Pharmacokinetic and glucodynamic variability: assessment of insulin glargine, NPH insulin and insulin ultralente in healthy volunteers using a euglycaemic clamp technique.

AIMS/HYPOTHESIS: This single-dose, double-blind, randomised, parallel-group study evaluated the reproducibility in systemic exposure and glucodynamic effect of insulin glargine, NPH insulin (NPH) and insulin ultralente (ultralente) using the manually adjusted euglycaemic clamp technique. METHODS: In total, 36 healthy volunteers received two consecutive s.c. injections (0.4 IU/kg) of glargine, NPH or ultralente with a wash-out period of 7 days between treatments. RESULTS: In healthy volunteers, glargine presented well-reproduced flat concentration profiles and no pronounced peaks in activity. NPH, by contrast, showed well-defined peaks in concentration and glucose disposal, while ultralente had highly variable profiles. Within-subject variability (ANOVA) for insulin exposure over 24 h was 15% for glargine and 19% for NPH, compared with 67% for ultralente (p<0.05, glargine and NPH vs ultralente). The 49% within-subject variability in total glucose disposal (glucose infusion rate [GIR]-AUC0-24 h) with ultralente was about twice as large as the 22% with NPH (p<0.05), but was intermediate with glargine at 31% (p=NS). By contrast, variability in the diurnal time-action profile (SD of diurnal day-to-day differences in GIR) for glargine was 30% (p<0.05) and 50% (p<0.05) less than with NPH and ultralente, respectively. No serious adverse events were reported. CONCLUSIONS/INTERPRETATION: Although representing insulins of different profiles, glargine and NPH showed a high and similar reproducibility of total absorption and glucodynamic effect, whereas ultralente proved to have poor reproducibility. However, while NPH yields peaks in concentration and activity, glargine shows flat and non-fluctuating profiles resulting in less variation in day-to-day 24-h activity.

Biotransformation of insulin glargine after subcutaneous injection in healthy subjects.

OBJECTIVE: It is important to establish pharmacokinetic or pharmacodynamic differences between novel insulin analogues and human insulin. This study examined the primary metabolic degradation products of insulin glargine (LANTUS) in humans. DESIGN: In this single dose, open-label study, insulin glargine was administered subcutaneously at a dose of 0.6 IU/kg; placebo was administered to one control subject. PATIENTS: Four healthy male subjects, plus one control subject, aged 18-50 years were enrolled in this study. MEASUREMENTS: Following insulin glargine administration, blood glucose levels were clamped at the subjects' fasting concentration for 6 h and the amount of 20% glucose infused to maintain this baseline concentration was recorded. Metabolite profiling was performed in plasma and injection site tissue using HPLC and radioimmunoassay (RIA). Pharmacokinetics were evaluated by RIA of serum and plasma immunoreactive insulin levels. The primary pharmacodynamic measure was the glucose infusion rate (GIR). Safety was evaluated by measuring blood glucose concentrations during the clamp and adverse events were observed by the investigator or reported by the subject. RESULTS: Metabolic profiling revealed a clear pattern: insulin glargine is metabolised by sequential cleavage at the carboxy terminus of the B chain, to yield products M1 and M2, which are both structurally similar to human insulin. These degradation products are present both at the injection site and in plasma. CONCLUSION: Thus, during treatment with a subcutaneous injection of insulin glargine, metabolic degradation is likely to be initiated at the injection site and continued within the circulatory system.

Equipotency of insulin glargine and regular human insulin on glucose disposal in healthy subjects following intravenous infusion.

The absolute glucose disposal of insulin glargine (Lantus) was compared to that of regular human insulin in healthy subjects (n=20) using the euglycaemic clamp technique in a single-dose, double-blind, randomized, two-way crossover design. Subjects received 30-minute intravenous infusions of insulin glargine (0.1 IU/kg) or human insulin (0.1 IU/kg) and a 20% glucose solution infused at a variable rate to maintain euglycaemia at the subject's baseline glucose level. At equal baseline blood glucose levels (4.42 mmol/l [range, 4.00-5.16 mmol/l] and 4.42 mmol/l [range, 4.01-4.94 mmol/l], respectively), the area under the glucose infusion rate (GIR) time curves from 0-6 hours (AUC(0-6h)) was within the bioequivalence range (insulin glargine, 663.92 mg/kg; human insulin, 734.85 mg/kg). Both the time to maximum GIR and the suppression of serum C-peptide were similar with insulin glargine and human insulin. The resulting maximum serum insulin concentrations (Cmax) were 151.16 microIU/ml and 202.23 microIU/ml, and the time to Cmax (Tmax) was 30 minutes (the duration of the infusion). The observed differences in the Cmax (the mean value for insulin glargine was about 25% lower than that of human insulin) could be explained by lower cross-reactivity of insulin glargine in the human insulin radioimmunoassay. The employed intravenous route, though definitely not the intended clinical use of insulin glargine, provided the clinical evidence in healthy subjects that on a molar basis insulin glargine is equipotent to regular human insulin regarding glucose disposal.

Pharmacokinetics and absolute oral bioavailability of an 800-mg oral dose of telithromycin in healthy young and elderly volunteers.

BACKGROUND: This two-way, randomized, single-dose, crossover study determined the pharmacokinetics and absolute oral bioavailability of telithromycin in young and elderly healthy subjects. METHODS: Twelve young (18-40 years) and 12 elderly (>65 years and

Pharmacokinetics of the new ketolide telithromycin (HMR 3647) administered in ascending single and multiple doses.

Telithromycin (HMR 3647) is a novel ketolide antimicrobial with good activity against both common and atypical respiratory pathogens, including many resistant strains. This randomized, three-period crossover study determined the dose proportionality of telithromycin pharmacokinetics after single and multiple dosing in healthy subjects. In each treatment period, subjects received a single oral dose of 400, 800 or 1,600 mg of telithromycin followed 4 days later by the same dose once daily for 7 days. Blood and urine samples were taken throughout the study for determination of pharmacokinetic parameters for telithromycin and RU 76363, its main metabolite. Telithromycin and RU 76363 achieved steady state within 2 to 3 days of once-daily dosing. A slight accumulation of telithromycin was observed after 7 days of therapy, with values of the area under the concentration-time curve from 0 to 24 h approximately 1.5 times higher than those achieved with the single dose. The pharmacokinetics of telithromycin and RU 76363 deviated moderately from dose proportionality. At a dose of 800 mg/day, telithromycin attained mean maximal and trough plasma concentrations of 2.27 and 0. 070 mg/liter respectively. Elimination was biphasic; initial and terminal half-lives were 2.87 and 9.81 h for the 800-mg dose. Study medication was well tolerated, although adverse events tended to be more frequent at the 1,600-mg dose. This study showed that telithromycin was generally well tolerated and suggests that a once-daily 800-mg oral dose of telithromycin maintains an effective concentration in plasma for the treatment of respiratory tract infections involving the key respiratory pathogens.