Isolation of Gonadal AAS
The use of gonadal steroids pre-dates their identification and isolation. Medical use of testicle extract began in the late 19th century while its effects on strength were still being studied. The isolation of gonadal steroids can be traced back to 1931, when Adolf Butenandt, a chemist in Marburg, purified 15 milligrams of the male hormone androstenone from tens of thousands of litres of urine. This steroid was subsequently synthesized in 1934 by Leopold Ruzicka, a chemist in Zurich.
In the 1930s, it was already known that the testes contain a more powerful androgen than androstenone, and three groups of scientists, funded by competing pharmaceutical companies in the Netherlands, Germany, and Switzerland, raced to isolate it. This hormone was first identified by Karoly Gyula David, E. Dingemanse, J. Freud and Ernst Laqueur in a May 1935 paper “On Crystalline Male Hormone from Testicles (Testosterone).” They named the hormone testosterone, from the stems of testicle and sterol, and the suffix of ketone. The chemical synthesis of testosterone was achieved in August that year, when Butenandt and G. Hanisch published a paper describing “A Method for Preparing Testosterone from Cholesterol.” Only a week later, the third group, Ruzicka and A. Wettstein, announced a patent application in a paper “On the Artificial Preparation of the Testicular Hormone Testosterone (Androsten-3-one-17-ol).” Ruzicka and Butenandt were offered the 1939 Nobel Prize in Chemistry for their work, but the Nazi government forced Butenandt to decline the honor, although he accepted the prize after the end of World War II.
Clinical trials on humans, involving either oral doses of methyltestosterone or injections of testosterone propionate, began as early as 1937. Testosterone propionate is mentioned in a letter to the editor of Strength and Health magazine in 1938; this is the earliest known reference to an anabolic steroid in a U.S. weightlifting or bodybuilding magazine. There are often reported rumors that German soldiers were administered anabolic steroids during the Second World War, the aim being to increase their aggression and stamina, but these are, as yet, unproven. Adolf Hitler himself, according to his physician, was injected with testosterone derivatives to treat various ailments. AAS were used in experiments conducted by the Nazis on concentration camp inmates, and later by the allies attempting to treat the malnourished victims that survived Nazi camps. President John F. Kennedy was administered steroids both before and during his presidency.
Development of Synthetic AAS
The development of muscle-building properties of testosterone was pursued in the 1940s, in the Soviet Union and in Eastern Bloc countries such as East Germany, where steroid programs were used to enhance the performance of Olympic and other amateur weight lifters. In response to the success of Russian weightlifters, the U.S. Olympic Team physician Dr. John Ziegler worked with synthetic chemists to develop an anabolic steroid with reduced androgenic effects. Ziegler’s work resulted in the production of methandrostenolone, which Ciba Pharmaceuticals marketed as Dianabol. The new steroid was approved for use in the U.S. by the Food and Drug Administration (FDA) in 1958. It was most commonly administered to burn victims and the elderly. The drug’s off-label users were mostly bodybuilders and weight lifters. Although Ziegler prescribed only small doses to athletes, he soon discovered that those having abused Dianabol suffered from enlarged prostates and atrophied testes. AAS were placed on the list of banned substances of the IOC in 1976, and a decade later the committee introduced ‘out-of-competition’ doping tests because many athletes used AAS in their training period rather than during competition.
Three major ideas governed modifications of testosterone into a multitude of AAS: Alkylation at 17-alpha position with methyl or ethyl group created orally active compounds because it slows the degradation of the drug by the liver; esterification of testosterone and nortestosterone at the 17-beta position allows the substance to be administered parenterally and increases the duration of effectiveness because agents soluble in oily liquids may be present in the body for several months; and alterations of the ring structure were applied for both oral and parenteral agents to seeking to obtain different anabolic to androgenic effect ratios.
