Etrasimod is a sphingosine-1-phosphate (S1P) receptor modulator indicated for the treatment of moderately to severely active ulcerative colitis (UC) in adults. It exerts its therapeutic effect by reversibly blocking the migration of lymphocytes from lymphoid tissues to the periphery, thereby reducing the number of lymphocytes in peripheral blood.
What Are the Side Effects of Etrasimod?
Common Side Effects
Headache (9%-27%).
Elevated liver enzymes (5%-6%).
Dizziness (5%).
Nausea (3%-4%).
Arthralgia (4%).
Hypertension (3%).
Urinary tract infection (3%).
Serious Side Effects Requiring Vigilance
Infection Risk
It can cause lymphopenia (with lymphocytes decreasing to an average of 45% of the baseline level), increasing the risk of infections caused by bacteria, viruses (e.g., herpes virus, varicella-zoster virus), and fungi (e.g., Cryptococcus).
Warning symptoms: Fever, painful urination, and neurological symptoms (headache accompanied by neck stiffness).
Management measures: Lymphocyte count should be measured before medication initiation. Patients with active infections should have treatment delayed, and treatment should be discontinued in cases of severe infections.
Cardiovascular Events
Bradycardia: A decrease in heart rate (an average reduction of 7.2 beats per minute) may occur after the first dose, which may be accompanied by atrioventricular (AV) conduction delay.
Contraindicated populations: Patients who have experienced myocardial infarction, stroke, or New York Heart Association (NYHA) Class III/IV heart failure within 6 months, or those with Mobitz Type II second-degree or third-degree AV block.
Hepatic Toxicity
4.5% of patients may experience alanine transaminase (ALT) levels ≥ 3 times the upper limit of normal (ULN).
Monitoring requirements: Liver enzymes should be tested before medication initiation and when symptoms such as nausea or jaundice occur.
Macular Edema
This is a class effect of S1P receptor modulators. Fundus examinations are required before treatment and regularly during treatment.
Symptoms: Blurred central vision and abnormal color perception.
Other Serious Risks
Progressive multifocal leukoencephalopathy (PML): Rare but potentially fatal.
Posterior reversible encephalopathy syndrome (PRES): Manifested by sudden headache, confusion, and seizures.
Cutaneous malignancies: Regular skin examinations are required before and during medication use.
Precautions for Etrasimod Use
Contraindicated Populations
Patients with severe hepatic impairment (Child-Pugh Class C).
Pregnant women (may cause fetal malformations).
Poor metabolizers of CYP2C9 who are co-administered with strong inhibitors of CYP2C8 or CYP3A4.
Management of Special Populations
Pregnant women: Effective contraception should be used during treatment and for 1 week after discontinuing the medication. Treatment should be stopped immediately if pregnancy is confirmed.
Lactating women: Breastfeeding should be avoided.
Elderly patients: No dose adjustment is needed, but enhanced monitoring is required.
Drug Interactions
Contraindicated combinations: Rifampicin (a strong inducer) and fluconazole (a dual inhibitor).
Combinations requiring caution: Beta-blockers and antiarrhythmic drugs (which increase the risk of bradycardia).
Vaccination
Live vaccines should be administered 4 weeks before initiating etrasimod treatment.
Administration of live vaccines should be avoided during treatment and for 5 weeks after discontinuing the medication.
