To the Editor: Levomepromazine, one of phenothiazines, has sedative properties and is used for the treatment of schizophrenia and schizoaffective disorder.¹ Male patients with schizophrenia treated with antipsychotics can suffer from a variety of sexually disabling side effects,² including retrograde ejaculation. Retrograde ejaculation has been reported in association with the use of risperidone.³ Presented here is the case of a patient with schizophrenia who developed retrograde ejaculation in association with levomepromazine.

A 29-year-old man, who met DSM-IV criteria for schizophrenia, had never experienced ejaculatory problems. He had his first psychotic episode, including delusions, auditory hallucinations, and ideas of reference at age 25, and was successfully treated with risperidone, 2 mg/day, without any major adverse effects. At age 28, he was admitted to a psychiatric inpatient ward after a second psychotic exacerbation of the disorder. At that time, the administration of olanzapine and leveomepromazine was initiated at a dose of 5 mg/day and 25 mg/day, respectively, and, 3 weeks later, they were increased to 20 mg/day and 100 mg/day, respectively. He was discharged home 2 months after starting levomepromazine treatment and then reported a complete failure to emit semen but a normal desire, erection, and sense of orgasm. Medications were olanzapine and levomepromazine at 20 mg/day and 150 mg/day, respectively. He was referred to the urology department, and sperm presence in the post-ejaculatory urine sample confirmed a diagnosis of retrograde ejaculation. A reduction of levomepromazine dose from 150 mg/day to 25 mg/day was associated with restoration of anterograde ejaculation, and the patient has subsequently been maintained on 20 mg/day of olanzapine without any ejaculatory problems.

Retrograde ejaculation occurs in 75% of male patients who have undergone transurethral resection of the prostate.⁴ Also, α₁-adrenergic receptor antagonists are reported to induce retrograde ejaculation.^3,5 Blockade of α_1A-adrenergic receptors is supposed to relax the smooth muscle of the bladder neck, leading to the backflow of seminal fluid from the prostatic urethra into the bladder.⁵ Levomepromazine has antagonistic effects on both α₁-adrenergic and dopamine D₂ receptors, which underlie its sedative properties.¹ In the present case, the antagonistic effect on α₁-adrenergic receptors induced by levomepromazine might contribute to the occurrence of retrograde ejaculation. Sexual side effects could interfere with the drug compliance of patients with schizophrenia but are still frequently overlooked by clinicians.² The case presented here suggests the need for monitoring of retrograde ejaculation, one of the sexually disabling side effects, after the administration of levomepromazine.