Norclostebol is a synthetic anabolic androgenic steroid also called 4 chloro 19 nortestosterone. Authority records link the parent drug with Lentabol and Anabol 4 19, while a separate record defines its acetate ester. Direct human outcome evidence is sparse. Chemical identity, animal research and historical names do not establish present medical approval, safe nonmedical exposure or product authenticity.
Evidence boundary: identity records can define a reference molecule. Animal and analytical studies can describe biological activity or metabolites. They do not establish a safe personal amount, a reliable physique result, human clearance, current approval or the contents of a product.
Sources checked 2 September 2026. This page gives general information. It does not provide a diagnosis, prescription, exposure plan, product source, administration method or drug testing advice.
What is norclostebol?
Norclostebol is a chlorinated estrane steroid. PubChem gives the formula C18H25ClO2 and compound identifier 166576.[1] The United States substance record assigns UNII VI1001O2DI, while the DEA uses controlled substance code 4000.[2][10]
The chemical name 4 chloro 17 beta hydroxyestr 4 en 3 one identifies two defining features. The estrane skeleton lacks the carbon 19 methyl group found in testosterone. A chlorine atom occupies carbon 4. The common description 4 chloro 19 nortestosterone expresses the same relationship in shorter terms.
Names such as Lentabol and Anabol 4 19 appear in current authority records as other names for norclostebol.[10] A name can help match records, but it cannot prove what a current vial, tablet or package contains.
| Primary name | Norclostebol |
|---|---|
| Plain chemical relationship | 4 chloro 19 nortestosterone |
| Molecular formula | C18H25ClO2 |
| PubChem record | Compound identifier 166576 |
| United States substance identifier | UNII VI1001O2DI |
| CAS registry number | 13583 21 6 |
| Authority listed names | Lentabol and Anabol 4 19 |
| Evidence limit | An identity record does not confirm a current medicine, approved use or held product. |
How do norclostebol and norclostebol acetate differ?
Norclostebol is the parent steroid. Norclostebol acetate carries an acetate group at the oxygen attached to carbon 17 beta. The FDA substance record calls the ester 4 chloro 19 nortestosterone acetate and assigns UNII JKP2S7674A.[3]
An ester changes the intact molecule and can alter formulation and release before enzymes split it. The parent released after cleavage is still norclostebol. The ester name does not show purity, sterility, concentration, approval or a safer health profile.
| Record | Defining feature | Recorded identity | What the record cannot prove |
|---|---|---|---|
| Norclostebol | Free hydroxyl group at carbon 17 beta | C18H25ClO2; UNII VI1001O2DI | Current approval, personal outcome or product contents |
| Norclostebol acetate | Acetate ester at carbon 17 beta | C20H27ClO3; UNII JKP2S7674A | Human safety, exact release pattern or product authenticity |
| Experimental cyclopentyl propionate | Longer ester named in a 1957 animal paper | A research compound in an animal tissue weight assay | A marketed product, current medicine or human result |
The current DEA list places Anabol 4 19 and Lentabol beside the parent entry.[10] The FDA record names the acetate by its chemical identity. The records are shown separately rather than forcing every old name into one chemical form.
Is norclostebol the same as clostebol or nandrolone?
No. Norclostebol, clostebol and nandrolone share parts of their steroid structures, but each is a separate molecule. A study, medicine record or legal statement about one does not automatically apply to another.
| Compound | Short chemical description | Carbon 4 chlorine | Carbon 19 methyl | Separate page |
|---|---|---|---|---|
| Norclostebol | 4 chloro 19 nortestosterone | Present | Absent | This page |
| Clostebol | 4 chlorotestosterone | Present | Present | Clostebol identity and evidence |
| Nandrolone | 19 nortestosterone | Absent | Absent | Nandrolone and Deca Durabolin |
Clostebol retains the carbon 19 methyl group that norclostebol lacks. Nandrolone shares the 19 nor skeleton but lacks chlorine at carbon 4.[4][5] These differences affect identity and can affect metabolism. They do not support a simple ranking of strength or safety.
