buprenorphine and thienorphine

Thienorphine hydrochloride is a new anti-relapse drug for opioid abusers that is currently in phase II clinical trial. In the present study, the antinociception, dependence, and signal transduction induced by thienorphine were examined. Thienorphine showed a potent antinociception effect in acetic acid-induced writhing test and formalin test. In the hot plate test and tail-flick test, thienorphine presented the typical partial opioid agonist character with a ceiling dose-response curve in addition to a bell-shaped curve. The hot plate test revealed that thienorphine induced approximately 50% of antinociception in μ receptor knockout (μ-KO) mice compared to wild-type controls (P < 0.05). The κ, δ selective antagonist nor-binaltorphimine (nor-BNI), and naltrindole decreased approximately 50-60% of theinorphine antinociception in μ-KO mice, respectively. The ORL1 receptor-selective antagonist J113397 did not affect theinorphine antinociception in μ-KO mice. Chronic treatment with thienorphine (1.5 mg/kg) induced some tolerance that was lower compared to buprenorphine or morphine addition. In contrast to buprenorphine or morphine, thienorphine did not lead to psychological dependence by conditioned place preference (CPP). The maximum inhibition of thienorphine on protein kinase A (PKA) activity was about 36%, 100%, 100%, and 12% in CHO-μ/κ/δ/ORL1-PKAcatEGFP cells, respectively. Similar results were observed in cyclic adenosine monophosphate (cAMP) accumulation inhibited by thienorphine in cells. Thienorphine significantly increased pERK1/2 in CHO-κ/δ-PKAcatEGFP cells. These results indicated that thienorphine induced analgesia through activation of κ- and δ-, partial activation of μ- opioid receptor without a bias between G-protein- and β-arrestin-mediated pathways. Thienorphine might be used for antinociception with minimal adverse effects.

Topics: Analgesics, Opioid; Animals; Brain; Buprenorphine; Cell Line, Tumor; Cyclic AMP; Female; Humans; Male; Mice; Mice, Knockout; Neurons; Nociception; Pain; Rats; Rats, Wistar; Receptors, Opioid, delta; Receptors, Opioid, kappa; Receptors, Opioid, mu

Poly (d,l-lactic-co-glycolide) nanoparticles (PLGA-NPs) have attracted considerable interest as new delivery vehicles for small molecules, with the potential to overcome issue such as poor drug solubility and cell permeability. However, their negative surface charge decreases bioavailability under oral administration. Recently, cationically modified PLGA-NPs has been introduced as novel carriers for oral delivery. In this study, our aim was to introduce and evaluate the physiochemical characteristics and bioadhesion of positively charged chitosan-coated PLGA-NPs (CS-PLGA-NPs), using thienorphine as a model drug. These results indicated that both CS-PLGA-NPs and PLGA-NPs had a narrow size distribution, averaging less than 130 nm. CS-PLGA-NPs was positively charged (+42.1 ± 0.4 mV), exhibiting the cationic nature of chitosan, whereas PLGA-NPs showed a negative surface charge (-2.01 ± 0.3 mV). CS-PLGA-NPs exhibited stronger bioadhesive potency than PLGA-NPs. Furthermore, the transport of thienorphine-CS-PLGA-NPs by Caco-2 cells was higher than thienorphine-PLGA-NPs or thienorphine solution. CS-PLGA-NPs were also found to significantly enhance cellular uptake compared with PLGA-NPs on Caco-2 cells. An evaluation of cytotoxicity showed no increase in toxicity in either kind of nanoparticles during the formulation process. The study proves that CS-PLGA-NPs can be used as a vector in oral drug delivery systems for thienorphine due to its positive surface charge and bioadhesive properties.

