Gastrointestinal effects SSRIs

Citalopram is a selective serotonin re-uptoke inhibitor (SSRI). These tend to have fewer ontimuscarinic effects than tricyclic antidepressant (TCA) drugs, such as dry mouth and constipation however, SSRIs tend to cause gastrointestinal effects, such as nausea and vomiting. MAOIs are monoamine oxidase inhibitors. 

Sedative effects, particularly with trazodone, can be quite pronounced. Thus, it is not surprising that the treatment of insomnia is currently the primary application of trazodone. The gastrointestinal effects appear to be dose-related and are less pronounced than those seen with SNRIs or SSRIs. Sexual effects are uncommon with nefazodone or trazodone treatment as a result of the relatively selective serotonergic effects of these drugs on the 5-HT2 receptor rather than on... 

SSRIs are the drugs of choice for PD. All SSRIs have demonstrated effectiveness in controlled trials, with 60% to 80% of patients achieving a panic-free state.28,48,49 With similar efficacy reported and no trials comparing SSRIs with other SSRIs, selection generally is based on pharmacokinetics, drug interactions, side effects, and cost differences (see Chap. 35 for more discussion). The most common side effects of SSRIs include headaches, irritability, nausea and other gastrointestinal complaints, insomnia, sexual dysfunction, increased anxiety, drowsiness, and tremor.49 SSRIs should not be discontinued abruptly to avoid a withdrawal syndrome characterized by dysphoric mood, irritability, and agitation. 

Be Patient. Probably the simplest way to manage a side effect is just to wait it out. Granted, this is easier said than done, but sometimes, a side effect that occurs upon starting a new medication resolves within a few days. For example, this is typically the case with the gastrointestinal side effects often experienced by patients prescribed serotonin renptake inhibitors. Within a few days, a patient beginning a SSRI will become adjnsted to the increased levels of serotonin and the stomach queasiness resolves. We find that when advising patients of potential side effects, it helps to reassnre them that certain side effects will likely be short-lived. 

Selective serotonin re-uptake inhibitors (SSRIs) and tricyclic antidepressants are equally effective. Hov/ever, SSRIs tend to have fewer antimuscarinic side-effects and are less cardiotoxic in case of overdosage. SSRIs tend to cause gastrointestinal side-effects. Both SSRIs and tricylic antidepressants exhibit a time lag before the action of the antidepressants becomes effective. 

Nausea is a common early side effect of all SSRIs. Early nausea is probably attributable to the stimulation of serotonin type 3 (5-HT3) receptors in the gastrointestinal tract, which downregulate after several weeks of treatment. Hence this side effect is both dose dependent and transient. Some patients report less nausea if they take the medication with food. Although rarely needed, medication that blocks the 5-HT3 receptor (e.g., ondansetron) can be used to reduce SSRI-induced nausea. 

The side-effect profile of venlafaxine is similar to that of SSRIs and includes gastrointestinal symptoms, sexual dysfunction, and transient discontinuation symptoms. Like the SSRIs, venlafaxine does not affect cardiac conduction or lower the seizure threshold. In most patients, venlafaxine is not associated with sedation or weight gain. Side effects that differ from those of SSRIs are hypothesized to be related to the increased noradrenergic activity of this drug at higher doses these side effects are dose-dependent anxiety (in some patients) and dose-dependent hypertension. 

The SSRIs, venlafaxine, or nefazodone may be reasonable alternatives to earlier generation antidepressants because of their less problematic side effect profiles (486). The propensity to increase activity, the lack of sedation, gastrointestinal symptoms, and alterations in blood pressure are potential complications, however. Given AIDS-induced altered metabolism, for many of these agents, TDM may be helpful in establishing an effective, nontoxic dose. 

The adverse effects of the most commonly prescribed antidepressants—the SSRIs—can be predicted from their potent inhibition of SERT. SSRIs enhance serotonergic tone, not just in the brain but throughout the body. Increased serotonergic activity in the gut is commonly associated with nausea, gastrointestinal upset, diarrhea, and other gastrointestinal... 

Antidepressants do not appear to elevate mood in healthy volunteers (see Chapter 10), but neither, as we have seen, is there good evidence that they do so in depressed patients. Although reports of effects of SSRIs suggest that effects on sleep may sometimes differ between patients and volunteers (Mayers Baldwin 2005), in general side effects of antidepressants in patient trials are consistent with those found in healthy volunteers. For example, tricyclics show sedation and cognitive impairment (Deptula Pomara 1990 Herrmann McDonald 1978), while SSRIs show gastrointestinal upset and drowsiness in both patients and volunteers (Dumont et al. 2005). 

