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Question

Posted on: April 8 2014

We have problems with the preparation of a testosterone gel.

Our formula is testosterone x% oleic acid 10ml HPC 3g water 30g ethanol 96% v ad 100g. At present, oleic acid is no longer available. We opted for isopropyl in a Carbopolgel as excipient. The composition reads: Testosterone 1g, Carbopol 940 500mg, alcohol 96% 65ml, Isopropyl 10g, triethanolamine QS Water AD 100ml. After a night, ethanol floats on top of the gel. Drive. Preparation method: Ethanol + IPM and testosterone mix all movable carbomer sprinkle water in it, ph adjust back water up to 100ml. What do we do wrong? Another possible solution could be to replace oleic acid with IPM in the original formula. But also in this case alcohol came above float.

Answer

The switching calibration of oleic acid to IPM is acceptable but why HPC is abandoned for Carbopol is not clear to me and seems to me not ideal because a good carbopolgel with a high ethanol content preparation is not easy. Although I opt for the top of IPM on the Carbopol gel earlier. As Thiss presumably is also the case when you add IPM to your original formula with HPC.  

Personally I would opt for the use of Octyldodecanol (Eutanol) instead of IPM.  

Following composition I found in the literature: Octyldodecanol 18 G, isopropanol 69 g and Water ad 100 g. This composition may serve as a starting point and you can modify it to approximate your original formula. You can take the Eutanol at 10 g, replace the isopropanol with ethanol and possibly bring more water.  

I would first run some previews like eg  

1. Dissolve 10 g Eutanol in 69 g ethanol and add water up to 100 g. You should not obtain a separation of the Eutanol!  

2. In this mixture the testosterone should dissolve  

3. And this mixture can convert you to a gel with HPC

Succeeds all this then you can unsubscribe the final composition. If an additional constituent is testosterone or HPC added   is getting these amounts in deduction of water.