What is the risk of serotonin syndrome in a patient taking Viibryd (vilazodone) and Skelaxin (cyclobenzaprine)?

From the Guidelines

The combination of Viibryd (vilazodone) and Skelaxin (cyclobenzaprine) poses a significant risk of serotonin syndrome, a potentially life-threatening condition. When considering the treatment of a patient with both Viibryd and Skelaxin, it is crucial to weigh the benefits against the risks, particularly the risk of serotonin syndrome, as highlighted in the clinical practice guideline for the assessment and treatment of children and adolescents with anxiety disorders 1. Key points to consider include:

• The mechanism of action of both medications, with Viibryd being an SSRI antidepressant that increases serotonin levels, and cyclobenzaprine having some structural similarity to tricyclic antidepressants and potentially increasing serotonin levels as well.
• The symptoms of serotonin syndrome, which can arise within 24 to 48 hours after combining medications and are characterized by mental status changes, neuromuscular hyperactivity, and autonomic hyperactivity 1.
• The importance of close monitoring for symptoms of serotonin syndrome, especially during the first few weeks of treatment or after dose increases, and educating patients about warning signs and the need to seek immediate medical attention if symptoms develop.
• The potential for alternative muscle relaxants with less serotonergic activity to be safer options when a patient is already taking Viibryd. Given the potential risks, it is recommended to exercise extreme caution when combining Viibryd and Skelaxin, and to consider alternative treatment options that minimize the risk of serotonin syndrome. In clinical practice, the decision to use this combination should be made on a case-by-case basis, taking into account the individual patient's needs and medical history, and with careful consideration of the potential risks and benefits, as outlined in the guideline 1.

From the FDA Drug Label

Vilazodone hydrochloride tablets may cause serious side effects, including: Serotonin Syndrome. A potentially life-threatening problem called serotonin syndrome can happen when vilazodone hydrochloride tablets are taken with certain other medicines. Patients should be cautioned about the risk of serotonin syndrome with the concomitant use of Cyclobenzaprine Hydrochloride and other drugs, such as selective serotonin reuptake inhibitors (SSRIs), serotonin norepinephrine reuptake inhibitors (SNRIs), tricyclic antidepressants (TCAs), tramadol, bupropion, meperidine, verapamil, or monoamine oxidase (MAO) inhibitors

The risk of serotonin syndrome in a patient taking Viibryd (vilazodone) and Skelaxin (cyclobenzaprine) is increased due to the potential interaction between these two medications. Serotonin syndrome is a potentially life-threatening condition that can occur when certain medications, including SSRIs like vilazodone, are taken with other serotonergic drugs, such as cyclobenzaprine.

• Key factors to consider:
  • Concomitant use of vilazodone and cyclobenzaprine may increase the risk of serotonin syndrome.
  • Patients should be cautioned about the signs and symptoms of serotonin syndrome and instructed to seek medical care immediately if they experience these symptoms.
  • Careful observation is advised when initiating or increasing the dose of either medication in patients taking both vilazodone and cyclobenzaprine 2 3.

From the Research

Serotonin Syndrome Risk with Viibryd and Skelaxin

• The risk of serotonin syndrome in a patient taking Viibryd (vilazodone) and Skelaxin (cyclobenzaprine) is a concern due to the potential for increased serotonergic activity 4.
• Viibryd is a selective serotonin reuptake inhibitor (SSRI) and a serotonin 5-HT1A receptor partial agonist, which can increase the risk of serotonin syndrome when combined with other serotonergic agents 5, 6, 7.
• Skelaxin, a muscle relaxant, may also have some serotonergic activity, although its exact mechanism of action is not fully understood.
• The combination of two or more serotonergic drugs can increase the risk of serotonin syndrome, and the simultaneous initiation of these drugs can precipitate severe serotonin syndrome 4.
• However, there is no direct evidence in the provided studies that specifically addresses the risk of serotonin syndrome with the combination of Viibryd and Skelaxin.
• It is essential to monitor patients taking these medications for signs and symptoms of serotonin syndrome, such as neuromuscular abnormalities, autonomic hyperactivity, and mental state changes 4.

Clinical Considerations

• The clinical presentation of serotonin syndrome can range from mild to severe and may include symptoms such as myoclonic jerks, clumsiness, gait difficulties, confusion, forgetfulness, agitation, and lethargy 8.
• The diagnosis of serotonin syndrome is primarily clinical, and treatment involves discontinuing the offending medications and providing supportive care 4.
• In severe cases, medications such as cyproheptadine and clonazepam may be used to manage symptoms 8.