Oral Minoxidil Compounding Errors May Have Serious Side Effects
Oral minoxidil is used for treating various types of hair loss. It is used at doses 0.25 mg to 5 mg. Oral minoxidil is available in various sized tablets, depending on the country one is speaking about. In some countries, such as the US and Canada, 2.5 mg oral minoxidil tablets are common. In some European coutntries, 5 mg tablets are common. In some countries, 10 mg tablets are the norm.
Minoxidil tablets can often be cut in order to get the desired dose. A 2.5 mg tablet can be cut in half to get 1.25 mg doses or in quarters to get 0.625 mg doses. A 5 mg tablet can be cut in quarters to get 1.25 mg doses. When it’s simply not possible to cut a tablet to get the desired dose, minoxidil tablets or pills can be made (or ‘compounded) by a pharmacy in the desired dose. For example, a compounding pharmacist can create 0.25 mg tablets or 0.5 mg tablets or 1.5 mg tablets or 2 mg tablets. Any dose can be made.
Compounding Minoxidil Opens the Door for Serious Errors
A was very interested to read a report by colleagues from Spain of 12 female patients who developed serious adverse effects when the wrong doses or oral minoxidil were prepared by a compounding pharmacy. All the patients were receiving doses higher than prescribed due to a compounding mistake (real dose ranging between 50 and 1000 mg per capsule). In 4 patients, the dose was 10 times higher than intended. In 7 patients it was 20-100 times above the intended dose. In 1 patient it was 1000 times higher than the intended dose.
None of the female patients had any previous cardiac condition or were being treated for hypertension. In 9 of 12 patients (75%), the adverse effects appeared immediately after the first dose and in the rest it occurred after the second dose (1 patient), third dose (1 patient) or within the first week (1 patient).
Side Effects with Oral Minoxidil Error
Side effects included reflex tachycardia (9 patients), angina (2 patients), elevated troponin (2 patients) headache (9 patients), generalized edema (6 patients) and episodes of hypotension or presyncope (7 patients). One patient suffered an ischemic stroke, and in this patient it was discovered that the dose formulated by the pharmacist was a thousand times higher than the medical prescription. One patient suffered a myocardial infarction, and in this patient it was determined that the dose was likely as high as 200 times the prescribed dose.
Recovery Occurred in All Patients
All the patients experienced a full recovery of their respective adverse effects. In four patients (33%), low dose oral minoxidil was restarted at the correct dose without any systemic adverse effect.
Comment and Conclusions
This is a really valuable report and the authors are congratulated for sharing this information. It’s clear that compounding minoxidil pills open the door to serious potential error. It is so fortunate that all 12 patients fully recovered in this study. It goes without saying that side effects such as heart attacks and strokes can be deadly and syncope can generate serious life altering injury and disability. It’s just amazing that everyone did so well.
An important message of this study is that any patient who uses compounded minoxidil and develops an unexpected or serious side effects must be encouraged to stop immediately until it can be determined that the minoxidil pills they are using are indeed the correct dose.
Ideally, a pharmacist chosen to compound minoxidil should be asked if her or she is comfortable compounding minoxidil
Moreno-Arrones OM et al. Serious Adverse effects From Compounding Errors With Low-Dose Oral Minoxidil for Alopecia Treatment. Actas Dermosifiliogr. 2022 May 12;S0001-7310(22)00414-8.