intravenous oxycodone was significantly higher in male than female SD rats (4.9 +/- 0.3 vs 3.1 +/- 0.3 L/h per kg, respectively; P < 0.01). Mean areas under the plasma concentration versus time curves (AUC) for oxycodone were significantly higher in female than male SD rats following intravenous (approximately 1.6-fold; P < 0.01) and oral (approximately sevenfold; P < 0.005) administration. 4. The oral bioavailability of oxycodone was low (at 1.2 and 5.0%, respectively) in male and female SD rats, a finding consistent with high first-pass metabolism. Noroxycodone : oxycodone AUC ratios were significantly higher in male than female SD rats after intravenous (approximately 2.4-fold; P < 0.005) and oral (approximately 12-fold; P < 0.005) administration. 5. Circulating oxymorphone concentrations remained very low following both routes of administration. Noroxycodone : oxymorphone AUC ratios were greater in male than female SD rats after intravenous (approximately 13- and fivefold, respectively) and oral (approximately 90- and sixfold, respectively) administration. 6. Sex differences were apparent in the pharmacokinetics, oxidative metabolism and oral bioavailability of oxycodone. Systemic exposure to oxycodone was greater in female compared with male SD rats, whereas systemic exposure to metabolically derived noroxycodone was higher in male than female SD rats. 7. Oral administration of oxycodone to the SD rat is a poor model of the human for the study of the pharmacodynamic effects of oxycodone.

Topics: Administration, Oral; Analgesics, Opioid; Animals; Biological Availability; Female; Male; Morphinans; Oxidation-Reduction; Oxycodone; Oxymorphone; Rats; Rats, Sprague-Dawley; Sex Characteristics

A method was developed for quantification of oxycodone, noroxycodone, and oxymorphone in small volumes (50 microl) of rat plasma by high-performance liquid chromatography-electrospray ionization-tandem mass spectrometry using turbo ion-spray. Deuterated (d3) opioid analogues acted as internal standards. Sample preparation involved protein precipitation with acetonitrile, centrifugal evaporation, and reconstitution in mobile phase; analyte separation was performed on a C18 (5 microm, 2.1 mm x 50 mm) column using a linear gradient program. Lower limits of quantitation (ng/ml) and their between-day accuracy and precision were-oxycodone, 0.9 (-0.2 and 7.8%); noroxycodone, 1.0 (0.6 and 6.2%); oxymorphone 1.0 (-1.8 and 9.5%).

Topics: Analgesics, Opioid; Animals; Calibration; Chromatography, High Pressure Liquid; Injections, Intravenous; Male; Molecular Structure; Morphinans; Oxycodone; Oxymorphone; Rats; Rats, Sprague-Dawley; Reproducibility of Results; Spectrometry, Mass, Electrospray Ionization; Tandem Mass Spectrometry; Time Factors

The pharmacology of oxycodone is poorly understood despite its growing clinical use. The discrepancy between its good clinical effectiveness after systemic administration and the loss of potency after spinal administration led the authors to study the pharmacodynamic effects of oxycodone and its metabolites using in vivo and in vitro models in rats.. Male Sprague-Dawley rats were used in hot-plate, tail-flick, and paw-pressure tests to study the antinociceptive properties of morphine, oxycodone, and its metabolites oxymorphone and noroxycodone. Mu-opioid receptor agonist-stimulated GTPgamma[S] autoradiography was used to study G-protein activation induced by morphine, oxycodone, and oxymorphone in the rat brain and spinal cord. Spontaneous locomotor activity was measured to assess possible sedation or motor dysfunction. Naloxone and the selective kappa-opioid receptor antagonist nor-binaltorphimine were used to study the opioid receptor selectivity of the drugs.. Oxycodone showed lower efficacy and potency to stimulate GTPgamma[S] binding in the spinal cord and periaqueductal gray compared with morphine and oxymorphone. This could relate to the fact that oxycodone produced only weak naloxone-reversible antinociception after intrathecal administration. It also suggests that the metabolites may have a role in oxycodone-induced analgesia in rats. Intrathecal oxymorphone produced strong long-lasting antinociception, whereas noroxycodone produced antinociception with very high doses only. Subcutaneous administration of oxycodone and oxymorphone produced thermal and mechanical antinociception that was reversed by naloxone but not by nor-binaltorphimine. Oxymorphone was more potent than oxycodone, particularly in the hot-plate and paw-pressure tests.. The low intrathecal potency of oxycodone in rats seems be related to its low efficacy and potency to stimulate mu-opioid receptor activation in the spinal cord.

Topics: Algorithms; Analgesics, Opioid; Animals; Area Under Curve; Autoradiography; Dose-Response Relationship, Drug; GTP-Binding Proteins; Guanosine 5'-O-(3-Thiotriphosphate); Injections, Intravenous; Injections, Spinal; Male; Morphinans; Morphine; Motor Activity; Oxycodone; Oxymorphone; Pain Measurement; Rats; Rats, Sprague-Dawley; Receptors, Opioid, kappa; Receptors, Opioid, mu; Signal Transduction

The use of opioid analgesics in renal dysfunction is potentially problematic and many patients with end stage renal disease are unable to tolerate these medications. A greater understanding of the pharmacokinetics of opioid analgesics is vital in informing safe and effective practice. Using pharmacokinetic analysis, this case study demonstrates for the first time that oxycodone and its metabolites are removed by haemodialysis. As such, care should be taken when using oxycodone in patients undergoing haemodialysis.

