|Viagra||25mg, 50mg, 100 mg tablets||March 27, 1998|
|Cialis||5mg, 10mg, 20mg tablets in bottles of 30.||November 21, 2003|
|Levitra||2.5mg, 5mg, 10mg, 20mg tablets in bottles of 30.||August 19, 2003|
|Drug||Protein Binding||Bioavailability||Metabolism||Half Life||Excretion|
|Viagra||95%||41%||Active Metabolite CYP3A4 and 2C9||4 hours||81% fecal and 12% renal|
|Cialis||Not determined||Not determined||Inactive Metabolite CYP3A4||18 hours||62% fecal and 37% renal|
|Levitra||95%||16%||Active Metabolite CYP3A4||4 hours||90-%-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.
|Drug||Food Effect||Median Action Time||Action Duration|
|Viagra||Fatty food decreases action time and peak concentration levels.||28 minutes||4 hours|
|Cialis||Fatty food has negligible effect.||45 minutes||36 hours|
|Levitra||Fatty food decreases peak concentration levels.||27 minutes||4 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.