How Do SSRI/5HT-1A Partial Agonist Antidepressants Work?

Selective serotonin reuptake inhibitor/5-hydroxytryptamine-1A (SSRI/5HT-1A) partial agonist antidepressants are dual-action medications prescribed to treat depression. SSRI/5HT-1A partial agonists increase the levels of serotonin and also enhance the activity of a specific type of serotonin receptors known as 5HT-1A receptors.

Serotonin is an important natural chemical (neurotransmitter) released by nerve cells (neurons) in the brain to transmit nerve signals. Serotonin plays a vital role in neurotransmission in the central and peripheral nervous systems and regulates virtually all the systems in the body.

Some of the functions of serotonin include regulation of sleep, digestion, cognition, mood and behavior. An increase in serotonin levels helps relieve anxiety and reduce depression symptoms. SSRI/HT-1A partial agonist antidepressants work in two ways to increase the level and activity of serotonin:

• Prevent reabsorption (reuptake) of serotonin by the neurons, a natural recycling process after the completion of neurotransmission. Consequently, serotonin concentration increases in the space (synapse) between neurons.
• Stimulate 5HT-1A receptors which are inhibitory serotonin receptors that have a calming effect. Serotonin receptors are protein molecules on the surface of nerve cells that activate regulatory processes when stimulated by serotonin.

SSRI/5HT-1A partial agonist antidepressants are oral tablets approved by the FDA for the treatment of major depressive disorder in adults.

Side effects of SSRI/5HT-1A partial agonist antidepressants may include the following:

• Diarrhea
• Nausea
• Dizziness
• Xerostomia (dry mouth)
• Insomnia
• Vomiting
• Fatigue
• Abnormal dreams
• Decreased libido
• Abnormal orgasm
• Dyspepsia (indigestion)
• Flatulence
• Gastroenteritis (infection and inflammation of the digestive system)
• Somnolence (drowsiness)
• Paresthesia (prickling sensation)
• Arthralgia (joint pain)
• Akathisia (restlessness)
• Nervousness
• Tremor
• Delayed ejaculation
• Erectile dysfunction
• Increased appetite
• Irritability
• Hallucinations
• Suicidal ideation and attempt
• Acute pancreatitis (inflammation of the pancreas)
• Sleep paralysis

Information contained herein is not intended to cover all possible side effects, precautions, warnings, drug interactions, allergic reactions, or adverse effects. Check with your doctor or pharmacist to make sure these drugs do not cause any harm when you take them along with other medicines. Never stop taking your medication and never change your dose or frequency without consulting your doctor.

Generic and brand names of SSRI/5HT-1A partial agonist antidepressant drugs include:

• Viibryd
• vilazodone