List of Anabolic Steroids
Exogenous Anabolic Androgenic Steroids
Endogenous Anabolic Androgenic Steroids
- Prasterone (dehydroepiandrosterone DHEA)
Metabolites and Isomers
Metabolites and isomers of endogenous anabolic androgenic steroids, including, but not limited to:
Routes of Administration
There are four common forms in which anabolic steroids are administered: oral pills, injectable steroids, creams/gels for topical application, and skin patches. Oral administration is the most convenient. Testosterone administered by mouth is rapidly absorbed, but it is largely converted to inactive metabolites, and only about 1/6 is available in active form. In order to be sufficiently active when given by mouth, testosterone derivatives are alkylated at the 17 position, e.g. methyltestosterone and fluoxymesterone. This modification reduces the liver’s ability to break down these compounds before they reach the systemic circulation.
Testosterone can be administered parenterally, but it has more irregular prolonged absorption time and greater activity in propionate, enanthate, undecanoate, or cypionate ester form. These derivatives are hydrolyzed to release free testosterone at the site of injection; absorption rate (and thus injection schedule) varies among different esters, but medical injections are normally done anywhere between semi-weekly to once every 12 weeks. A more frequent schedule may be desirable in order to maintain a more constant level of hormone in the system. Injectable steroids are typically administered into the muscle, not into the vein, to avoid sudden changes in the amount of the drug in the bloodstream. In addition, because estered testosterone is dissolved in oil, intravenous injection has the potential to cause a dangerous embolism (clot) in the bloodstream.
Transdermal patches (adhesive patches placed on the skin) may also be used to deliver a steady dose through the skin and into the bloodstream. Testosterone-containing creams and gels that are applied daily to the skin are also available, but absorption is inefficient (roughly 10%, varying between individuals) and these treatments tend to be more expensive. Individuals who are especially physically active and/or bathe often may not be good candidates, since the medication can be washed off and may take up to six hours to be fully absorbed. There is also the risk that an intimate partner or child may come in contact with the application site and inadvertently dose himself or herself; children and women are highly sensitive to testosterone and can suffer unintended masculinization and health effects, even from small doses. Injection is the most common method used by individuals administering anabolic steroids for non-medical purposes.
The traditional routes of administration do not have differential effects on the efficacy of the drug. Studies indicate that the anabolic properties of anabolic steroids are relatively similar despite the differences in pharmacokinetic principles such as first-pass metabolism. However, the orally available forms of AAS may cause liver damage in high doses.
Mechanism of Action
The pharmacodynamics of anabolic steroids are unlike peptide hormones. Water-soluble peptide hormones cannot penetrate the fatty cell membrane and only indirectly affect the nucleus of target cells through their interaction with the cell’s surface receptors. However, as fat-soluble hormones, anabolic steroids are membrane-permeable and influence the nucleus of cells by direct action. The pharmacodynamic action of anabolic steroids begin when the exogenous hormone penetrates the membrane of the target cell and binds to an androgen receptor located in the cytoplasm of that cell. From there, the compound hormone-receptor diffuses into the nucleus, where it either alters the expression of genes or activates processes that send signals to other parts of the cell. Different types of anabolic steroids bind to the androgen receptor with different affinities, depending on their chemical structure. Some anabolic steroids such as methandrostenolone bind weakly to this receptor in vitro, but still exhibit androgenic effects in vivo. The reason for this discrepancy is not known.
The effect of anabolic steroids on muscle mass is caused in at least two ways: first, they increase the production of proteins; second, they reduce recovery time by blocking the effects of stress hormone cortisol on muscle tissue, so that catabolism of muscle is greatly reduced. It has been hypothesized that this reduction in muscle breakdown may occur through anabolic steroids inhibiting the action of other steroid hormones called glucocorticoids that promote the breakdown of muscles. Anabolic steroids also affect the number of cells that develop into fat-storage cells, by favouring cellular differentiation into muscle cells instead. Anabolic steroids can also decrease fat by increasing basal metabolic rate (BMR), since an increase in muscle mass increases BMR.
Anabolic and Androgenic Effects
As the name suggests, anabolic-androgenic steroids have two different, but overlapping, types of effects: anabolic, meaning that they promote anabolism (cell growth), and androgenic (or virilising), meaning that they affect the development and maintenance of masculine characteristics.
