Description
Vardenafil is the third of the classic PDE5 inhibitors and sits between the two better-known members. Like sildenafil and tadalafil it blocks phosphodiesterase type 5, the enzyme that breaks down cyclic guanosine monophosphate in erectile tissue. The review by Ormrod and colleagues describes the chain: if cGMP persists, smooth muscle relaxes, arterial inflow rises and the expanding tissue compresses the draining veins against the tunica albuginea, restricting outflow.
The decisive point is that PDE5 inhibitors amplify an existing signalling chain rather than starting a new one. Without sexual stimulation nothing happens, because no nitric oxide is released and no cGMP is produced that could be protected from breakdown. That holds equally for every substance in this class.
Of the three classic members, vardenafil has the highest selectivity for PDE5 over PDE6, the related enzyme in the retina. In practice that means fewer visual disturbances than with sildenafil. Absorption is rapid and bioavailability high, while duration of action sits well below that of tadalafil.
The efficacy data are extensive. Ormrod and colleagues summarise, among others, a 26-week trial in 736 men in which 85 percent on 20mg reported improved erectile function versus 28 percent on placebo. An effect was also seen in harder populations: a 12-week trial in 452 men with diabetes mellitus and a placebo-controlled trial in 440 patients after radical prostatectomy both showed improved IIEF erectile function domain scores versus placebo.
Alongside the film-coated tablet there is an orodispersible form. The review by Sanford points out explicitly that the two are not pharmacokinetically equivalent: the orodispersible tablet consistently delivers greater systemic exposure, so the formulations are not interchangeable.
You can order Vardenafil as oral tablets with 20mg per tablet, 10 tablets per blister.
This information is for research and educational purposes only. No medical advice.
Risks & Safety
The PDE5 class carries one absolute contraindication that costs lives every year because people are unaware of it.
- Nitrates are an absolute contraindication: Nitroglycerin, isosorbide dinitrate, isosorbide mononitrate, amyl nitrite and the alkyl nitrites sold as poppers. Nitrates and PDE5 inhibitors act on the same signalling chain. Together they can drop blood pressure to life-threatening levels. This holds even when hours separate the two.
- Alpha blockers: With substances such as tamsulosin or alfuzosin the blood-pressure-lowering effects can add up. Relevant for anyone being treated for the prostate.
- Cardiovascular status: Sexual activity is physical exertion. With unstable angina, a recent heart attack or stroke, or severe heart failure, the question is not the medication but the capacity to exert.
- Common adverse effects: Ormrod and colleagues list headache, flushing, dyspepsia and rhinitis, mostly dose-dependent and mild to moderate.
- Visual disturbances: Not excluded despite the higher PDE5 over PDE6 selectivity. Any sudden loss of vision is a reason to stop and an emergency.
- Priapism: An erection lasting more than four hours is a urological emergency. Untreated, permanent damage to erectile tissue can follow.
- The orodispersible tablet is not the same: Switching from the film-coated tablet means switching to higher exposure. Per Sanford the two forms are explicitly not interchangeable.
This classification does not replace medical advice. Risk and responsibility for any actual use lie entirely with the buyer.
Studies
- Vardenafil - Drugs & Aging 2002, Ormrod et al: review of the PDE5 inhibition mechanism, the 26-week trial in 736 men with 85 percent reporting improved erectile function on 20mg and the trials in diabetes mellitus and after radical prostatectomy.
- Vardenafil orodispersible tablet - Drugs 2012, Sanford: analysis of the POTENT I and POTENT II trials of the orodispersible tablet, noting that the formulations are not interchangeable because of greater systemic exposure.
