Though the population-based data demonstrate equal response to antidepressant medication, there are, of course, compelling reasons to choose a particular medication for a given individual. Primary among predictors of depression remission is previous response to a medication — if a patient has done well before with particular medication, then it should obviously be the first choice should a new episode of depression occur.
A family history of response to a specific antidepressant medication is also a response predictor, and a reason to make that agent a first-line choice for the treatment of depression.
In most cases, however, notably those of new onset depression, there is often no history of either personal or familial response. In these instances, considerations such as ease of administration and potential interaction effects with other medications or medical conditions are important in rational prescribing. The next section of this chapter, however, will be devoted to what is probably the most compelling factor in making a prescription decision: the side-effect profile of the medication.
Numerous texts have been written regarding the side effects of antidepressant medications, and much of the advertising of pharmaceutical companies focuses on the lack of side effects of their particular medication. Though side-effect profile in general should obviously be considered when choosing an antidepressant, there are several side effects that are specific to men, which should be considered by both clinicians and their patients. With males, these are related to sexual functioning, and include changes in libido, erectile dysfunction, and anorgasmia or delayed ejaculation. Table Antidepressant-induced Changes in Sexual Functioning in Males summarizes the potential antidepressant-induced side effects related to sexual functioning in men.
Antidepressant-induced Sexual Side Effects: General Considerations
Untreated affective disorders have long been known to be associated with impaired sexual functioning. Successful treatment of the depression has been shown to result frequently in improvement in or a return to normal sexual functioning.
TABLE Antidepressant-induced Changes in Sexual Functioning in Males
| Changes in libido |
| Changes in erectile functioning |
| Anorgasmia |
| Delayed ejaculation |
| Priapism |
| Penile anesthesia |
| Painful orgasm |
Because of this, differentiating sexual impairment due to depression from that which may be caused by medication is often very difficult. The clinician is obligated to take a very careful history. Often, the time course of changes in sexual functioning can help determine whether it is a primary symptom of depression or due to medication. Cases in which sexual functioning is initially impaired, and continues to be so even after medication treatment has brought about resolution of other neurovegetative symptoms, may also make determination of the cause of impairment difficult. In addition to depression, many other factors that may cause sexual problems which must also be considered. Table Antidepressant-induced Changes in Sexual Functioning in Males outlines some of the potential causes of sexual dysfunction in depressed men.
Another factor that profoundly affects the diagnosis and treatment of sexual dysfunction during depression is the effect of the source of the report of the symptoms. The incidence of sexual problems spontaneously reported by patients during clinical encounters is dramatically less than that reported when patients are directly questioned about sexual problems. Monteiro, Noshirvani, Marks, and Lelliott (1987), in a study evaluating the sexual side effects of clomipramine, a tricyclic anti-depressant used for both depression and obsessive-compulsive disorder, found that while only about one-third of patients with obsessive — compulsive disorder spontaneously reported sexual problems, 96% of patients reported becoming anorgasmic on the medication when directly queried about sexual side effects. Similarly, Montejo, Liorce, and Izquierdo (1996) reported that sexual dysfunction was spontaneously reported by about 2-7% of depressed patients treated with selective serotonin reuptake inhibitors as compared to 55% of patients who reported such symptoms on direct questioning.
It is also extremely important when considering sexual side effects to recognize that patients who are receiving placebos in medication trials typically report significant rates of sexual dysfunction.
TABLE Causes of Sexual Dysfunction in Depressed Men
| Depression |
| Antidepressant-induced side effects |
| Primary sexual dysfunction |
| Medical illness |
| Marital conflict |
| Multifactorial causes |
Though sexual functioning is multidetermined, and is highly correlated with many psychological factors, reports of changes in sexual functioning may be widely reported by patients receiving placebo because of the subjective nature of many of the complaints. Thus, the calculation of rates of sexual dysfunction due to medication should include the rate reported by patients taking the medication less the placebo rate. Most calculations are simply estimates based on small, retrospective series. The bias towards reporting adverse effects of medication also influences the estimates of incidence rates adversely. In sum, the rates of sexual dysfunction induced by antidepressant treatment are unknown.