Methylclostebol is also a separate compound. Its added methyl group and own authority record prevent its claims from being transferred to norclostebol.
How may norclostebol act in the body?
Norclostebol belongs to the anabolic androgenic steroid class. These drugs can activate androgen receptors and alter gene transcription in responsive tissues. That frame supports biological plausibility. It does not provide a measured human benefit, an event rate or a safe exposure level for norclostebol.
The 1957 research reported muscle and prostate tissue weight responses for chlorinated testosterone analogs in an animal assay.[6] Norclostebol acetate and an experimental ester produced myotrophic activity in that model. The assay did not measure strength, body composition, heart outcomes, fertility or psychiatric effects in people.
| Process | What it supports | What it does not establish |
|---|---|---|
| Androgen receptor activity | Norclostebol can belong to the same signalling class as other steroidal androgens. | A reliable human gain, risk percentage or preferred use. |
| Acetate cleavage | The ester can release the parent steroid after enzymatic cleavage. | An exact release time for an unverified product. |
| Endocrine feedback | External androgen activity can suppress pituitary and gonadal signals. | The degree or recovery time for one person. |
| Animal tissue response | Early assays detected anabolic and androgenic biological activity. | Clinical benefit, human safety or a modern treatment role. |
Mechanism is one link in an evidence chain. A human claim also needs a known product, a defined exposure, a suitable comparison group and a measured outcome. Those parts are largely missing for norclostebol.
What do Lentabol and Anabol 4 19 show about medical history?
Lentabol and Anabol 4 19 are historical names associated with norclostebol in the current DEA alphabetical list.[10] The list is useful for identity and control status. It does not supply a present prescribing label, approved indication, manufacturer, market date or withdrawal reason.
The FDA substance records define norclostebol and its acetate ester. A substance identifier is not the same as an approved drug application. The NCATS record classifies norclostebol as an anabolic steroid and records the approval year as unknown.[9]
| Record | Supported point | Unresolved point |
|---|---|---|
| FDA substance record | Preferred name, formula, synonyms and UNII for the reference substance. | Current human indication or approved finished product. |
| DEA alphabetical list | Schedule III status, code 4000 and the names Lentabol and Anabol 4 19. | Medical approval or historic label details. |
| NCATS Inxight Drugs | Anabolic steroid class and prohibited sport status. | Approval year, present indication and authorised product. |
| Old research literature | The compound and selected esters were studied by the late 1950s. | A current benefit to harm assessment in patients. |
The reviewed primary records do not provide enough detail to state where every historical product was licensed or when it left each market. The record allows a narrow statement. Historical names and current identity records exist. The checked sources did not show a modern approved human role.
What has direct norclostebol research studied?
The direct record is dominated by chemistry, animal assays and food animal surveillance. Those study types answer useful identity and analytical questions. They do not replace controlled human outcome research.
| Year and source | Model | Main question | Main limit for readers |
|---|---|---|---|
| 1957 tissue weight study | Animal assay | Did 4 substituted testosterone analogs show myotrophic and androgenic activity? | Organ weight responses do not predict human performance or safety. |
| 2004 metabolism study | The invertebrate Neomysis integer plus laboratory analysis | Which compounds might serve as analytical metabolites of norclostebol acetate? | An invertebrate model cannot supply human metabolism or clearance. |
| 2006 cattle study | Cattle exposure and urine analysis | Which bovine metabolites could support food animal surveillance? | Cattle results do not show human effects, safety or a personal detection period. |
The 2004 paper proposed norclostebol and a dione metabolite after work with Neomysis integer, then added those targets to an analytical method.[7] The 2006 study followed norclostebol acetate in cattle and identified urinary metabolites.[8] Neither paper studied patients or healthy volunteers.
