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Biotech / Medical : VVUS: VIVUS INC. (NASDAQ) -- Ignore unavailable to you. Want to Upgrade?

To: Mkilloran who wrote (18510)	2/3/1999 12:19:00 PM
From: VLAD	Respond to of 23519

martin, In regards to the ICOS drug for erectile dysfunction, there is a perception that this drug is going to be "better" than Viagra but in a sense this is misleading. The ICOS drug if more specific than Viagra may not have the visual side effects seen with Viagra since the blue haze which occurs with Viagra is caused by non specific binding of the PDE6 receptors in the retinal cones. However, when it comes to the most important side effect of the potentially deadly hypotensive effects there will be ABSOLUTELY NO ADVANTAGE over Viagra. This is due to the fact that the hypotensive effects seen with Viagra is not due to non specific binding of PDE. It is due to the fact that PDE5 is not only found in the penis but also in the body's peripheral vasculature. In essence the concern over coronaries in the CVD patient will still be the same since even the most specific PDE5 binding drug will still bind to peripheral PDE5 thus creating the hypotensive effect. Technically speaking, if the ICOS drug does not bind at all to the PDE6 enzyme in the retinal cones then it will be superior to Viagra in that it will eliminate the visual concerns. If long term studies prove that chronic Viagra use actually creates retinal degeneration via binding of PDE6 sites in the retinal cones and the ICOS drug does not, then Pfizer and Viagra will certainly replace Viagra. The FDA has a history of pulling drugs with a particular safety concern if another improved and safer drug becomes available. A good example of this is the history surrounding Seldane. The FDA knew for a long time about Seldane's side effects but didn't think that they were serious enough to pull the drug but once a similar drug was formulated (essentially the same drug as Seldane after Seldane undergoes conjugation in the liver) they decided to withdraw Seldane in favor for the newer and safer version. I believe that it would be of great financial advantage for ICOS to fund research on chronic Viagra use as it pertains to potential permanent retinal degeneration. If it can be proved that sildenafil binding to PDE6 receptors in the retinal cones leads to permanent destruction of this important visual function then Viagra will be screwed and the new ICOS drug when approved can totally replace Viagra. I believe that this is one reason that Lily was glad to pay ICOS $75M on a drug that is still at least 2 years away from approval with no guarantee of approval. You can bet that before Lily shelled out $75M for the ICOS deal, they had their researchers carefully scrutinize the ICOS research as it pertained to the reports of fewer side effects than Viagra. The other thing to consider is figuring out the actual cause of the unpleasant side effect of headaches as seen with about 10% of Viagra patients. I do not know if the headaches are secondary to peripheral PDE5 binding or perhaps a reflexive side effect to the retinal PDE6 binding. If the later is the case then this will spell even more trouble for Viagra as the ICOS drug would then eliminate both headaches and visual side effects. The important point for Vivus investors to realize is that when it comes to the most important side effect pertaining to PDE5 peripheral binding(hypotention), there will NEVER be a PDE5 inhibitor developed that will not have this side effect. The only way to prevent such a side effect would be to remove the peripheral PDE5 enzyme which is impossible.