Standard Nandrolone acetate
Chemical Name 17beta-Hydroxyestra-4,9,11-trien-3-one
Estrogenic Activity none
Progestational Activity moderate
Parabolan is the most recognized brand name for trenbolone hexahydrobenzylcarbonate, a slow-acting injectable ester of the potent anabolic steroid trenbolone. Trenbolone appears most commonly as trenbolone acetate, which is a much faster-acting form of the drug (see: trenbolone acetate). The hexahydrobenzylcarbonate ester used here extends the release of trenbolone for more than 2 weeks, which has always been thought of as more suitable for human use due to the less frequent injection schedule. The base steroid trenbolone is roughly three times more androgenic than testosterone, making it a fairly potent androgen. It also displays about 3 times greater tissue-building activity in comparison to its androgenic properties, making its official classification as that of an anabolic steroid. The muscle-building effect of trenbolone is often compared to such popular bulking agents as testosterone or Dianabol, but without the same estrogenrelated side effects. It is most commonly identified as a lean-mass-building drug, and is extremely popular with athletes for its ability to promote the rapid buildup of strength, muscle size, and definition.
The first long-acting trenbolone ester (undecanoate) was studied in 1967, described during a series of experiments into synthetic anabolic steroids by Roussel-UCLAF.571 Trenbolone hexahydrobenzylcarbonate was a subsequent and uniquely French slant to this long-acting anabolic steroid, possessing an unusual but roughly equivalent compound. Trenbolone hexahydrobenzylcarbonate was developed into a medicine by Negma Laboratoires in France, which sold the drug under the Parabolan trade name. It was also sold for a period of time as Hexabolan, a name that referred to the unusual ester it possesses. Trenbolone hexahydrobenzylcarbonate is the only known form of trenbolone ever produced as a medicine for human consumption. The most notable appearance of trenbolone comes as trenbolone acetate, which is used widely and exclusively in veterinary medicine.
Parabolan was prescribed in France as a protein-sparing anabolic agent in cases of cachexia (lean body mass wasting) and malnutrition, as well as to combat certain forms of osteoporosis. Its prescribing guidelines included recommendations for the treatment of androgen-sensitive populations, such as women and the elderly. Owing to its moderate androgenic properties, however, the drug was contraindicated in children, especially young females. Parabolan remained on the French market for a very long time, although it was finally discontinued (voluntarily) by Negma in 1997. For a brief period of time it seemed that the demise of Parabolan would mark the end of human-use trenbolone preparations, as no other medicine approved for human use was known to exist worldwide at the time. A very small number of Parabolan preparations have been brought to market since, however, so while the drug is still poorly available, it is not completely defunct.
Parabolan is no longer produced as a prescription drug product. When manufactured in France it came in the form of a 1.5 mL ampule containing 76 mg of steroid (product information lists this as equivalent to 50 mg of base trenbolone).
Trenbolone is a modified form of nandrolone. It differs by the introduction of double bonds at carbons 9 and 11, which inhibit aromatization (9-ene), increase androgen-binding affinity,572 and slows its metabolism. The resulting steroid is significantly more potent as both an anabolic and an androgen than its nandrolone base. The trenbolone here is modified with a hexahydrobenzylcarbonate ester at the 17-beta hydroxyl group, so that the free steroid is released more slowly from the area of injection.
Side Effects (Estrogenic):
Trenbolone is not aromatized by the body, and is not measurably estrogenic. It is of note, however, that this steroid displays significant binding affinity for the progesterone receptor (slightly stronger than progesterone itself ).573 574 The side effects associated with progesterone are similar to those of estrogen, including negative feedback inhibition of testosterone production and enhanced rate of fat storage. Progestins also augment the stimulatory effect of estrogens on mammary tissue growth. There appears to be a strong synergy between these two hormones here, such that gynecomastia might even occur with the help of progestins, without excessive estrogen levels. The use of an anti-estrogen, which inhibits the estrogenic component of this disorder, is often sufficient to mitigate gynecomastia caused by progestational anabolic/androgenic steroids. Note that progestational side effects are more common when trenbolone is being taken with other aromatizable steroids.
Side Effects (Androgenic):
Although classified as an anabolic steroid, trenbolone is sufficiently androgenic. Androgenic side effects are still common with this substance, and may include bouts of oily skin, acne, and body/facial hair growth. Anabolic/androgenic steroids may also aggravate male pattern hair loss. Women are also warned of the potential virilizing effects of anabolic/androgenic steroids. These may include a deepening of the voice, menstrual irregularities, changes in skin texture, facial hair growth, and clitoral enlargement. Additionally, the 5-alpha reductase enzyme does not metabolize trenbolone575, so its relative androgenicity is not affected by finasteride or dutasteride.
Side Effects (Hepatotoxicity):
Trenbolone is not c-17 alpha alkylated, and is generally not considered a hepatotoxic steroid; liver toxicity is unlikely. This steroid does have a strong level of resistance to hepatic breakdown, however, and severe liver toxicity has been noted in bodybuilders abusing trenbolone.576 Although unlikely, hepatotoxicity cannot be completely excluded, especially with high doses.