Topics: Administration, Oral; Animals; Biological Availability; Buprenorphine; Caco-2 Cells; Chemistry, Pharmaceutical; Chitosan; Drug Carriers; Drug Delivery Systems; Excipients; Humans; Lactic Acid; Male; Nanoparticles; Particle Size; Polyglycolic Acid; Polylactic Acid-Polyglycolic Acid Copolymer; Rats; Rats, Wistar

Opioid analgesics are widely used in moderate to severe pain including renal colic. Morphine is believed to cause spasm of ureter and affect the bladder contractions. Thienorphine is a partial opioid agonist that is a good candidate for the treatment of opioid dependence and pain. This study examined the effects of thienorphine on the guinea pig isolated ureter and bladder. The contractile amplitude of isolated ureter induced by KCl (40mM) was not influenced by thienorphine or buprenorphine, whereas morphine increased the amplitude of the isolated ureter. Thienorphine, buprenorphine or naloxone concentration-dependently antagonized the isolated ureter contraction induced by morphine. Thienorphine (1.0-32.0μM) or buprenorphine (1.0-32.0μM) had no effects on the spontaneous or acetylcholine (Ach) induced contractions of isolated bladder, but decreased the amplitude of the contractions of isolated bladder at 100μM concentration. Morphine (0.1-3.2mM) concentration dependently increased the spontaneous movement and Ach (1μM) induced contractions of isolated bladder. The mRNA levels of μ receptor in the ureter and bladder was as the same as that in the frontal cortex. In comparison, the mRNA levels of κ receptor, δ receptor and N/OFQ receptor was fewer than that in the frontal cortex. In summary, thienorphine has little influence on the guinea pig isolated ureter and bladder compared with morphine, which may result in a lack of adverse renal colic effects.

Topics: Analgesics; Animals; Buprenorphine; Female; Gene Expression Regulation; Guinea Pigs; Male; Muscle Contraction; Nociceptin Receptor; Potassium Chloride; Receptors, Opioid; RNA, Messenger; Ureter; Urinary Bladder

It is considered that a long-acting therapy would be advantageous in the treatment of addiction. In a search for novel buprenorphine analogues, thienorphine was demonstrated to be an extremely long-acting orally active partial opioid agonist. This study explored the mechanisms underlying the long-lasting effects of thienorphine.. The binding kinetics of [(3) H]thienorphine were measured in membrane preparations expressing cloned rat opioid receptors. Flow cytometric analysis was used to determine the effect of thienorphine on the surface opioid receptor number. The long-lasting effects of thienorphine were also confirmed at the tissue level and in vivo.. At 37°C, [(3) H]thienorphine showed rapid association with μ- and κ-opioid receptors, while its dissociation was sluggish and biphasic (K-1 = 0.21 min(-1) , K-2 = 0.0078 min(-1) for the μ-receptor; K-1 = 0.17 min(-1) , K-2 = 0.0042 min(-1) for the κ-receptor). Treatment with thienorphine for 24, 48, and 72 h downregulated surface μ-receptor in a dose- and time-dependent manner. The inhibitory effect of thienorphine on guinea pig ileum persisted for more than 120 min after prolonged washing. In vivo, thienorphine exhibited significant antagonism of morphine-induced antinociception for more than 7 days.. These results indicate that multiple factors, including persistent receptor occupation and enhanced receptor downregulation, may contribute to the long-lasting effects of thienorphine that would be beneficial for its application in addiction treatment.

Topics: Acetylcholine; Animals; Buprenorphine; Cell Line, Transformed; Disease Models, Animal; Dose-Response Relationship, Drug; Female; Guinea Pigs; Ileum; Male; Mice; Mice, Inbred Strains; Morphine Dependence; Muscle Contraction; Narcotic Antagonists; Protein Binding; Rats; Receptors, Opioid; Time Factors; Tritium

Opioid analgesics are widely believed to cause spasm of the bile duct sphincter and so impede bile flow. Thienorphine is a partial opioid agonist that is a good candidate for the treatment of opioid dependence; however, to date, no studies have reported the effects of thienorphine on the function of the biliary tract. This study examined the in vivo effects of thienorphine on the guinea pig isolated sphincter of Oddi, choledochus and gall bladder and on bile flow. The area under the curve (AUC) of isolated sphincter of Oddi was not influenced by thienorphine or buprenorphine, whereas morphine increased the AUC of the isolated sphincter of Oddi in a concentration-dependent manner. Thienorphine and buprenorphine concentration-dependently decreased the AUC of isolated choledochus, while morphine increased the AUC of isolated choledochus. Thienorphine had no effect on the contractile amplitude or basal tension of isolated gall bladder muscle strips. In contrast, buprenorphine and morphine increased the contractile basal tension of isolated gall bladder muscle strips in a concentration-dependent manner. Thienorphine (0.01-1.0mg/kg) had no significant inhibitory effect on bile flow. However, morphine (1.0-10mg/kg) and buprenorphine (1.0mg/kg) significantly inhibited bile flow. The maximum inhibition of bile flow by buprenorphine was 63.9±12.9% and by morphine was 74.1±11.3%. In summary, thienorphine has little influence on the guinea pig isolated sphincter of Oddi, choledochus and gall bladder or on bile flow, which may result in a lack of adverse biliary colic effects.

