Furazan

Synopsis

Furazan and the Furazan Ring System in Dietary Supplements: A Reference Article

1. Overview and Scope

The term furazan is used in two interrelated but distinct senses relevant to the dietary supplement industry. First, it refers to a specific heterocyclic chemical scaffold — 1,2,5-oxadiazole — which appears as a structural motif in several pharmacologically active compounds. Second, and more directly relevant to the supplement context, furazan is the identifying ring system in two closely related anabolic compounds that have circulated in dietary supplement markets: furazabol (the pharmaceutical-grade anabolic steroid from which the supplement-market compound is derived) and furazadrol (also marketed as Orastan-A), a synthetic non-methylated steroidal compound sold as a prohormone in the sports nutrition sector. This article covers the chemistry of the furazan ring system, the pharmacological history of furazabol, and the contemporary supplement use of furazadrol in full detail, with all claims grounded in verifiable scientific and institutional sources.

2. Chemical Identity

2.1 The Furazan Ring System

Furazan, or 1,2,5-oxadiazole, is a heterocyclic aromatic organic compound consisting of a five-atom ring containing 1 oxygen and 2 nitrogen atoms. Its IUPAC name is 1,2,5-oxadiazole; it has CAS number 288-37-9, PubChem CID 67517, and a molecular formula of C₂H₂N₂O. Furazan and its derivatives are obtained from the oxime derivatives of 1,2-diketones.

1,2,5-Oxadiazole (furazan) and other oxadiazole isomers appear in a variety of pharmaceutical drugs, including raltegravir, butalamine, fasiplon, oxolamine, and pleconaril. In addition to pharmaceutical applications, 1,2,5-oxadiazole (furazan) has attracted attention in the field of energetic materials research due to its high heat of formation and good oxygen balance. This latter use is entirely separate from any nutritional or pharmacological context and is noted only to clarify the chemical breadth of furazan derivatives.

2.2 The Furazan Ring in Steroids: Furazabol

The furazan ring system is also found in the steroid furazabol. Furazabol (INN, JAN; brand names Frazalon, Miotalon, Qu Zhi Shu), also known as androfurazanol, is a synthetic, orally active anabolic-androgenic steroid which has been marketed in Japan since 1969. It is a 17α-alkylated derivative of dihydrotestosterone (DHT) and is closely related structurally to stanozolol, differing from it only by having a furazan ring system instead of pyrazole. Both furazabol and Winstrol (stanozolol) are modified dihydrotestosterone (DHT) molecules; the former possesses a furazan group and the latter a pyrazole group.

2.3 Furazadrol: The Supplement-Market Compound

The NIH Office of Dietary Supplements Dietary Supplement Label Database (DSLD) categorizes furazadrol as a Non-nutrient/non-botanical ingredient. Related terms found on product labels include: 5a-androstanol[2,3]furazan-17b-tetrahydropyranol; 5a-androstanol[2,3]furazon-17b-tetrahydropyranol; 5a-etioallocholan 2 3-c furazan-17b-tetrahydropyranol; 5a-etioallocholan(2 3-c)furazan 17b-tetrahydropyranol ether; Furazadrol; Orastan a; and Orastan-a.

The active compound of furazadrol prohormones is 5a-androstano[2,3-c]furazan-17b-tetrahydropyranol-ether (also written as 5a-etioallocholan[2,3-c]furazan-17b-tetrahydropyranol ether). Furazadrol (Orastan-A) is a prohormone derived from furazabol, a rare Japanese oral steroid with similar effects to Winstrol (stanozolol). Furazadrol is the non-methylated supplement-market derivative, meaning it lacks the 17α-methyl group present in furazabol itself.

3. Natural Source and Origin

Furazadrol is a synthetic compound that has been incorporated into various nutritional products, particularly within the fitness and bodybuilding communities. Historically, furazadrol emerged as a prohormone designed to mimic certain anabolic effects while offering a legal alternative to more strictly regulated substances. It does not have a long-standing tradition in ancient medicinal systems or folk remedies.

