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Biotech / Medical : VVUS: VIVUS INC. (NASDAQ)
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To: BigKNY3 who wrote (19682)3/13/1999 2:06:00 PM
From: DaiS  Read Replies (2) of 23519
 
BigK,

Thanks very much for posting this abstract. If you typed this out for me that is very generous! The RESULTS section makes it clear that all the 16 men failed both on 100mg sildenafil and on 1000ug alprostadil. The experiment would hardly make sense otherwise.

Although it might be tricky for Vivus to promote the combo, to me the result is highly important. For what the experiment shows is a huge positive interaction between the two drugs.

Suppose that a proportion 0.25 of men had sufficient erections with viagra alone, and a proportion 0.125 had sufficient erections with muse alone. If we treat these values as probabilities then if the two drugs acted in a manner that was independent and multiplicative we would expect that,

16 x (1-0.25)(1-0.125) = 10.5 men would fail on the combo and therefore 5.5 men would get sufficient erections with the combo. If it happened that 10 men got sufficient erections on the combo then the difference 10-5.5=4.5 would reflect a positive interaction between the drugs.

So we can break the 10 successes down and say that 5.5 derive from the direct effect of the drugs and 4.5 derive from the positive interaction. Neither Pfizer nor Vivus can claim these 4.5 successes as their own!

On this basis in the present study we can say that of the 16 successes on the combo, 0 are due to the direct effects of the drugs and 16 are due to the interaction! The result is even more impressive given that the combo had 500ug not 1000ug of alprostadil.

I suspect that there is a clear and massive synergistic effect that could not be replicated by increasing more and more the dose of sildenafil alone or alprostadil alone, rather than an effect of overcoming some underlying threshhold to create an erection. Now it would be very interesting to repeat these experiments with lower doses of sildenafil and alprostadil.

I missed all the excitement because I was away the beginning of last week. You have made me aware that there are problems to be overcome in promoting the combo. But if you had told me on Thursday that there had been a pop to near 6, and asked me to choose the news, either,

1. Topical alprostadil for women
2. Combo gives 100% success on men failing both muse and viagra.

I would undoubtedly have chosen option 2.

DaiS
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