Gossypol blood levels and inhibition of spermatogenesis in men taking gossypol as a contraceptive

The (+)- and (−)-gossypols potently inhibit human and rat 11β-hydroxysteroid dehydrogenase type 2

“…A recent study using low doses (7.5 mg/day) of (±)gossypol showed that blood gossypol levels reached 186 ± 113 ng/mL (about 0.36 ± 0.22 M) after 12 weeks of treatment [23]. However, the large-scale clinical trials performed in 1980 used much higher gossypol doses (20 mg/day) which may lead much higher blood gossypol levels [8].…”

“…A more recent clinical trial with reduced dose of gossypol regime proved that this reduced regime of gossypol remained to be very effective as a male contraceptive without side effects of hypokalemia [23]. To further reduce this effect, one of selections is to choose (−)-gossypol since (−)-gossypol is the only active component to inhibit spermatogenesis in racemic gossypol while (+)-gossypol is inactive [9,10].…”

The (+)- and (−)-gossypols potently inhibit both 3β-hydroxysteroid dehydrogenase and 17β-hydroxysteroid dehydrogenase 3 in human and rat testes

“…Different letters indicates that there was significant difference between two groups at P < 0.05. pol in clinical use as a male contraceptive. A recent study using low doses (7.5 mg/day) of racemic (±)-gossypol showed that blood gossypol levels reached 186 ± 113 ng/ml (about 0.36 ± 0.22 M) after 12 weeks of treatment [16]. The large-scale clinical trials performed in 1980 used much higher gossypol doses (20 mg/day) which may result in much higher blood gossypol levels [3].…”

Control of Spermatogenesis in Primate and Prospect of Male Contraception

“…Spermatogenesis was suppressed in all subjects. The potassium levels fluctuated within the normal range, and there was no obvious side-effect on sexual desire and frequency of intercourse [6]. However, 18% of the subjects taking 10 mg gossypol=day group still had a low sperm count one year after stopping the gossypol.…”