Because Mr. Q had no other past erectile problems, we strongly suspected his priapism was medication-induced. He reported he had neither been drinking nor taking illicit drugs or other medications when the erection occurred.
Mr. Q also was convinced that the trazodone had caused the sustained erection. He said, however, he was never informed that priapism was a potential side effect of that medication.
Would you resume trazodone, switch to another sleep-promoting or antianxiety medication, or consider other therapy?
Dr. Freed’s and Dr. Muskin’s observations
The prevalence of priapism is not known, although yearly estimates range from 1/1,000 to 1/10,000 patients who take trazodone.2
Trazodone, an alpha-adrenergic blocker, is most commonly implicated among psychotropics in causing priapism.2 Blockade of alpha-adrenergic receptors in the corpora cavernosa creates a parasympathetic imbalance favoring erection and prevents sympathetic-mediated detumescence. Histaminic, beta-adrenergic, and adrenergic/cholinergic components may also contribute to priapism.
Other medications associated with priapism include antipsychotics, antihypertensives, anticoagulants, some antidepressants, and antiimpotence medications injected into the penis.
Low-flow priapism can also be caused by systemic disorders (Table 2), including malignancies—particularly when a tumor has infiltrated the penis—and carcinoma of the bladder or prostate. Prostatitis has been implicated in some cases.
Table 2
Systemic illnesses and conditions that can cause priapism
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Because Mr. Q has had at least one priapism episode, we would avoid prescribing any agent with alpha-adrenergic blocking properties.
Could Mr. Q’s response to trazodone have been dose-related? How would you ensure that the patient understands a medication’s risks?
Dr. Freed’s and Dr. Muskin’s observations
No findings indicate that trazodone-related priapism is dose-related. Several cases of men developing sustained priapism—resulting in permanent injury and impotence—have been reported after initial dosages of 25 and 50 mg/d.1,4,7 In a study using the FDA Spontaneous Reporting System, Warner et al found that priapism with trazodone was most likely to occur within the first month of treatment and at dosages 150 mg/d.7 Still other reports indicate that new-onset priapism may occur after years of treatment.3
Sample informed consent form for patients taking priapism-causing drugs
Priapism refers to a painful, prolonged erection that occurs in the absence of sexual stimulation or does not remit after sexual activity.
Several psychotropic drugs, most often trazodone (Desyrel), can cause priapism. This can occur even if the medication is taken at a low dosage or taken only once.
Individuals who have had prior prolonged erections are more susceptible to priapism. Certain medical conditions, many medications, and substance abuse can also increase the risk of priapism. This effect may be additive.
If the erection lasts more than 2 hours, the patient must obtain emergency care. Impotence has been reported after erections lasting 4 hours or longer.
Drug-induced priapism leads to malpractice judgment
Mr. Z filed suit in Pennsylvania state court against his pharmacy and emergency room doctor. He alleged that he developed priapism after taking one dose of trazodone for disordered sleep. He subsequently became impotent.
Christopher T. Rhodes, PhD, a professor of pharmaceutics at the University of Rhode Island, was an expert witness in that 2000 trial. According to Dr. Rhodes, court testimony revealed that the ER physician had not informed the patient about the possibility of priapism or about the need to obtain emergency treatment for a sustained erection. Dr. Rhodes adds that the pharmacy handout for trazodone did not list priapism as a possible adverse effect.
The court ruled in favor of the patient, judging that the “quality of advice” was inadequate. The patient was awarded an unspecified sum.
Despite its association with priapism, trazodone is used frequently in men and is a popular medication for disordered sleep. Nierenberg et al demonstrated improved sleep in 67% of depressed patients with insomnia who received trazodone either for depression or disordered sleep.8
When prescribing a priapism-causing agent, make sure the patient understands that erectile effects—though rare—can occur. Consider giving patients an informed consent form explaining the association between psychotropics and priapism and the potential long-term health implications (Box 1). Include the form in the patient’s record for documentation in the event of a malpractice lawsuit (Box 2).
FURTHER TREATMENT: Learning how to cope
Self-hypnosis/relaxation therapy was initiated to address Mr. Q’s anxiety and insomnia. The patient quickly learned the hypnosis techniques and his anxiety/insomnia symptoms began to resolve almost immediately.