Q13 Patients who take SSRIs might develop gastrointestinal disturbances such as dyspepsia, nausea and vomiting, weight gain, headaches because of the vasodilator effects of serotonin in some patients insomnia may occur. 

The major advantages of SSRIs over the tricyclic antidepressants are their less pronounced anticholinergic adverse effects and lack of severe cardiotoxicity. However, some studies have shown some degree of nervousness or agitation, sleep disturbances, gastrointestinal symptoms, and perhaps sexual adverse effects more commonly in patients treated with SSRIs than in those treated with tricyclic antidepressants. SSRIs may also be associated with an increased risk of suicide, particularly in children under 16 (9). 

There seems to be little difference between SSRIs with respect to frequency and severity of adverse effects. The most common adverse effects are gastrointestinal disturbances (nausea, diarrhea/loose stools, constipation incidence 6-37%), nervous system effects (insomnia, somnolence, tremor, dizziness and headache 11-26%), and effects on the autonomic nervous system (dryness of the mouth and sweating 9-30%) (2,10). Weight gain or weight loss have been documented relatively infrequently (2). A high frequency of sexual disturbances has been... 

Gastrointestinal adverse effects are one of the major disadvantages of SSRIs. The most common is nausea, and the incidence is said to be 20% or more for paroxetine (45,46), sertraline (47), fluvoxamine (5), fluoxetine (48), and citalopram (10,49). Although nausea can lead to drug withdrawal, it usually disappears after a few weeks. Other gastrointestinal symptoms that occur commonly with fluoxetine and sertraline are loose stools and diarrhea (47,48,50), while constipation has been more often reported with fluvoxamine (5) and paroxetine (45,46). 

Gastrointestinal adverse effects are one of the major disadvantages of SSRIs. The most common is nausea, and the incidence is said to be 20% or more for citalopram (19,20). 

Adding mirtazapine s 5FIT3 antagonism to venlafaxine or SSRIs may reverse drug-induced nausea, diarrhea, stomach cramps, and gastrointestinal side effects... 

Often a preferred treatment of anxious depression as well as major depressive disorder comorbid with anxiety disorders Withdrawal effects may be more likely than for some other SSRIs when discontinued (especially akathisia, restlessness, gastrointestinal symptoms, dizziness, tingling, dysesthesias, nausea, stomach cramps, restlessness)... 

Lithium augmentation of antidepressants is a well-established treatment for resistant depression and is usually well tolerated with all classes of antidepressants, although there have been a few reports of the serotonin syndrome with SSRIs (474). It is possible that shared adverse effects could be magnified by combining lithium with various antidepressants (for example tremor, weight gain, gastrointestinal upset). Hyponatremia secondary to the SIADH has been linked to SSRIs and tricyclic antidepressants, especially in elderly patients, and could predispose to lithium toxicity. 

Adverse Effects. Typical antidepressant doses of SSRIs can cause side effects of insomnia, jitteriness, restlessness, and agitation, and lead to drug discontinuation in patients with panic disorder. Transient gastrointestinal disturbances occur more frequently with SSRIs than with TCAs. Thus low initial SSRI doses should be prescribed. Sleep disturbances, headaches, and sexual dysfunction often are problematic. ... 

Clomipramine, fluvoxamine, sertraline, and fluoxetine are approved by the FDA for treatment of OCD in children and adolescents. Childhood and adult OCD appear to respond similarly to drug therapy. The SSRIs appear to be effective and well tolerated in treatment of OCD in children and are generally considered first-line agents. Treatment with an SSRI produces a favorable response in 75% of children and adolescents with OCD. A combination of SSRIs and CBT is preferred in most cases. In children, the most commonly described side effects of SSRI therapy include nausea, headache, tremor, gastrointestinal complaints, drowsiness, akathisia, insomnia, disinhibition, and agitation. Clomipramine was significantly better than placebo in the treatment of OCD in children and adolescents, with 75% of patients having a moderate to marked improvement. Clomipramine was also more effective than desipramine in children and adolescents. ... 

Figure 4.1 Second generation antidepressants, some of which are listed here, have the fewest side effects of drugs for depression treatment. Except for Amoxapine and Venlafaxine, the incidence of sexual dysfunction is very low, compared to the high probability of sexual dysfunction occurring with TCAs and SSRIs (see Figures 2.1 and 3.2). However, unlike TCAs and SSRIs, gastrointestinal upset can occur more frequently with second generation antidepressants.

Despite its proven efficacy, Effexor is not a perfect drug. There are some side effects associated with it, the most common being drowsiness and gastrointestinal upset. Less commonly reported symptoms are nervousness, dry mouth, and sexual dysfunction (although much less sexual dysfunction than SSRIs). 

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