US Pharm. 2016;41(11):13-14.

Most Commonly Used Antidepressants

Selective serotonin reuptake inhibitors, or SSRIs, are a group of drugs approved for use in the treatment of depression. Many of the medications in this category are also approved for use in anxiety disorders such as generalized anxiety, panic disorder, social anxiety, obsessive-compulsive disorder (OCD), and posttraumatic stress disorder (PTSD). SSRIs work by increasing the amount of serotonin in the brain. Serotonin is a brain chemical that improves mood. SSRIs are safer and have fewer side effects than older antidepressants. Unlike most antianxiety medications, they are not addictive. These medications have also shown activity in treating other conditions for which they are not currently approved, such as migraine and fibromyalgia.

Also Approved for the Treatment of Anxiety Disorders

Selective serotonin reuptake inhibitors (SSRIs) are the most frequently prescribed antidepressants. SSRIs are called selective because they affect serotonin rather than other chemicals in the brain. These drugs block the reuptake (removal) of serotonin, which keeps the level of serotonin balanced and helps regulate mood.

SSRIs Affect Serotonin Levels in the Brain

There are currently seven SSRI drugs on the market in the United States (TABLE 1). These medications are generally safer than older antidepressants, with fewer side effects and drug interactions. In general, SSRIs have received approval from the FDA as safe and effective in the treatment of major depressive disorder. Many are also approved for anxiety disorders such as panic disorder, generalized anxiety disorder, and social anxiety disorder. Certain drugs in this category are also approved for use in obsessive-compulsive disorder (OCD), posttraumatic stress disorder (PTSD), premenstrual dysphoric disorder (PMDD), and bulimia.

SSRIs are slightly different in how quickly they work and how long they stay in the body. Their side effects also differ somewhat. Common side effects include nervousness, problems sleeping, headache, dry mouth, nausea, changes in sexual desire, and erectile dysfunction. Nausea can be reduced by taking the medicine with food. Nervousness and insomnia can be reduced by taking the drug just before bedtime. Most adverse effects of SSRIs gradually disappear after a few weeks of therapy.

SSRIs show an effect after 4 to 6 weeks of daily use. If one drug in this category does not work in a particular person, another drug may work.

SSRIs can interact with other medications that also cause increased serotonin levels in the brain. These include other antidepressants, prescription opioids, migraine medications, cocaine, and St. John’s wort (a medicinal herb used to treat depression). If one or more of these drugs are used with an SSRI, a high level of serotonin in the brain can result in serotonin syndrome. Symptoms such as extreme anxiety, tremors, fast heartbeat, sweating, and confusion require emergency care.

Although SSRIs are not addictive, stopping them abruptly can cause symptoms that mimic withdrawal. A doctor should provide guidelines for slowly tapering off an SSRI to avoid symptoms of nausea, dizziness, and fatigue.

Warnings and Precautions

Generally, SSRIs are safe and carry few risks. All antidepressants, including SSRIs, can cause an increase in suicidal thoughts or actions, especially in young adults beginning therapy or changing dosages. SSRIs can increase the risk of gastrointestinal bleeding when taken with nonsteroidal anti-inflammatory drugs (NSAIDs), such as aspirin or ibuprofen, or with drugs with a side effect of bleeding, such as warfarin. Taking a drug that lowers stomach acid may be helpful. Women who are considering pregnancy, who are pregnant, or who are breastfeeding should discuss the potential effects of SSRIs on the fetus or infant and consider a break in therapy to avoid exposure.

Several SSRIs are being studied for diseases other than those specified in their FDA labeling. Some of the uses that have shown promise include prevention of migraine, pain of diabetic neuropathy, fibromyalgia, vasovagal syncope (fainting), and premature ejaculation.

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