Viibryd Side Effects

Viibryd Side Effects - Serotonin Syndrome

Viibryd (vilazodone hydrochloride) Update: New FDA Warning

In January 2017, the US Food and Drug Administration (FDA) issued a mandatory label update for Viibryd (vilazodone hydrochloride), requiring that the label now include a warning stating the risk of serotonin syndrome. The new warning states: “Serotonin Syndrome: Increased risk when co-administered with other serotonergic agents (e.g. SSRI, SNRI, triptans, amphetamines), but also when taken alone.”

What is serotonin?
Serotonin is a neurotransmitter located primarily in the gastrointestinal (GI) tract that performs a wide range of important functions throughout the body, many of which still are not well understood. In the central nervous system (CNS), serotonin helps in the regulation of mood, appetite, sleep, memory, and learning. In the blood, the release of serotonin plays an important role in stimulating the coagulation of platelets. In the gut, serotonin controls motility, or the contraction of the muscles in GI tract.

Serotonin Syndrome. According to the US National Library of Medicine, serotonin syndrome (SS) is a drug-induced condition resulting in an excess of serotonin in the body. Most frequently, serotonin syndrome occurs when multiple medications impacting the body’s serotonin levels are taken simultaneously, causing the buildup of unhealthy amounts of the naturally occurring neurotransmitter. However, as the FDA warns, serotonin syndrome also has been diagnosed in patients taking Viibryd by itself.

Serotonin is found primarily in the gastrointestinal tract, where approximately 90% of the body’s serotonin is concentrated, with the remaining 10% spread between the central nervous system (CNS) and blood platelets, which cannot produce serotonin themselves but acquire it from the surrounding plasma. Despite its heavy concentration in the gastrointestinal (GI) tract, the effects of serotonin are experienced primarily by the cardiovascular system, as well as the respiratory system, the central nervous system, and the intestines.

An excess of serotonin can impact a host of essential bodily functions in ways ranging from the mild to the life-threatening. From a mental health perspective, serotonin syndrome can cause feelings of agitation, restlessness, and confusion, while in the digestive system, it can result in severe diarrhea. Serotonin syndrome also can produce abnormalities in the functioning of muscle tissue, which reveal themselves in the form of symptoms like involuntary twitching of the muscle, loss of muscle coordination, and muscle rigidity, an extremely painful and debilitating condition. The cardiovascular system—highly dependent on serotonin for its proper functioning—can be subject to high blood pressure, increased heart rate, and an irregular heartbeat in patients suffering from serotonin syndrome. The central nervous system (CNS) also can be heavily impacted, sometimes resulting in seizures or a loss of consciousness.

Sometimes, serotonin syndrome can be treated simply by ceasing treatment with the offending medication(s). In other cases, patients may be given a drug intended to block serotonin uptake until the body’s serotonin returns to a safer level.

While often associated with prescription medications designed to affect the body’s serotonin levels, according to the National Library of Medicine, serotonin syndrome also has been observed in patients using recreational drugs “such as ecstasy, LSD, cocaine, and amphetamines.”

The Signs of Serotonin Syndrome
According to the Mayo Clinic, the signs of serotonin syndrome include: