|new videx dosing announcement
Aug 21, 2000
Have you heard about the letter to physicians recommending 2x vs. 1x daily dosing for Videx?? Here is the excerpt. WHat is your opinion and what is the correct dosage. I take two 400mg tabs once a day. are they advocating 200mg 2x day?
"BMS has sent letters to physicians concerning a new study which shows that Videx, an anti-AIDS drug, should be given twice daily, not once daily. The study of 756 treatment-naive HIV-infected adults compared Videx given once daily with stavudine and nelfinavir treatment to AZT/lamivudine/nelfinavir therapy. Fifty-nine percent of the AZT group had HIV-RNA levels under 400, but only 50 percent of the Videx group had similar levels. Furthermore, of the patients with HIV RNA under 50 at 48 weeks, 47 percent of the AZT group had undetectable levels, versus only about one-third of the Videx once-daily cohort."
| Response from Dr. Cohen
Thanks for asking about this important issue -- a few comments of course.
First I hope you are NOT taking two 400 mg tabs once a day (!) -- since (a) it doesn't come in 400 mg tabs and (b) the standard correct once a day dose is 400 mg total, versus 200 mg taken twice a day. And since you need to take two tablets at each dose, most are now taking 200 mg tabs, two of these, once a day. So -- based on this FDA letter -- do we need to go back to twice a day ddI?
The short answer is no. Here's what the FDA letter told us -- in a study using nelfinavir as the "third drug" combined with one of two nucleoside combos, the combination of once a day ddI with d4T was compared to azt/3tc. And as you summarized, the ddI arm didn't do as well as the 3tc arm. So why might this have happened? Can we conclude the once a day ddI isn't as good as other options?
Well the first most obvious confusion in the FDA letter is that once a day ddI wasn't compared to twice a day ddI -- it was compared to azt/3tc. So concluding that once a day ddI isn't as good as twice a day is a stretch given this information -- you would need a different study to actually know if twice a day ddI was better than once a day ddI. And there have been several reasonably sized studies all completed and presented before this study -- all of which did compare once a day to twice a day ddI -- and they all showed very very similar results regardless of how the ddI was given.
So why did the once a day ddI arm not do so well here? Well, it may help to recall that nelfinavir must be taken with food to be successful. ddI must be taken on an empty stomach to work. So this arm containing ddI was actually not so easy to do -- it was not just taking study medication twice a day as you could do with azt/3tc/nelfinavir. (I think I recall that the nelfinavir might have been at least initially taken as three times a day -- if so, then the ddI would be even harder, requiring a fourth time each day to take this medication apart from the nelfinavir). And since this arm was harder to do, it isn't surprising that it doesn't do as well. We have learned over and over that any complexity in dosing gets in the way of people's success... and this was just too complex to expect. Nonetheless, when the study was designed, the researchers hoped that this would still work out. And with the benefits of hindsight, there are now several easier ways (like using other "third drugs") to design the research that documents even more that once a day ddI is as good as twice a day ddI -- and since it is easier, it could actually be better than twice a day. (Finally recall that both ddI and nelfinavir have some looser stools as a side effect -- which may have made this a somewhat less successful combo overall...)
So what to do? Well, the letter does NOT require we switch people back. The FDA evaluates these agents, and gives clinicians the freedom to use them as we see fit. Which in this case means that the letter allows us to use once a day ddI if we are convinced that the data support that this is just as effective as twice a day. Many (if not all?) of us are convinced so we won't switch back. The letter actually says we should use once a day when there are reasons to do so, and since most find taking meds, including this one, easiest to do when just once a day, then you can continue to do as you have been.
Hope that clarifies this timely issue.
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