Antidepressant-Induced Changes in Libido
Almost all of the antidepressant medications have been reported to have an effect on libido in males. These include the monoamine oxidase inhibitors (MAOIs — phenelzine and tranylcypromine), tricyclic antidepressants (TCAs — amitriptyline, imipramine, desipramine, clomipramine, nortriptyline), the selective serotonin reuptake inhibitors (fluoxetine, paroxetine, sertraline), as well as the newer generation antidepressants such as venlafaxine and citalopram. Both buproprion and trazodone have been reported to increase libido above predepression levels, in some cases. However, the prescribing information for buproprion indicates that libido was reported as decreased in about 3% of patients receiving the medication and in about 1.5% of patients receiving placebo, while the reported rate with trazodone was about 1% with a less than 1% report by patients receiving placebo. It has been the experience of the author that, although rare, depressed males treated with the selective serotonin reuptake inhibitors may also report increased libido.
The incidence of sexual side effects in comparison to placebo are typically reported for all phase III medication efficacy trials, along with information about all other side effects which are spontaneously reported. The prescription inserts for most antidepressant medications report decreased libido in approximately 2-5% of patients, and a placebo rate of about 1%. There have been very few placebo controlled studies comparing the sexual side effects of antidepressants. In one study comparing imipramine and phenelzine, Harrison, and Morris (1986) found that decreased libido was reported on direct inquiry in about 30% of patients taking phenelzine and about 20% of patients treated with imipramine, as compared to 10% who were taking a placebo.
With the data that is available at present, the incidence of antidepressant-induced changes in libido is not clear. Based on efficacy trials of antidepressants, the incidence appears to consistently be in the range of 2 — 5%, with an incidence of about 1% related to treatment with placebo. In contrast, studies in which sexual side effects are specifically evaluated have reported much higher rates. What is clear is that for some patients, decreased libido is a substantial problem that warrants either a change in medication or some other type of intervention.
Management of antidepressant-induced decreased libido requires close clinical consultation with the patient being treated. During the evaluation, close attention must be paid to the time course of the development of the dysfunction — libido problems which develop after the initiation of the medication and which persist for several weeks during treatment can be considered to be due to the medication. It is also crucial to work collaboratively with the patient regarding possible treatment options. Some patients, despite a decrease in libido, will opt to continue the antidepressant medication if it has otherwise been effective rather than risk the return of depressive symptoms with a drug holiday or a switch to another medication. Patients who opt to continue with the same medication should be assured that all data suggests return of sexual functioning to baseline once the medication is stopped.
There are several options for those patients who do not wish to continue the same antidepressant. The most obvious is to switch from the antidepressant suspected of causing the libido problems to one in another class. There is some evidence that buproprion may be associated with a lower incidence of decreased libido, making it a reasonable choice in such cases. Two open-label studies involving a switch from either a variety of antidepressant medications or from fluoxetine to buproprion noted an increase in libido with buproprion for those patients who had complaints on their initial antidepressants. Another small study of patients switched from sertraline to nefazodone also noted improvement in libido, suggesting that nefazodone may be associated with fewer libido problems.
Several other recommendations have been made regarding treatment of the decreased libido. The use of 7.5 to 15 mg of neostigmine prior to coitus has been reported to restore libido in some cases, and yohimbine has also been recommended and has been shown to be of benefit in an open trial.
One last option is to plan a drug holiday. However, careful consideration should be given to stopping antidepressant medication given the morbidity associated with depression. In addition, the rather lengthy half-life of many of the newer antidepressants would suggest that a rather long drug holiday would be required before sexual functioning normalized. Moreover, the provision of drug holidays may undermine the physician’s message to the patient that daily compliance with medication is needed to treat depression. Given these risks, the weight of evidence at present would suggest that, for those patients who cannot tolerate a change in libido, a switch to another category of antidepressant medication, particularly buproprion or nefazodone, is indicated. Table Management of Antidepressant-Induced Sexual Side Effects summarizes recommendations for the management of medication-induced sexual side effects.
Antidepressant-Induced Erectile Dysfunction
Historically, the TCAs have been anecdotally associated with reports of erectile dysfunction in depressed males. As with changes in libido, however, case reports abound for nearly all of the antidepressant medications, including imipramine, desipramine, nortriptyline, amitriptyline, fluoxetine, paroxetine, sertraline, trazodone, doxepin, and venlafaxine. As with impairment of libido, erectile dysfunction can also be a symptom of depression, making it difficult to distinguish drug effects. A careful review of the time course of the problem will usually identify the cause.
