Both Cialis (tadalafil) and Viagra (sildenafil) treat erectile dysfunction by increasing blood flow to the penis, but they achieve this through slightly different pathways.
Cialis’s Mechanism
Cialis primarily inhibits the phosphodiesterase-5 (PDE5) enzyme. This inhibition is more selective and longer-lasting than Viagra’s. The result is a prolonged elevation of cyclic guanosine monophosphate (cGMP), a crucial molecule for smooth muscle relaxation in the penis. This sustained relaxation allows increased blood flow for a more extended period.
- Key Feature: Longer duration of action (up to 36 hours). Implication: More spontaneous sexual activity is possible.
Viagra’s Mechanism
Viagra also inhibits PDE5, but its effect is less selective and shorter-lived compared to Cialis. While it also leads to increased cGMP levels and subsequent smooth muscle relaxation, the duration of action is significantly shorter. This means the effect on blood flow to the penis is less prolonged.
- Key Feature: Shorter duration of action (typically 4-5 hours). Implication: Requires more precise timing in relation to sexual activity.
Summary of Differences
Selectivity: Cialis exhibits greater selectivity for PDE5. Duration: Cialis’s effects last considerably longer than Viagra’s. Onset: Viagra’s effects may appear slightly faster than Cialis.
These differences mean that Cialis and Viagra might suit different individuals based on their needs and preferences regarding timing and duration of effect.
