So you’ve taken the pills and the last one is down the hatch.

You now enter the stressful time when we have to wait and see if the response is durable – SVR

Over the first few days the medications rapidly wash out of your system (except Riba which is slow). Sofosbuvir’s active metabolite – GS-331007 – has a half life of 24 hours, for daclatasvir it is 12 hours, and for Ledipasvir it is 48 hours. The half life is the time taken for your body to get rid of 1/2 the current quantity it contains.

Across days 1-7 the levels of the active Sofosbuvir metabolite GS-331007 reduce by half every day so you have 1/2, 1/4, 1/8, 1/16, 1/32, 1/64, 1/128 etc

So by the end of 7 days off treatment you have 1/128th as much (~ 1%) as you did at EOT. For daclatasvir you reach that point in 3.5 days and for ledipasvir 14 days due the difference in wash out rates (1/2 life).

Most medications have side effects of some description so it’s reasonable to assume these will dissipate. Mental side effects can range from high to low – consider alcohol – it can be pretty good while taking it and pretty bad after. Anyway over time we get to the point where there is effectively no medication left in your system and therefore no side effects relating to it being there.

Within a couple of weeks at the most there will not be enough medication left in your system to suppress viral replication so the virus will grow back. The incubation period for a new infection is 2 weeks to 6 months with 6-9 weeks being average, thus the use of SVR12 – 3 weeks washout, 9 weeks to grow.

That said the experience from trials like:

http://www.ncbi.nlm.nih.gov/pubmed/25314116
http://www.natap.org/2013/AASLD/AASLD_26.htm

indicate the the vast majority of patients with SVR4 (~98%) will also go on to SVR12 and SVR24 (we are seeing this as well)

So the shortest wait time is 4 weeks post treatment to get a good idea about ultimate cure.

PCR is expensive and if you were in the vast majority with elevated ALT at baseline relapse will show up as an out of range elevated ALT days before the PCR is availabke so the “poor man’s SVR4” is just to do an ALT and save the PCR for 12 weeks.

Being anxious during this period is normal. Checking your ALT (remember it’s OUT OF RANGE not a tiny blip up) may help, but then again a tiny blip up (normal) may worry you for no reason. There are a few people at SVR who worried about the usual wandering up and down of ALT.

Anyway here’s the sunscreen song…..

[video]https://www.youtube.com/watch?v=MQlJ3vOp6nI[/video]