Cialis (Tadalafil) Monitoring for Young Adults (18 to 29): What Labs and Check-Ins You Actually Need

What the Cialis label asks for

The label says evaluation of erectile dysfunction and BPH should include an appropriate medical assessment to identify potential underlying causes, as well as treatment options [1].

The other requirement is cardiovascular. Cialis should not be used in men for whom sexual activity is inadvisable because of their underlying cardiovascular status [1]. The label lists groups that were not studied and for whom Cialis is therefore not recommended: a heart attack within the last 90 days, unstable angina or angina during intercourse, NYHA class 2 or worse heart failure within 6 months, uncontrolled arrhythmia, blood pressure below 90/50 mm Hg, uncontrolled hypertension, or a stroke within 6 months [1].

Which labs change a tadalafil dose

Creatinine clearance and the severity of liver impairment (Child-Pugh class) can change Cialis dosing [1].

Kidney function. For as-needed use, a creatinine clearance of 30 to 50 mL/min means a starting dose of 5 mg and a maximum of 10 mg not more often than every 48 hours; below 30 mL/min or on hemodialysis, the maximum is 5 mg not more often than every 72 hours [1]. Once-daily Cialis is not recommended below 30 mL/min [1].

Liver function. In mild or moderate impairment (Child-Pugh A or B) the as-needed dose should not exceed 10 mg; in severe impairment (Child-Pugh C) Cialis is not recommended [1].

A man with normal kidney and liver function does not trigger either adjustment.

Blood pressure and the heart check

In healthy volunteers, tadalafil 20 mg lowered supine blood pressure by a mean maximal 1.6/0.8 mm Hg compared with placebo [1]. The average change was small, but Cialis can add to the blood-pressure-lowering effects of nitrates, alpha-blockers, antihypertensives and substantial alcohol [1].

Hypertension in this age group is not rare. In 2017-2018, 22.4% of US adults aged 18 to 39 had hypertension by the 2017 ACC/AHA definition, and the figure was 31.2% among men aged 18 to 39 [3]. Blood pressure is the measurement the label's warnings turn on, because uncontrolled hypertension and blood pressure below 90/50 mm Hg both sit on its not-recommended list [1].

Do you need testosterone tests?

Not for tadalafil's sake. The label reports no adverse effect of tadalafil 10 or 20 mg on mean testosterone, luteinizing hormone or follicle-stimulating hormone concentrations compared with placebo, and tadalafil is not approved to treat low testosterone [1].

Testing for hypogonadism is a separate question with its own rules. The Endocrine Society recommends making a diagnosis of hypogonadism only in men with symptoms and signs consistent with testosterone deficiency plus unequivocally and consistently low serum testosterone. The initial test is a fasting morning total testosterone, confirmed by repeating the measurement; free testosterone is added when total testosterone is near the lower limit of normal or when a condition alters sex hormone-binding globulin [2].

In one study of men seeking help for new-onset ED, those aged 40 or younger had higher mean total testosterone than older men [4]. In that series of 439 consecutive men, 114 (26%) were 40 or younger, with a mean age of 32.4 [4]. Those younger men had fewer other medical conditions, but they smoked and used illicit drugs more often, and premature ejaculation was more common [4]. Central obesity is associated with arteriogenic erectile dysfunction and lower testosterone, and ED in an obese man marks higher cardiovascular risk, especially at a young age [5].

Interactions and symptoms to watch

Nitrates. Any form of organic nitrate, taken regularly or intermittently, is contraindicated with Cialis [1]. In a crossover study of 150 men given tadalafil 20 mg or placebo daily for 7 days and then sublingual nitroglycerin 0.4 mg, standing systolic blood pressure fell below 85 mm Hg in more men on tadalafil than on placebo at 4, 8 and 24 hours, with no difference at 48, 72 and 96 hours [6]. The label's emergency rule: where a nitrate is medically necessary in a life-threatening situation, at least 48 hours should have elapsed since the last Cialis dose, and the nitrate should still only be given under close medical supervision with hemodynamic monitoring [1].

Alpha-blockers. Both classes lower blood pressure. In one doxazosin study, tadalafil 20 mg with doxazosin 8 mg daily produced a placebo-subtracted maximal standing systolic blood-pressure fall of 9.8 mm Hg. In a separate doxazosin study, 16 of 24 subjects had a systolic reading below 85 mm Hg or a fall over 30 mm Hg after tadalafil, versus 6 on placebo [1]. For ED, the label says to be stable on the alpha-blocker first and start Cialis at the lowest dose; for BPH, the combination is not recommended [1].

CYP3A4 inhibitors. Ketoconazole 400 mg daily raised exposure to a single 20 mg tadalafil dose by 312% and peak concentration by 22% [1]. With such inhibitors the label caps as-needed Cialis at 10 mg every 72 hours and once-daily Cialis at 2.5 mg [1]. The label says erythromycin, itraconazole and grapefruit juice were not studied but would likely increase exposure [1]. In the other direction, rifampin 600 mg daily cut tadalafil 10 mg exposure by 88% and peak concentration by 46%; the label recommends no dose adjustment but notes the efficacy of once-daily Cialis may fall by an unknown amount [1].

Alcohol. Both alcohol and tadalafil are mild vasodilators; 5 units or more with Cialis can increase orthostatic signs and symptoms, including a rise in heart rate, a fall in standing blood pressure, dizziness and headache [1]. Tadalafil did not change alcohol levels and alcohol did not change tadalafil levels [1].

Common side effects. In the eight 12-week as-needed ED studies, tadalafil 20 mg versus placebo gave headache in 15% versus 5%, dyspepsia in 10% versus 1%, back pain in 6% versus 3%, myalgia in 3% versus 1% and flushing in 3% versus 1%; discontinuation for adverse events was 3.1% on 10 or 20 mg versus 1.4% on placebo [1]. Back pain or myalgia usually began 12 to 24 hours after dosing and resolved within 48 hours [1].

Symptoms the label addresses directly. An erection lasting over 4 hours, painful or not, needs emergency care, because priapism can cause irreversible damage to erectile tissue [1]. Sudden vision loss in one or both eyes may be non-arteritic anterior ischemic optic neuropathy (NAION), reported rarely with all PDE5 inhibitors; the label says patients should stop Cialis and seek medical attention, and that prior NAION or a crowded optic disc warrants caution [1]. It gives the same instruction for a sudden decrease or loss of hearing, sometimes with tinnitus and dizziness [1].

What once-daily dosing means for check-ins

Once-daily Cialis gives continuous tadalafil levels: steady state is reached within 5 days, with exposure about 1.6-fold that of a single dose, and the mean terminal half-life is 17.5 hours in healthy subjects [1]. Because once-daily Cialis provides continuous plasma levels, the label tells physicians to consider that when evaluating interactions with nitrates, alpha-blockers, antihypertensives, potent CYP3A4 inhibitors and substantial alcohol [1].

The trials describe an older population than a 25-year-old: the eight 12-week as-needed ED studies had a mean age of 59 (range 22 to 88), and the three once-daily ED studies of 12 or 24 weeks had a mean age of 58 (range 21 to 82) [1]. In the integrated analysis of 1,112 men (mean age 59, range 22 to 82), tadalafil 20 mg improved the erectile function domain of the IIEF by a mean 7.9 points, 75% of intercourse attempts were successful, and 81% reported improved erections versus 35% on placebo [7].

Fertility in your twenties

The label reports that less than 0.0005% of a dose appears in semen [1]. The fertility question the Endocrine Society guideline addresses directly is testosterone therapy: it recommends against starting testosterone therapy in men who are planning fertility in the near term [2].

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