Furazadrol itself is not a natural herb. The furazan ring system present in these compounds is entirely synthetic; there is no established botanical source for this specific steroid scaffold. The compound is produced through organic synthesis, and its appearance in the supplement market is a modern phenomenon with no traditional or ethnobotanical heritage.

4. Historical and Pharmaceutical Background

4.1 Furazabol: Pharmaceutical Origins (1960s–1980s)

Furazabol was first described in 1965. The only modern pharmaceutical preparation of record containing furazabol, at least known to researchers in the West, was Miotolan from Daiichi Seiyaku Labs in Japan, which was sold in Japan mainly during the 1970s and '80s. Furazabol was prescribed in Japan under the trade name Miotolan in the 1970s as a treatment for hypercholesterolemia.

The drug has been described as an antihyperlipidemic and is claimed to be useful in the treatment of atherosclerosis and hypercholesterolemia, but according to William Llewellyn, such properties of furazabol are a myth. The effects of Miotolan (furazabol) are similar to Winstrol, except instead of having an adverse effect on cholesterol values, therapeutic doses of furazabol purportedly improve a person's blood lipid profile. This was presumed to account for the different effects on blood lipids between the two agents.

Diversion of this obscure pharmaceutical steroid to the black market rarely occurred while it was being manufactured by Daiichi Seiyaku Company in Japan.

4.2 Furazabol and the 1988 Olympics

Furazabol was a popular steroid among Olympic athletes during the 1980s, when it was quietly known among certain trainers that testing officials had not yet identified the agent, and therefore could not test for it. Previously a relatively unknown drug to North American athletes, furazabol gained notoriety in a Commission of Inquiry into the Use of Drugs and Banned Practices. Canadian sprinter Ben Johnson initially denied the allegations of doping at the 1988 Seoul Olympics, asserting he had never taken banned substances, and later claimed the positive finding was the result of sabotage and that he had actually taken furazabol, which at the time could not be detected by the Gas Chromatography–Mass Spectrometry assay used to analyze samples at the Games.

University of Toronto physiologist Prof. Barry Lubek, who had studied anabolic steroids for 13 years, stated he had never heard of furazabol (also called "estrogol"). Upon research, he found it to be a little-known product produced by only one company in the world — Daiichi of Japan — and that it was also known as Miotolon and Androfuragol.

4.3 Emergence of Furazadrol as a Dietary Supplement (2006 onward)

Furazadrol (Orastan-A) was first released in 2006 by Gaspari Nutrition. Since then, many other manufacturers launched their own furazadrol prohormone products. Furazadrol was developed by Axis Labs as an alternative to methylated prohormones such as Havoc or Dymethazine. As a non-methylated compound, it appealed to users on the grounds of being considered safer, and was often used by beginners new to prohormones, either alone or in a stack.

5. Chemical Structure and Key Constituents

5.1 Structural Relationship to Stanozolol

Furazabol is an oral anabolic steroid derived from dihydrotestosterone. This agent is moderately anabolic, with only mild androgenic properties. This is attributed to the modification of the steroid's A-ring, which allows the steroid structure to remain stable and bind receptors in muscle tissue long enough to provide an anabolic benefit. Dihydrotestosterone, in comparison, is a poor anabolic, quickly metabolized in muscle tissue to inactive metabolites.

Furazabol is a fairly potent oral anabolic steroid with properties somewhat similar to Winstrol (stanozolol). Furazadrol (the supplement compound) is a non-methylated derivative of furazabol, and as a result may share certain functional characteristics with this agent.

5.2 The Furazan A-Ring Modification

The distinguishing chemical feature of both furazabol and furazadrol relative to other anabolic steroids is the replacement of the steroid A-ring ketone group with a furazan (1,2,5-oxadiazole) ring. Furazabol is closely related structurally to stanozolol, differing from it only by having a furazan ring system instead of a pyrazole ring system. This structural change, like stanozolol's pyrazole modification, imparts resistance to aromatization (conversion to estrogen) and resistance to reduction in muscle tissue, which is hypothesized to underlie its anabolic activity profile.

