Which medication is most likely causing sexual dysfunction in this patient?

Identifying the Medication Most Likely Causing Sexual Dysfunction

Quetiapine is most likely causing the patient's sexual dysfunction, with gabapentin and clonazepam as other significant contributors. 1

Medication Analysis by Sexual Dysfunction Risk

High Risk Medications

1. Quetiapine (50mg)

   • Directly associated with sexual dysfunction through prolactin elevation
   • FDA label specifically lists "impotence" and "dyspareunia" as urogenital adverse effects 1
   • Hyperprolactinemia can impair gonadal steroidogenesis affecting reproductive function in both sexes 1

2. Gabapentin (200mg)

   • Can cause total sexual dysfunction (loss of libido, anorgasmia, and impotence) even at low doses of 300mg 2
   • Case reports document dose-dependent sexual dysfunction

3. Clonazepam (0.75mg)

   • Benzodiazepines are known to cause sexual dysfunction through CNS depression

Moderate Risk Medications

1. Mirtazapine (7.5mg)

   • Has lower rates of sexual dysfunction (24.4%) compared to SSRIs (58-73%) 3
   • Generally considered more sexually-sparing than many antidepressants

2. Bupropion (75mg SR)

   • Actually has a favorable sexual side effect profile
   • Often used to treat sexual dysfunction caused by other antidepressants 4, 5
   • American College of Physicians recommends bupropion as preferred initial treatment for depression due to its favorable sexual side effect profile 6

Low Risk Medications

1. Tadalafil (5mg)

   • Used to treat erectile dysfunction rather than cause it
   • Would be counteracting any sexual dysfunction

2. Other medications

   • Thyroxine, pantoprazole, domperidone, empagliflozin, fenofibrate, lemborexant, melatonin CR, and nutraceuticals have minimal documented sexual side effects compared to the above medications

Mechanism of Sexual Dysfunction

Quetiapine likely causes sexual dysfunction through:

1. Elevation of prolactin levels, which suppresses hypothalamic GnRH 1
2. Reduced pituitary gonadotrophin secretion
3. Impaired gonadal steroidogenesis 1

This can manifest as:

• Decreased libido
• Erectile dysfunction in males
• Impaired lubrication in females
• Orgasmic difficulties

Management Considerations

If addressing the sexual dysfunction:

1. Consider dose reduction or medication switch:

   • Quetiapine could potentially be switched to a more sexually-neutral antipsychotic
   • Gabapentin dose could be reduced if clinically appropriate

2. Medication review:

   • During sexual counseling, it's beneficial to review medications to consider impact on sexual function 7
   • Encourage the patient to report side effects related to sexual activity 7
   • Consider changing medication dosage or type to minimize impact on sexual function 7

3. For males with antidepressant-induced erectile dysfunction:

   • The patient is already on tadalafil which should help with erectile function 4

4. For diabetic patients:

   • Note that diabetic autonomic neuropathy (if present with empagliflozin use) may also contribute to sexual dysfunction 7

Conclusion

While multiple medications could be contributing to sexual dysfunction, quetiapine is most likely the primary cause due to its documented effects on prolactin levels and sexual function. Gabapentin and clonazepam are also significant potential contributors. Careful medication review and potential adjustment of these medications could help improve the patient's sexual function.