Synovex (Testosterone Propionate & Estradiol)

ALTERNATIVE STEROID NAMES: Synovex, Testosterone Propionate, Estradiol
ACTIVE SUBSTANCE: Testosterone Propionate & Estradiol
Strength Gains: Strength gains 2/10
Mass & Weight Gains: Mass & Weight gains 3/10
Fat Burning: Fat burning 0/10
Cutting/Definition: Definition gains 0/10
Side Effects: Side effects 10/10
Ability to keep Gains: Ability to keep gains 3/10
Usual dosages: 100 – 200 mg per week
Detection time: 3 months
Best combined with:
Bulking: NA
Cutting: NA
Beginner Use: Use for beginners 0/10
Female Use: Female use 0/10
Pros: Can be obtained without papers in the US
Cons: Extreme side effects, low gains, hard to administer.


This is a veterinary product that is packed in pellets, each containing 25mg of Testosterone Propionate. It is usually used as a skin topic so the doses are hard to evaluate. It has noticeable side effect – and all things combined is it of use only for the most desperate.


Synovex is a steroid implant preparation, which is available only as a veterinary item for use in cattle (livestock). The implant comes in the form of small pellets, which are pushed into the ear of an animal with a large implant gun. Here they slowly dissolve and provide an extended release of steroid, lasting for many weeks. The hormone content of Synovex is mixed, with each pellet containing 25 mg testosterone propionate and 2.5 mg Estradiol Benzoate. The number of pellets in each cartridge will also vary depending on the intended target. Implants denoted “H” for heifer carry the most; in the case of U.S. Synovex-H it is 80 pellets (10 doses consisting each of 8 pellets We will see a slightly lower pellet count in the “S” implants (steer) and “C” (calf) cartridges.

The combination of estrogen with testosterone (in a 10:1 ratio) has proven to provide an added anabolic/weight gaining effect in feed animals. Athletes have long been aware that strong androgens like testosterone, which aromatize into estrogen quite readily, are the strongest anabolics. It is also observed that anti estrogen drugs like Nolvadex® can decrease the muscle and strength gains received from androgen therapy. It has been therefore theorized that the added estrogen level is in some way responsible for increasing the anabolic effect of androgens. Perhaps this is accomplished by somehow increasing the number of available receptor sites or receptor sensitivity.

With this understanding one might think the estrogen combination in Synovex would prove to be a powerful mix for athletes. But those who have experimented with it have been generally disappointed with the results, as the estrogen in this product is very likely to produce many unwanted side effects. This includes severe gynecomastia, noticeable body fat accumulation and water retention. In many cases the water retained will lead to an unsightly bloated look (extreme loss of definition). Synovex is clearly a good cattle item, but not the ideal steroid for humans. I really think athletes have only become attracted to this product out of sheer desperation for legitimate anabolics. Here in the U.S., cattle implants like this are not controlled substances to spite their steroid content. Synovex is often easy to purchase directly from Agricultural or Veterinary supply stores, as no paperwork is required.

An athlete will typically grind up these pellets, and either rub them on the skin mixed with DMSO and water for transdermal delivery, or mix up his own injection. One should remember that the practice of preparing this for injection would obviously not be very sterile and could be potentially dangerous. Others feel that simply snorting the Synovex powdered is a sufficient delivery method. Some have additionally worked out methods of removing the estrogen from the pellets, to make the drug much more comfortable to use. While this is possible, I think such procedures are generally much more trouble than they are worth. They involve the use of highly flammable materials and take a number of different steps to complete. All of the estrogen will likely not be removed after all is done. and I cannot see the end product as being the most sanitary thing to administer. In addition to the U.S. version on made by Syntex, Synovex is also available in other countries but is never imported due to lack of demand. No counterfeits currently exist, nor are they likely to show up in the future.

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