Urgent Alert Issued for Healthcare Professionals and Patients Regarding Mektovi Dosage Confusion

The French National Agency for the Safety of Medicines and Health Products (ANSM) and the pharmaceutical laboratory Pierre Fabre have jointly issued a critical alert to healthcare professionals and patients concerning a significant risk of medication errors associated with Mektovi (binimetinib) in its 15 mg and 45 mg tablet formulations. This directive underscores the imperative for heightened vigilance to prevent potentially severe adverse events stemming from confusion between the two available dosages of this important oncology medication.

Background: The Introduction of Mektovi 45 mg

Mektovi, containing the active ingredient binimetinib, is a targeted therapy used in the treatment of certain types of cancer, often in combination with other medications. The 15 mg dosage has been available for some time, but the introduction of a higher strength, Mektovi 45 mg, in July 2025, aimed to simplify the treatment regimen for patients. This new dosage, being three times stronger than the 15 mg formulation, allows for a reduced number of pills per administration, theoretically improving patient adherence and convenience. Both the 15 mg and 45 mg strengths share the same therapeutic indications, further contributing to the potential for confusion if not managed with extreme care.

The intended benefit of the 45 mg dosage was to reduce the daily pill burden from three 15 mg tablets to a single 45 mg tablet per dose, thereby streamlining the patient’s treatment schedule. This simplification was a welcomed development in the management of conditions where Mektovi is prescribed. However, the very similarity in naming and indication, coupled with the introduction of a higher dose, has regrettably created a fertile ground for medication errors.

The Emergence of Medication Errors

In recent months, France has recorded a concerning number of medication errors involving Mektovi. Investigations by the ANSM and Pierre Fabre have pinpointed two primary causes for these errors:

• Incorrect Prescription: In some instances, prescriptions have been written for Mektovi 45 mg without clearly specifying the number of tablets required per dose, or by inaccurately indicating the number of 45 mg tablets that should be taken when the intent was to prescribe the equivalent dose using 15 mg tablets. Conversely, prescriptions intended for the 45 mg dosage have been mistakenly filled with 15 mg tablets, leading to underdosing.
• Dispensing Errors at the Pharmacy: Pharmacists, faced with prescriptions that may be ambiguous or lacking in explicit detail, have at times dispensed the incorrect dosage or quantity of Mektovi. This can occur due to misinterpretation of handwritten prescriptions, transcription errors within pharmacy software, or a failure to double-check the dosage against the patient’s profile and the prescriber’s intent. The visual similarity between the two product names, Mektovi 15 mg and Mektovi 45 mg, also presents a challenge.

These errors, while seemingly straightforward, carry a significant risk of underdosing or, more critically, overdosing, with potentially severe health consequences for patients undergoing cancer treatment.

The Grave Risk of Overdosing

The recommended daily dosage of binimetinib is 90 mg. This translates to specific administration schedules depending on the formulation:

• Mektovi 15 mg: Two 15 mg tablets taken twice daily (2 x 15 mg x 2 = 60 mg per day), or three 15 mg tablets taken twice daily (3 x 15 mg x 2 = 90 mg per day).
• Mektovi 45 mg: One 45 mg tablet taken twice daily (1 x 45 mg x 2 = 90 mg per day).

The danger arises when confusion leads to an incorrect number of 45 mg tablets being administered. For example, if a patient is prescribed Mektovi 45 mg twice daily but mistakenly takes three 45 mg tablets twice daily, they would be receiving 270 mg of binimetinib per day – a three-fold overdose of the recommended daily dose.

The consequences of such an overdose can be severe and life-threatening. Clinical data and product information highlight the potential for serious adverse effects when binimetinib is administered at higher than recommended doses. These can include:

• Ocular Toxicity: This can manifest as chorioretinopathy, a condition affecting the retina and choroid, potentially leading to vision impairment or loss. The Summary of Product Characteristics (SmPC) specifically notes that the highest dose of binimetinib evaluated alone in clinical studies (80 mg twice daily, or 160 mg per day) was associated with ocular toxicities.
• Dermatological Reactions: Severe skin reactions, such as acneiform dermatitis, can occur. These can be debilitating and significantly impact a patient’s quality of life.
• Gastrointestinal Disturbances: Patients may experience severe nausea, vomiting, diarrhea, and abdominal pain.
• Cardiovascular Events: In some cases, higher doses could potentially exacerbate or lead to cardiac issues.
• Hematological Abnormalities: Changes in blood cell counts may also be observed.