The direct sources checked for this refresh did not include a controlled human outcome trial of norclostebol. That gap prevents reliable statements about treatment benefit, physique change, strength, common adverse event rates or recovery after exposure.
How strong is the evidence for common norclostebol claims?
| Claim | Best source type | Confidence | Boundary |
|---|---|---|---|
| Norclostebol is 4 chloro 19 nortestosterone. | Government and chemical identity records | High | This identifies the reference molecule, not a product. |
| Norclostebol acetate is a related ester. | FDA substance record and analytical literature | High | The record does not establish current human approval. |
| The compound has anabolic and androgenic activity. | Early animal assay and drug class records | Moderate for biological activity | The size of a human effect is unknown. |
| Norclostebol produces a predictable physique result. | Direct controlled human outcome research | Very low in the checked record | No suitable trial was found in the reviewed sources. |
| One ester is safer than another. | Direct human comparison | Very low | Chemical release theory cannot establish a safer choice. |
| Human clearance can be predicted from the cattle paper. | Human metabolism research would be needed | Unsupported | Species, route, matrix and study purpose differ. |
| Current law and sport rules name norclostebol. | Government and sport authority text | High for the named date and system | Another country or later rule may differ. |
A strong identity record cannot carry a weak outcome claim. The evidence matrix keeps each source inside the question it can answer. This prevents chemical names, animal findings and old brand words from being blended into a false human profile.
What health concerns are relevant to norclostebol?
No modern human label supplies norclostebol adverse event rates, contraindications or a tested monitoring plan. Health discussion must so separate direct evidence from broader anabolic steroid class findings. Class evidence supports concern, but it cannot assign a personal probability to this compound.
| Body system | Concern from anabolic steroid class evidence | Norclostebol limit |
|---|---|---|
| Heart and circulation | Higher blood pressure, adverse cholesterol, heart muscle change, coronary disease, heart attack and stroke. | A compound specific event rate is not available. |
| Blood | Androgen exposure can raise hemoglobin and hematocrit, adding concern with other clot risks. | A single normal count cannot certify safety. |
| Hormones and fertility | Pituitary suppression can reduce natural gonadal hormone production and sperm formation. | Recovery time and fertility outcome cannot be predicted online. |
| Virilising effects | Voice change, body hair growth, acne, scalp hair loss, menstrual change and clitoral growth can occur with androgen exposure. | Some changes can persist, while exact norclostebol rates are unknown. |
| Mood and dependence | Irritability, anxiety, aggression, mood elevation, depression, sleep change and dependence are class concerns. | Symptoms can have many causes and need clinical context. |
| Liver and kidneys | Mixed steroid exposure, hidden ingredients, high blood pressure, dehydration and severe muscle injury can affect these organs. | Norclostebol lacks a modern human organ safety record. |
| Injected product harms | Abscess, tissue injury, bacterial infection, blood borne infection and contamination can occur. | Risk depends on the product and event, not only the named steroid. |
Norclostebol does not carry the 17 alpha alkyl group found in many oral anabolic steroids. That structural fact does not prove liver safety. A product may contain another compound, and cardiovascular or endocrine harms do not depend on that single feature.
Class reviews describe concern across cardiovascular, reproductive, psychiatric, liver, kidney, infectious and musculoskeletal outcomes.[15][16] Read anabolic steroid health risks by body system for the wider evidence and its limits.
Which interactions and situations may raise concern?
