pharmacology of sildenafil.
The headache, facial flushing and nasal stuffiness side effects mentioned are pretty accurate, and are associated with all drugs that cause vasodilitation. Addtionally, sildenafil rarely (meaning less than 1%) causes temporary blue-green color blindness.
Pfizer used to make 25, 50 and 100mg doses. Later, the 25mg dose was determined to not be able to exceed its own placebo effect, so Pfizer d/c’ed it and only mfrs. the 50 and 100mg. In other words, 25mg is considered a subtherapeutic/placebo dose.
If you want a little extra bang for your Viagra buck, take 800mg of cimetidine (Tagamet) with your pill. Both cimetidine and sildenafil compete as substrates for the same metabolic channel in the liver, called the P-450 cytochromes. Sildenafil is cleared exclusively by the hepatic route. When you have two substances competing for the same “drain”, they will back up like a clogged sink ,and blood levels of sildenafil increase significantly, to the tune of around 58%. Over the counter Tagamet/cimetidine comes in 200mg tablets, so you have to take four of them (this is okay.)
If you wish to read up on it further, look it up on viagra’s home site, I believe ,and look toward the end of the professional section monograph in the “drug interactions” section.
If you have any further questions regarding this or the pharmacology of any other drug, let me know.
Regards,