Routine monitoring of blood pressure, heart rate, weight, and renal and liver function may not be routinely needed in asymptomatic patients with normal baseline hemodynamic and biochemical profiles who receive low-dose oral minoxidil for hair loss, according to findings from a retrospective study that researchers said provides the first longitudinal monitoring data beyond 6 months of therapy.
Researchers reviewed patients treated with low-dose oral minoxidil at a specialist hair clinic in the United Kingdom between April 2017 and June 2020. Of 115 patients prescribed treatment, 74 female patients with at least 2 documented visits 6 months apart were included. Follow-up monitoring data were reported through 30 months, although treatment duration ranged from 6 to 36 months.
All patients started oral minoxidil at 0.625 mg daily, with dose escalation according to tolerability up to 5 mg daily. Among patients whose doses were escalated, 35 reached 1.25 mg, 11 reached 2.5 mg, and 2 reached 5 mg. The researchers noted that these doses were substantially lower than antihypertensive oral minoxidil doses of 10 to 100 mg per day.
Female pattern hair loss was the most common indication, reported in 48 patients, followed by persistent chemotherapy-induced alopecia in 9 patients. Other diagnoses included alopecia areata, fibrosing alopecia in a pattern distribution, frontal fibrosing alopecia, congenital hypotrichosis, monilethrix, central centrifugal cicatricial alopecia, chronic telogen effluvium, and traction alopecia.
Forty-seven patients received minoxidil monotherapy, and 27 received concurrent or overlapping systemic therapies, including spironolactone, finasteride, hydroxychloroquine, methotrexate, cyclosporine, tetracycline antibiotics, pioglitazone, and oral contraceptives. The researchers noted that coexisting systemic therapies or comorbidities may have contributed to some adverse effects.
Treatment-emergent adverse events were reported in 34 patients, or 46%. Hypertrichosis was most common, occurring in 18 patients, followed by dizziness in 8 patients, lower limb edema and palpitations in 4 patients each, and headache, nausea, chest tightness, and weight gain in 2 patients each. Rash and abdominal pain were each reported in 1 patient.
Thirteen patients discontinued treatment. Eleven discontinued because of adverse effects, and 2 discontinued because of patient preference, including 1 patient with a lupus flare and 1 patient who had achieved satisfactory cosmetic improvement. Dizziness and palpitations were the most common adverse effects associated with discontinuation, each reported in 3 patients, although these symptoms often occurred with other symptoms such as nausea, headache, abdominal pain, fever, or weight gain.
Mean systolic and diastolic blood pressure appeared stable through most of follow-up. At the final plotted time point, mean systolic blood pressure was 7 mmHg lower and mean diastolic blood pressure was 3 mmHg lower, but the researchers noted wide confidence intervals. No patients had symptoms suggestive of hypotension.
Heart rate values remained within normal ranges throughout treatment, although the researchers noted wide confidence intervals and found insufficient evidence of a clinically relevant change. However, they noted that tachycardia associated with oral minoxidil typically occurs during the first 1 to 3 days of treatment as a result of reflex sympathetic activation following vasodilation. Because heart rate was not measured during that early period, the study may not have captured early tachycardia.
The researchers also cited prior multicenter data in patients with hypertension and arrhythmia, which found low-dose oral minoxidil to be generally well tolerated in patients with conditions such as supraventricular extrasystole, atrial fibrillation, sinus tachycardia, and cardiac syncope. In that study, 1 patient with supraventricular extrasystole required dose reduction from 1 mg to 0.25 mg daily following symptoms.
Weight measurements were stable overall. Although mean weight increased at 24 months, the values were variable, had a wide confidence interval, and normalized at the subsequent reading.
Renal and liver function measures also appeared stable. All patients had normal liver function tests at baseline, and 27 patients had reduced baseline estimated glomerular filtration rate. Among patients with reduced baseline estimated glomerular filtration rate, 4 patients, or 15%, had increased creatinine levels during treatment, although creatinine levels remained within normal ranges. The researchers reported no serious cardiovascular adverse events, including among patients with impaired renal function. Still, they advised continued renal function monitoring in patients with preexisting renal impairment, particularly those with moderate-to-advanced disease. They noted that minoxidil-induced pericardial effusion and pericarditis have been reported most often among patients with advanced kidney disease or those receiving dialysis, and occur in approximately 3% of patients treated with high-dose oral minoxidil.
The findings are limited by the study’s retrospective, single-center design; relatively small sample size; all-female analyzed population; absence of a comparator group; and reliance on graphical exploration without adjusted analyses. Comorbidities and coexisting systemic medications were not accounted for in the analysis, and the study was not designed to detect rare cardiovascular events. These limitations may restrict generalizability to male patients, patients with cardiovascular disease, and those with advanced renal impairment.
The researchers suggested that monitoring should remain individualized according to baseline risk. Patients with normal baseline hemodynamic and biochemical profiles who remain asymptomatic may not need routine monitoring, whereas patients with renal impairment or a cardiovascular history may require closer follow-up.
“These data support the position that regular monitoring is not required during treatment with LDOM in asymptomatic patients with normal baseline values,” wrote lead study author Donna M. Cummins, of Salford Royal Hospital, Northern Care Alliance NHS Foundation Trust, Manchester Academic Health Science Centre, and colleagues. “We recommend those with preexisting renal disease treated with LDOM are still monitored regularly during therapy.”
Matthew Harries was supported by the NIHR Manchester Biomedical Research Centre. The researchers reported no conflicts of interest.