What Happens to Sildenafil, Tadalafil and Vardenafil Inside the Body

BrandFormulationsFDA Approval
Viagra25mg, 50mg, 100 mg tabletsMarch 27, 1998
Cialis5mg, 10mg, 20mg tablets in bottles of 30.November 21, 2003
Levitra2.5mg, 5mg, 10mg, 20mg tablets in bottles of 30.August 19, 2003
A lot of attention has been given to what PDE5 inhibitors do to the human body, but now lets have a brief look at  how the the drugs – Viagra, Cialis and Levitra themselves change once they are introduced in the body. This article is not meant as an in depth reference, but aims to give a very basic outlook of the parameters involved.

Pharmacokinetics

DrugProtein BindingBioavailabilityMetabolismHalf LifeExcretion
Viagra95%41%Active Metabolite CYP3A4 and 2C94 hours81% fecal and 12% renal
CialisNot determinedNot determinedInactive Metabolite CYP3A418 hours62% fecal and 37% renal
Levitra95%16%Active Metabolite CYP3A44 hours90-%-96% fecal and 1-6% renal

Pharmacokinetics is the study of how the body changes the drug and what happens to it inside the human body. If you notice – the half life of Cialis is much higher than Viagra or Levitra- this translates to higher active window, remember it works for upto 36 hours. Again the increased half life means slower onset of action meaning it takes longer than Viagra and Levitra to work but stays in the body for longer.

Pharmacodynamics

DrugFood EffectMedian Action TimeAction Duration
ViagraFatty food decreases action time and peak concentration levels.28 minutes4 hours
CialisFatty food has negligible effect.45 minutes36 hours
LevitraFatty food decreases peak concentration levels.27 minutes4 hours

The above statistic is interesting. What it tells us is that the effect of Cialis is unaffected with fatty food whereas Viagra and Levitra show decreased action time and concentration levels when a man eats fatty food.

 


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