Some examples of the anabolic effects of these hormones are increased protein synthesis from amino acids, increased appetite, increased bone remodeling and growth, and stimulation of bone marrow, which increases the production of red blood cells. Through a number of mechanisms anabolic steroids stimulate the formation of muscle cells and hence cause an increase in the size of skeletal muscles, leading to increased strength.
The androgenic effects of AAS are numerous. Depending on the length of use, the side effects of the steroid can be irreversible. Processes affected include pubertal growth, sebaceous gland oil production, and sexuality (especially in fetal development). Some examples of virilizing effects are growth of the clitoris in females and the penis in male children (the adult penis size does not change due to steroids[medical citation needed] ), increased vocal cord size, increased libido, suppression of natural sex hormones, and impaired production of sperm. Women become more masculine, their voices deepen, they grow facial hair, and their breasts size decreases. Men however become more feminine. Development of breasts, reduced testicle size, and reduced sperm count are all indirect effects of AAS.
The androgenic:anabolic ratio of an AAS is an important factor when determining the clinical application of these compounds. Compounds with a high ratio of androgenic to an anabolic effects are the drug of choice in androgen-replacement therapy (e.g., treating hypogonadism in males), whereas compounds with a reduced androgenic:anabolic ratio are preferred for anemia and osteoporosis, and to reverse protein loss following trauma, surgery, or prolonged immobilization. Determination of androgenic:anabolic ratio is typically performed in animal studies, which has led to the marketing of some compounds claimed to have anabolic activity with weak androgenic effects. This disassociation is less marked in humans, where all anabolic steroids have significant androgenic effects.
A commonly used protocol for determining the androgenic:anabolic ratio, dating back to the 1950s, uses the relative weights of ventral prostate (VP) and levator ani muscle (LA) of male rats. The VP weight is an indicator of the androgenic effect, while the LA weight is an indicator of the anabolic effect. Two or more batches of rats are castrated and given no treatment and respectively some AAS of interest. The LA/VP ratio for an AAS is calculated as the ratio of LA/VP weight gains produced by the treatment with that compound using castrated but untreated rats as baseline: (LAc,t–LAc)/(VPc,t–VPc). The LA/VP weight gain ratio from rat experiments is not unitary for testosterone (typically 0.3–0.4), but it is normalized for presentation purposes, and used as basis of comparison for other AAS, which have their androgenic:anabolic ratios scaled accordingly (as shown in the table above). In the early 2000s, this procedure was standardized and generalized throughout OECD in what is now known as the Hershberger assay.
Body Composition and Strength Improvements
A review spanning more than three decades of experimental studies in men found that body weight may increase by 2–5 kg as a result of short-term (<10 weeks) AAS use, which may be attributed mainly to an increase of lean mass. Animal studies also found that fat mass was reduced, but most studies in humans failed to elucidate significant fat mass decrements. The effects on lean body mass have been shown to be dose-dependent. Both muscle hypertrophy and the formation of new muscle fibers have been observed. The hydration of lean mass remains unaffected by AAS use, although small increments of blood volume cannot be ruled out.
The upper region of the body (thorax, neck, shoulders, and upper arm) seems to be more susceptible for AAS than other body regions because of predominance of androgen receptors in the upper body. The largest difference in muscle fiber size between AAS users and non-users was observed in type I muscle fibers of the vastus lateralis and the trapezius muscle as a result of long-term AAS self-administration. After drug withdrawal, the effects fade away slowly, but may persist for more than 6–12 weeks after cessation of AAS use.
The same review observed strength improvements in the range of 5–20% of baseline strength, depending largely on the drugs and dose used as well as the administration period. Overall, the exercise where the most significant improvements were observed is the bench press. For almost two decades, it was assumed that AAS exerted significant effects only in experienced strength athletes, particularly based on the studies of Hervey and coworkers. In 1996, a randomized controlled trial published in the New England Journal of Medicine demonstrated, however, that even in novice athletes a 10-week strength training program accompanied by testosterone enanthate at 600 mg/week may improve strength more than training alone does. The same study found that dose to be sufficient to significantly improve lean muscle mass relative to placebo even in subjects that did not exercise at all. A 2001 study by the same first author, showed that the anabolic effects of testosterone enanthate were highly dose dependent.