PDE-5 Inhibitors (Sildenafil / Tadalafil)

Evidence: ★★★★★ · Status: FDA Approved

In plain English

Keeps blood vessels relaxed and blood flowing where it's needed. Extremely well-established; daily low-dose tadalafil also has vascular-health interest.

How it works

Inhibit phosphodiesterase-5 (PDE5A), preserving cGMP → sustained nitric-oxide-driven vasodilation in erectile tissue; tadalafil's long half-life also aids BPH and is studied for endothelial/longevity effects.

Molecular target & official sources

PDE5A phosphodiesterase 5A (NCBI Gene) · Sildenafil (PubChem CID 135398744)

Watch out

Never with nitrates or high-dose beetroot (dangerous BP drop).

Bottom line

Gold-standard ED treatment; low-dose daily has broader vascular appeal.

Helps with: Live Longer · Sexual Health

Stacks with

Shares a pathway — often paired with: Caffeine, Minoxidil, L-Citrulline / Citrulline Malate, Caffeine (thermogenic).

Availability & where to buy

Available over the counter. Widely available OTC — e.g. iHerb (ships worldwide); in Singapore also Guardian, Watsons, GNC, Shopee / Lazada. Look for a third-party-tested / GMP mark and check the dose per serving.

How it works: the Nitric oxide / cGMP pathway →

Used in these protocols

• Low Libido

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