What is the elimination half‑life of tadalafil?

Tadalafil Half-Life

The elimination half-life of tadalafil is 17.5 hours. 1, 2

Pharmacokinetic Profile

• Tadalafil has a mean terminal half-life of 17.5 hours in healthy subjects, with a mean oral clearance of 2.5 L/hr 2
• This long half-life distinguishes tadalafil from other phosphodiesterase type 5 (PDE5) inhibitors like sildenafil and vardenafil, which have half-lives of approximately 4 hours 1
• The extended half-life enables therapeutic plasma concentrations to be sustained for up to 36 hours after a single dose 3, 4, 5

Clinical Implications of the 17.5-Hour Half-Life

Nitrate Interaction Window

• Patients taking tadalafil must avoid nitroglycerine for at least 48 hours after the last dose due to the risk of severe hypotension 1
• This is a longer contraindication period compared to sildenafil or vardenafil (24 hours), directly reflecting tadalafil's longer half-life 1
• The combination of tadalafil with nitrate medications is absolutely contraindicated in patients with chronic coronary disease 1

Dosing Flexibility

• The 17.5-hour half-life makes tadalafil suitable for both on-demand dosing and once-daily continuous therapy 4, 6
• With once-daily dosing, steady-state plasma concentrations are achieved within 5 days, with exposure approximately 1.6-fold greater than after a single dose 2
• Maximum plasma concentration (Cmax) occurs between 30 minutes and 6 hours after administration (median 2 hours) 2

Special Populations

• Elderly patients (≥65 years) have 25% higher tadalafil exposure (AUC) due to lower oral clearance, though no dose adjustment is routinely required based on age alone 2
• Patients with diabetes mellitus show approximately 19% reduced exposure with no clinically significant impact on efficacy 2