5.3 Methylation Status

Furazabol has a 17α-methyl group, which allows it to be taken orally and causes hepatotoxicity in some individuals. Furazadrol, by contrast, is the non-methylated version, which is presumed to reduce — though not eliminate — hepatic stress. Furazabol has a relatively high ratio of anabolic to androgenic activity.

6. Mechanisms of Action

6.1 Androgen Receptor Binding

The primary proposed mechanism of both furazabol and furazadrol is agonist activity at the androgen receptor (AR). Any effect on androgen receptor density likely mimics those of other anabolic steroids, which may include some period of upregulation. Overall, these compounds can be expected to be mild to moderately effective anabolics, with low relative androgenicity. It has been claimed that furazadrol may have a "unique potency toward increasing androgen receptor density," but such a connection cannot be substantiated by the published literature.

Furazadrol has a high anabolic-to-androgenic ratio, meaning muscle gains with low risk of androgenic side effects. It does not convert to estrogen, meaning gains are lean in nature, with an absence of water retention.

6.2 Fibrinolytic and Coagulation Effects (Animal Data)

One area that received specific scientific investigation is the effect of furazabol on the fibrinolytic system. The effect of long-term ingestion of furazabol was studied on coagulo-fibrinolytic systems in the rat. During the administration of furazabol at a daily dose of 0.04, 0.2 or 1 mg/rat for 3 months, the most remarkable changes were an increase in the plasminogen activator activity in blood and the lung tissue, and decreases in plasma fibrinogen level and plasma cholesterol. It was a notable finding that in most of the rats, the furazabol treatment was effective in reducing susceptibility to lactic acidosis-induced pulmonary thrombosis. No meaningful changes were observed in other parameters tested, including ADP-induced platelet aggregability, plasma recalcification time, plasma plasminogen, plasma antiplasmin activity, plasminogen activator content of tissues other than the lungs, and the release of vascular activator induced by venous occlusion. One month after cessation of furazabol treatment, these altered parameters tended to return to normal.

These results are derived entirely from animal (rat) studies and cannot be extrapolated to human clinical outcomes. Anabolic steroids as a class increase the activity of the fibrinolytic system by reducing plasma levels of inhibitors (plasminogen activator inhibitor type I, histidine-rich glycoprotein, alpha-2-macroglobulin) and increasing plasma levels of tissue-type plasminogen activator activity, plasminogen, and plasmin activity. Such abnormalities in disease states can be reversed by anabolic steroids. However, the clinical benefits and adverse effects of such treatment remain to be established by large, randomized controlled trials.

6.3 Cholesterol Modulation (Animal Data and Disputed Clinical Claims)

Furazabol was marketed in Japan partly based on claims of cholesterol-lowering activity. Animal data showed decreases in plasma cholesterol under furazabol administration (see Section 6.2 above). However, the drug has been described as an antihyperlipidemic and is claimed to be useful in the treatment of atherosclerosis and hypercholesterolemia, but according to William Llewellyn, such properties of furazabol are a myth. No large-scale, peer-reviewed clinical trial in humans has established furazabol or furazadrol as a legitimate cholesterol-lowering therapeutic.

7. Scientific Evidence by Area of Use

7.1 Muscle Anabolism and Body Composition

Claimed uses: In the context of wellness and fitness, furazadrol has been utilized for its purported ability to enhance muscle hardness, strength, and lean mass retention, especially during cutting cycles.

Evidence assessment: There are no published peer-reviewed clinical trials in humans specifically evaluating furazadrol for muscle hypertrophy, body composition changes, or athletic performance outcomes. The evidence base consists entirely of animal pharmacology studies of furazabol (the parent compound), anecdotal user reports, and extrapolations from the general anabolic steroid literature. The gains associated with furazabol are described as not extreme, more closely resembling the quality growth of a mild non-aromatizing anabolic like stanozolol or drostanolone, rather than the watery bulk of a testosterone, making it most often applied during cutting phases of training and by athletes in speed and weight-restricted sports. This characterization is based on comparative pharmacological reasoning and anecdotal evidence, not controlled human trials. Evidence strength: very weak; no human clinical trials available.

