Head-To-Head Pharmacokinetic And Pharmacodynamic Comparison Of Subcutaneous Versus Intramuscular Leuprorelin Acetate Formulations In Male Patients.

e589Background: Leuprolide acetate (LA) is the standard-of-care luteinizing hormone-releasing hormone (LHRH) agonist used to suppress serum testosterone (T) in the treatment of advanced prostate cancer. There are currently two LA formulations available: a controlled-release implant injected subcutaneously (SC) or a microsphere intra-muscular (IM) injection. The study compared the pharmacokinetics/pharmacodynamics of both formulations at the same one-month dose. Methods: Thirty-two healthy men were randomized to receive a single 7.5 mg injection of SC-LA (n = 16) or IM-LA (n = 16) in this phase 1, open-label, parallel-group study. Serum LA, T, and luteinizing hormone (LH) were assessed. Results: The initial surge of LA was higher for IM-LA than SC-LA (Cmax 27±4.9 vs. 19±8.0 ng/mL, respectively), with a shorter tmax (1.0±0.4 vs. 2.1±0.8 hrs). Mean serum LA remained above the level of quantification (LOQ, 50 pg/mL) through Day 49 for SC-LA, whereas for IM-LA, mean serum LA dropped below the LOQ after Day 28....