My 2nd Favorite Method of TRT (Testosterone Replacement Therapy). Compounding pharmacies can be a life saver for some guys on Hormone Replacement Therapy (HRT). This is because both of the blockbuster HRT gels, Testim and Androgel, don't work for all guys. Some guys could bathe in these two drugs and still not get enough testosterone into their blood stream. And they are very expensive - more on that later.
This is where a compounding pharmacy comes in. A good compounding pharmacy takes the same bioidentical testosterone and puts into a gel or cream at the dosage the doctor specifies. (Again, this is MUCH cheaper than either Testim or Androgel as testosterone is a relatively cheap molecule to manufacture.) Many guys who cannot seem to get past the 200's or 300's with Testim or Androgel break those barriers easily with compounding. (Most docs will try to get you right around 500 from what I have seen.)
WHAT ABOUT INSURANCE? I was actually able to get compounded testosterone through insurance because Androgel did not work for me. However, compounded testosterone is so inexpensive that my copay was not that much below the cost of just paying cash!
Besides cost and effectiveness what are the other big advantages to using compounded testosterones?
1) Potentially Enjoy the Freedom of Paying Cash. Many men do not have the option of insurance or would just like the convenience and control of running their own TRT (in conjunction with a good physician of course). Well, you can afford to do this with compounded products! If you don't mind paying cash, you can a) pick and choose an expert TRT physician, b) and stop worrying about prior auths, changing formularies, delays in getting refills, etc. and c) control your target level (wth your doc), something that is more difficult with a product like Androgel.
2) Diurnal Rhythm. If you apply the cream in the morning every day, you will be somewhat mimicking the body's natural diurnal rhythm of higher testosterone levels in the morning that then taper off in the evening. This may be important for physiologically in some way that we do not yet understand.
3) Increased DHT Levels. This is a pro or con depending on how you look at it. All topicals will tend to raise DHT levels more than other delivery systems. This can be good for middle-aged and older men from the libido standpoint. You do have to be careful in my opinion as you can go supraphysiological, i..e well over the top of the lab range, which is true for any compounded or brand name cream or gel. You can pull your DHT levels here: Inexpensive Testosterone Labs.
4) Control Over Concentration. With the name brand name products, you get what you get when it comes to concentrations. For example, Androgel is 1.62% and virtually all men using Androgel use this concentration. Want 3% Androgel? Too bad - it's not offered. But with a compounded cream or gel, your physician can order almost any reasonable strength.
Figuring out the dosage of the prescription that your doctor wrote is not as difficult as it might seem. Think of 1,000 mg of water, or the cream, as the starting point. Let's say you mixed in 10 mg of testosterone into that 1,000 mg. That would be considered a 1% compounded solution. A 2% solution would be 20 mg mixed into the 1,000 mg. Common prescriptions are anywhere from about 3% to 20%.
So why can't you go above 20%? Technically, you can go get about 30% into a cream or gel from what I have heard. However, it starts to get "gritty" at that levels and so 20% seems to be the maximum out there in the real world.
What about absorption? I have heard that it is typically in the 5-10% range. Look at this description from one of our Peak Testosterone Forum posters (cujet):
"I'm now using about 1.5 grams of 5% compounded T cream. I mix it with a splash of water to make it spread out. I then apply to shaved shoulders, shaved armpits and any remainder to shaved scrotum/thighs. I spread it thin and rub it in vigorously. It takes a bit to dry. Works like magic. Last T levels were at 700. I've been low T for a very long time, so I have a good "feel" for when it's right and when it's not. I cannot use Androgel. Even with massive doses, it simply does not work for me." 
Cujet also thins his out with a little water. He said, otherwise, it is like trying to spread "peanut butter." For both cujet and myself, compounded testosterone was a life saver. (Androgel never raised my testosterone a nonogram.)
My monthly supply of testosterone was about $50! This was quite a few years ago and now costs tend to be about $75 per month usually from what I have seen. Compare that to a month of Androgel, which is about $250 the last time I checked. In my opinion this is a ridiculously high price for something that has been around for decades. It is like Good Year suddenly declaring that only their tires are safe and then charging the consumer $500 a tire! Remember: bioidentical testosterone, which is in all topicals, is not an expensive molecule to manufacture and compounders were safely dispensing testosterone creams for years before the large pharmaceutical companies got involved.
The reasons that compounding can deliver so much more testosterone has mostly to do with the increased concentration. The delivery systems from what I have read are comparable in absorption rates to Androgel, or at least close. The most common system used is called PLO(Pluronic Lecithin Organogel), "penetration enhancer". Many drugs are delivered in PLO, which helps the drug pass through the stratum corneum, a big name for the upper layer of your skin. PLO is usually made from soy but can be made from eggs as well. It is composed primarily of lecithin, isopropyl palmitate and Pluronic F127. Isopropyl palmitate helps the testosterone penetrate the skin and is also a solvent. It can definitely cause skin irritation, clogged pores, etc. and this is one of the potential downsides to PLO.
The Pluronic F127 is a "surfactant", which means that it spreads the product out evenly so that it does not bind or coagulate together. These two chemicals are considered safe and they are pretty widely used. Isopropyl palmitate is a low hazard expection compound according to the Environmental Working Group for example.  And the Pluronic F127 is in mouthwashes and toothpastes for what that is worth. Again, this has not bee tested long term as far as I know.
The only other disadvantage that I know with compounded testosterone is that its effect on family members is undocumented. After reports of children being affected through their father's topical application of testosterone therapy, the FDA asked for the manufacturers to do additional testing to make sure this wasn't an issue with their product.
Personally, I doubt that Testim or Androgel has unusual potent penetration capabilites as a significant percentage of guys find they get little to no penetration. Plus, again from what I have heard, these cases are usually from fathers who are being careless. Androgel, for example, is applied to the chest and upper arms. Some dads go shirtless or forget to wash off the product before doing physical things with their family.
If you thoroughly wash the area of application, your family members should be safe, i.e. your wife and kids should not be overabsorbing supplemental testosterone. However, you should realize that the FDA is only working with the mainline manufacturers and not with compounding pharmacies. Talk to your doc, of course, about all of the above. CAUTION: Be careful about love make sessions with your woman unless you've thoroughly washed the product off: her testosterone is just a fraction of yours!