Chloroquine and Hydroxychloroquine as treatments for Covid-19

Presumably you meant 'arms' .

 

I understand the concept of half life and exponential decay, but could you explain (without getting too medically technical) how it relates to medication please.

And I'm guessing that when you talk about a loading dose this is like when I've had to go on emergency doses of antibiotics, a double first dose is typically recommended. Presumably to get a faster ramp up of medicine level within the body.

 

The median ages of the two arms also reflect this, 66 vs 77.

Surely this is so basic they must have attempted some kind of correction for this, even if also potentially flawed? Feels like kindergarten science.

 

If the therapeutic dose of a drug is 100mg in the body and the half life is a day then if you give 100mg a day the level just before taking the next dose is right (1/2 + 1/4 + 1/8 + 1/16... =1). But if the half life is 2 days you will end up with twice as much on board. You want to take 100mg every two days or 50mg a day. If the half life is 7 weeks, as for chloroquine, you want to take 2mg a day. But if you take 2mg a day you will not have an effective level for 7 weeks, which is not much good for treating an emergency.

 

Half life basically means the time it takes for half of the substance to decay.

So if half life is 1 day and you start on a single dose of 100 units then
Day 1 = 100
Day 2 = 50
Day 3 = 25
Day 4 = 12.5. Etc

If you then start taking 100 every day the amount will accumulate over time, so Day 2 = 150 etc

So care would need to be taken with the daily dose in order to have the desired amount in the bloodstream over time.

See Jonathan’s post above

 

Yes, so in the same way the dose decays exponentially, there will also be an equivalent exponential approach toward the target quiescent level. Which is why - I'm guessing - when you need antibiotics pretty urgently they give you them intravenously ... presumably the half life is drastically reduced in terms of ramp up.

Is intravenous administration of chloroquine not viable?

 

The dynamics of getting drug in are a bit different. But IV is certainly given to bypass delay in absorption. Chloroquine may not have an available IV formulation on the shelf known to be safe but it may do (for falciparum malaria?). The delay in absorption is normally only about half an hour from the stomach (if empty) so it is probably not a big issue. IV antibiotics are given because bacterial infection can become critically lethal within maybe an hour or so and vomiting or diarrhoea may lose all the drug. Viruses aren't quite like that.

 

A very rigorous systematic review from French researchers on the use of HCQ and HCQ+AZT for the treatment of COVID19.

https://www.clinicalmicrobiologyandinfection.com/article/S1198-743X(20)30505-X/fulltext

"Hydroxychloroquine was not significantly associated with mortality: pooled Relative Risk RR=0.83 (95% CI: 0.65-1.06, n=17 studies) for all studies and RR=1.09 (95% CI: 0.97-1.24, n=3 studies) for RCTs. Hydroxychloroquine with azithromycin was associated with an increased mortality: RR=1.27 (95% CI: 1.04-1.54, n=7 studies). We found similar results with a Bayesian meta-analysis."

Abstract:

The authors are 6 young researchers who teamed up via social media. They're now receiving ad hominem (not scientific) criticism from pro-HCQ French MDs, as well as insults & threats from HCQ "supporters". So are journalists who have reported on their review.

Insults and threats for conducting rigorous research. Politics stepping over science. This is beyond horrible.

 

A user on YouTube has sent me this reply when I pointed out that the non-HCQ group was not age matched to the HCQ group. Here is what they said....

"The study controls for other variables which are statistically ruled out. HCQ works independent of the other variables. That is the whole point of an observational study. Big numbers make that easier to do and makes the results more reliable."

Is there any way this could be true? Seems bunk to me.

 

It certainly seems garbled. None of the arguments follow.

 

The issue is not about the "other variables" surely, and so whether HCQ works independently of them has no relevance to the question posed ... even if that statement of theirs has any credibility anyway.

The issue is about the age variables, which have not been controlled for. So I think the evasive response acknowledges it's a 'fail'.

 

thanks for the link to the twitter thread. This part is illuminating.....

"One of the authors of this study (Philippe Gautret) is part of the editorial committee of the journal that accepted this publication. Without being a unique situation in the academic world, it seems to be a well-established tradition in this team." (-David Hajage)