AimsThe influence of ageing on the pharmacokinetics of zolpidem, an extensively prescribed hypnotic medication, was evaluated in healthy human volunteers. Methods A series of 16 elderly (age: 61-85 years) and 24 young (age: 22-42 years) volunteers received single 5 mg oral doses of zolpidem tartrate. Serum zolpidem concentrations were determined by HPLC with fluorescence detection in samples drawn during 8 h after dosage. The effect of testosterone on zolpidem biotransformation was evaluated in vitro using human liver microsomes. Possible induction of CYP3A protein expression and function was studied in cultured human hepatocytes. Results Among men, apparent oral clearance of zolpidem was decreased in elderly compared to young subjects (3.8 vs 11.0 ml min -1 kg -1 , P < 0.01), C max was increased (93 vs 40 ng ml -1 , P < 0.01), and half-life increased (2.7 vs 1.5 h, P < 0.03). Among women, zolpidem oral clearance was decreased in the elderly (3.0 vs 5.8 ml min -1 kg -1 , P < 0.02), C max increased (108 vs 60 ng ml -1 , P < 0.001), with no difference in t 1 / 2 (2.3 vs 2.4 h). Among male subjects, free serum testosterone concentrations were lower in the elderly (10.5 vs 19.0 pg ml -1 , P < 0.01), and were significantly correlated with zolpidem clearance ( r 2 = 0.46, P < 0.001). Multiple regression analysis indicated a greater relative contribution of serum testosterone than age to the oral clearance of zolpidem among men. In human liver microsomes, co-incubation of zolpidem (10 m M ) with varying concentrations of testosterone produced activation of biotransformation of zolpidem to its principal hydroxylated metabolite. Maximum activation was achieved at equimolar concentrations of testosterone (10 m M ). However, testosterone did not induce immunoactive CYP3A4 expression or catalytic function in cultured human hepatocytes. Conclusions The increased C max and lower oral clearance of zolpidem in the elderly are consistent with recommendations of lower clinical doses of zolpidem in the elderly. Our clinical and in vitro data both suggest that reduced free serum testosterone may have a modulatory role in age-dependent changes in zolpidem pharmacokinetics in men.

Similarities in different regions of the world among people with diabetes suffering newly presenting foot lesions include a predominance of males and patients with Type 2 diabetes, as well as a high frequency of diabetic neuropathy. However, differences concerning age, diabetes duration, peripheral vascular disease, and precipitating factors contributing to injury are also observed.

Single 25 mg intravenous and 50 mg oral doses of trazodone were given to 43 healthy subjects, divided into young men and women (aged 18 to 40 years) and elderly men and women (aged 60 to 76 years). Among men, trazodone volume of distribution (Varea) was increased in elderly vs. young subjects (1.15 vs. 0.89 L/kg; P less than 0.05), and clearance decreased (1.65 vs. 2.31 ml/min/kg; P less than 0.05), thereby increasing elimination half-life (t1/2) in elderly men (8.2 vs. 4.7 hours; P less than 0.001). Varea in women was also increased in the elderly (1.5 vs. 1.27 L/kg; P less than 0.02), causing increased t1/2 (7.6 vs. 5.9 hours; P less than 0.05), but clearance was unrelated to age. Absolute bioavailability of oral trazodone averaged 70% to 90% and was unrelated to age or sex. In 23 obese subjects (mean weight 112 kg) vs. 23 matched control subjects of normal weight (mean 65 kg), Varea was greatly increased (162 vs. 67 L; 1.43 vs. 1.04 L/kg; P less than 0.001) and was highly correlated with body weight (r = 0.91). Clearance was unchanged between groups (146 vs. 136 ml/min), but the increased Varea caused prolonged t1/2 in obese subjects (13.3 vs. 5.9 hours; P less than 0.001). Reduced clearance of trazodone among elderly men may indicate a need for dosage reduction during chronic therapy. In obese individuals, choice of dosage during chronic treatment should be based on ideal rather than total body weight.