Pharmacokinetics and tolerability of a bioadhesive buccal testosterone tablet in hypogonadal men

A phase I single centre, open label study of the pharmacokinetics and tolerability of a buccal testosterone tablet (COL 1621) was carried out.

Twelve testosterone-deficient males were treated with the buccal tablet twice daily for 7 consecutive days. Multiple blood samples were drawn for testosterone, dihydrotestosterone (DHT), bioavailable testosterone and sex hormone-binding globulin (SHBG).

After COL 1621, means+/-S.D. serum testosterone level increased to a peak concentration of 26.6+/-5.8 nmol/l (7.7+/-1.7 ng/ml) at 4.8+/-5.8 h and stayed in the eugonadal range. Steady state was achieved within the first 24 h and was maintained in the normal range. The bioavailable testosterone, DHT and free testosterone index followed a pattern very similar to that of testosterone. The mean serum testosterone to DHT ratio was within the normal male range throughout treatment. There was only one treatment-related adverse event (headache). Two-thirds of patients indicated that treatment with COL 1621 was acceptable and that the tablet was convenient to use. Six patients (50.0%) preferred COL 1621 to their previous testosterone replacement therapy, two patients gave preference to their previous treatment and three patients found both treatments to be equally acceptable. Data for one patient was not available.

We conclude that COL 1621 can efficiently elevate serum testosterone and DHT levels in hypogonadal men within the first day of application, achieve a steady state within 24 h and maintain serum testosterone in the normal range with a twice-daily treatment regimen. COL 1621 provides an effective alternative oral testosterone replacement therapy that gives physiological levels of testosterone and is well tolerated by the patients.