Answer
When sexual stimulation releases nitric oxide locally, tadalafil's inhibition of PDE5 increases cGMP in the corpus cavernosum, relaxing smooth muscle and increasing blood flow into penile tissues to produce an erection; tadalafil has no effect without sexual stimulation.
Sources for this answer
- Cialis 2.5mg film-coated tabletsEli Lilly and Company Limited · emc · SmPC §5.1 Pharmacodynamic properties · Version 33Document updated
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