Finasteride in Adults 65 and Older: Dosing, Safety, and Transition to Adult Care

Does the dose change after 65?

Neither label's dosing section lists an age-based adjustment. Propecia is one 1 mg tablet once daily, with or without meals, for male pattern hair loss [1]. Proscar is one 5 mg tablet once daily for symptomatic BPH, alone or with doxazosin [2]. Generic 1 mg and 5 mg tablets carry the same labeled risks as the brands [3].

The pharmacokinetics do shift. Mean terminal half-life is about 5 to 6 hours in men 18 to 60 and about 8 hours in men over 70 [1]. Finasteride is extensively metabolized in the liver, mainly by CYP3A4, into two metabolites with no more than 20% of the activity of the parent drug; about 39% is excreted in urine as metabolites and 57% in feces [1]. Because the Type II enzyme complex turns over slowly (roughly 30 days), the effect on DHT outlasts the plasma half-life [1].

BPH: what the 5 mg dose is approved to do

BPH is common at this age; NIDDK estimates it affects 29% to 33% of men 65 and older [6]. Proscar is indicated to improve BPH symptoms in men with an enlarged prostate, to reduce the risk of acute urinary retention, and to reduce the risk of surgery including TURP and prostatectomy; with doxazosin it is indicated to reduce the risk of symptomatic progression [2]. It is not approved to prevent prostate cancer [2].

PLESS was a 4-year study of 3,040 men aged 45 to 78 with symptomatic BPH and an enlarged prostate: 1,524 received finasteride 5 mg and 1,516 received placebo [2]. In year 1, impotence was reported by 8.1% on finasteride versus 3.7% on placebo, decreased libido by 6.4% versus 3.4%, decreased ejaculate volume by 3.7% versus 0.8%, and ejaculation disorder by 0.8% versus 0.1%; in years 2 to 4 there was no significant difference between groups for impotence, decreased libido or ejaculation disorder [2]. Discontinuation for sexual adverse reactions was 3.7% versus 2.1% [2].

MTOPS randomized 3,047 men to finasteride, doxazosin, both, or placebo for 4 to 6 years [2]. Postural hypotension was reported by 8.0% on placebo, 16.7% on doxazosin, 9.1% on finasteride and 17.8% on the combination; the label notes the trial was not designed for statistical comparison between groups [2].

Hair loss after 65: what the hair-count data cover

Propecia is indicated for male pattern hair loss in men only, and efficacy in bitemporal recession has not been established [1]. The labeled efficacy data come from men aged 18 to 41: two 1-year placebo-controlled trials in 1,553 men, with 1,215 continuing into a second blinded year, in which hair count in a 1-inch circle of vertex scalp was 107 hairs higher than placebo at 1 year and 138 higher at 2 years (P<0.001), while the placebo group kept losing hair [5]. Those results do not establish the effect in men in their 70s.

The Propecia label says daily use for three months or more is usually needed before benefit is seen, continued use is needed to sustain benefit, and withdrawal leads to reversal of effect within 12 months [1]. HealthRX.com offers finasteride 1 mg by prescription.

PSA: the number that has to be read differently

The Proscar label says it lowers serum PSA by approximately 50% within six months, predictably across the PSA range but with individual variation [2]. For interpretation, the label says a new PSA baseline should be established at least six months after starting, with periodic monitoring thereafter; an isolated PSA in a man treated for six months or more should be doubled for comparison with normal ranges in untreated men; and any confirmed increase from the lowest on-treatment value may signal prostate cancer and should be evaluated, even if the value is still within the normal range for untreated men [2]. For percent free PSA, the label says no adjustment appears necessary [2]. It also notes that non-compliance may affect PSA results [2].

In Propecia studies of men aged 18 to 41, mean PSA fell from 0.7 to 0.5 ng/mL at month 12 [1].

The high-grade prostate cancer signal belongs with these numbers. In the 7-year Prostate Cancer Prevention Trial (18,882 men aged 55 or older taking finasteride 5 mg or placebo), Gleason 8 to 10 cancer occurred in 1.8% on finasteride versus 1.1% on placebo, while overall prostate cancer prevalence was 18.4% versus 24.4% [2][7]. The label states that 5-alpha reductase inhibitors may increase the risk of high-grade prostate cancer, and that whether reduced prostate volume or study-related factors influenced these results has not been established [2]; for the 1 mg dose the label says the clinical significance is unknown [1].

