Cialis (Tadalafil) Adult Dosing for Ages 30 to 49: Complete Clinical Guide

Does the dose change for men in their 30s and 40s?

No. The Cialis label sets doses for adults with ED, BPH, or both, and contains no age-based adjustment for the 30 to 49 range [1]. Its age-related statements concern patients 65 and older: AUC is 25% higher in healthy men aged 65 or older, and across the as-needed ED trials diarrhea was reported more often in patients 65 and older who took Cialis [1].

The five as-needed ED trials in the integrated analysis enrolled 1,112 men with a mean age of 59 and a range of 22 to 82 [2]. The two BPH trials cited below enrolled men aged 45 or older [3][4], so a man in his 30s taking 5 mg daily for urinary symptoms falls outside the population those two trials studied.

On-demand dosing for ED

Start with 10 mg before anticipated sexual activity. The dose may be increased to 20 mg or decreased to 5 mg based on efficacy and tolerability, and the maximum is once per day [1]. Tablets should not be split; the entire dose is taken [1]. Cialis may be taken with or without food [1].

Peak plasma concentration occurs between 30 minutes and 6 hours after a dose (median 2 hours), and the mean terminal half-life is 17.5 hours [1]. The label's statement is specific: erectile function improved compared with placebo for up to 36 hours after dosing, which does not mean a continuous erection, because sexual stimulation is still required [1].

In the integrated analysis of 1,112 men, tadalafil 20 mg improved the IIEF erectile function domain by a mean 7.9 points from baseline (P<0.001 versus placebo), 75% of intercourse attempts were successful, and 81% of men reported improved erections versus 35% on placebo [2]. Headache and dyspepsia were the most common adverse events [2]. That analysis pooled fixed doses from 2.5 to 20 mg; it did not compare men under 50 with older men.

Once-daily dosing: 2.5 mg, 5 mg, and BPH

For ED, once-daily Cialis starts at 2.5 mg taken at approximately the same time every day, without regard to the timing of sexual activity, and may be increased to 5 mg based on efficacy and tolerability [1]. Steady state is reached within 5 days, with exposure about 1.6-fold that of a single dose [1].

For BPH, and for ED with BPH, the dose is 5 mg once daily at approximately the same time every day [1]. When Cialis is used with finasteride to start BPH treatment, the label recommends 5 mg daily for up to 26 weeks, because the added benefit of Cialis falls from week 4 to week 26 and the benefit beyond 26 weeks is unknown [1].

Two studies support the 5 mg BPH dose. In a 12-week trial of men aged 45 or older, tadalafil 5 mg once daily (n=161) lowered total IPSS by 5.6 points versus 3.6 on placebo (n=164, P=0.004), an effect apparent after 1 week and significant by week 4; peak urine flow and post-void residual volume did not change significantly [3]. In a dose-finding study of 1,058 men, 5 mg lowered IPSS by 4.9 points versus 2.3 on placebo (P<0.001), and the investigators concluded that 5 mg appeared to offer a positive risk-benefit profile among the doses studied [5].

In the 26-week finasteride study of 695 men, IPSS fell by 4.0, 5.2 and 5.5 points at weeks 4, 12 and 26 with tadalafil plus finasteride, versus 2.3, 3.8 and 4.5 with placebo plus finasteride (P 0.022 or lower at every visit) [4].

Generic tadalafil tablets are approved under ANDAs for the same ED and BPH indications, and tadalafil is prescription only [6]. Drugs@FDA lists the brand Cialis 2.5 mg tablet as discontinued, while generic tadalafil 2.5 mg tablets are approved [6]. HealthRX.com offers tadalafil by prescription.

Dose adjustments: kidney, liver, and drug interactions

Kidney function changes the numbers. For as-needed use with creatinine clearance 30 to 50 mL/min, the starting dose is 5 mg not more than once per day and the maximum is 10 mg not more often than every 48 hours; with creatinine clearance below 30 mL/min or on hemodialysis, the maximum is 5 mg not more often than every 72 hours, and once-daily use is not recommended [1]. For BPH or ED with BPH at 30 to 50 mL/min, the label recommends starting at 2.5 mg and considering 5 mg [1].

