- Sep 30, 2017 -
Absorption: According to a pharmacokinetic study of healthy female volunteers, the plasma concentration reached a peak at a dose of 4.6-10.2 ng / ml after a single intramuscular injection of leuprolide acetate at 3.75 mg for 4 hours , But failed to distinguish between the prototype leuprolide and its inactive metabolites in the study. After 2 days, the plasma concentration of the drug began to stabilize at 0.30 ng / ml, and the steady-state plasma concentration was relatively stable for 4-5 weeks.
Distribution: According to a study by healthy male volunteers, intravenous injection, the drug's average steady-state distribution volume of 27L, in vitro experiments show that the drug and human plasma protein binding range of 43-49%.
• Metabolism: A study of healthy male volunteers showed that the average systemic clearance rate was 7.6 L / h with intravenous injection of 1 ml bolus drug, and the final elimination half-life was close to 3 hours, following a two-compartment model.
Studies in rats and dogs showed that 14C-labeled leuprolide was administered to animals, and the drug was metabolized to some inactive polypeptide fragments, including pentapeptide (metabolite 1), tripeptide (metabolites 2 and 3) And dipeptide (metabolite 4). These polypeptide fragments will also be further degraded. Pentapeptide is the main metabolite of drugs.
In the study of 5 patients with prostate cancer, the plasma concentration of the major metabolites pentapeptide (MI) reached a maximum concentration of 2-6 hours after administration, which was 6% of the plasma concentration of the original drug. After one week of administration, The average plasma concentration of pentapeptide (MI) was close to 20% of the original drug concentration.
Excretion: In three patients, it was shown that at least 5% of leuprolide acetate microspheres were excreted from the urine in the form of prototypes and metabolites 1 (M-I).
In a study of 77 cases of endometriosis patients with subcutaneous injection of leuprolide acetate microspheres 3.75mg or 1.88mg, 4 times every 4 times a total of 6 times the determination of plasma concentration in the study, the prototype drugs and their metabolites The plasma concentration of MI (cheese-D-bright-bright-proline-proline amide) did not show accumulation. Subcutaneous injection of leuprolide acetate microspheres 3.75mg, once every four times a total of 6 times, 24 hours after the first administration of drugs and 24 hours after the first 6 days of administration, urinary prototype drugs and metabolites MI excretion rate (%) See table below:
Numbers indicate urinary excretion rate (%), and numbers in parentheses indicate the number of patients.
Uterine fibroids in patients with pharmacokinetics and endometriosis pharmacokinetics of the same uterine fibroids and endometriosis are estrogen-dependent disease, the two almost occurred in the same age The
For patients with liver and kidney disease, no pharmacokinetic studies have been done.