Long Term Stability of Bimix, Trimix and Alprostadil

[Bluewhippet]

There have been lots of posts concerning the life and effectiveness of the 3 main injection therapies - Bimix, Trimix and Alprostadil (PGE-1, Caverject and Edex) used by itself. I thought that I would do some research and see if this has been scientifically tested. I eventually came across a peer reviewed study by the Division of Pharmacy at the University of Texas. (http://www.stabilis.org/FichesBiblio/1899-recherche)
This was a comprehensive study and, in summary, the principal findings were as follows:

Bimix, Trimix and Alprostadil can be frozen at -20degC for 6 months and then thawed to room temperature (23degC) with no loss greater than 5% of any of the drugs. They tested up to 4 freeze/thaw cycles with no adverse effects.

The least stable component of Trimix is Alprostadil (the only drug in Caverject and Edex) loses about 12.5% of its concentration at room temperature (23degC) after 7 days and 44% after one month. However, at normal domestic refrigerator temperature (4degC) there is only a 2% loss after 7 days and less than 6% after one month. Even better, if stored in a freezer at -20degC the loss was less than 3% after 6 months.

The figures for the other components of Trimix and the sole components of Bimix are 7 days at room temperature no significant degradation, the same as in a refrigerator or frozen. After 6 months frozen at -20DegC the loss was less than 5%.

So it would appear that those using Trimix could, when travelling, leave it unrefrigerated for 24 hours with, at worst, only a minor degradation in one component (Alprostadil). Clearly the temperature to which it is exposed is important and left in a hot car when parked it could be much more than 23degC and this might degrade the Alprostadil much faster.

This explains why many Franktalk members have found their Trimix to be only slightly less effective after even 12 months in a fridge (probably a small loss of Alprostadil). Bimix remains stable for long periods even at room temperature.

Finally, of course, it is always important that the contents of a vial remains sterile. If storing injection compounds for extended periods freezing will inhibit any bacteria growth and from the study it would appear that this is not harmful to the product even if frozen/thawed and refrozen up to 4 times.

I am based in England so the only personal experience I have is with Caverject which I have stored in the fridge after reconstitution for up to 7 days with no loss of effectiveness. Trimix is simply not available in the UK but I would be keen to try it if I can find a source when next on holiday is the USA.

[dtwarren1942]

Nice work and great information.

[antelope]

Yep, good stuff. Thanks.

greg

[dw_william]

I read that paper and that's why I freeze my Trimix. I freeze it right in the syringes at the proper dose. It defrosts almost right away and works great.

I've tried this with Caverject recently and have the same experience. This is even though they (Pfizer) says not to freeze - but I suppose that's so you will throw out the left over part and they can sell you more.