Author: DaftNotStupid

Posted: Wed Nov 28, 2012 7:49 pm

I sent this as a private message to the chart’s author, but not getting a response after a few days, I thought I’d post it here too:

I like your taper model but I’ve found a problem with it. Using the default 37 hour half-life, it seems to work pretty well, but as the half-life is increased towards 72 – a frequently specified number, though I have also seen 37 to 72 mentioned as a range – the graph looks increasingly wrong. According to your model, while a single 1mg dose taken on day 1 decays to 0.5 after one day using a 24 hour half-life – what you would expect – it never decays at 48 hours, and grows to nearly 130Kg over 30 days at 72. This is obviously wrong – maybe someone else could check it out.

I have a few other comments and questions:

How go you calculate the plasma levels from the actual dose? Have you thought of building in activation time into your model – I’ve seen numbers like 30-60 mins to full effectiveness. I’ve also seen mention to variable sloped decay.
I can tell that you calculate the residual once per day, adding it to the next dose. That’s what I do in my spreadsheet model, as well. I was thinking about this approach, and wondered if the drug actually decays more quickly – if you calculate the half-life hourly rather than daily, you get slightly different results.
It would be useful if you could specify a daily dose, instead of having to input each day separately. Being able to input or change each day’s dose will help people who want to see their levels when planning their tapers and final skips

J