PharmaceuticalPharmaceuticalVasodilatorPDE5 inhibitor

Udenafil

Also known as Zydena · DA-8159

Written by enwyReviewed 5 Aug 20262 sources0 comments

Udenafil is a long-acting PDE5 inhibitor developed and approved in South Korea (as Zydena) but not marketed in the US or most of Europe. It combines a relatively fast onset with a long half-life, positioning it between sildenafil and tadalafil, and supports both on-demand and once-daily dosing.

01 Overview

Udenafil selectively inhibits PDE5 with a half-life of around 11-13 hours, giving a duration intermediate between the short-acting agents and tadalafil. It has been studied for erectile dysfunction, benign prostatic hyperplasia and, in trials, single-ventricle Fontan circulation, but its clinical footprint remains largely confined to South Korea and a few other Asian markets.

Because it is not widely licensed, PED users typically obtain it through grey-market channels, and product quality is less assured than for globally marketed agents. The pharmacology and precautions mirror the rest of the class, including the absolute nitrate contraindication.

02 Mechanism

Selective PDE5 inhibitor with intermediate half-life, raising cGMP in cavernosal and vascular smooth muscle.

03 Dosing

Tier	Dose	Route	Notes
Once-daily	50–75 mg/day	Oral	Continuous dosing regimen studied for ED and BPH.
On-demand	100–200 mg	Oral	Taken 1-3 hours before activity in Korean labelling.

04 Effects

Effect	Magnitude	Evidence
Improved erectile functionSignificant improvement in erectile-function scores in Korean phase 3 trials.	IIEF improvement	Clinical
Intermediate durationLonger window than sildenafil without the very long tail of tadalafil.	~11-13 h half-life	Clinical

05 Side effects

Effect	Severity	Frequency	Evidence
Headache and flushingClass-typical vasodilatory headache and facial flushing.	Mild	Common	Clinical
Uncertain product quality (grey market)Not licensed in Western markets, so material is usually obtained from unregulated suppliers with variable purity and dosing.	Moderate	Depends on source	Anecdotal
Nitrate interaction (severe hypotension)Additive, potentially fatal hypotension with nitrates.	Life-threatening	Rare but potentially fatal	Clinical

06 Legal status

Prescription drug

Approved and marketed in South Korea as Zydena. · as of Jan 2026

United States

Not FDA-approved

Not marketed in the US; no approved medical product. · as of Jan 2026

07 References

Efficacy and safety of udenafil for erectile dysfunctionJ Sex Med, 2008

Udenafil clinical pharmacology reviewDrug Des Devel Ther

08 Discussion0 comments

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This page is reference information, not medical advice. Doses and protocols are documented as they appear in the clinical literature and in practice — describing them is not a recommendation to use them. Countermeasures listed here are not a substitute for a physician. Legal status varies by jurisdiction and changes.