7.2 Cardiovascular and Fibrinolytic Effects

Claimed uses: Furazabol was historically prescribed in Japan for hypercholesterolemia and atherosclerosis, with some researchers claiming the furazan ring modification conferred lipid-friendly properties distinct from other anabolic steroids.

Evidence assessment: The effect of long-term ingestion of furazabol was studied on the coagulo-fibrinolytic systems in the rat. During administration at daily doses of 0.04, 0.2, or 1 mg per rat for 3 months, the most remarkable changes were an increase in plasminogen activator activity and decreases in plasma fibrinogen and cholesterol. The furazabol treatment was effective in reducing susceptibility to lactic acidosis-induced pulmonary thromboembolism in the rat. These findings suggest that pharmacological enhancement of tissue activator content may be effective for preventing thrombotic tendency. This study was published in Thrombosis Research (1976) and represents preclinical (rodent) evidence only. No controlled human trials on furazabol's cardiovascular effects have been published in the peer-reviewed literature accessible to this review. Evidence strength: preclinical only; no human clinical evidence.

In the broader AAS literature, abuse of AAS induces profound alterations in hemostatic balance, shifting it toward a prothrombotic state. Numerous case reports have demonstrated that young AAS users without significant atherosclerosis experience acute thromboembolic events, including myocardial infarction, ischemic stroke, deep vein thrombosis, and pulmonary embolism. The pathophysiology is multifactorial and involves erythropoietic stimulation, platelet hyperreactivity, increased synthesis of coagulation factors, and impaired fibrinolysis. Whether furazadrol specifically diverges from this pattern has not been established in clinical studies.

7.3 Athletic Performance and Sport

Furazadrol is seldom used for bulking and tends to be more appropriate for recomping (building muscle while losing fat) or cutting. No controlled, peer-reviewed human performance trials have been conducted with furazadrol specifically. Evidence strength: no clinical human data.

8. Body Systems and Health Areas

Musculoskeletal system: Primary intended use — anabolic effects on skeletal muscle mass and strength via androgen receptor activation. No human clinical trials exist.
Endocrine system: Acts on the androgen receptor as an agonist, potentially suppressing the hypothalamic-pituitary-gonadal (HPG) axis — a class effect of all exogenous androgens.
Hepatic system: As with other 17α-alkylated AAS (in the case of furazabol), there may be a risk of hepatotoxicity. Furazadrol, as a non-methylated analog, is considered less hepatotoxic, though animal-level risk cannot be fully excluded.
Cardiovascular / hemostatic system: The parent compound furazabol showed animal-model evidence of altered fibrinolysis and cholesterol levels. AAS as a class are associated with dyslipidemia and cardiovascular risk in human users.
Reproductive system: The main risks of chronic androgen use include menstrual irregularities and virilization in women, and impotence and prostatic hypertrophy in men.
Central nervous system: Psychiatric changes can occur during use or after cessation of anabolic steroid agents.

9. Dosage Forms and Reported Dosages

Furazadrol and furazabol have appeared in the following dosage forms:

Oral capsules (furazadrol — supplement market): Product labels for one commercial preparation (Furuza-A) specified a serving size of 1 capsule containing 50 mg of 5a-etioallocholan[2,3-c]furazan-17b-tetrahydropyranol ether, with directions to take 1 capsule 2 to 3 times per day. Product labeling stated not to use the product for more than 6 weeks and to take at least an 8-week break between cycles.
Oral tablets (furazabol — pharmaceutical-grade Japan): Research conducted by Daiichi Seiyaku Co., Ltd. used furazabol at daily doses of 0.04, 0.2, or 1 mg per rat in animal studies. No standardized human clinical dose is established in the peer-reviewed literature reviewed here.