Liver impairment: with Child-Pugh class A or B, the as-needed dose should not exceed 10 mg once per day; Cialis is not recommended in class C [1].

CYP3A4 inhibitors cut the ceiling sharply. With a strong inhibitor, as-needed use is limited to 10 mg every 72 hours and once-daily use to 2.5 mg [1]. Ketoconazole 400 mg daily raised tadalafil 20 mg exposure (AUC) by 312%, and ritonavir 200 mg twice daily raised it by 124% [1]. In the other direction, rifampin 600 mg daily cut tadalafil 10 mg AUC by 88%; the label calls for no dose adjustment but notes that the efficacy of once-daily Cialis may fall by an unknown amount [1].

Alpha-blockers: for ED, the label says a man should be stable on the alpha-blocker first, with tadalafil started at the lowest dose [1]. For BPH, the label does not recommend combining Cialis with an alpha-blocker, because efficacy has not been adequately studied and blood pressure can drop [1]. Doxazosin 8 mg daily with tadalafil 20 mg gave a placebo-subtracted maximal standing systolic fall of 9.8 mm Hg; tamsulosin 0.4 mg gave 1.7 mm Hg with 10 mg and 2.3 mm Hg with 20 mg [1].

Common antihypertensives (amlodipine, ARBs, bendroflumethiazide, enalapril, metoprolol) produced small additional blood pressure reductions with tadalafil compared with placebo [1]. Alcohol counts as a vasodilator too: 5 units or more with Cialis can increase orthostatic signs and symptoms such as higher heart rate, lower standing blood pressure, dizziness and headache, and tadalafil did not change alcohol levels nor alcohol change tadalafil levels [1].

Safety points that matter at any age

Nitrates are contraindicated in any form, taken regularly or intermittently [1]. In a life-threatening situation where a nitrate is medically necessary, at least 48 hours should elapse after the last Cialis dose, and the nitrate should only be given under close medical supervision with hemodynamic monitoring [1]. In a 150-man crossover study, standing systolic pressure fell below 85 mm Hg in more men on tadalafil than on placebo at 4, 8 and 24 hours after sublingual nitroglycerin 0.4 mg, with no difference at 48, 72 and 96 hours [7]. That 48-hour rule is an emergency provision, not a safe-spacing schedule.

Riociguat and other guanylate cyclase stimulators are also contraindicated [1]. Cialis should not be used by men for whom sexual activity is inadvisable for cardiovascular reasons, and it is not recommended after a heart attack within 90 days, with unstable angina, NYHA class 2 or greater heart failure within 6 months, uncontrolled arrhythmia, blood pressure below 90/50 mm Hg, uncontrolled hypertension, or stroke within 6 months [1]. In healthy volunteers, tadalafil 20 mg lowered supine blood pressure by a mean maximal 1.6/0.8 mm Hg versus placebo [1].

An erection lasting more than 4 hours, painful or not, needs emergency care; painful erections over 6 hours are priapism and can damage erectile tissue [1]. Sudden vision loss in one or both eyes may be NAION and needs medical attention; two observational case-crossover studies suggested about a 2-fold risk (estimates 2.15 and 2.27), and the label states that neither the reports nor these studies substantiate a causal relationship [1]. Sudden hearing decrease or loss has been reported, and the label says it cannot tell whether it is directly related [1].

Rates from the eight 12-week as-needed ED trials: headache 5% on placebo versus 11% on 5 mg, 11% on 10 mg and 15% on 20 mg; dyspepsia 1% versus 4%, 8% and 10%; back pain 3% versus 3%, 5% and 6%; myalgia 1% versus 1%, 4% and 3%; flushing 1% versus 2%, 3% and 3% [1]. Discontinuation for adverse events was 3.1% on 10 or 20 mg versus 1.4% on placebo [1]. Back pain and myalgia usually began 12 to 24 hours after dosing and resolved within 48 hours [1].