Assessment of Drug-Drug Interactions between Taspoglutide, a Glucagon-Like Peptide-1 Agonist, and Drugs Commonly Used in Type 2 Diabetes Mellitus: Results of Five Phase I Trials.

BACKGROUND AND OBJECTIVE: Taspoglutide, a glucagon-like peptide-1 agonist, like native glucagon-like peptide-1, delays gastric emptying time and prolongs intestinal transit time, which may alter the pharmacokinetics of concomitantly administered oral drugs. The effect of taspoglutide on the pharmacokinetics of five oral drugs commonly used in patients with type 2 diabetes mellitus was assessed in healthy subjects. METHODS: Five clinical pharmacology studies evaluated the potential drug-drug interaction between multiple subcutaneous taspoglutide doses and a single dose of lisinopril, warfarin, and simvastatin and multiple doses of digoxin and an oral contraceptive containing ethinylestradiol and levonorgestrel. The extent of interaction was quantified using geometric mean ratios and 90% confidence intervals for the maximum plasma concentration and area under the plasma concentration-time curve. In addition to pharmacokinetics, pharmacodynamic effects were assessed for warfarin and the oral contraceptive. RESULTS: Among the tested drugs, the effect of taspoglutide on the pharmacokinetics of simvastatin was most pronounced, on the day of taspoglutide administration, the average exposure to simvastatin was decreased by - 26% and - 58% for the area under the plasma concentration-time curve and maximum plasma concentration, respectively, accompanied by an increase in average exposure to its active metabolite, simvastatin ß-hydroxy acid (+ 74% and + 23% for area under the plasma concentration-time curve and maximum plasma concentration, respectively). Although statistically significant changes in exposure were observed for other test drugs, the 90% confidence intervals for the geometric mean ratio for maximum plasma concentration and area under the plasma concentration-time curve were within the 0.7-1.3 interval. No clinically relevant changes on coagulation (for warfarin) and ovulation-suppressing activity (for the oral contraceptive) were apparent. CONCLUSION: Overall, multiple doses of taspoglutide did not result in changes in the pharmacokinetics of digoxin, an oral contraceptive containing ethinylestradiol and levonorgestrel, lisinopril, warfarin, and simvastatin that would be considered of clinical relevance. Therefore, no dose adjustments are warranted upon co-administration.

Effect of varying degrees of renal impairment on the pharmacokinetics and tolerability of taspoglutide.

AIM: To evaluate single-dose pharmacokinetics and tolerability of taspoglutide in people with varying degrees of renal impairment and matched healthy participants. METHODS: Participants in the present study were people with mild renal impairment (n = 10), moderate impairment (n = 10), severe impairment (n = 9), and a matched healthy control group (n = 10). Participants received a single subcutaneous injection of taspoglutide (10 mg) on day 1. Plasma and urine drug concentration, antibody formation, vital signs, ECGs and routine laboratory variables were measured frequently and adverse events (AEs) were monitored for 9 weeks. RESULTS: Taspoglutide exposure was higher among participants with moderate and severe renal impairment compared with participants with normal renal function. Mean AUClast was 13% and 38% higher in participants with moderate and severe renal impairment, respectively compared with participants with normal renal function. Likewise, mean peak plasma concentration (Cmax ) was 57% and 93% higher in participants with moderate and severe renal function impairment, respectively, compared with participants with normal renal function. Linear regression analyses showed a statistically significant inverse relationship between taspoglutide exposure parameters (AUC and Cmax ) and creatinine clearance. Higher incidences of gastrointestinal (GI) AEs were reported in participants with severe renal impairment. CONCLUSION: Renal impairment altered the pharmacokinetics of taspoglutide. The degree of renal impairment was associated with an increased exposure to taspoglutide and an increased risk of GI AEs.

Effect of gastric pH on erlotinib pharmacokinetics in healthy individuals: omeprazole and ranitidine.

The aim of this study was to evaluate the effect of coadministration of acid-reducing agents on the pharmacokinetic exposure of orally administered epidermal growth factor receptor inhibitor erlotinib, a drug that displays pH-dependent solubility. Two studies were conducted, the first with the proton pump inhibitor omeprazole and the second with the H2-receptor antagonist ranitidine. Twenty-four healthy male and female volunteers were enrolled in each study. Erlotinib was administered as a single oral 150 mg dose on day 1. After the washout a subsequent study period evaluated 150 mg erlotinib administered with the acid-reducing agent. Omeprazole (40 mg once daily) was given on days 11-14, concomitantly with erlotinib on day 15, and for two additional days (days 16-17). In the ranitidine study, on day 13, participants were randomized to either concomitant dosing (treatment B) or staggered administration (treatment C) of erlotinib and ranitidine and crossed over to the other treatment starting on day 27. For treatment B, ranitidine (300 mg once daily) was administered in the morning for 5 days, 2 h before erlotinib. For treatment C, ranitidine was administered as a divided dose (150 mg twice daily) for 5 days, with erlotinib given 10 h after the previous evening dose and 2 h before the next ranitidine morning dose. Plasma samples were obtained for determination of the concentrations of erlotinib and its metabolite OSI-420, following each erlotinib dose. All participants were monitored for safety and tolerability. The geometric mean ratios of AUC0-∞ and Cmax for erlotinib and AUC0-last and Cmax for OSI-420 were substantially decreased when erlotinib was dosed with omeprazole. The estimated mean ratio (90% confidence interval) for erlotinib was 0.54 (0.49-0.59) for AUC0-∞ and 0.39 (0.32-0.48) for Cmax. For OSI-420, the estimated mean ratio was 0.42 (0.37-0.48) for AUC0-last and 0.31 (0.24-0.41) for Cmax. AUC0-∞ and Cmax for erlotinib were substantially decreased by 33 and 54%, respectively, upon coadministration with ranitidine, but the decrease was only 15 and 17% when ranitidine and erlotinib were given staggered. Similar results were observed for the metabolite OSI-420. Erlotinib was generally well-tolerated alone or in combination with omeprazole or ranitidine. Erlotinib pharmacokinetic exposure was substantially reduced upon coadministration with omeprazole and ranitidine, but not when administered with a staggered dosing approach to ranitidine. Therefore, it is recommended that the concomitant use of erlotinib with proton pump inhibitors be avoided. If treatment with an H2-receptor antagonist such as ranitidine is required, erlotinib must be administered 10 h after the H2-receptor antagonist dosing and at least 2 h before the next dose of the H2-receptor antagonist.