Pharmacokinetics of naloxone in rats and in man: basis for its potency and short duration of action.

摘要: Using a specific and sensitive radioimmunoassay, naloxone concentrations in the brains sera of rats were measured at intervals for four hours following iv injection (5 mg/kg). Decrement curves compared with those after morphine Serum concentration 5 minutes was 1.45 +/- 0.1 mug/ml (mean SE) that 1.0 0.08 mug/ml. Their serum half-lives from one to approximately same, 30-40 minutes. With naloxone, brain-serum ratios ranged 2.7 4.6. Concentration brain declined parallel serum. However, initial tenth (0.096 0.04 mug/ml). The sustained hour, while 0.19 during this period. Two HCl (0.4 mg) nine healthy volunteers, drug 0.01 .001 At minutes, 97 per cent administered dose no longer found serum, being 0.004 .0003 From 20 two injection, calculated mean half-life 64 These results suggest rapid penetrance into high ratio contribute its onset action potency as narcotic antagonist. decline animal model, contrast morphine, could be basis relatively short duration action.