Topics: Analgesics, Opioid; Female; Humans; Kidney Failure, Chronic; Middle Aged; Morphinans; Nephrectomy; Oxycodone; Oxymorphone; Renal Dialysis

Oxycodone undergoes N-demethylation to noroxycodone and O-demethylation to oxymorphone. The cytochrome P450 (P450) isoforms capable of mediating the oxidation of oxycodone to oxymorphone and noroxycodone were identified using a panel of recombinant human P450s. CYP3A4 and CYP3A5 displayed the highest activity for oxycodone N-demethylation; intrinsic clearance for CYP3A5 was slightly higher than that for CYP3A4. CYP2D6 had the highest activity for O-demethylation. Multienzyme, Michaelis-Menten kinetics were observed for both oxidative reactions in microsomes prepared from five human livers. Inhibition with ketoconazole showed that CYP3A is the high affinity enzyme for oxycodone N-demethylation; ketoconazole inhibited >90% of noroxycodone formation at low substrate concentrations. CYP3A-mediated noroxycodone formation exhibited a mean K(m) of 600 +/- 119 microM and a V(max) that ranged from 716 to 14523 pmol/mg/min. Contribution from the low affinity enzyme(s) did not exceed 8% of total intrinsic clearance for N-demethylation. Quinidine inhibition showed that CYP2D6 is the high affinity enzyme for O-demethylation with a mean K(m) of 130 +/- 33 microM and a V(max) that ranged from 89 to 356 pmol/mg/min. Activity of the low affinity enzyme(s) accounted for 10 to 26% of total intrinsic clearance for O-demethylation. On average, the total intrinsic clearance for noroxycodone formation was 8 times greater than that for oxymorphone formation across the five liver microsomal preparations (10.5 microl/min/mg versus 1.5 microl/min/mg). Experiments with human intestinal mucosal microsomes indicated lower N-demethylation activity (20-50%) compared with liver microsomes and negligible O-demethylation activity, which predict a minimal contribution of intestinal mucosa in the first-pass oxidative metabolism of oxycodone.

Topics: Aryl Hydrocarbon Hydroxylases; Biotransformation; Cytochrome P-450 CYP2D6; Cytochrome P-450 CYP3A; Cytochrome P-450 Enzyme System; DNA, Complementary; Humans; Intestinal Mucosa; Intestines; Ketoconazole; Kinetics; Metabolic Clearance Rate; Methylation; Microsomes; Microsomes, Liver; Molecular Structure; Morphinans; Oxidoreductases, N-Demethylating; Oxycodone; Oxymorphone; Protein Binding; Quinidine

Sensitive and reproducible methods for the determination of oxycodone, oxymorphone and noroxycodone in Ringer solution, rat plasma and rat brain tissue by liquid chromatography/mass spectrometry are described. Deuterated analogs of the substances were used as internal standards. Samples in Ringer solution were analyzed by direct injection of 10 microL Ringer solution diluted by an equal volume of water. The limit of quantification was 0.5 ng/mL and the method was linear in the range of 0.5-150 ng/mL for all substances. To analyze oxycodone and oxymorphone in rat plasma, 50 microL of plasma were precipitated with acetonitrile, and the supernatant was directly injected onto the column. To analyze oxycodone, oxymorphone and noroxycodone in rat plasma, 100 microL of rat plasma were subjected to a C18 solid-phase extraction (SPE) procedure, before reconstituting in mobile phase and injection onto the column. For both methods the limit of quantification in rat plasma was 0.5 ng/mL and the methods were linear in the range of 0.5-250 ng/mL for all substances. To analyze the content of oxycodone, oxymorphone and noroxycodone in rat brain tissue, 100 microL of the brain homogenate supernatant were subjected to a C18 SPE procedure. The limit of quantification of oxycodone was 20 ng/g brain, and for oxymorphone and noroxycodone 4 ng/g brain, and the method was linear in the range of 20-1000 ng/g brain for oxycodone and 4-1000 ng/g brain for oxymorphone and noroxycodone. All methods utilized a mobile phase of 5 mM ammonium acetate in 45% acetonitrile, and a SB-CN column was used for separation. The total run time of all methods was 9 min. The intra-day precision and accuracy were <11.3% and <+/-14.9%, respectively, and the inter-day precision and accuracy were <14.9% and <+/-6.5%, respectively, for all the concentrations and matrices described.

Topics: Analgesics, Opioid; Animals; Brain Chemistry; Chromatography, High Pressure Liquid; Injections, Intravenous; Isotonic Solutions; Morphinans; Oxycodone; Oxymorphone; Rats; Reproducibility of Results; Ringer's Solution; Spectrometry, Mass, Electrospray Ionization

Plasma concentrations of oxycodone, oxymorphone, and noroxycodone were determined after administration of 20 mg oral controlled-release oxycodone tablets to four subject groups: young (aged 21 to 45 years) men, elderly (aged 65 to 79 years) men, young women, and elderly women. Area under the oxycodone and noroxycodone concentration-time curve (AUC) values were comparable among the four groups. Compared with oxycodone, the oxymorphone AUC values were small, with significant differences between subject groups. AUC values were also calculated for the pharmacodynamic variable "drug effect," scored on a 100 mm visual analog scale. The two groups with the highest oxycodone AUC values (young and elderly women) had the lowest oxymorphone AUC values and the greatest drug effect AUC values. The two groups with the lowest oxycodone AUC values (young and elderly men) had the highest oxymorphone AUC values and the lowest drug effect AUC values. These results support oxycodone, and not oxymorphone, as being primarily responsible for pharmacodynamic and analgesic effects.

Topics: Administration, Oral; Adult; Aged; Analgesics, Opioid; Delayed-Action Preparations; Female; Humans; Male; Morphinans; Oxycodone; Oxymorphone; Reference Values