TABLE Management of Antidepressant-Induced Sexual Side Effects
| Decreased libido |
| Continue the same antidepressant medication if otherwise effective |
| Switch to different class of antidepressant |
| Add Neostigmine before coitus |
| Add yohimbine before coitus |
| Erectile dysfunction |
| Dose reduction |
| Switch to different class of antidepressant |
| Add Bethanechol before coitus |
| Delayed ejaculation |
| Dose reduction |
| Switch to different class of antidepressant |
| Add Cyproheptadine before coitus |
| Add Bethanechol before coitus |
| Add yohimbine before coitus |
The incidence of antidepressant-induced erectile dysfunction is not known. Data from efficacy trials of antidepressant medications suggest that it is fairly infrequent — while case reports are found frequently, erectile dysfunction is rarely reported as a side effect in efficacy trials, meaning that it does not surpass the threshold of 1% incidence during either antidepressant or placebo treatment. Data from the few studies that have specifically examined erectile dysfunction also suggest that the incidence is low. A double-blind, placebo-controlled study of imipramine and phenelzine found minimal evidence that either medication interfered with erectile function. In a double-blind study using nondepressed volunteers, amitriptyline and mianserin (the latter is not currently available in the United States) were found to slightly decrease the magnitude and duration of nocturnal erections as measured by penile tumescence, but there was no reported difference in waking sexual functioning in the exposed subjects.
Treatment options for patients experiencing antidepressant-induced erectile dysfunction are similar to those for decreased libido. There is some evidence that buproprion may be a reasonable alternative antidepressant: a clinical series found that patients who were receiving a variety of antidepressant medications who reported erectile problems reported resolution of the problems with substitution of buproprion. Bethanechol taken prior to intercourse has been reported to be of benefit, though its use has not been empirically evaluated. The available evidence suggests that switching to a different class of antidepressant medication is the best course, and that buproprion may be associated with a lower incidence of erectile dysfunction than other antidepressants (see Table Management of Antidepressant-Induced Sexual Side Effects).
Antidepressant-induced Anorgasmia and Delayed Ejaculation
Although anorgasmia can certainly be induced by antidepressant medication, it is probably more accurate to speak of delayed orgasm, or more specifically in men, delayed ejaculation, than of complete absence of orgasm. Much attention has been given to this issue in the medical press — the selective serotonin reuptake inhibitors in particular have been associated with this side effect. As with other antidepressant-induced sexual side effects, the true incidence of delayed ejaculation is not known. Rates vary greatly, depending on the method by which reports about side effects are elicited. Anecdotally, however, delayed ejaculation does appear to present a greater clinical problem than either loss of libido or erectile dysfunction.
Case reports have suggested all of the selective serotonin reuptake inhibitors are associated with delayed ejaculation. From these case reports, it has been estimated that up to 30% of patients taking an selective serotonin reuptake inhibitor will experience problems with ejaculatory delay. The validity of establishing incidence from retrospective cases, however, makes the estimates of side effect incidence with the selective serotonin reuptake inhibitors suspect. In contrast, the Physician’s Desk Reference (1999), reporting information from efficacy studies in which patient self-report was used to determine the incidence of treatment-emergent side effects, reports an incidence of less than 1% (comparable to placebo) for depressed patients and 7% for obsessive-compulsive patients treated with fluoxetine; 7% for depressed patients and 17% for obsessive — compulsive patients treated with sertraline, and 1.6% for depressed patients and 2.1% for obsessive — compulsive patients receiving paroxetine. Though it is likely that the selective serotonin reuptake inhibitors are associated with a much higher incidence of ejaculatory problems than the TCAs, case reports of such side effects have also been published regarding the use of amitriptyline, desipramine, and nortriptyline. Doxepin and trazodone have also been implicated.
Two additional lines of evidence exist, however, which strongly suggest that the selective serotonin reuptake inhibitors are associated with delayed ejaculation The TCAs (with the exception of clomipramine) have not been systematically studied in the same fashion. In addition to controlled studies of sertraline, several of the selective serotonin reuptake inhibitors have been evaluated as treatments for premature ejaculation, lending credence to their ability to induce delayed orgasm.
