Finasteride Evolution: What's Next After the 1mg Pill

What the 1 mg tablet already does

Propecia, the 1 mg tablet, was approved on 19 December 1997 for male pattern hair loss in men only; efficacy in bitemporal recession was not established and it is not indicated for women [3][1]. Finasteride is a competitive, specific inhibitor of type II 5-alpha-reductase, the enzyme that converts testosterone to DHT; that isozyme is responsible for about two-thirds of circulating DHT, and finasteride binds it roughly 100 times more readily than type I [1]. A 1 mg tablet produces about 65% suppression of serum DHT within 24 hours [1].

Two 1-year vertex-baldness trials enrolled 1,553 men aged 18 to 41, and a third trial studied anterior mid-scalp hair loss [1][4]. In the two vertex trials, 1,215 men continued into blinded second-year extensions. Hair count in a 5.1 cm2 circle of vertex scalp was 107 hairs higher than placebo at one year and 138 higher at two years (P<0.001), while the placebo group kept losing hair [4].

The trade-off is measured in the same trials. In three 12-month controlled studies, 3.8% of men on finasteride reported one or more sexual adverse events versus 2.1% on placebo (p=0.04), and each individual rate fell to 0.3% or lower by year five [1]. A meta-analysis of 15 randomized placebo-controlled trials in 4,495 men with androgenetic alopecia put the relative risk of sexual dysfunction with finasteride 1 mg at 1.66 (95% CI 1.20 to 2.30) [5].

The topical spray is the furthest along

The most developed alternative is a topical finasteride spray tested in a phase III trial published in 2022 [2]. That study was randomized, double-blind, double-dummy and parallel-group, ran 24 weeks at 45 sites in Europe, randomized 458 men, evaluated 446 for safety and saw 323 complete the study [2].

On the primary endpoint, change in target area hair count at week 24, topical finasteride produced an adjusted mean increase of 20.2 hairs against 6.7 with placebo (P<0.001), and the topical result was numerically similar to oral finasteride [2]. Investigator-assessed change in hair growth at week 24 also favored topical finasteride over placebo [2]. The incidence and type of adverse events, and the reasons men discontinued, did not differ meaningfully between topical finasteride and placebo, and no serious adverse event was treatment related [2].

How much DHT does the spray suppress?

This is where the numbers matter most. Maximum plasma finasteride concentrations were more than 100 times lower with the spray than with oral finasteride, and the reduction from baseline in mean serum DHT was 34.5% with topical versus 55.6% with oral finasteride [2]. The mean fall with the spray was smaller than with the oral tablet [2].

A separate systematic review of seven studies of topical finasteride found that both scalp and plasma DHT fell with application, while serum testosterone did not change; the authors described the evidence as preliminary and limited [6].

Is any of this FDA-approved?

No. Drugs@FDA lists only oral finasteride tablets, the 1 mg and 5 mg strengths, and generic versions of both are FDA-approved; there is no FDA-approved topical or injectable finasteride [3][8]. Finasteride 1 mg is prescription-only and the label covers men only [1]. HealthRX.com offers finasteride 1 mg by prescription.

Other combinations and formulations

Finasteride has been studied alongside the alpha-blocker doxazosin for enlarged prostate, and the Proscar label includes that combination as an indication [7]. Drugs@FDA lists no finasteride tablet other than 1 mg and 5 mg [3][8].

The 5 mg tablet is not a hair-loss upgrade

Proscar, the 5 mg tablet, is indicated for symptomatic benign prostatic hyperplasia and is not approved for the prevention of prostate cancer [8][7]. In the 7-year Prostate Cancer Prevention Trial, 18,882 men aged 55 or older were assigned to finasteride 5 mg or placebo. Gleason 8 to 10 cancer occurred in 1.8% of the finasteride group versus 1.1% of the placebo group [7][9]. The 1 mg label states that the clinical significance of this finding for men taking 1 mg is unknown [1].

What the current 1 mg label lists

• Dosing: one 1 mg tablet once daily, with or without meals; daily use for three months or more is usually needed before benefit is seen, and withdrawal of treatment leads to reversal of effect within 12 months [1].
• PSA: mean PSA fell from 0.7 to 0.5 ng/mL at month 12 in men aged 18 to 41, and the label states that a confirmed increase from the lowest PSA value while on treatment should be evaluated [1].
• Postmarketing sexual effects: the label lists sexual dysfunction that continued after discontinuation, including erectile dysfunction, libido disorders, ejaculation disorders and orgasm disorders, plus male infertility and poor seminal quality with reports of normalization or improvement after stopping [1].
• Postmarketing psychiatric effects: the label lists depression, suicidal ideation and behavior, and states that these reports are voluntary, come from a population of uncertain size and cannot reliably establish causation. There is no boxed warning on the product [1][10].
• Pregnancy: finasteride is contraindicated in women who are or may be pregnant, and the label states that women should not handle crushed or broken tablets [1].