Short-term pharmacokinetic comparison of a novel testosterone buccal system and a testosterone gel in testosterone deficient men

Objective: The primary objective of the study was to compare the percentage of men with mean serum total T (C _ave(0-24)) within normal range during the 24-h pharmacokinetic (PK) sampling period on Days 14 and 15. Methods: Treatment with a new testosterone (T) buccal system, (Striant ^*), 30 mg twice daily was compared to a transdermal gel delivery system, (T-gel) [AndroGel + 5 g containing 1% (50mg) T] daily for 14 days in T-deficient men. Safety parameters included laboratory assessments and collection of adverse events. Patients were otherwise healthy T-deficient men with total T ≤ 8.7 nmol/L (≤ 2.5 ng/mL). Results: Twenty-six of the 28 patients enrolled completed the 24-h PK assessment. Of the evaluable patients, 92.3%.of T buccal system and 83.3% of T-gel patients had C ^ave(0-24) within the normal range of 10.4-36.4 nmol/L (3.0-10.5 ng/mL). Mean total T values were not different in the T buccal system group (C ^ave(0-24) 16.7 ± 4.7 nmol/L; 4.8 ± 1.4 ng/mL) compared to the T-gel group (C ^ave(0-24) 15.9 ± 4.8 nmol/L; 4.6 ± 1.4 ng/mL). All T values returned to baseline levels after the study drug was stopped. Serum LH and FSH levels decreased, and E ₂ increased as expected following T administration. Differences in DHT concentrations between treatment groups were significant (p = 0.012) with mean DHT levels on Day 14 of 1.9 ± 1.4 nmol/L (0.55 ± 0.42 ng/mL) for the T buccal system and 3.2 ± 1.3 nmol/L (0.93 ± 0.38 ng/mL) for T-gel, which was greater than the upper level of normal (2.9 nmol/L; 0.85 ng/mL). Statistically significant differences were seen in the mean T/DHT ratio on Days 14 and 15 with the T buccal system (9.3) and T-gel (5.0) (normal 9-12) (Day 14, p < 0.00001; Day 15, p < 0.0001). All adverse events were mild to moderate in severity. Three of 12 adverse events were considered related to the study drug and included headache (1 for each of the T buccal system and T-gel), and breast pain (T-gel). Summary and conclusions: In this short-term study, the T buccal system produced steady-state T levels comparable to those with T-Gel without significant adverse effects in T-deficient men. The T buccal system provides an additional safe, effective and convenient option for testosterone replacement therapy in hypogonadal men.