betadex and Arrhythmias--Cardiac

Novel formulations and administration routes of established drugs may result in higher maximum concentrations or total exposures and potentially cause previously unrecognized adverse events.. This study evaluated the proarrhythmic potential of hydroxypropyl-β-cyclodextrin (HPβCD)-diclofenac, a novel injectable diclofenac formulation solubilized with hydroxypropyl-β-cyclodextrin (HPβCD), on ventricular electrical conduction in preclinical and clinical models.. We assessed the effects of diclofenac, HPβCD, and HPβCD-diclofenac on the human delayed rectifier potassium channel (IKr) using human embryonic kidney (HEK) 293 cells transfected with a human ether-à-go-go-related gene (hERG) using whole-cell patch-clamp. In a single-dose, active- and placebo-controlled, 4-period crossover, thorough QT in vivo study, 70 healthy volunteers (mean age, 23.3 years; range, 18-49 years; 55.75% male) received HPβCD-diclofenac at 37.5- and 75-mg doses, inactive vehicle (placebo), and an active control (moxifloxacin).. In vitro, diclofenac produced no statistically significant effect on IKr. Significant, non-dose-dependent effects were observed in the presence of HPβCD or HPβCD-diclofenac of similar magnitude across the 300-fold dose range of concentrations tested, suggesting an artifact due to the detergent effect of HPβCD in this in vitro model. In vivo, neither HPβCD-diclofenac dose resulted in QTc prolongation ≥2 ms (≥5 ms is the threshold of clinical concern). No correlation was evident between changes in QTc and plasma concentrations of diclofenac or HPβCD. Confirming study sensitivity, moxifloxacin produced a mean QTc prolongation >10 ms.. The findings from the present study suggest that HPβCD-diclofenac does not have a dose-dependent effect in the in vitro hERG assay system and does not produce proarrhythmic QTc prolongation in vivo. ClinicalTrials.gov identifier: NCT01812538.

Topics: 2-Hydroxypropyl-beta-cyclodextrin; Adolescent; Adult; Anti-Inflammatory Agents, Non-Steroidal; Arrhythmias, Cardiac; Aza Compounds; beta-Cyclodextrins; Cross-Over Studies; Diclofenac; Dose-Response Relationship, Drug; ERG1 Potassium Channel; Ether-A-Go-Go Potassium Channels; Female; Fluoroquinolones; HEK293 Cells; Humans; Long QT Syndrome; Male; Middle Aged; Moxifloxacin; Patch-Clamp Techniques; Potassium Channels, Inwardly Rectifying; Quinolines; Young Adult

Intravenous amiodarone (AIV) is used to treat cardiac arrhythmias. Hypotension is the dose-limiting adverse event of AIV and is considered to be due to the cosolvents (polysorbate 80 and benzyl alcohol) in the formulation. To minimize hypotension, the initial loading dose of AIV (150 mg) is diluted to 1.5 mg/ml and slowly infused over 10 minutes. PM101 is a cosolvent-free intravenous formulation of amiodarone. The present study was designed to assess any potential hypotensive effect of PM101 (50 mg/ml) on the administration of the loading dose (150 mg) as an undiluted bolus push. This was a randomized, double-blind, placebo- and active-controlled study in healthy human subjects receiving placebo (5% dextrose in water, n = 112) or PM101 (bolus push, n = 112). The primary end point was the noninferiority assessment of placebo versus PM101 for change in systolic blood pressure. For comparison, the standard loading dose of AIV (150 mg) was infused at 1.5 mg/ml over 10 minutes, and a rapid loading dose of AIV (150 mg) was infused undiluted (50 mg/ml) over 15 seconds. PM101 was noninferior to placebo, with changes from baseline systolic blood pressure for placebo and PM101 of -4.25 +/- 4.2 and -4.83 +/- 5.0 mm Hg, respectively. Neither regimen of AIV altered systolic blood pressure compared to placebo. Transient and significant increases in heart rate were observed in both AIV groups and with PM101 but not placebo. In conclusion, the results of this study demonstrate that PM101 is devoid of hypotension in healthy human subjects. The absence of a hypotensive effect of AIV in this population suggests that further evaluation is needed in a patient population with cardiac disease.

Topics: Adolescent; Adult; Amiodarone; Anti-Arrhythmia Agents; Arrhythmias, Cardiac; beta-Cyclodextrins; Blood Pressure; Dose-Response Relationship, Drug; Double-Blind Method; Female; Follow-Up Studies; Heart Rate; Humans; Injections, Intravenous; Male; Middle Aged; Prognosis; Reference Values; Young Adult

