Can Remeron (mirtazapine) cause priapism?

Mirtazapine (Remeron) and Priapism Risk

Mirtazapine (Remeron) is not commonly associated with priapism, unlike antipsychotics and certain other psychotropic medications that have significant alpha-adrenergic blocking properties.

Mechanism and Risk Assessment

Priapism is a urologic emergency defined as a persistent, painful erection lasting more than 4 hours without sexual stimulation. The primary mechanism for medication-induced priapism is alpha-1 adrenergic receptor blockade in the corpora cavernosa of the penis 1.

• Mirtazapine has a different pharmacological profile compared to medications commonly associated with priapism:

  • It acts primarily as an alpha-2 adrenergic antagonist and serotonin 5-HT2/5-HT3 receptor blocker 2
  • It lacks significant alpha-1 adrenergic blocking properties that are typically responsible for priapism

• Medications with high priapism risk:

  • Antipsychotics (account for approximately 50% of drug-related priapism cases) 1
  • Trazodone (antidepressant with strong alpha-1 blocking properties)
  • Certain antihypertensives and alpha-blockers

Evidence on Mirtazapine and Sexual Function

Research suggests mirtazapine may actually improve sexual function rather than cause priapism:

• A study of depressed patients taking mirtazapine found improvements in sexual desire, arousal, and orgasm satisfaction in both men and women 2
• Mirtazapine's 5-HT2 blocking properties may counteract the sexual dysfunction commonly seen with other antidepressants 2

Clinical Implications and Management

If a patient on mirtazapine experiences priapism (which would be extremely rare):

1. Immediate discontinuation of the medication and urgent urological consultation is required 3
2. First-line treatment involves intracavernosal phenylephrine (100-500 μg/mL), administered in 1 mL injections every 3-5 minutes 3
3. If pharmacologic measures fail, aspiration with or without irrigation and potentially surgical intervention may be necessary 3

Monitoring and Patient Education

• While priapism risk with mirtazapine is minimal, patients should be informed about:
  • The signs of priapism (painful, persistent erection)
  • The need to seek immediate medical attention if an erection lasts >4 hours
  • The potential for permanent erectile dysfunction if priapism is not treated promptly

Alternative Considerations

For patients with a history of priapism who require antidepressant therapy:

• Mirtazapine may actually be a safer choice compared to other antidepressants with stronger alpha-1 blocking properties
• Amisulpride is currently the only antipsychotic without alpha-adrenergic affinity and is preferred in patients with a history of priapism 4

Key Points for Clinicians

• Priapism is a rare but serious adverse effect primarily associated with medications having alpha-1 adrenergic blocking properties
• Mirtazapine's pharmacological profile makes it an unlikely cause of priapism
• Time is critical in managing priapism, with treatment efficacy decreasing after 48 hours and significant risk of erectile dysfunction after 18 hours 3
• Patients with a history of prolonged erections are at higher risk for developing priapism with any medication 1

In conclusion, while monitoring for rare adverse effects is always prudent, priapism is not a significant concern with mirtazapine therapy compared to other psychotropic medications.