Mirodenafil

Why this exists

This experiment starts from a negative result. Daily low-dose tadalafil produced a very specific ache pattern: lower-body muscle discomfort, worse at rest and lying down, that began cutting into sleep. That is close enough to the tadalafil label's back pain/myalgia description that I am treating it as a real intolerance, not random soreness. The question was not "which PDE5 inhibitor is strongest?" It was whether there was a cleaner blood-flow test that avoided the long-tail side effect that stopped tadalafil.

What it is

Mirodenafil is a PDE5 inhibitor developed in South Korea and used there for erectile dysfunction. It is not FDA-approved in the United States. The relevant pharmacology is its shorter profile: clinical literature describes a time to peak around 1.25 hours and a half-life around 2.5 hours, much closer to the short-acting PDE5 lane than to tadalafil's roughly 17.5-hour tail.

Why not nortadalafil

Nortadalafil is the wrong workaround for my failed tadalafil experiment. It is a demethyl-tadalafil analog, appears in FDA alerts as an undeclared tadalafil-like drug ingredient, and does not have a clean clinical dose ladder, half-life, safety profile, or PDE11 selectivity profile that I can use. Structurally similar is not the same as clinically interchangeable. If the goal is to avoid tadalafil-style muscle pain, nortadalafil gives me less certainty right where I need more.

Why mirodenafil is more rational

Mirodenafil is at least a distinct PDE5 inhibitor with human data, not just a tadalafil impurity or adulterant-type analog. Its shorter half-life is the main reason it is interesting for this N-of-1: if my tadalafil problem was driven by long exposure, accumulation, or recumbency-worse muscle discomfort across the day and night, then a shorter-acting compound was the more coherent next test. That did not prove it would avoid the problem. It only made the hypothesis less sloppy.

PDE11, kept honest

The usual tadalafil pain explanation is PDE11 inhibition, because tadalafil is much less selective for PDE5 over PDE11 than some other PDE5 inhibitors, and PDE11 is discussed in skeletal-muscle context. But the mechanism is not settled. The tadalafil label itself says the clinical consequence of PDE11 inhibition in humans has not been defined. For mirodenafil, I do not have a clean human PDE11-sparing answer. The practical rule is simpler: do not assume the muscle-pain risk disappears just because the molecule is different.

Approved-drug comparison

If this were purely a regulated-medication decision, avanafil would be the cleaner molecule to discuss with a prescriber: it is FDA-approved, short acting, and the label describes strong selectivity for PDE5 over PDE11. Sildenafil is also an approved short-acting option with a deeper U.S. clinical history. Mirodenafil sits in a different bucket for me: more rational than nortadalafil, but not as clean as a prescribed U.S.-approved PDE5 inhibitor.

Evidence gap for gym blood flow

PDE5 inhibition clearly changes vascular signaling, but that does not automatically mean better lifting performance or a useful pump in a healthy trained person. The tadalafil page already documents the problem: a healthy-athlete trial with tadalafil did not show the performance signal I would want, while the cleaner muscle blood-flow data come from Duchenne muscular dystrophy, where nitric-oxide signaling is impaired. This page is therefore a narrow tolerability and subjective training-feel result, not proof that PDE5 inhibition is a gym-performance tool.

Safety boundary

PDE5 inhibitors can lower blood pressure and can interact dangerously with nitrates, guanylate-cyclase stimulators, alpha-blockers, antihypertensives, alcohol, and CYP3A4 inhibitors. This matters more because the use case is training, where dehydration, stimulants, and vasodilating pre-workout ingredients can stack in unhelpful ways. This page is a personal ledger entry about a kept experiment, not a protocol, dose recommendation, or sourcing guide.

Sources

• Tadalafil prescribing information, DailyMed - half-life, steady-state timing, tadalafil back pain/myalgia pattern, PDE11 selectivity, and nitrate interaction.
• FDA public notification on nortadalafil - nortadalafil identified as a hidden tadalafil-like drug ingredient with blood-pressure interaction concerns.
• Mirodenafil phase IV ODF study, World Journal of Men's Health - Korean clinical data, 50 mg and 100 mg study arms, and the reported pharmacokinetic profile.
• Stendra (avanafil) prescribing information, FDA - approved-use framing, contraindications, blood-pressure cautions, half-life, and PDE selectivity language.
• Avanafil PDE selectivity review, PubMed - comparative selectivity discussion and musculoskeletal adverse event context.
• Tadalafil in healthy athletes, PubMed - the trial that did not show a useful aerobic or anaerobic threshold signal in healthy athletes.
• PDE5 inhibition and Duchenne muscle blood flow, PubMed - disease-model blood-flow rescue data, not healthy-athlete proof.

Protocol

This is listed in the pre-workout section of the daily stack as a 50 mg Mirodenafil entry. That is a record of what I tested and am keeping, not a recommendation. The point of the experiment was not to find a human tadalafil-equivalent conversion. There is no defensible conversion from 2.5 mg or 5 mg tadalafil to a research-sourced mirodenafil amount.

What counted as success

The useful signal was a noticeable improvement in training blood-flow feel and pump on lifting days, with no recurrence of the tadalafil ache pattern and no worse sleep, dizziness, headache, flushing, blood-pressure symptoms, or stimulant stacking with the rest of the pre-workout routine.

Watch signals

I am still watching for the exact failure mode that stopped tadalafil: deep glute, thigh, leg, calf, low-back, or thoracolumbar ache, especially if it is worse sitting or lying down. I am also watching for dizziness, lightheadedness, headache, flushing, nasal congestion, unusual heart-rate changes, sleep disruption, and whether the perceived pump is strong enough to matter outside novelty.

Decision

Mirodenafil earned continued use because the training signal was clear and the tadalafil pain signature did not return. The guardrail stays in place: any recumbency-worse lower-body ache, sleep disruption, or meaningful lightheadedness would end this rather than trigger dose-chasing. The bar stays high because the previous PDE5 experiment already failed on recovery cost.