The Health Science Authority (HSA), Singapore, has announced that Sanofi-Aventis Pte Ltd has issued a “Dear Healthcare Professional Letter” to provide critical updates on the safety profile of Plaquenil® (Hydroxychloroquine sulphate). Healthcare professionals are urged to take note of these new findings, particularly in patients who are pregnant, those with myasthenia gravis, or individuals at risk of developing phospholipidosis.

Key Safety Update – Increased Risk of Major Congenital Malformations: A 2021 study by Huybrechts et al. has reported a small but significant increase in the relative risk of major congenital malformations linked to hydroxychloroquine when administered during the first trimester of pregnancy. The risk becomes more pronounced at higher daily dosages (≥ 400 mg/day).

Phospholipidosis: A Newly Identified Risk: Hydroxychloroquine has also been linked to phospholipidosis, a condition marked by the excessive accumulation of phospholipids in tissues. This can potentially impair cardiac, renal, muscular, or nerve function.

Aggravation of Myasthenia Gravis Symptoms: New reports indicate that hydroxychloroquine may worsen symptoms in individuals with myasthenia gravis. This could further impair neuromuscular function and increase the risk of severe symptoms.

These newly identified risks remind us that it remains essential to exercise clinical judgment in balancing the risks and benefits for individual patients, particularly for those at higher risk.

Further reading:

Huybrechts KF, Bateman BT, Zhu Y, et al. Hydroxychloroquine early in pregnancy and risk of birth defects. Am J Obstet Gynecol 2021;224:290.e1-22.

Plaquenil® (Hydroxychloroquine sulfate) – Risk of major congenital malformations and new risks of phospholipidosis and aggravation of myasthenia gravis symptoms