Selective Serotonin Reuptake Inhibitors

The SSRIs first were prescribed in the United States in the late 1980s and are now the most widely prescribed class of antidepressant medications. Today, over two-thirds of the prescriptions for SSRIs are written by non-mental health practitioners.

At this time, the Food and Drug Administration (FDA) has approved the following SSRIs for the treatment of depression:

Prozac (fluoxetine)
Paxil (paroxetine)
Zoloft (sertraline)
Celexa (citalopram)
Lexapro (escitalopram)
SSRI Side Effects
Sexual dysfunction is common side effect of antidepressants; however it can also be a symptom of depression. For this reason, it is important to assess sexual functioning before starting any medication.

Problems with sexual function can occur during any stage of sexual functioning, including

Arousal/Erectile Dysfunction
Most antidepressants stimulate 5-HT (Serotonin) receptors, which can cause reduce dopamine neurotransmission.

Exercise immediately prior to sexual activity may improve sexual desire and global sexual function in women with anti-depressant-induced sexual dysfunction. The same study showed that simply scheduling regular sexual activity improved orgasm function.
SSRI Weight Gain
Studies have documented problems of unwanted weight gain with SSRIs. Weight gain occurs most often after prolonged treatment with SSRIs although weight loss is common during the first few weeks of treatment.

For many patients, weight gain is an intolerable side effect. Meta-analyses have shown that although weight gain is a common side effect of antidepressants, the average weight gain per patient is small. For those patients who experience significant weight gain, it is likely that multiple factors in addition to drug mechanism are contributory, including genetic predisposition.

If significant weight gain occurs, it is typically gradual over the course of many months, and does not appear to depend on the dosage.

A weight change of 7% from baseline is considered clinically significant in a healthy adult. A 7% weight change translates to 11 pounds for a 150 pound person. Patients are willing to gain only an average of 5.37 pounds as a side effect of medication use in the treatment of a non-life-threatening psychiatric condition. Therefore, in this example (a 150 pound person), an approximate 5 pound weight difference exists between clinical significance (the area of practitioner’s concern) and the weight gain patients are willing to tolerate from SSRIs. Discontinuation of antidepressants occurs 62% of the time during the acute phase of treatment and 66% during the late phase of treatment due to side effects.

More importantly, it must be acknowledged that there are no definitive studies that clearly demonstrate the use of SSRIs cause weight gain in a majority of participants. However, many of the current studies demonstrate weight gain in some subjects, especially during long term treatment. Treatment for clinical depression is essential and should be continued for at least 1 year after response to prevent relapse and provide maintenance treatment.

Weight gain caused by SSRIs can affect a patient’s physical health, appearance, self-confidence, self-esteem and feelings of self-worth. A positive body perception is an important part of self image.
SSRI Sedation
Sedation is more common with medications that have histamine-blocking or alpha receptor blocking. Although, all SSRIs can cause sedation, the most sedating SSRIs are Luvox (fluvoxamine), Paroxetine (Paxil), and Citalopram (Celexa).

If possible, sedation may be best managed by adjusting the time of dosing to correspond with bedtime. Increasing daytime exercise can also be beneficial. If the SSRI is very effective, it may be worth adding a stimulating medication such as Wellbutrin, Provigil, or Strattera. If dosing adjustments and augmentation are not beneficial, a switch to a non-sedating antidepressant may be necessary.
SSRI Activation
Activation from SSRIs can be in the form of anxiety, jitteriness, insomnia, or agitation/irritability. It usually subsides within the first few weeks of treatment, but it can be very distressing. Patients with antidepressant-induced activation should not reduce their medication, but may need a temporary dosage reduction or a more gradual increasing of the dosage.

Of the SSRIs, Prozac (fluoxetine) is the most likely to cause activation, following by Zoloft (sertraline). The latter is due to the effects Zoloft has on dopamine receptors. Although activation can be troublesome, it can be helpful for those with severe fatigue, low motivation, or excessive sleepiness.
SSRI Gastrointestinal Side Effects
In the short term, the most common side effects from SSRIs are nausea, vomiting, and diarrhea.

Management to decrease nausea include

lowering the dose
dividing the dose
taking the dose with food
taking OTC medications (Pepto-Bismol)

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