Topics: Animals; Bile; Buprenorphine; Common Bile Duct; Female; Gallbladder; Guinea Pigs; Male; Muscle Contraction; Sphincter of Oddi

The partial opioid agonist thienorphine is currently in Phase II clinical trials in China as a candidate drug for the treatment of opioid dependence. However, its effect on synaptic plasticity in the NAc (nucleus accumbens) remains unclear. In the present study, we measured structural parameters of the synaptic interface to investigate the effect of thienorphine, morphine or a combination of both on synaptic morphology in the NAc of rats. Expression of synaptophysin was also examined. Ultrastructural observation showed that synaptic alterations were less pronounced after chronic thienorphine administration than after chronic morphine administration. Animals that received thienorphine had thinner postsynaptic densities and shorter active zones in the NAc compared with those in the saline group, but the active zone was larger, and the cleft narrower, than those in the morphine group. Furthermore, synaptophysin expression in the NAc was significantly greater after chronic administration of thienorphine, morphine, or both, than after saline. These results identified interesting differences between thienorphine and morphine in their effects on synaptic structure and synaptophysin expression in the rat NAc. Further study is deserved to investigate thienorphine as a new treatment for opioid dependence.

Topics: Analgesics, Opioid; Animals; Buprenorphine; Male; Nucleus Accumbens; Rats; Rats, Wistar; Synapses; Synaptophysin

Opioid dependence is a serious worldwide health problem. Buprenorphine was used as an alternative to methadone for the treatment of opioid dependence, especially for pregnant women. Thienorphine was a partial opioid agonist with long-lasting antinociceptive effect and high oral bioavailability compared with its analogue buprenorphine. Till now, there was still no research about the effect of thienorphine on the isolated uterine muscles. This study examined the effects of thienorphine on the isolated rat oestrus and pregnant uterine strips. Area under the curve (AUC), amplitude and frequency were studied. Thienorphine induced a concentration-dependent decrease in the frequency and amplitude of the contraction on the isolated oestrus and pregnant uterine strips. Thienorphine exhibited less inhibition on the contractile amplitude of the isolated uterine strips from pregnant rats with the IC50 of 54.11 ± 7.41 μΜ, compared with buprenorphine (IC50, 19.42 ± 2.34 μΜ). In addition, thienorphine also exhibited less inhibition on the contractile frequency of the isolated uterine strips from pregnant rats, with the IC50 of 70.68 ± 12.44 μΜ, compared with buprenorphine (IC50, 19.20 ± 3.87 μΜ). On the isolated uterine muscle from pregnant rats, the AUC was decreased by thienorphine but was less potent than buprenorphine, the IC50 was 37.31 ± 7.43 μΜ for thienorphine and 13.52 ± 2.03 μΜ for buprenorphine. Thienorphine exhibited longer duration on the isolated rat pregnant uterine strips than buprenorphine. Thienorphine has less influence and longer duration on the isolated rat uterine muscles during pregnancy, which may be a new useful candidate for the opioid dependent pregnant women.

Topics: Analgesics, Opioid; Animals; Buprenorphine; Calcium Chloride; Female; In Vitro Techniques; Isometric Contraction; Opiate Substitution Treatment; Opioid-Related Disorders; Pregnancy; Rats; Rats, Sprague-Dawley; Receptors, Opioid; Uterine Contraction; Uterus