It is crucial to note that there is no specific antidote for binimetinib overdose. Management of an overdose would therefore be purely symptomatic and supportive, emphasizing the critical need for prevention.

Recommendations for Prescribing Physicians

Given the gravity of the situation, the ANSM and Pierre Fabre are urging all physicians, particularly oncologists and specialists in cancer care who are authorized to prescribe Mektovi, to exercise extreme caution:

• Clarity in Prescriptions: Prescriptions must clearly and unambiguously state both the correct dosage of Mektovi (15 mg or 45 mg) and the precise number of tablets to be taken per dose. For example, a prescription should read "Mektovi 45 mg, one tablet twice daily" or "Mektovi 15 mg, two tablets twice daily."
• Verification of Dosage and Quantity: Physicians should double-check that the prescribed dosage aligns with the intended number of tablets per administration, ensuring consistency between the strength and quantity ordered. This is especially important when transitioning patients between dosages or formulations.
• Patient Education: Physicians must ensure that patients fully understand their prescribed dosage, the number of tablets to take at each administration, and the critical importance of adhering strictly to these instructions.

Safeguarding Dispensation at the Pharmacy

Pharmacists play a pivotal role in preventing medication errors and are on the front lines of patient safety. The following recommendations are crucial for ensuring secure dispensing of Mektovi:

• Thorough Prescription Review: Pharmacists must meticulously review every prescription for Mektovi, verifying the dosage (15 mg or 45 mg) and the specified quantity of tablets. Any ambiguity or potential for misinterpretation must be clarified with the prescribing physician before dispensing.
• Patient Counseling: Upon dispensing, pharmacists should engage in thorough counseling with the patient, confirming the correct dosage, the number of tablets per dose, and the administration schedule. This includes reinforcing the distinction between the 15 mg and 45 mg formulations.
• Visual Inspection and Verification: Pharmacists should visually inspect the packaging and tablets to ensure they match the prescribed dosage. The distinct color and packaging of the two Mektovi formulations are designed to aid in this verification process.
• Internal System Alerts: The laboratory strongly recommends that pharmacies implement internal alerts within their dispensing software or utilize team notes. These alerts should flag the coexistence of Mektovi 15 mg and 45 mg and highlight the potential for confusion, prompting extra vigilance during the dispensing process.

Key Distinguishing Features for Error Prevention

To further assist healthcare professionals and patients in differentiating between the two Mektovi dosages, several key distinctions have been highlighted:

• Tablet Color: The 15 mg tablets are characterized by their yellow color, while the 45 mg tablets are green. This color difference is a critical visual cue for identification.
• Packaging: The packaging for each dosage is also distinct. The 15 mg tablets are typically found in boxes of 21 tablets, whereas the 45 mg tablets are packaged in boxes of 14 tablets. These variations in tablet count per box also serve as an important indicator.

Broader Implications and Future Considerations

The alert regarding Mektovi dosage confusion serves as a stark reminder of the persistent challenges in medication safety, particularly with complex therapies like oncology drugs. The introduction of new strengths or formulations, while intended to improve patient care, necessitates robust communication and educational strategies to mitigate the inherent risks.

The ANSM and Pierre Fabre’s proactive stance in issuing this alert is commendable and demonstrates a commitment to patient well-being. The collaborative effort between regulatory bodies and pharmaceutical manufacturers is essential in navigating such critical safety issues.

Looking ahead, the incident may prompt a review of labeling practices and the introduction of even more prominent differentiating features for medications with similar names but different strengths. Enhanced patient engagement in their own medication management, through clear instructions and accessible information, will also be crucial.

The successful prevention of medication errors hinges on a multi-faceted approach involving prescribers, pharmacists, patients, and pharmaceutical companies working in concert. Continuous vigilance, clear communication, and rigorous adherence to established safety protocols are paramount in ensuring that the benefits of advanced medical treatments like Mektovi are realized without compromising patient safety. The ongoing monitoring of medication error reports related to Mektovi will be essential to assess the effectiveness of these new directives and to identify any further necessary interventions.