Mechanism of Action
Part of the physiological process of erection involves the release of nitric oxide (NO) in vasculature of the corpus cavernosum as a result of sexual stimulation. NO activates the enzyme guanylate cyclase which results in increased levels of cyclic guanosine monophosphate (cGMP), leading to smooth muscle relaxation in blood vessels supplying the corpus cavernosum, resulting in increased blood flow and an erection.
PDE5 inhibitors inhibit the degradation of cGMP by phosphodiesterase type 5 (PDE5), increasing bloodflow to the penis during sexual stimulation.
This mode of action means that PDE5 inhibitors are ineffective without sexual stimulation.
Read more about this topic: PDE5 Inhibitor
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