Tadalafil (Generic) Post-Bariatric Surgery Use: Dosing, Absorption, and Clinical Guidance

Is the dose different after bariatric surgery?

The Cialis label organizes dosing by indication, with separate limits for kidney function, liver function and interacting drugs [1]. As needed for erectile dysfunction, Cialis starts at 10 mg before sexual activity, can be raised to 20 mg or lowered to 5 mg, and is limited to one dose per day. The label describes improved erectile function versus placebo for up to 36 hours; sexual stimulation is still required [1]. For erectile dysfunction, it lists 2.5 mg once daily at about the same time each day, which may increase to 5 mg. For BPH or erectile dysfunction with BPH, it lists 5 mg once daily [1]. The label says not to split the tablets and to take the entire dose [1].

Drugs@FDA lists the Cialis 5, 10 and 20 mg tablets as prescription and the Cialis 2.5 mg tablet as discontinued. Generic tadalafil is approved in 2.5, 5, 10 and 20 mg tablets that follow the Cialis indications [2].

Does bariatric surgery change absorption?

The Cialis label does not give an absorption figure or dose adjustment for people after bariatric surgery. It reports that tadalafil reaches peak concentration between 30 minutes and 6 hours after a dose, with a median of 2 hours. Food does not change the rate or extent of absorption. Terminal half-life is 17.5 hours in healthy subjects, and once-daily dosing reaches steady state within 5 days at about 1.6 times the exposure of a single dose [1].

What else limits the dose

• Kidney: At creatinine clearance 30 to 50 mL/min, the as-needed start is 5 mg with 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, and once-daily use is not recommended [1].
• Liver: In mild or moderate impairment (Child-Pugh A or B), the as-needed dose is not above 10 mg. In severe impairment (Child-Pugh C), the label does not recommend use [1].
• Nitrates: Nitrates in any form are contraindicated. The label allows a nitrate in a life-threatening situation only after at least 48 hours since the last Cialis dose, under close medical supervision with hemodynamic monitoring. This is an emergency rule, not permission to combine them [1]. In a 150-man crossover study, standing blood pressure fell below 85 mm Hg in more men on tadalafil than on placebo after nitroglycerin at 4, 8 and 24 hours, with no difference at 48, 72 and 96 hours [3].
• CYP3A4 inhibitors: Ketoconazole 400 mg daily raised tadalafil 20 mg exposure (AUC) by 312%. With CYP3A4 inhibitors such as ketoconazole or ritonavir, the label caps as-needed Cialis at 10 mg not more often than every 72 hours, and once-daily Cialis at 2.5 mg [1].

Common reactions in the as-needed erectile dysfunction trials included headache, reported by 15% on tadalafil 20 mg versus 5% on placebo, and dyspepsia, 10% versus 1% [1]. The label says patients should seek emergency care for an erection lasting more than 4 hours, and should stop the drug and seek care for sudden vision loss or sudden hearing decrease or loss [1].