Promobal versus Masteron

This is a hard to answer question as there are no face to face clinical trials to answer it (and most probably never will be) so we have to rely on secondary evidence, meaning, their pharmacological profiles and street information.

Primobolan (methenolone acetate) is an oral anabolic androgenic steroid (AAS), it has a reputation for having low androgenic properties thereby causing ittle aromatization, water retention or liver damage. It is generally considered to be one of the safest AAS. Muscle gains are reported to be slow to develop but of good quality. Primobolan is popular as a pre-contest drug, as it is believed that it causes little water retention, and with women because of its relatively low androgenic properties. [1]

On the other side:

Masteron (drostanolone propionate) is an injectable anabolic with moderate anabolic properties and anti-estrogenic effect, “often used by dieting bodybuilders and athletes in speed sports, where it is highly favored for its ability to produce solid increases in lean muscle mass and strength, which are usually accompanied by reductions in body fat level and minimal side effects”. [2]

In the following table we will summarize some of the most important pharmacological information available about these two products:

Characteristic Primobolan Masteron
Androgenicity level 44-57 25-40
Anabolic level 88 62-130
Estrogenic activity None None
Progestational activity Low Low
Duration
(Elimination from the body) 24 hours 2-3 days
Administration Oral Injectable
Table 1. Primobolan and Masteron pharmacology.

So if we have to come to a conclusion, we could say that primobolan has a more confortable route of administration, with similar anabolic and androgenic profile, without estrogenic activity, and one of the few non-c17-alpha-alkylated oral AAS, reducing significantly the hepatotoxicity (liver damage).

Masteron users could easily argue this, so we must consider that there is not much information about this and there is moderate variability between users and combinations, so many body builders may see better results with one or the other.

Bibliography

1-. Patrick Lenehan. Anabolic steroids. 1st Ed, CRC Press, 2003.
2-. William Llewellyn. Anabolics, 10th ed. Molecular Nutrition, 2010.
3-. Br J Pharmacol. 2008 Jun; 154(3): 502–521. Pharmacology of anabolic steroids. A T Kicman
(http://onlinelibrary.wiley.com/doi/10.1038/bjp.2008.165/abstract )