Wright C E, Antal E J, Gillespie W R, Albert K S
Clin Pharm. 1983 Sep-Oct;2(5):435-8.
The influence of injection volume on the absorption and bioavailability of medroxyprogesterone acetate (MPA) was studied. A single i.m. injection of MPA 400 mg was administered to 24 healthy men; 12 of the subjects received 4 ml of a 100 mg/ml suspension of the drug, and the other 12 subjects were given 1 ml of a 400 mg/ml suspension. Blood samples for MPA determinations were collected periodically during a 202-day period after drug administration. Mean steady-state serum concentrations of MPA were simulated from single-dose data to reflect those achieved after standard dosage regimens. Values for area under the serum concentration-time curve and time required to reach peak serum concentrations were compared between subjects receiving different injection volumes of MPA. Mean peak serum concentration were significantly higher and occurred significantly sooner in subjects receiving the 4-ml injection of MPA than in those given the 1-ml injection. No significant differences in areas under the serum concentration-time curve were noted in subjects receiving different injection volumes. The rate but not the extent of absorption of injectable MPA suspension is enhanced by increasing the injection volume of equivalent doses from 1 ml to 4 ml.
研究了注射体积对醋酸甲羟孕酮（MPA）吸收及生物利用度的影响。对24名健康男性进行400mg MPA的单次肌内注射；其中12名受试者接受4ml浓度为100mg/ml的药物混悬液，另外12名受试者接受1ml浓度为400mg/ml的混悬液。给药后202天内定期采集血样测定MPA。根据单剂量数据模拟MPA的平均稳态血清浓度，以反映标准给药方案后达到的浓度。比较接受不同注射体积MPA的受试者血清浓度-时间曲线下面积及达到血清峰浓度所需时间的值。接受4ml MPA注射的受试者平均血清峰浓度显著更高，且出现时间显著更早。接受不同注射体积的受试者血清浓度-时间曲线下面积无显著差异。将等效剂量的注射用MPA混悬液的注射体积从1ml增加到4ml可提高吸收速率，但不影响吸收程度。
