PE 01. A randomized crossover trial of amoxapine and vitamin B₁₂ in the treatment of retrograde ejaculation

Objective: To evaluate the effectiveness and side effects of amoxapine in treating retrograde ejaculation (RE).

Methods: Totally 25 RE patients who were treated in our reproduction center were included into this study. The age ranged from 28 to 54 years old (mean 40.8 years old), and the duration of RE ranged from 1 month to 25 years (mean 4.5 years). After dividing into 2 groups randomly, 13 patients took amoxapine 50 mg daily before sleep for 1 month after a washout period of 1 week; the medication was changed to vitamin B₁₂ 500 μg thrice daily after meals for 1 month. The other 12 patients were placed on the reverse regimen. All patients masturbated at least twice during each 1-month treatment period. The primary endpoint was ejaculation of white fluid (semen), as reported by patients, more than once during a 1-month treatment period.

Results: The total success rate of the two drugs in treating RE was 88% (22/25 patients). Compared with vitamin B₁₂, amoxapine was significantly more effective (80%, 20 patients vs. 16%, 4 patients, P<0.0001). Eighteen patients (72%) were cured by amoxapine only, but failed by vitamin B12. On the other hand, 2 patients (8%) were only responsive to vitamin B₁₂, but not to Amoxapine. Moreover, 2 patients (8%) were both responsive to the two drugs, while 3 patients (12%) failed to neither of them. Only 1 case (4%) was observed sleepiness as the side effect when using amoxapine.

Conclusions: Amoxapine is more effective in the treatment of RE than vitamin B₁₂. The side effects are rare and well tolerated. Amoxapine may become a promising medicine to treat RE in the near future.