Stenbolone acetate was first marketed by Syntex in 1963, but has since been discontinued almost 15 years ago now, despite a great popularity. I get the strange impression that a lot of popular steroids disappeared around that time, which is a real shame. Syntex had previously marketed oxymetholone, but with the high doses needed of oxymetholone and its poor androgenic properties, it lead to problems with excessive bloating, gyno and liver toxicity. Syntex's answer was Stenbolone. It was mistakenly called injectable anadrol by a lot of users, even though the steroids were as different as night and day (similar mistakes were made with Searle's Nilevar and Anavar).
Stenbolone actually closely resembles the steroid methenolone (Primobolan). The only difference is that instead of a 1-methyl group, it has a 2-methyl group. The same difference that separates drostanolone (Masteron) and mesterolone (Proviron). In characteristics this changes very little, one can assume stenbolone to have roughly the same effect as methenolone. It's a 5-alpha-structure, a 5-alpha reduced version of boldenone. That means it doesn't aromatize to estrogen and does not cause problems with bloating through water retention, or gynocomastia (growth of breast tissue in men). That took care of the first problem. But at the same time the 1,2-double bond in its structure made it less androgenic than one would expect from a 5-alpha-reduced steroid. As with boldenone, which is only half as androgenic as testosterone, Stenbolone is only half as androgenic as Dihydrotestosterone, the 5-alpha-reduced version of testosterone. So despite the fact that it did not cause estrogenic problems, it didn't really cause androgenic problems to a great extent either. So a user would worry less about hair loss, acne, prostate hypertrophy and deepening of voice than he would with say, testosterone.
So what really is the difference between stenbolone and methenolone (Primobolan)? Well, there really isn't one. The 1-methyl group serves a function to increase oral activity. But since there is no oral stenbolone, that point is irrelevant. The 1-methyl group serves no real purpose to the injectable form of methenolone. So they are the same. I would assume the addition of a 2-methyl group on stenbolone was the same as that of drostanolone, to protect the 3-keto group and improve stability and androgenic binding. But here too the alteration is fairly useless. The reason methenolone and stenbolone have reduced androgenic activity is the 1,2-double bond, but that same double bond also keeps it from being readily deactivated by the 3a-hydroxysteroid dehydrogenase enzyme, as the case is with Dihydrotestosterone (drostanolone is 2-methyl-DHT). So the need for the 2-methyl alteration is minimal at best.
So we've established that in characteristics there is no difference between injectable methenolone and stenbolone. But what is of relevance is that stenbolone is only made as an acetate ester, and that injectable methenolone is only made as an enanthate ester. That means upon injection methenolone stayed active much longer and a single weekly injection would suffice for proper action. The acetate ester on stenbolone only lasted two days at best, so it was to be injected daily for proper effect. So for convenience one would have preferred methenolone enanthate over stenbolone acetate. A good use for a shorter ester may have been to avoid testing positive in a drug test. The shorter ester could be used longer, closer to contest time, and needed less time to clear the blood and urine. But oddly enough stenbolone disappeared off the market around the time that drug testing became really popular. In that aspect stenbolone was ahead of its time.
The use of such a drug, being mild and non-aromatizing, was mainly as a base compound during cutting phases. An athlete would find that stenbolone made a great anti-catabolic, that allowed him to keep his mass while on a hardcore diet. And it made a good match for other steroids that served the same purpose like stanozolol (Winstrol) and trenbolone (Finaplix, although at that time Parabolan was still available). Like one would use Nandrolone (Deca-durabolin, Laurabolin) during a mass phase, stenbolone and methenolone were used during cutting phases. Because of its mild nature, several female competitors liked stenbolone as well.
As a non-aromatizing injectable, the male athlete would typically use around 50 mg of stenbolone, to be injected daily. Around 350 mg/week. Strong competitors even went as high as injected the 100 mg/ml amps daily, totaling a whopping 700 mg per week. It was rarely if ever used alone. It made a good match for other mild non-aromatizing compounds during cutting phases, drugs like oxandrolone (Anavar) and stanozolol (Winstrol/Stromba) at 30-50 mg/day. One could use it for mass gaining purposes as well, as a base for the likes of testosterone, methandrostenolone (Dianabol) or oxymetholone (Anadrol). Usually with good success, although today's athletes would prefer a longer-acting compound like Primobolan Depot for that purpose, which is convenient since the Primobolan is still made, and stenbolone is now extinct.
As far as ancillary drugs are concerned with stenbolone, their use is minimal. No anti-estrogens are required because it is incapable of forming estrogen. Since its only a mild, and due to its short ester, very controllable androgen, no real precautions need to be taken on that front either. Simply discontinuing the product when problems arise should suffice. Post-cycle use of Nolvadex or clomid for a short period of time is recommend, but has a limited use. After long cycles (10+ weeks) one may consider using HCG and a longer therapy with Nolvadex and or clomid to bring back natural testosterone faster and help one retain the gains made.
Females will find that 25-50 mg injected every other day will more than suffice for good results. Females are also advised to keep an anti-androgen like spironolactone handy in case virilizing symptoms surface. Product should then be discontinued and using 50 mg/day of spironolactone (Aldactone) for 3-4 days should remedy the worst.