Side Effects (Cardiovascular):
Anabolic/androgenic steroids can have deleterious effects on serum cholesterol. This includes a tendency to reduce HDL (good) cholesterol values and increase LDL (bad) cholesterol values, which may shift the HDL to LDL balance in a direction that favors greater risk of arteriosclerosis. The relative impact of an anabolic/androgenic steroid on serum lipids is dependant on the dose, route of administration (oral vs. injectable), type of steroid (aromatizable or non-aromatizable), and level of resistance to hepatic metabolism. Due to its non-aromatizable nature and strong resistance to metabolism, trenbolone has a moderate to strong (negative) impact on lipid values and atherogenic risk. Anabolic/androgenic steroids may also adversely affect blood pressure and triglycerides, reduce endothelial relaxation, and support left ventricular hypertrophy, all potentially increasing the risk of cardiovascular disease and myocardial infarction.
To help reduce cardiovascular strain it is advised to maintain an active cardiovascular exercise program and minimize the intake of saturated fats, cholesterol, and simple carbohydrates at all times during active AAS administration. Supplementing with fish oils (4 grams per day) and a natural cholesterol/antioxidant formula such as Lipid Stabil or a product with comparable ingredients is also recommended.
Side Effects (Testosterone Suppression):
All anabolic/androgenic steroids when taken in doses sufficient to promote muscle gain are expected to suppress endogenous testosterone production. Without the intervention of testosterone-stimulating substances, testosterone levels should return to normal within 1-4 months of drug secession. Note that prolonged hypogonadotrophic hypogonadism can develop secondary to steroid abuse, necessitating medical intervention. In experimental studies, trenbolone was determined to be approximately three times stronger at suppressing gonadotropins than testosterone on a milligram for milligram basis.
The above side effects are not inclusive. For more detailed discussion of potential side effects, see the Steroid Side Effects section of this book.
Parabolan was generally administered in a clinical dosage of 3 ampules per month. Therapy was initiated the first month with all 3 ampules given over the first 15 days. During the subsequent 3 months, one injection (76 mg) was given every 10 days. For physique- or performance-enhancing purposes, trenbolone hexahydrobenzylcarbonate is most often administered at a dosage of 152-220 mg per week. The drug would be taken in cycles ranging from 6 to 12 weeks. Although a weekly administration schedule would be more than sufficient, athletes usually injected a single ampule (76mg) at a time, and the total amount would be spread evenly throughout the week. Although not necessary, this type of schedule helps to reduce injection volume per application. The results with the use of trenbolone hexahydrobenzylcarbonate should be a visibly more muscular physique (larger, leaner), and, if body fat levels are low enough, that hard ripped look most valued by dieting and competitive bodybuilders.
While this drug is quite potent when used alone, it is sometimes combined with other steroids for an even greater effect. Leading up to a show one could successfully add a non-aromatizing anabolic such as Winstrol® or Primobolan®. Such combinations will elicit a greater level of density and hardness to the build, often proving dramatic for a stage appearance. We could also look for bulk with this drug, and addition stronger compounds like Dianabol or Testosterone. While the mass gain would be quite formidable with such a stack, some level of water retention would probably also accompany it. Moderately effective anabolics such Deca-Durabolin® or Equipoise® would be somewhat of a halfway point, providing extra strength and mass but without the same level of water bloat we see with more readily aromatized steroids.
Parabolan was generally administered in a clinical dosage of 3 ampules per month. Therapy was initiated the first month with all 3 ampules given over the first 15 days. During the subsequent 3 months, one injection (76mg) was given every 10 days. Given the risk of virilization, lower doses were likely used by physicians with many female patients. This agent is generally not recommended for women for physique- or performance-enhancing purposes due to strong androgenic nature and tendency to produce virilizing side effects.
Pharmaceutical preparations containing trenbolone hexahydrobenzylcarbonate remain scarce.
571. J. Mathieu, Proc. Intern. Symp. Drug Res. 1967, p 134. Chem. Inst. Can., Montreal, Canada.
572. Unique steroid congeners for receptor studies. Ojasoo, Raynaud. Cancer Research 38 (1978):4186-98.
573. Characterisation of the affinity of different anabolics and synthetic hormones to the human androgen receptor, human sex hormone binding globulin and to the bovine progestin receptor. Bauer, Meyer et al. Acta Pathol Microbiol Imunol Scand Suppl 108 (2000):838-46.
574. Unique steroid congeners for receptor studies. Ojasoo, Raynaud. Cancer Research 38 (1978):4186-98.
575. Disposition of 17 beta-trenbolone in humans. Spranger, Metzler. J Chromatogr 564 (1991):485-92.
576. Cholestasis induced by Parabolan successfully treated with the molecular adsorbent recirculating system. Anand JS et al. ASAIO 2006. JanFeb;52(1):117-8.