In a following study (Nieschlag et al 1999) 13 hypogonadal men received 4 intramuscular injections of TU at 6-week intervals. T serum levels were never found to lie below the lower limit of normal, and only briefly after the 3rd and 4th injection were T serum levels above the upper limit of normal (Figure 1) while values peak and trough levels increased over the 24-week observation period. Serum estradiol and DHT followed the same pattern, not exceeding the normal limits. In order to better establish (von Eckardstein and Nieschlag 2002) suitable injection intervals for TU, 7 hypogonadal men received injections at gradually increasing intervals between the 5th and 10th injection (starting with 6-weeks injection interval) and from then on every 12-weeks. Steady state kinetics were assessed after the 13th injection.
Cmax was 32.0 ± 11.7 nmol/L and half-life was 70.2 ± 21.1 days. The mean Cmax of 32 nmol/L seen during steady-state with TU administration was lower than that achieved by Testogel® (Bayer) 100 mg/day (37.5 nmol/L); however, it was higher than with Testogel® 50 mg/day (28.8 nmol/L) and Androderm® (Watson Pharmaceuticals, Inc.,) patch 5mg/day (26.5 nmol/L). Before the next injection, the serum levels for T and its metabolites DHT and estradiol were mostly within the normal (eugonadal) range and showed a tendency to decrease with increasing injection intervals. The study concluded that after initial loading doses at 0 and 6-weeks, injection intervals of 12-weeks establish eugonadal values of serum testosterone in almost all men. A later study (Yassin and Saad 2005) analyzing 58 hypogonadal men receiving TU treatment every 3 months did not report elevations of DHT levels exceeding the physiological threshold.
Source: Testosterone depot injection in male hypogonadism: a critical appraisal
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In a following study (Nieschlag et al 1999) 13 hypogonadal men received 4 intramuscular injections of TU at 6-week intervals. T serum levels were never found to lie below the lower limit of normal, and only briefly after the 3rd and 4th injection were T serum levels above the upper limit of normal (Figure 1) while values peak and trough levels increased over the 24-week observation period. Serum estradiol and DHT followed the same pattern, not exceeding the normal limits. In order to better establish (von Eckardstein and Nieschlag 2002) suitable injection intervals for TU, 7 hypogonadal men received injections at gradually increasing intervals between the 5th and 10th injection (starting with 6-weeks injection interval) and from then on every 12-weeks. Steady state kinetics were assessed after the 13th injection. Cmax was 32.0 ± 11.7 nmol/L and half-life was 70.2 ± 21.1 days. The mean Cmax of 32 nmol/L seen during steady-state with TU administration was lower than that achieved by Testogel® (Bayer) 100 mg/day (37.5 nmol/L); however, it was higher than with Testogel® 50 mg/day (28.8 nmol/L) and Androderm® (Watson Pharmaceuticals, Inc.,) patch 5mg/day (26.5 nmol/L). Before the next injection, the serum levels for T and its metabolites DHT and estradiol were mostly within the normal (eugonadal) range and showed a tendency to decrease with increasing injection intervals. The study concluded that after initial loading doses at 0 and 6-weeks, injection intervals of 12-weeks establish eugonadal values of serum testosterone in almost all men. A later study (Yassin and Saad 2005) analyzing 58 hypogonadal men receiving TU treatment every 3 months did not report elevations of DHT levels exceeding the physiological threshold.
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