Sexual side effects: trial rates and the reports that persisted

In Propecia's three 12-month controlled trials (945 men on 1 mg, 934 on placebo, aged 18 to 41), decreased libido was reported by 1.8% versus 1.3%, erectile dysfunction by 1.3% versus 0.7%, and ejaculation disorder by 1.2% versus 0.7%; 3.8% versus 2.1% reported one or more of these (p=0.04), discontinuation for drug-related sexual events was 1.2% versus 0.9%, and the incidence of each fell to 0.3% or lower by year 5 [1]. A self-administered questionnaire at month 12 showed significant differences favoring placebo in 3 of 4 domains: sexual interest, erections, and perception of sexual problems [1].

Pooled across 15 randomized placebo-controlled trials in 4,495 men with androgenetic alopecia, 5-alpha reductase inhibitors carried a relative risk of sexual dysfunction of 1.57 (95% CI 1.19 to 2.08); finasteride alone was 1.66 (1.20 to 2.30) [8]. A separate review of 34 finasteride trials found none with adequate safety reporting, 76% evaluating safety for a year or less, and funnel plots suggesting under-detection of sexual adverse effects [9].

The Propecia label also lists sexual dysfunction that continued after stopping (erectile dysfunction, libido disorders, ejaculation disorders and orgasm disorders), plus male infertility and poor seminal quality, with normalization reported after discontinuation [1]. For Proscar, the label says persistent sexual adverse events were reported rarely in men taking 5 mg for BPH; most affected men were older and taking other medicines, and the independent role of Proscar is unknown [2]. One interview study of 71 otherwise healthy men aged 21 to 46 who reported sexual dysfunction lasting at least three months after stopping found mean use of 28 months and mean persistence of 40 months; the group was self-selected, so it cannot establish frequency or cause [10].

Mood, memory, and the boxed-warning myth

Neither Propecia nor Proscar has a boxed warning; both current labels list depression and suicidal ideation in the postmarketing section, and state that these voluntary reports come from a population of uncertain size and cannot reliably establish causality [1][2]. The history: the June 2021 Propecia label listed postmarketing depression; on May 31, 2022 FDA issued a safety labeling change order citing new information on suicidal ideation and behavior, additional sexual dysfunction and psychoneurocognitive events; supplement S-030, approved 08/01/2022, changed the wording to 'depression, suicidal ideation and behavior' [11].

Two large cohorts of older men looked for the signal. In Ontario, 93,197 men aged 66 or older starting a 5-alpha reductase inhibitor, mostly for BPH, were compared with matched unexposed men: suicide HR 0.88 (95% CI 0.53 to 1.45), self-harm HR 1.88 (1.34 to 2.64) confined to the first 18 months, and depression HR 1.94 (1.73 to 2.16) in the first 18 months and 1.22 (1.08 to 1.37) afterward [12]. In a Swedish register of 2,236,876 men aged 50 to 90 (70,645 finasteride starters, median age 73), depression HR was 1.61 (1.48 to 1.75) and suicide was not associated (HR 1.22, 0.99 to 1.49) [13]. Both cohorts were mostly men treated for prostate enlargement, not younger men treating hair loss.

On cognition, one small trial gave 60 men aged 60 or older with low testosterone one year of finasteride 5 mg or placebo alongside testosterone or vehicle; finasteride produced a small increase in performance on the Benton Judgment of Line Orientation test, and neither treatment produced major cognitive improvement [14]. In the Swedish cohort, finasteride use was associated with increased all-cause dementia risk overall, but the association faded over time, which the authors said may partly reflect more dementia detection in men with BPH [13].

Interactions on a long medicine list

The two labels state that no drug interactions of clinical importance have been identified and that finasteride does not appear to affect the cytochrome P450 system; antipyrine, digoxin, propranolol, theophylline and warfarin were tested with no clinically meaningful interactions [1][2]. Both labels also list alpha-blockers, ACE inhibitors, beta blockers, calcium-channel blockers, diuretics, cardiac nitrates, statins, NSAIDs, benzodiazepines, anticonvulsants and quinolones as drugs used alongside finasteride in clinical studies without evidence of clinically significant adverse interactions [1][2]. Finasteride is itself metabolized mainly by CYP3A4, but the labeled interaction sections do not discuss CYP3A4 inhibitors or inducers [1].

Doxazosin is the one alpha-blocker with its own labeled combination indication [2]. In MTOPS, postural hypotension was reported by 17.8% on the combination, 16.7% on doxazosin alone and 9.1% on finasteride alone [2].

Transferring care: the details that change the next decision

Four details change how a new clinician reads the case:

• Strength and indication. 1 mg is labeled for hair loss and 5 mg for BPH [1][2]. The 50% PSA rule applies to the 5 mg dose [2].
• Start date. The label's on-treatment PSA baseline is set at least six months after starting [2].
• The lowest on-treatment PSA. The label says a confirmed rise from that value should be evaluated for prostate cancer, even when the value is still within the normal range for untreated men [2].
• The full medicine list, alpha-blockers in particular, given the postural hypotension rates above [2].