To evaluate the effect of thienorphine on small intestinal transit in vivo and on guinea-pig ileum (GPI) contraction in vitro.. The effects of thienorphine on intestinal transit were examined in mice and in isolated GPI. Buprenorphine and morphine served as controls. The distance traveled by the head of the charchol and the total length of the intestine were measured in vivo. Gastrointestinal transit was expressed as a percentage of the distance traveled by the head of the marker relative to the total length of the small intestine. The isolated GPI preparations were connected to an isotonic force transducer and equilibrated for at least 1 h before exposure to drugs. Acetylcholine was used for muscle stimulation.. Thienorphine (0.005-1.0 mg/kg, ig) or buprenorphine (0.005-1.0 mg/kg, sc) dose-dependently significantly inhibited gut transit compared with saline. Thienorphine inhibited gut transit less than buprenorphine. The maximum inhibition by thienorphine on the intestinal transit was 50%-60%, whereas the maximum inhibition by morphine on gut transit was about 100%. Thienorphine also exhibited less inhibition on acetylcholine-induced contraction of GPI, with a maximum inhibition of 65%, compared with 93% inhibition by buprenorphine and 100% inhibition by morphine. Thienorphine induced a concentration-dependent decrease in the basal tonus of spontaneous movement of the GPI, the effect of which was weaker than that with buprenorphine. The duration of the effect of thienorphine on the GPI was longer than that with buprenorphine.. Thienorphine had less influence, but a longer duration of action on GPI contraction and moderately inhibited intestinal transit.

Topics: Analgesics, Opioid; Animals; Buprenorphine; Cholinergic Agonists; Dose-Response Relationship, Drug; Gastrointestinal Transit; Guinea Pigs; Ileum; Male; Mice; Morphine; Muscle Contraction; Muscle, Smooth; Narcotic Antagonists; Time Factors

Thienorphine is a new, non-selective partial agonist of opioid receptors. In our previous study using microdialysis, thienorphine persistently increased the levels of 3,4-dihydroxyphenylacetic acid (DOPAC) and homovanillic acid (HVA) in the striatum of rats, without affecting the level of dopamine. This finding suggested that monoamine oxidase (MAO) activity in the striatum of rats increased by chronic thienorphine treatment. In the present study, we investigated whether chronic treatment of thienorphine affected MAO activity in the striatum of rats compared with morphine. Rats were treated subcutaneously (three times/day) with either saline (control), morphine, thienorphine, or a pre-treatment of thienorphine followed by morphine, for 3 or 5 continuous days. A 20-min naloxone challenge given to a sub-group of animals from each group occurred at the end of their 5-day treatment. The results showed that repeated administration of thienorphine significantly elevated MAO activity in the striatum, thus restoring MAO activity, which was inhibited by chronic morphine treatment. These results suggest that increased activity of MAO in the striatum may accelerate the metabolism of dopamine, leading to the elevations of DOPAC and HVA. Furthermore, these findings implicate the involvement of MAO in the pharmacological characteristics of thienorphine.

Topics: Analgesics, Opioid; Animals; Buprenorphine; Corpus Striatum; Dopamine; Dose-Response Relationship, Drug; Drug Partial Agonism; Injections, Subcutaneous; Male; Monoamine Oxidase; Morphine; Naloxone; Rats; Rats, Wistar; Receptors, Opioid; Time Factors; Up-Regulation

Thienorphine is a new nonselective partial agonist of opioid receptors, which is currently under a Phase II clinical trial in China as a new treatment for opioid dependence. In this study, we compared the effect of thienorphine with morphine on long-term potentiation (LTP) in the lateral perforant path (LPP)-granule cell synapse of the rat dentate gyrus (DG). Furthermore, the effect of thienorphine on the synaptic structure of the CA1 hippocampal region and the expression of synaptophysin was investigated. Results indicated interesting differences between thienorphine and morphine on the modulation of hippocampal synaptic plasticity. Chronic thienorphine treatment facilitated LTP in the LPP-DG cell synapses more than chronic morphine treatment. Morphometric measurement and analysis showed that chronic thienorphine administration decreased the length of the active zone and reduced the thickness of CA1 postsynaptic densities compared with the saline group (control), but were elevated compared with the morphine group. Furthermore, the expression of hippocampal synaptophysin was increased with chronic thienorphine administration but reduced with chronic morphine treatment. Taken together, our study clearly demonstrates that chronic thienorphine treatment enhances LTP, modulates hippocampal synaptic structure, and increases the expression of hippocampal synaptophysin. Therefore, further study is warranted to investigate thienorphine as a new treatment for opioid dependence.

