There Is a Positive Dose-Dependent Association between Low-Dose Oral Minoxidil and Its Efficacy for Androgenetic Alopecia: Findings from a Systematic Review with Meta-Regression Analyses

Abstract

<b><i>Background:</i></b> Recently, low-dose oral minoxidil (LDOM) has entered the landscape of therapies for androgenetic alopecia (AGA). We determined whether using LDOM is associated with improving AGA in a dose-dependent manner; secondarily, we examined whether a dose-dependent association also exists for safety. <b><i>Methods:</i></b> Systematic searches were conducted in PubMed and Scopus to identify studies that would be eligible for our quantitative analyses; the logistics of our analyses was determined by the data we gathered. <b><i>Results:</i></b> Six studies were eligible for quantitative analyses; we conducted meta-regressions. We found that, for persons with AGA, increasing the dosage of LDOM by 1 mg/day was – after six months – significantly associated with an expected sex-adjusted increase in hair diameter (mean difference = 1.4 μm, <i>p</i> = 0.01), total hair density (mean difference = 47.1 hairs/cm<sup>2</sup>, <i>p</i> = 0.007), terminal hair density (mean difference = 9.1 hairs/cm<sup>2</sup>, <i>p</i> = 0.001), risk of hypertrichosis (mean difference = 17.9%, <i>p</i> = 0.006), and cardiovascular adverse events (mean difference = 4.8%, <i>p</i> = 0.004). <b><i>Conclusions:</i></b> Our study produced new evidence as our work is the first to show a positive dose-dependent association between the use of LDOM and change in hair diameter, hair density, risk of hypertrichosis, and cardiovascular adverse events for persons with AGA. Future randomized trials could produce causal evidence that would corroborate these dose-dependent associations.

Clinical efficacy and safety of low‐dose oral minoxidil versus topical solution in the improvement of androgenetic alopecia: A randomized controlled trial

“…The results of our study and the two previous clinical trials regarding comparing oral and topical minoxidil suggest that 1 mg oral minoxidil is at least as effective as standard topical therapy in improving AGA. However, it has been proven that there is a positive dose‐dependent relationship between low‐dose oral minoxidil and its effectiveness for AGA, while the optimum dosage of oral minoxidil for treating AGA still needs to be delineated 9 …”

“…8,3,6,7,17,18 Typically, topical minoxidil causes a therapeutic response rate of 40% in male patients with AGA, while another 40% experience hair loss, and the remaining 20% report no impact on their hair. 9,23 However, recent studies suggest that oral minoxidil not only by follicular sulfotransferase but also by liver and platelet sulfotransferase might lead to higher follicular accumulation. 7 This suggests that a lower enzyme activity threshold is required for the activation of oral minoxidil compared to topical minoxidil.…”

“…However, it has been proven that there is a positive dose-dependent relationship between low-dose oral minoxidil and its effectiveness for AGA, while the optimum dosage of oral minoxidil for treating AGA still needs to be delineated. 9 While topical minoxidil is an effective treatment for AGA, patient compliance can be poor due to undesirable hair texture, the need for twice-daily application, scalp irritation, and developing allergic Oral Minoxidil contact dermatitis. 1,25 In this regard, low-dose oral minoxidil has been found to be well tolerated with only minor adverse effects.…”

Low-Dose Oral Minoxidil for Alopecia: A Comprehensive Review

“…Notably, the efficacy and side effects of LDOM for treating AGA appear to be dose-dependent [50, 51]. A meta-regression analysis of clinical trials found that increasing the daily dose of oral minoxidil by 1 mg in AGA patients led to an increase in total hair density of 47.1 hairs/cm 2 ( p = 0.0071) and an increase in terminal hair density of 9.1 hairs/cm 2 ( p = 0.0014), as well as a rise of 1.4 μm in hair thickness ( p = 0.013), after 24 weeks [50]. However, the study also found that a minoxidil dose increase by 1 mg may lead to a higher chance of hypertrichosis and cardiovascular side effects.…”

“…However, the study also found that a minoxidil dose increase by 1 mg may lead to a higher chance of hypertrichosis and cardiovascular side effects. The risk of hypertrichosis rose by 17.6% ( p = 0.0057), and the risk of cardiovascular side effects increased by 4.8% ( p = 0.00382), after 24 weeks [50].…”