leuprolide acetate maintains testosterone below the castrate level for up to seven years.
PHARMACODYNAMICS
Following the first dose of ELIGARD®, mean serum testosterone concentrations transiently increased, then fell to below castrate threshold (≤ 50 ng/dL) within three weeks for all ELIGARD® concentrations.
Continued monthly treatment with ELIGARD® 7.5 mg maintained castrate testosterone suppression throughout the study. No breakthrough of testosterone concentrations above castrate threshold (> 50 ng/dL) occurred at any time during the study once castrate suppression was achieved (Figure 1).
One patient received less than a full dose of ELIGARD® 22.5 mg at baseline, never suppressed and withdrew from the study at Day 73. Of the 116 patients remaining in the study, 115 (99%) had serum testosterone levels below the castrate threshold by Month 1 (Day 28). By Day 35, 116 (100%) had serum testosterone levels below the castrate threshold. Once testosterone suppression was achieved, one patient (< 1%) demonstrated breakthrough (concentrations > 50 ng/dL after achieving castrate levels) following the initial injection; that patient remained below the castrate threshold following the second injection (Figure 2).
One patient withdrew from the ELIGARD® 30 mg study at Day 14. Of the 89 patients remaining in the study, 85 (96%) had serum testosterone levels below the castrate threshold by Month 1 (Day 28). By Day 42, 89 (100%) of patients attained castrate testosterone suppression. Once castrate testosterone suppression was achieved, three patients (3%) demonstrated breakthrough (concentrations > 50 ng/dL after achieving castrate levels) (Figure 3).
One patient at Day 1 and another patient at Day 29 were withdrawn from the ELIGARD® 45 mg study. Of the 109 patients remaining in the study, 108 (99.1%) had serum testosterone levels below the castrate threshold by Month 1 (Day 28). One patient did not achieve castrate suppression and was withdrawn from the study at Day 85. Once castrate testosterone suppression was achieved, one patient (< 1%) demonstrated breakthrough (concentrations > 50 ng/dL after achieving castrate levels) (Figure 4).
Leuprolide acetate is not active when given orally.
PHARMACOKINETICS
Absorption
ELIGARD® 7.5 mg
The pharmacokinetics/pharmacodynamics observed during three once-monthly injections in 20 patients with advanced prostate cancer is shown in Figure 1. Mean serum leuprolide concentrations following the initial injection rose to 25.3 ng/mL (Cmax) at approximately 5 hours after injection. After the initial increase following each injection, serum concentrations remained relatively constant (0.28 – 2.00 ng/mL).
Figure 1 Pharmacokinetic/Pharmacodynamic Response (N=20) to ELIGARD® 7.5 mg – Patients Dosed Initially and at Months 1 and 2
A reduced number of sampling timepoints resulted in the apparent decrease in Cmax values with the second and third doses of ELIGARD® 7.5 mg (Figure 1).
ELIGARD® 22.5 mg
The pharmacokinetics/pharmacodynamics observed during two injections every three months (ELIGARD® 22.5 mg) in 22 patients with advanced prostate cancer is shown in Figure 2. Mean serum leuprolide concentrations rose to 127 ng/mL and 107 ng/mL at approximately 5 hours following the initial and second injections, respectively. After the initial increase following each injection, serum concentrations remaine |