Topics: Animals; Buprenorphine; CA1 Region, Hippocampal; Dentate Gyrus; Long-Term Potentiation; Male; Morphine; Narcotic Antagonists; Post-Synaptic Density; Rats; Rats, Wistar; Synaptophysin

Thienorphine has been demonstrated to be a potent, long-acting partial opioid agonist. It is being developed as a good candidate to treat opioid dependence. The thienorphine's glucuronide was detected after thienorphine was incubated with human liver microsomes (HLMs). Recombinant UGT isoforms screening experiment and enzyme kinetic study showed that UGT1A1 completely contributed to the glucuronidation of thienorphine. Among the tested UGT isoforms, UGT1A3 and UGT2B7 were inhibited by thienorphine, with other UGT isoforms negligibly influenced. The inhibition type is competitive, and inhibition kinetic parameters (K(i)) were 1.65 and 5.27 μM for UGT1A3 and UGT2B7, respectively. However, due to low plasma concentration of thienorphine, in vivo drug-drug interaction might not occur.

Topics: Analgesics, Opioid; Buprenorphine; Glucuronosyltransferase; Humans; Hymecromone; Isoenzymes; Kinetics; Microsomes, Liver

Thenorphine is a new potent long-acting partial opioid agonist. In present study, the effect of thienorphine on noradrenalin (NA) in the locus coeruleus (LC) and dopamine (DA) and its metabolites in the nucleus acumbens (NAc) and the striatum were examined in freely moving rats during acute and chronic thienorphine treatment followed by naloxone-precipitated withdrawal using the in vivo microdialysis technique. Acute thienorphine (1.0mg/kg, s.c.) treatment had no effect on the level of NA in the LC and the level of DA in the NAc and the striatum. Chronic thienorphine (1.0mg/kg, s.c.) third per day for continued 5 days treatment followed by naloxone-precipitated (5.0mg/kg, i.p.) had not alter the extracellular NA level in the LC and the extracellular level of DA in the NAc and the striatum, but significantly increased the level of DOPAC in the striatum. These changes are thought to reflect a direct effect of thienorphine on release of NA and DA. Thus thienorphine deserves further study as a new treatment for opioid dependence.

Topics: 3,4-Dihydroxyphenylacetic Acid; Analgesics, Opioid; Animals; Buprenorphine; Corpus Striatum; Dopamine; Locus Coeruleus; Male; Microdialysis; Naloxone; Norepinephrine; Nucleus Accumbens; Rats; Rats, Wistar; Substance Withdrawal Syndrome

Thienorphine hydrochloride (ThH) is a highly insoluble and readily metabolized partial-opioid agonist. It is used for the treatment of pain and heroin addiction. This study aimed to formulate and evaluate sublingual delivery systems containing ThH. Dimethyl-β-cyclodextrin (DM-β-CD) can enhance the solubility and permeability of hydrophobic drugs. In this paper, ThH cyclodextrin inclusion complexes were prepared and administrated sublingually with the objective of improving the drug's aqueous solubility, in vitro permeation rate, and in vivo absorption rate. The formulation was prepared with DM-β-CD using the freeze-dried method and characterized using phase solubility, differential scanning calorimetry (DSC), X-ray and NMR analyses. The results of each test indicated the formation of dynamic inclusion complexes between ThH and DM-β-CD. The inclusion complexes also showed significant increases in in vitro aqueous solubility and mucosal permeability. According to the pharmacokinetic study of the complex in rats, the AUC and C(max) values of the sublingual delivery group were 40 and 46 times higher than those of the gastrointestinal group, whereas t(max) was shorter, which proved that in vivo absorption and metabolism had been improved. It can therefore be concluded that the inclusion technology and sublingual delivery system were suitable for ThH development.