Several controlled studies have been conducted in which the sexual side effects of antidepressant medication were evaluated. Harrison and colleagues compared imipramine and phenelzine over six weeks. Questionnaires about sexual functioning were administered prior to treatment and at the end of the treatment trial. Delayed orgasm was reported by 21% of the men taking imipramine, and by 30% of the men taking phenelzine; none of the men taking placebo reported problems.
Sertraline was compared to nefazodone in a controlled double-blinded study of depressed patients. Sixty-seven percent of the men taking sertraline reported emergence of delayed ejaculation with treatment on direct questioning, while there appeared to be no increase in incidence with nefazodone. There was no difference, however, in the reported incidence of changes in libido or erectile functioning. Another study of men with orgasmic problems while taking sertraline assigned patients in double-blinded fashion to either sertraline or nefazodone for eight weeks. Seventy-one percent of patients who continued on sertraline reported continued delayed ejaculation, while only 30% of those who switched to nefazodone reported such problems. Sertraline has also been used to treat premature ejaculation. No controlled trials examining the sexual side effects of fluoxetine and paroxetine have been conducted; however, both have been reported to be beneficial in the treatment of premature ejaculation.
While the true incidence of ejaculatory delay with antidepressant treatment is unknown, it is clearly a clinically significant side effect of the selective serotonin reuptake inhibitors and may occur, though likely less frequently, with other anti-depressant medications as well. In the author’s experience, it is a significant, though not highly prevalent, problem which is spontaneously reported by male patients much more frequently than either decreased libido or erectile dysfunction.
In addition to switching antidepressants, several other treatment strategies have been reported in the literature. There have been some reports of tolerance developing with some of the antidepressants and the effect on ejaculatory dysfunction may be dose related. Several reports have noted that decreasing the dose of medication may be effective in relieving anorgasmia.
There have been several medications that have been used to counteract the delayed ejaculation associated with antidepressant medications. Cyproheptadine at 4 — 8 mg prior to coitus has been reported to be of benefit for patients taking clomipraine, nortriptyline, imipramine, tranlcypromine, fluoxetine, fluvoxamine, and citalopram. Yohimbine at 5.4 to 10.8 mg 1 — 32 hours prior to coitus has also been reported to reverse anorgasmia associated with use of selective serotonin reuptake inhibitors and with clomipramine. Bethanechol given 1 to 2 hours prior to coitus has been reported to reduce ejaculatory dysfunction when used with impramine. Case reports describing successful treatment of selective serotonin reuptake inhibitor-induced anorgasmia have also been published regarding amantadine, buproprion, dextroamphetamine, and buspirone. A small open trial of buproprion also suggests that it may be effective in the treatment of delayed ejaculation induced by other antidepressants.
Based on the available evidence, it appears that delayed ejaculation and anorgasmia are relatively common side effects of antidepressant treatment, particularly with the selective serotonin reuptake inhibitors and clomipramine. A trial of a decreased dose or a switch to another class of antidepressants is usually indicated. There is some evidence that buproprion is associated with a lower incidence of sexual dysfunction, and switching to buproprion, from selective serotonin reuptake inhibitors in particular, may be effective in relieving the dysfunction .
Other Sexual Side Effects Induced by Antidepressant Medications
Among other antidepressant-induced side effects, priapism, though apparently quite uncommon, is the most serious. Trazodone has been reported to be associated with priapism, though the incidence is unknown. A single case report also describes priapism associated with paroxetine. Painful ejaculation has been reported with imipramine and clomipramine. Penile anesthesia has been reported with fluoxetine.
In sum, there are a variety of sexual side effects which may result from use of antidepressant medication in males. The incidence of these dysfunctions is unknown, but it does appear that they may be more common during treatment with the selective serotonin reuptake inhibitors and that delayed ejaculation is the most clinically significant of the reported side effects. The incidence is not great enough, however, that it should outweigh other considerations noted above which are associated with a positive response, namely, previous response to a particular antidepressant or a familial response to a particular antidepressant.
In those cases in which intolerable sexual side effects do develop, rational prescribing suggests either a trial of a reduced dose of medication or a switch to a different class of antidepressant. For males, buproprion and nefazodone appear to be associated with a lower incidence of sexual side effects. Other strategies, such as the addition of medications to counteract the sexual dysfunction caused by the antidepressant, may also be tried, but there is a lack of compelling empirical data supporting their use.