Anavar: + Caffeine = Greater Bioavailability (Maybe)

TL:DR Oxandrolone (anavar) when dosed with caffeine increases its bioavailability according to this flawed study.

0.4mg of anavar was given to a single test subject both without caffeine and then with 300mg of caffeine. Excretion of anavar without caffeine was 10ng/min at peak, but increased to 150ng/min with caffeine. Maximum excretions occurred at <4h and 6h respectively.

This seems to indicate that caffeine alters excretion of anavar:

With 300mg of caffeine, there were very large increases (about 20 times) in the amount and rate of excretion for both oxandrolone and epioxandrolone… epioxandrolone increased 15-fold….

The researchers believe that caffeine increases bioavailability of anavar by increasing gut emptying, probably. We actually see this with some drugs - paracetamol as an example, where caffeine speeds its absorption.

What Is Excretion And Why Does It Matter?

But Comic, excretion is bad right? Why do I want the anavar to leave in higher concentrations? And what has that got to do with increasing its bioavailability?

The researchers make a pretty bold conclusion by connecting increased excretion with high bioavailability, especially since it has a high availability already of 97%. They do so because excretion is associated with bioavailability, or specifically there is more compound presenting to organs to be cleared.

In order to be eliminated, a drug must be presented to the organs of elimination by the plasma flow. The higher the drug concentration, the more drug is presented to the organs and thus can be eliminated.

What the researchers here are saying is that caffeine with anavar increased the amount of anavar that was being made available to the body. It may result in a shorter half-life given the higher excretion, but it would be tremendously more effective.

What’s Wrong In The Study

Besides the obvious issue of n=1, where there is nonlinear renal clearance bioavailability estimates have error rates ranging between -53% to 125%. And what we see is a spike and absolutely nonlinear clearance, and as a result we can expect errors in measurement.

But I can’t help but feel that the researchers are all very smart people, far smatter than myself and they must have accounted for this before making such a conclusion. Or maybe not. Who knows?


The conclusion then is that high dose effects can be achieved with low doses… or for us, a high dose of anavar can achieve even greater anabolic effects by coupling it with caffeine. db has starting dose listed as 20mg ED, considerably more than the 0.4mg the researchers used. However, words of caution - this study is not reliable, and while it’s not surprising to see caffeine enhancing the effectiveness of compounds, I’d like to see follow up studies firstly replicating the the result. Further, no lbm or enhanced anabolic effect was evaluated - sure measurements of an increased bioavailability.