A Microdose Cocktail to Evaluate Drug Interactions in Patients with Renal Impairment.

Renal impairment (RI) is known to influence the pharmacokinetics of nonrenally eliminated drugs, although the mechanism and clinical impact is poorly understood. We assessed the impact of RI and single dose oral rifampin (RIF) on the pharmacokinetics of CYP3A, OATP1B, P-gp, and BCRP substrates using a microdose cocktail and OATP1B endogenous biomarkers. RI alone had no impact on midazolam (MDZ), maximum plasma concentration (Cmax ), and area under the curve (AUC), but a progressive increase in AUC with RI severity for dabigatran (DABI), and up to ~2-fold higher AUC for pitavastatin (PTV), rosuvastatin (RSV), and atorvastatin (ATV) for all degrees of RI was observed. RIF did not impact MDZ, had a progressively smaller DABI drug-drug interaction (DDI) with increasing RI severity, a similar 3.1-fold to 4.4-fold increase in PTV and RSV AUC in healthy volunteers and patients with RI, and a diminishing DDI with RI severity from 6.1-fold to 4.7-fold for ATV. Endogenous biomarkers of OATP1B (bilirubin, coproporphyrin I/III, and sulfated bile salts) were generally not impacted by RI, and RIF effects on these biomarkers in RI were comparable or larger than those in healthy volunteers. The lack of a trend with RI severity of PTV and several OATP1B biomarkers, suggests that mechanisms beyond RI directly impacting OATP1B activity could also be considered. The DABI, RSV, and ATV data suggest an impact of RI on intestinal P-gp, and potentially BCRP activity. Therefore, DDI data from healthy volunteers may represent a worst-case scenario for clinically derisking P-gp and BCRP substrates in the setting of RI.

A randomized study of the effects of food on the pharmacokinetics of once-daily extended-release hydromorphone in healthy volunteers.

This randomized, open-label, crossover study investigated the influence of food on the pharmacokinetics of extended-release hydromorphone in 30 healthy volunteers. Participants received extended-release hydromorphone 16 mg in the fasted state and immediately after a high-fat breakfast. In addition, the pharmacokinetics of a 16-mg dose of extended-release hydromorphone and a 16-mg daily dose (4 mg qid) of immediate-release hydromorphone in the fasted state were compared. Treatments were separated by washout periods of 7 to 14 days. Naltrexone was given throughout each treatment period to block the opioid effects of hydromorphone. The 90% confidence intervals (CIs) of the ratios of geometric means for maximum plasma concentrations (C(max)) and area under the plasma concentration-time curve (AUC) for extended-release hydromorphone in the fed and fasted states were within the bioequivalence criteria range of 80% to 125%. In the fasted state, the 90% CIs of the ratios of AUC geometric means for extended-release hydromorphone and immediate-release hydromorphone were also within the bioequivalence range. Both hydromorphone treatments were well tolerated. This study shows that the bioavailability of extended-release hydromorphone is not affected by food and that the bioavailability of extended-release hydromorphone under fasting conditions is comparable with that of the immediate-release formulation when administered at the same total daily dose.

Steady-state pharmacokinetics of extended-release hydromorphone (OROS hydromorphone): a randomized study in healthy volunteers.

The steady-state pharmacokinetics of an extended-release formulation of hydromorphone, OROS hydromorphone, was investigated in a randomized, open-label, crossover study in healthy volunteers. Participants were randomly assigned to receive 16 mg of OROS hydromorphone once daily and 4 mg of immediate-release hydromorphone four times daily for five consecutive days. The two treatments were separated by a washout period of 7-14 days. Naltrexone was given throughout both treatment periods to block the opioid effects of hydromorphone. Steady-state hydromorphone concentrations were statistically analyzed using Helmert contrasts to determine when steady state was reached. A total of 30 participants were enrolled, of whom 29 completed both treatment periods. The two treatments produced comparable steady-state plasma drug concentrations, but peak-to-trough fluctuations were smaller with OROS hydromorphone (61 percent vs 172 percent) in comparison with immediate release hydromorphone. Overall systemic exposure to hydromorphone was similar between the two formulations. The ratio of the geometric means between the two formulations for the area under the concentration-time curves at steady state was 105.2 percent with a 90% confidence interval (CI) of 99.8-110.8 (geometric mean: 102.7 percent; 90% CI: 97.6-108.2 after correcting for measured drug content), which was within the bioequivalence range (80-125 percent). The analysis of Helmert contrasts showed that steady state conditions were attained by day 4. Both treatments were well tolerated. This study shows that OROS hydromorphone maintains steady-state plasma drug concentrations within the same range as immediate-release hydromorphone at the same total daily dose, with less fluctuation.

Clinical pharmacokinetic studies with INN 00835 (nemifitide), a novel pentapeptide antidepressant.

Nemifitide (4-fluoro-L-phenylalanyl-trans-4-hydroxy-L-prolyl-L-arginylglycyl-L-tryptophanamide ditrifluoroacetate) is a novel antidepressant, currently in phase 2/3 clinical trials. The purpose of our phase 1 clinical trials (conducted over a three year period) was to provide safety and pharmacokinetic data to support its clinical development as an antidepressant drug. Single and multiple doses ranging from 18 to 320 mg were administered subcutaneously to healthy volunteers in five phase 1 studies. Plasma concentrations of unchanged parent drug were determined by a validated LC/MS/MS method in blood samples collected at timepoints between 10 min and 72 h after dosing. Nemifitide was rapidly absorbed (C(max) at 10 min) and eliminated (t(1/2) 15-30 min) in most subjects. Regression and power model analyses were used to evaluate the data. The results indicate that pharmacokinetic parameters: AUC(0-t), AUC (0-infinity) and C(max), were close to dose proportional in the dose range investigated. There was no evidence of systemic accumulation of drug following 5 daily doses. No serious adverse events or clinically significant systemic adverse events occurred at any of the doses investigated in the over 100 subjects dosed in these studies. Drug-related adverse events were limited to local and transient skin reactions (pain and/or erythema) at the injection site, especially at the high doses administered: 240 and 320 mg.