Sildenafil vs Tadalafil: what is the difference?

How they differ

Both are PDE5 inhibitors, keeping cyclic GMP from being broken down so blood vessels stay relaxed, and the difference that matters is duration. Sildenafil acts for roughly four to six hours; tadalafil's half-life is around 17.5 hours and its effect can span a day and a half, which is why it acquired the weekend nickname. Sildenafil is the more affected by a fatty meal, which slows its absorption, and tadalafil much less so. Their side effect profiles follow their off-target selectivity: sildenafil has some activity at PDE6 in the retina, which produces the occasional blue tinge to vision, while tadalafil has more at PDE11, which is associated with back and muscle ache. Both were developed for cardiovascular indications before their current ones and both remain in use for pulmonary hypertension.

Side by side

Common questions

What is the difference between Sildenafil and Tadalafil?

Both are PDE5 inhibitors, keeping cyclic GMP from being broken down so blood vessels stay relaxed, and the difference that matters is duration. Sildenafil acts for roughly four to six hours; tadalafil's half-life is around 17.5 hours and its effect can span a day and a half, which is why it acquired the weekend nickname. Sildenafil is the more affected by a fatty meal, which slows its absorption, and tadalafil much less so.

Is Sildenafil bigger than Tadalafil?

Sildenafil is the heavier molecule, 474.6 g/mol against 389.4 g/mol for Tadalafil. Sildenafil is C22H30N6O4S and Tadalafil is C22H19N3O4.