PDE5 inhibitor
Sildenafil
Inhibits phosphodiesterase-5, preserving and amplifying nitric-oxide–mediated smooth-muscle relaxation in corpus cavernosum and pulmonary vasculature.
Primary Mechanism of Action
Clinical / Scientific
Sexual or endothelial NO stimulates guanylate cyclase to form , which relaxes smooth muscle. hydrolyzes ; sildenafil inhibits , so persists and vasodilation is potentiated in tissues that express .
Pathway Targets
PDE5
Scientific explanation
Competitive inhibition of hydrolysis.
NO / cGMP signalling
Scientific explanation
Amplification of existing nitric-oxide signals — not NO generation de novo.
Pathway Convergence
Clinical / Scientific
Target → pathway → downstream effect → biological consequence. This is a mechanistic map, not a treatment claim.
cGMP-preserving vasodilation
Target to downstream effect: Endothelial or nitrergic NO → cGMP formation → PDE5 inhibition → Sustained smooth-muscle relaxation
Mechanistically Relevant Repurposed & Adjunctive Applications
Erectile dysfunction
EstablishedMechanistic rationale
Established labelled indication.
Pulmonary arterial hypertension (specific products/doses)
EstablishedMechanistic rationale
inhibition in pulmonary vasculature is an established PAH mechanism for appropriately labelled products and doses — not automatically identical to ED regimens.
Mechanistic Application Matrix
| Biological Target | Mechanism | Potential Relevance | Evidence Level |
|---|---|---|---|
| PDE5 | Inhibition | cGMP persistence / vasodilation | Established mechanism |
Mechanistic Interaction Considerations
Absolute contraindication with nitrates due to profound hypotension. Caution with other antihypertensives, alpha-blockers, and strong inhibitors. Avoid combining inhibitors without clinical direction.
In Plain Language
An erection and some blood-vessel relaxation depend on a signal called . is the that breaks down. Sildenafil pauses that so an existing nitric-oxide signal lasts longer. It does not create desire or nitric oxide from nothing.
Compounds Sharing Pathways
Other library compounds whose structured pathway data overlap this ingredient. Shared pathways are not combination recommendations.
Mechanistic information is provided for scientific and educational purposes. Discussion of biological pathways or investigational applications does not establish clinical efficacy or constitute individualized medical advice.