Topics: Administration, Sublingual; Animals; beta-Cyclodextrins; Buprenorphine; Calorimetry, Differential Scanning; Drug Delivery Systems; Intestinal Mucosa; Magnetic Resonance Spectroscopy; Molecular Conformation; Permeability; Rats; Rats, Wistar; Solubility; X-Ray Diffraction

To investigate possible pharmacological mechanisms underlying the antinociceptive effect of and tolerance to N-methyl-7α-[(R)-1-hydroxy-1-methyl-3-(thien-3-yl)-propyl]-6,14-endo-ethanotetrahydronororipavine (030418), a derivative of thienorphine.. The binding affinity and efficacy of 030418 were determined using receptor binding and guanosine 5'-O-(3-[(35)S]thio)triphosphate ([(35)S]GTPγS) assays in CHO-μ, CHO-κ, CHO-δ, and CHO-ORL1 cell membranes. The analgesic activity of and tolerance to 030418 were evaluated in thermal nociceptive tests in mice. The effects of 030418 on opioid receptors were further investigated using in vivo pharmacological antagonist blockade and in vitro tissue preparations.. The compound 030418 displayed high binding affinity to all subtypes of opioid receptors with K(i) values in the nanomolar range. In [(35)S]GTPγS binding assay, the maximal stimulation of 030418 to μ-, κ-, δ-receptors and the ORL1 receptor was 89%, 86%, 67% and 91%, respectively. In hot-plate test, the antinociceptive effect of 030418 was more potent and longer than morphine. The nonselective opioid receptor antagonist naloxone could completely block 030418-induced antinociception, while both the μ-opioid receptor antagonist β-FNA and the κ-opioid receptor antagonist nor-BNI attenuated 030418-induced antinociception. In contrast, the ORL1 receptor antagonist J-113397 enhanced the antinociceptive effect of 030418. Additionally, chronic treatment with 030418 resulted in a dramatic development of tolerance that could not be effectively prevented by J-113397. In guinea pig ileum preparation, the existing action of 030418 could be removed with difficulty after prolonged washing.. The compound 030418 is a novel agonist of opioid receptors with high efficiency, long-lasting effect and liability to tolerance, which may be closely correlated with the methyl group at the N(17) position and the high hydrophobicity of the C(7)-thiophene group in its chemical structure.

Topics: Analgesics; Animals; Buprenorphine; CHO Cells; Cricetinae; Drug Tolerance; Female; Guinea Pigs; Male; Mice; Nociception; Pain Measurement; Receptors, Opioid; Thebaine

Ionizing radiation can be used as a drug sterilization technique, provided that the drug itself is not modified and that no toxic products are produced; moreover, if the irradiated product is a drug delivery system, its drug release characteristics must not be significantly altered by radiation. The aim of this work was to study the effects of sterilization by ionizing radiation on PLGA microspheres, containing thienorphine. Thienorphine PLGA microspheres were prepared by the O/W solvent evaporation method and characterized by HPLC, SEM and laser particle size analysis. Our experimental results showed that gamma-rays did not alter the drug content, and did not modify the kinetics of drug release from microspheres. Moreover, no significant changes in the shape and in the size distribution of microspheres were found after irradiation. In conclusion, the sterilization method is adequate because microspheres not underwent any change after exposition to gamma-irradiation.

Topics: Buprenorphine; Chemistry, Pharmaceutical; Delayed-Action Preparations; Drug Compounding; Excipients; Gamma Rays; Lactic Acid; Microspheres; Particle Size; Polyglycolic Acid; Polylactic Acid-Polyglycolic Acid Copolymer; Solubility

Thienorphine-loaded microspheres composed of poly(D,L-lactide-co-glycolide) were prepared by an O/W emulsion solvent evaporation method. HPLC was used to determine the drug loading and drug release, while a LC-MS-MS system was employed to analyze the plasma drug concentration. Results indicated that the PLGA particles obtained were spherical and of appropriate size. The formulation was stable during the test period. In vitro drug release from the microspheres was sustained for about 28 days mostly by the diffusion mechanism. The plasma drug concentration-time profiles were relatively smooth for about 28 days after subcutaneous injection of the drug-loaded microspheres to rats, compared with that for drug suspension. In vitro and in vivo correlation was established.

