You have both, so I'd use both. Take the diazepam throughout the day, maybe 10 mg every 4 or 6 hours. That is quite a bit of diazepam, but if you are in the middle of heroin withdrawal, that much sedation is probably a good thing. I'd take the alprazolam when you want to sleep, maybe 0.75 mg - 1 mg. 1 mg alprazolam for someone with no benzo tolerance should pack a "punch" so to speak, and hopefully put you to sleep along with the diazepam. As you build up diazepam and its active metabolites in your system, you will become more effected by the drug. An initial 10 mg diazepam might not feel like to much, but diazepam really builds up. It will definitely help with sleep, too. The diazepam I'd use for general sedation, and comfort round-the-clock until the wd symptoms subside, and the alprazolam to kind of "knock you out". Diazepam will really ease all of the symptoms better than alprazolam would, I'd think. Alprazolam of course, has its place. I am giving these recommendations assuming you have no benzo tolerance, and want to be rather sedated for this, and that you have an ample supply of diazepam and alprazolam to work with. Hope this helps some.