Sexual Dysfunction

(1)

Departments of Internal Medicine & Psychiatry, Yale University School of Medicine, New Haven, CT, USA

The prevalence of sexual dysfunction (SD), including mild, moderate, and severe dysfunction is estimated as high as 50% in both men and women and increases with age [1, 2].

Pathology

Disruption of sexual function can occur in any stage of the sexual cycle—desire, arousal, and ejaculatory phases. The most common SD in men is erectile dysfunction and can be caused by any factor that interferes with vascular and neural innervation to the penis. In women, the dysfunction can manifest in any phase including the desire/arousal phase.

Etiology

Each phase of sexual function is distinct and the particular dysfunction depends on the etiology. However, in clinical practice, patients present with dysfunction across phases and a clear distinction is not easily made.

Common causes of sexual dysfunction seen in practice are psychological problems (performance anxiety and relationship problems), recreational substances (tobacco, alcohol), obesity, diabetes, cardiovascular disease, liver or renal dysfunction, advanced age (postmenopausal, testosterone deficiency), and medications. Underlying depressive or anxiety disorders frequently cause sexual dysfunction.

The table in appendix lists examples of etiologies associated with each stage of sexual dysfunction.

Psychotropic Medications and Sexual Dysfunction

Medications may affect one sexual cycle phase more than others but typically the phases are interdependent and generally patients complain of side effects across phases. Men commonly complain of decreased libido and erectile dysfunction . Women commonly complain of decreased libido. Both men and women usually have decreased arousal and delayed orgasm, which may only be elicited on detailed questioning.

Even though medications may affect one sexual phase more than the other, generally patients present with dysfunction across phases.

All three major neurotransmitters , dopamine, serotonin, noradrenaline, affect sexual function. Agents that affect dopamine and serotonin are more commonly implicated in SD.

Prevalence of psychotropic-related SD is highly variable [3] and unreliable as many studies do not differentiate from SD caused by the underlying illness; also many are based on self-reported SD, which is likely lower. SD is reported anywhere from 20 to 80% across studies, it is likely in the 30–50% range. It may be slightly more prevalent in men than women [4].

SD appears to be dose related. It occurs early in treatment. It is reversible upon stopping the medication though there are case reports of persistent SD post-SSRI treatment [5]. Tolerance to this side effect usually does not develop and it only rarely resolves with time if medication is continued.

Sexual dysfunction from psychotropic medications is dose related, occurs early in treatment, and usually reverses when medication is stopped.

Rare side effects reported with psychotropic medications are priapism (trazodone, some antipsychotics), painful ejaculation (tricyclic antidepressants), and spontaneous orgasms (serotonergic antidepressants) [4]. Priapism is discussed in more detail in Chapter 45.

Antidepressants

While there are no reliable rates of SD between different classes of antidepressants, strongly serotonergic agents are associated with higher rates of SD. Activation of 5HT2 receptor is thought to impair sexual function while activation of 5-HT1A may enhance sexual function. There is some suggestion that men commonly experience decreased desire, ejaculatory dysfunction, and delayed orgasm whereas women experience decreased arousal. See table for likelihood of SD with different antidepressants based on available evidence.

Phosphodiesterase inhibitors (PDE-5i) have shown efficacy in improving ejaculatory function and orgasm in men and there is some evidence to suggest a positive effect in women also. The effect on libido is smaller. Bupropion as an adjunctive therapy has shown equivocal benefit. Many other pharmacological agents such as buspirone, stimulants, dopamine agonists, antihistamines, and plant extracts have been studied but show mixed or negative results [6].

Antidepressants and sexual dysfunction

High risk	SSRIs—paroxetine > sertraline > escitalopram > venlafaxine > desvenlafaxine > fluoxetine > fluvoxamine > citalopram > duloxetine
Moderate risk	Tricyclic antidepressants, monoamine oxidase inhibitors
Low likelihood	Mirtazapine, bupropion

Generally strongly serotonergic antidepressants are associated with higher rates of sexual dysfunction.

Antipsychotics

Prolactin elevation due to dopamine blockade is thought to be the predominant mechanism in antipsychotic-induced SD but anticholinergic and alpha-adrenergic antagonistic effects also contribute. Retrograde ejaculation is associated with antipsychotics that have alpha adrenergic antagonistic activity. More commonly, men experience ejaculatory dysfunction and both men and women experience orgasmic dysfunction. Evidence comparing rates of SD among different antipsychotics is lacking. See table for grading of antipsychotics based on limited evidence.

There is some evidence for efficacy of PDE-5i for treatment of antipsychotic-induced SD [7]. Dopamine agonists have also been suggested as potential adjuncts but there is little evidence to support this.

Antipsychotics and sexual dysfunction

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