Topics: Animals; Area Under Curve; Buprenorphine; Drug Compounding; Excipients; Half-Life; Lactic Acid; Male; Microspheres; Opiate Substitution Treatment; Particle Size; Polyglycolic Acid; Polylactic Acid-Polyglycolic Acid Copolymer; Rats; Rats, Wistar; Solubility

The inter-species differences of thienorphine metabolism were investigated in human, Beagle dog and rat liver microsomes, by comparing enzyme kinetics of the parent drug and the formation of its major metabolites. The incubation systems of thienorphine with liver microsomes of the three species were optimized in terms of thienorphine concentration, microsomal protein content and incubation time. The concentrations of thienorphine and its metabolites in incubates were measured by a LC-MS/MS method. The biotransformation of thienorphine by human liver microsomes was the lowest among the three species. The K(m), V(max), CL(int) and T1/2 of thienorphine obtained from human liver microsomes were (4.00 +/- 0.59) micromol x L(-1), (0.21 +/- 0.06) micromol x L(-1) x min(-1), (117 +/- 3.19) mL x min(-1) x kg(-1) and (223 +/- 6.10) min, respectively. The corresponding kinetic parameters for dog and rat liver microsomes were (3.57 +/- 0.69) and (3.28 +/- 0.50) micromol x L(-1), (0.18 +/- 0.04) and (0.14 +/- 0.04) micromol x L(-1) x min(-1), (213 +/- 1.06) and (527 +/- 7.79) mL x min(-1) x kg(-1), (244 +/- 1.21) and (70.7 +/- 1.05) min, respectively. A total of six phase I metabolites were observed in liver microsomes, including one N-dealkylated metabolite, three oxidative metabolites and two N-dealkylated oxidation metabolites. All these six metabolites were detected in the liver microsomes of the three species. However, the relative amounts of the metabolites generated were different in three species. The results indicated that the major phase I metabolic pathway of thienorphine was similar in the liver microsomes from all three species. However, the inter-species differences observed were relative amounts of the metabolites as well as the metabolic characteristics of thienorphine in liver microsomal incubates.

Topics: Animals; Biotransformation; Buprenorphine; Chromatography, High Pressure Liquid; Dogs; Humans; Male; Microsomes, Liver; Rats; Rats, Sprague-Dawley; Species Specificity; Tandem Mass Spectrometry

Thienorphine is a chemically-new opioid developed in Beijing Institute of Pharmacology and Toxicology. To elucidate the chemical basis for the unique pharmacological effects of thienorphine, 15 derivatives were synthesized according to combinatorial chemistry and the structure-activity relationships of these compounds were studied. It is demonstrated that thienorphine is a potent long-acting partial agonist. N-Cyclopropylmethyl is responsible for the antagonist effect of thienorphine. More importantly, thiophene at the end of side chain is most likely the pharmacophore accounts for the long-lasting effect of thienorphine. Change of the connection of thiophene and the side chain does not result in changes in the antinociceptive activity.

Topics: Animals; Buprenorphine; Combinatorial Chemistry Techniques; Dose-Response Relationship, Drug; Female; Male; Mice; Mice, Inbred Strains; Morphine; Rats; Rats, Wistar; Receptors, Opioid; Structure-Activity Relationship

Thienorphine is an oripavine with long-lasting antinociceptive effects in mice that are thought to be mediated by mu-opioid receptors. This study examined the receptor binding of thienorphine in cell membrane homogenates and its behavioral effects in rhesus monkeys (Macaca mulatta). Affinity and potency were determined using radioligand displacement and stimulation of guanosine 5'-O-(3-[35S]thio)triphosphate binding in C6 (mu, delta) and Chinese hamster ovary (kappa) cell membranes. Thienorphine displayed high affinity for kappa-, mu-, and delta-opioid receptors with K(i) values of 0.14, 0.22, and 0.69 nM, respectively. Thienorphine partially stimulated kappa-opioid (75%) and mu-opioid (19%) receptors and not delta-opioid receptors. Thienorphine dose-dependently increased tail-withdrawal latency for 50 degrees C water and not 55 degrees C water with effects lasting for more than 7 days. The kappa-opioid receptor antagonist nor-binaltorphimine (nor-BNI) (3.2 mg/kg) and a large dose (1.0 mg/kg) of naltrexone prevented thienorphine-induced antinociception. Thienorphine enhanced the antinociceptive effects of morphine and U50,488 [trans-3, 4-dichloro-N-methyl-N-[2-(1-pyrrolidinyl)-cyclohexyl]-benzeneacetamide] with 50 degrees C water; with 55 degrees C water, thienorphine enhanced the effects of morphine and attenuated the effects of U50,488. In other monkeys, thienorphine decreased responding in both components of a multiple schedule of food presentation and stimulus shock termination for up to 8 days; naltrexone and nor-BNI partially prevented these rate-decreasing effects. In morphine-treated monkeys discriminating naltrexone, thienorphine, and U50,488 neither substituted for nor modified the naltrexone discriminative stimulus. Thienorphine and U50,488 produced the same directly observable signs. These results show that thienorphine has long-lasting effects that seem to be mediated by low-efficacy agonism at kappa-opioid receptors, both in vitro and in vivo.