No human clinical dose-ranging trials have been conducted for furazadrol. The supplement market dosages above are drawn from product labeling, not from peer-reviewed pharmacological studies.

10. Safety Considerations and Interactions

10.1 Hepatotoxicity

There is no serious risk from acute poisoning with anabolic steroids, but chronic use can cause harm. The main risks are those of excessive androgens: menstrual irregularities and virilization in women, and impotence, premature cardiovascular disease, and prostatic hypertrophy in men. Both men and women can suffer liver damage with oral anabolic steroids containing a substituted 17-alpha-carbon. Furazabol (the methylated parent) carries this 17α-alkylation risk. Furazadrol, the non-methylated supplement compound, is believed by community sources to carry less hepatic risk; however, this has not been formally studied.

Furazadrol presents minimal liver toxicity as a non-methylated compound, but could negatively affect cholesterol levels.

10.2 Cardiovascular Risk

Chronic ingestion of high doses of anabolic steroids can cause elevations in blood pressure, left ventricular hypertrophy, and premature coronary artery disease. Abuse of anabolic-androgenic steroids is suspected to increase the risk of cardiovascular disease and cardiovascular mortality in otherwise healthy individuals. AAS abuse may increase the incidence of cardiovascular disease by altering the hemostatic balance toward a procoagulant state.

10.3 Cholesterol and Lipid Effects

Furazadrol presents minimal liver toxicity as a non-methylated compound but could negatively affect cholesterol levels. No controlled human lipid-panel data specific to furazadrol is available in the peer-reviewed literature.

10.4 Long-Term Risks

Patients who persistently abuse high doses of anabolic steroids are at risk of death from premature heart disease or cancer, especially prostatic cancer. Non-fatal but long-lasting effects include voice changes in women and fusion of the epiphyses in children. Other effects are reversible over weeks or months.

10.5 Anti-Doping Status

Furazabol and its derivatives fall under the WADA prohibited list category of anabolic androgenic steroids. Substances prohibited by WADA in the anabolic agents category (S1) include a broad range of anabolic steroids and related compounds. One of the risks associated with the use of dietary supplements is unintended doping originating from contaminated products, and the presence of undeclared compounds in dietary supplements is a serious concern. Athletes subject to anti-doping testing should be aware that furazabol metabolites may trigger adverse analytical findings.

10.6 Regulatory Status

The NIH Office of Dietary Supplements DSLD lists furazadrol as a non-nutrient, non-botanical ingredient with no associated scientific resources cited. Furazadrol (Orastan-A) is classified as an illegal and non-methylated prohormone. Products containing furazadrol have been marketed as dietary supplements in the United States; however, their legal classification under the Anabolic Steroid Control Act and FDA enforcement authority is contested, as the compound's scheduling status has evolved over time.

10.7 Contraindications Noted on Product Labels

Product labeling for at least one commercial furazadrol preparation warned: do not use the product if you are under 21 years of age; the product should not be used by women; do not use the product if you have high blood pressure, diabetes, or any other physical and/or psychiatric condition. These label warnings are not equivalent to formal clinical guidance but reflect manufacturer acknowledgment of known risks of anabolic steroid–class compounds.

11. Summary of Evidence Quality

The overall evidence base for furazadrol as a dietary supplement is extremely limited. The NIH DSLD entry for furazadrol lists no scientific resources. There are no published, peer-reviewed, placebo-controlled human clinical trials evaluating the safety or efficacy of furazadrol in any health outcome. Available scientific evidence consists of: (1) animal pharmacology studies of the parent compound furazabol (principally a 1976 rat study on fibrinolysis); (2) general AAS class-effect literature; (3) anecdotal user reports; and (4) comparative structural pharmacology reasoning. Claims regarding anabolic efficacy, lipid modulation, and safety must therefore be regarded as unsubstantiated in human evidence.