Cocaine intoxication leads to over 500,000 emergency department visits annually in the United States and ethanol cointoxication occurs in 34% of those cases. Cardiotoxicity is an ominous complication of cocaine and cocaethylene overdose for which no specific antidote exists. Because infusion of lipid emulsion (Intralipid) can treat lipophilic local anesthetic toxicity and cocaine is an amphipathic local anesthetic, the authors tested whether lipid emulsion could attenuate cocaine cardiotoxicity in vivo. The effects of lipid emulsion were compared with the metabolically inert sulfobutylether-β-cyclodextrin (SBE-β-CD; Captisol) in an isolated heart model of cocaine and cocaethylene toxicity to determine if capture alone could exert similar benefit as lipid emulsion, which exhibits multimodal effects. The authors then tested if cocaine and cocaethylene, like bupivacaine, inhibit lipid-based metabolism in isolated cardiac mitochondria.. For whole animal experiments, Sprague-Dawley rats were anesthetized, instrumented, and pretreated with lipid emulsion followed by a continuous infusion of cocaine to assess time of onset of cocaine toxicity. For ex vivo experiments, rat hearts were placed onto a nonrecirculating Langendorff system perfused with Krebs-Henseleit solution. Heart rate, left ventricle maximum developed pressure (LVdevP), left ventricle diastolic pressure, maximum rate of contraction (+dP/dtmax), maximum rate of relaxation (-dP/dtmax), rate-pressure product (RPP = heart rate × LVdevP), and line pressure were monitored continuously during the experiment. A dose response to cocaine (10, 30, 50, and 100 μmol/L) and cocaethylene (10, 30, and 50 μmol/L) was generated in the absence or presence of either 0.25% lipid emulsion or SBE-β-CD. Substrate-specific rates of oxygen consumption were measured in interfibrillar cardiac mitochondria in the presence of cocaine, cocaethylene, ecgonine, and benzoylecgonine.. Treatment with lipid emulsion delayed onset of hypotension (140 seconds vs. 279 seconds; p = 0.008) and asystole (369 seconds vs. 607 seconds; p = 0.02) in whole animals. Cocaine and cocaethylene induced dose-dependent decreases in RPP, +dP/dtmax, and -dP/dtmaxabs (p < 0.0001) in Langendorff hearts; line pressure was increased by cocaine and cocaethylene infusion, but not altered by treatment. Lipid emulsion attenuated cocaine- and cocaethylene-induced cardiac depression. SBE-β-CD alone evoked a mild cardiodepressant effect (p < 0.0001) but attenuated further cocaine- and cocaethylene-induced decrements in cardiac contractility at high concentrations of drug (100 μmol/L; p < 0.001). Finally, both cocaine and cocaethylene, but not ecgonine and benzoylecgonine, inhibited lipid-dependent mitochondrial respiration by blocking carnitine exchange (p < 0.05).. A commercially available lipid emulsion was able to delay progression of cocaine cardiac toxicity in vivo. Further, it improved acute cocaine- and cocaethylene-induced cardiac toxicity in rat isolated heart while SBE-β-CD was effective only at the highest cocaine concentration. Further, both cocaine and cocaethylene inhibited lipid-dependent mitochondrial respiration. Collectively, this suggests that scavenging-independent effects of lipid emulsion may contribute to reversal of acute cocaine and cocaethylene cardiotoxicity, and the beneficial effects may involve mitochondrial lipid processing.

Topics: Animals; Arrhythmias, Cardiac; beta-Cyclodextrins; Bupivacaine; Cardiotoxicity; Cocaine; Coronary Circulation; Depression, Chemical; Fat Emulsions, Intravenous; Heart; Heart Rate; Male; Myocardial Contraction; Rats; Rats, Sprague-Dawley

Delayed cardiac repolarization and fatal proarrhythmia have been linked to block of the repolarizing current, Ikr or hERG (human ether-a-go-go related gene) current. Thus, determining the potency of hERG block is critical in evaluating cardiac safety during preclinical development. Hydroxypropyl beta-cyclodextrins (HbetaC) are cyclic oligosaccharides used to enhance drug solubility. To evaluate the utility of HbetaC to enhance drug solubility in hERG screening assays, we studied the effect of HbetaC on hERG current and the sensitivity of the hERG assay to 3 structurally different hERG blocking drugs using whole-cell voltage clamp technique and HEK-293 cells expressing the hERG channel. HbetaC inhibited hERG activation and tail current and accelerated current deactivation in a concentration-dependent manner. HbetaC (6%) reduced the apparent potency of block by terfenadine (IC50 12000 nM vs 45 nM), cisapride (IC50 281 nM vs 28 nM), and E-4031 (163 nM vs 26 nM). Reduced potency of block was consistent with loss of activity as a result of complexation with HbetaC by terfenadine and cisapride (demonstrated in solubility studies) and interactions with HbetaC by E-4031 (demonstrated in absorbance studies). These results demonstrate that HbetaC is an unsuitable agent for enhancing compound solubility in the in vitro hERG current assay and may mask drug effects, allowing potentially dangerous drugs to advance into clinical development.

Topics: 2-Hydroxypropyl-beta-cyclodextrin; Anti-Arrhythmia Agents; Arrhythmias, Cardiac; beta-Cyclodextrins; Biological Assay; Cisapride; Dose-Response Relationship, Drug; Electrophysiology; Ether-A-Go-Go Potassium Channels; Excipients; Gastrointestinal Agents; Histamine H1 Antagonists; Humans; Inhibitory Concentration 50; Myocytes, Cardiac; Piperidines; Potassium Channel Blockers; Pyridines; Solubility; Terfenadine; Time Factors