Originally Posted by sinista63
i'll try to organize my response
1. thank you for taking the time to post your references as i can tell that took some time. my original support of bask8kace was in the statement that he made concerning the selectivity of cialis. nowhere in your references does it state the selectivity ratios for vardenafil vs. tadalafil. the studies that i listed aside, if you look at Seanz de Tejada et al. Int J Impot Res 2002; 14(Supp4):20 (this was actually a quick rehash of a poster presentation by the authors) and Bischoff E. Int J Impot Res 2004; 16: S11-14, you will see that, based on in vitro data, cialis has a greater selectivity for PDE5 than the other PDE isoenzymes. it is also more selective across the board than the sildenafil and vardenafil. the only downfall is that it is more selective than the other two agents for PDE11 which may be the reason for the backpain that may be associated with it. PDE11 is also localized in other tissues (prostate, liver, kidney, pituitary, testis) and what problems this may cause has not been completely elucidated at this point. so yes, cialis, with time, may be found to be inferior to levitra due to its side effect profile but this is not currently the case.
2. you state that levitra is not selective for the PDE6 enzyme which causes vision disturbances but in my review of the literature, i found articles (see above) that show levitra to be more selective for PDE6 than sildenafil.
3. good job finding the articles i posted as references. but as advice for future discussions, do not tear apart the references i posted based on the abstracts of the articles. i know that there are not many AR members that have access to these full-text articles, but i'm not one to post references without having read the complete article unless the article was published in the Journal of Obscure Medicine and is totally unaccessable to me (I was spoiled for years having Harvard's Medical Library in my backyard, but now that I'm in Vegas I do not have this luxury). The Porst article was not a press release. I do not use press releases nor to I use webpages (unless there is ABSOLUTELY NOTHING in the scientific literature) to back up my statements. It was a review article published in the International Journal of Impotence Research. What you found was a website that simply copied and pasted the abstract from the article. The abstract does not contain all the information that the full text contains in regards to the selectivity of the drug.
4. i do agree that levitra is more potent than cialis (this is evidenced by the lower concentration required for inhibition of the PDE5 enzyme, 2 nmol/ml vs. 0.7 nmol/ml) (Sorbera et al. Drugs Fut 2001;26:15-19) but in no way does this mean that it is more selective. selectivity and potency are not to be confused (as has been stated by SexyKitty). when you use the term "focused", i take it as you stating "selective" which would not be the case in the many instances you used that terminology.
5. as has been stated by others (including yourself), trial and error is currently the only way to figure out which is better for a patient. this is until head-to-head randomized trials are performed.
6. "significant potency" means that the drug causes a statistically significant inhibition of PDE5 (in this case) as compared to placebo. the abstract is uninformative as to the selectivity of the agents. you need the full-text for that.
7. you need access to the canadian journal of urology for that last article. i only have a hard copy of the article but i might be able to dig something up in electronic form and email it to you if you so desire.
my thoughts have been a little scattered today. hopefully this somehow organized my thoughts and made them a little easier to read. this is one hell of a discussion. probably one of the better ones i've been a part of. so kudos to you tryingtogetbig. hopefully you don't find my comments to be any type of personal attack. i'm just adding 2 more cents into the debate.
peace