The partition coefficient of the ester in question is important because is effects how long the drug itself stays in the system. If the testosterone transfers too quickly from the oil to the blood, the result is a sudden spike in testosterone which then rapidly drops once the dose has been used up. In the example of free testosterone injected into the muscle from a water suspension (as in Aquiviron, mentioned above), the testosterone is essentially immediately available to the bloodstream due to its low partition coefficient, and thus there is an immediate spike of testosterone which is used up quickly in the body.
However, in December 2004 the United States the 14-member Food and Drug Administration (FDA) advisory committee, plus voting consultants, for Reproductive Health Drugs unanimously rejected Procter and Gamble's fast-track request for Intrinsa citing concerns about off-label use . In Canada, post-menopausal women have been able to obtain government-approved testosterone treatment since 2002. In Australia, post-menopausal women can use Organon testosterone implants which have to be surgically inserted and last from three to six months. 
There have been stories the DEA/FDA may frown upon the dispensing of testosterone propionate instead of testosterone cypionate or enanthate by physicians. The reason given: “it is used more often for performance optimization like growth hormone (GH) and is a red flag”. There are numerous physicians prescribing testosterone propionate in their practices without issue. This may warrant further monitoring for any doctor using testosterone propionate. In my book, I recommend 30-50 mg of Testosterone Propionate injected every other day (EOD) as an excellent option for long term TRT administration.