Mektovi Dosage Changes Lead to Multiple Medication Errors

The issues emerged following the July 2025 launch of a 45mg tablet formulation. Since then, the ANSM has reported seven medication errors stemming from confusion between the original 15mg tablets and the newer 45mg version. These errors have resulted in overdoses that caused severe adverse effects, including serous retinal detachment, hepatocyte cytolysis, intense fatigue, nausea, and elevated lipase levels indicating pancreatitis.

The recommended daily dosage for Mektovi is 90mg. This can be achieved through two different regimens: taking three 15mg tablets twice daily, or taking one 45mg tablet twice daily. The similarity or overlap in these dosing options appears to be the primary driver of the reported errors.

To mitigate these risks and ensure patient safety, the ANSM is urging oncology healthcare providers and pharmacists to implement strict verification procedures. These measures include:

• Ensuring absolute consistency between the prescription and the dispensed dosage.
• Avoiding any substitution between the 15mg and 45mg formulations without explicit authorization from the prescribing physician.
• Providing patients with clear, unambiguous instructions on how to take their medication.

This warning underscores the critical importance of dosage verification when fresh formulations of high-potency anticancer drugs enter the market, as errors in targeted therapies can lead to life-threatening complications.