Topics: 3,4-Dichloro-N-methyl-N-(2-(1-pyrrolidinyl)-cyclohexyl)-benzeneacetamide, (trans)-Isomer; Analgesics, Non-Narcotic; Animals; Behavior, Animal; Binding, Competitive; Buprenorphine; Cells, Cultured; Discrimination, Psychological; Dose-Response Relationship, Drug; Female; Hot Temperature; Ligands; Macaca mulatta; Male; Naltrexone; Narcotic Antagonists; Receptors, Opioid; Reinforcement Schedule

A simple, sensitive and reliable method was developed to determine simultaneously the concentrations of thienorphine and its metabolite thienorphine glucuronide conjugate in rat plasma by liquid chromatography-tandem mass spectrometry (LC-MS/MS). The metabolite was identified by MS: thienorphine glucuronide conjugate. Sample preparation involved protein precipitation with methanol. Analytes were separated on Finnigan BetaBasic-18 column (150 mm x 2.1mm i.d., 5 microm) using methanol: water: formic acid (56:44:0.1, v/v/v) as mobile phase at a flow rate of 0.2 ml/min. The method had a linear calibration curve over the concentration range of 0.1-50 ng/ml for thienorphine and 2-1000 ng/ml for thienorphine glucuronide conjugate, respectively. LOQ of thienorphine and thienorphine glucuronide conjugate was 0.1 and 2 ng/ml, respectively. The intra- and inter-batch precisions were less than 12% and their recoveries were greater than 80%. Pharmacokinetic data of thienorphine and its metabolite thienorphine glucuronide conjugate obtained with this method following a single oral dose of 3mg/kg thienorphine to rats were also reported for the first time.

Topics: Animals; Buprenorphine; Calibration; Chromatography, Liquid; Glucuronides; Male; Rats; Rats, Wistar; Sensitivity and Specificity; Tandem Mass Spectrometry

A strategy in the development of new treatment for opioid addiction is to find partial opioid agonists with properties of long duration of action and high oral bioavailability. In a search for such compounds, thienorphine, a novel analog of buprenorphine, was synthesized. Here, we reported that, like buprenorphine, thienorphine bound potently and nonselectively to mu-, delta-, and kappa-opioid receptors stably expressed in CHO (Chinese hamster ovary) cells and behaved as a partial agonist at mu-opioid receptor. However, some differences were observed between the pharmacological profiles of thienorphine and buprenorphine. In vitro, thienorphine was more potent than buprenorphine in inhibiting [3H]diprenorphine and stimulating guanosine 5'-O-(3-[35S]thio)triphosphate binding to rat mu-opioid receptor stably expressed in CHO cells. In vivo, thienorphine exhibited a less potent but more efficacious antinociceptive effect with an ED50 value of 0.25 mg/kg s.c. and more potent antimorphine effect with an ED50 value of 0.64 mg/kg intragastric, compared with buprenorphine. Additionally, the bioavailability of thienorphine was greatly higher than that of buprenorphine after oral administration. Moreover, compared with buprenorphine, thienorphine showed a similar long-lasting antinociceptive effect but a much longer antagonism of morphine-induced lethality (more than 15 days). These results indicate that thienorphine is a potent, long-acting partial opioid agonist with high oral bioavailability and may have possible application in treating addiction.

Topics: Analgesics, Opioid; Animals; Buprenorphine; CHO Cells; Cricetinae; Dose-Response Relationship, Drug; Female; Mice; Pain Measurement; Protein Binding; Rats; Receptors, Opioid; Time Factors