The reviewed sources do not provide a tested human interaction table for norclostebol. The absence of a named interaction is not proof of compatibility. A clinical assessment should include every medicine, steroid, stimulant, supplement, alcohol exposure and recreational drug used in the same period.
| Context | Reason for concern | Useful disclosure |
|---|---|---|
| Other anabolic steroids or hormones | Overlapping endocrine, blood pressure, lipid and mood effects make attribution harder. | Names, dates, claimed forms and last exposure. |
| Stimulants or thyroid drugs | Heart rate, blood pressure, sleep and anxiety can change through more than one pathway. | All prescribed and unprescribed products. |
| Anticoagulants or clotting disorders | Bleeding and clot decisions need individual review when blood measures or liver function change. | Medicine name, reason for treatment and recent results. |
| Heart, liver or kidney disease | Existing disease can narrow the margin for added blood pressure, fluid or metabolic stress. | Diagnoses, symptoms and earlier test trends. |
| Fertility plans or pregnancy | External androgens can suppress reproductive function and cause fetal harm. | Pregnancy possibility, menstrual history and fertility goals. |
| Mental health or dependence history | Mood change, withdrawal symptoms and unsafe impulses can need prompt support. | Current symptoms, prior episodes and immediate safety concerns. |
| Adolescence | Hormonal exposure can affect development, growth and decision capacity. | Age, growth history and all exposures. |
Do not stop prescribed medicine or add another drug merely to change a symptom or laboratory number. A clinician can weigh the purpose of each medicine against the full exposure record. The site page on anabolic steroid interactions and contraindications explains the wider class context.
What may a clinician assess after suspected exposure?
A useful record starts with the claimed product, parent or ester name, first and last dates, route, symptoms and all other substances. Bring packaging or clear photographs when available. They show what was claimed, not what laboratory analysis would find.
The examination and symptoms determine which checks are useful. A clinician may consider blood pressure, pulse, a blood count, lipids, liver and kidney measures, reproductive hormones or fertility testing. Chest symptoms can lead to an electrocardiogram, cardiac markers or imaging. A painful site can need direct examination and infection testing.
No fixed online panel suits every person. Timing, hydration, exercise, illness, laboratory method and earlier results can change interpretation. A normal panel does not certify continued exposure as safe or exclude every heart, vascular, hormone, fertility, psychiatric or infection problem.
Describe uncertainty directly. A clinician can work from an incomplete history, while hidden exposure can point the assessment in the wrong direction. See how to talk with a doctor about anabolic steroid use and what blood tests can and cannot show.
What is the legal and sport status of norclostebol?
Medicine approval, controlled drug law and sport rules answer different questions. Each also depends on a date and jurisdiction. A substance can appear in a chemical register without being an approved medicine.
| System | Recorded status | Boundary |
|---|---|---|
| United States federal law | The DEA alphabetical list records norclostebol under Schedule III with code 4000. | State law and the facts of possession, supply, import, research or prescribing still matter. |
| United Kingdom | The Home Office list records norclostebol as Class C and Schedule 4 Part 2. | Possession, supply and import rules differ. Current legal advice is needed for a real case. |
| Canada | The Controlled Drugs and Substances Act lists norclostebol in Schedule IV. | The Act applies different controls to possession, trafficking, production, import and export. |
| Sport under the World Anti Doping Code | The 2026 list names norclostebol under category S1 among anabolic agents prohibited at all times. | An athlete must check the current list, ester coverage and governing body rules. |
The 2026 World Anti Doping Agency list took effect on 1 January 2026.[14] No drug test timing, masking method, sample manipulation or rule evasion instruction appears on this page.
This is general legal and sport information, not advice for an individual matter. Rules can change, and another country may classify the same substance differently.
Can a label or product appearance confirm norclostebol?
No. A name, colour, viscosity, package design, seller statement or price cannot prove chemical identity, concentration, sterility or batch consistency. A product sold as norclostebol can contain another steroid, an undeclared mixture, too little or too much active material, unsuitable solvent, bacteria, endotoxin or particles.
A PubChem or FDA substance record describes a reference identity. It does not authenticate a reader’s product. Laboratory analysis answers only the method and sample tested. One sample cannot prove that another vial or batch is identical.
After suspected exposure or an adverse reaction, record the claimed name, dates, route, other substances and symptoms. Share the record with a clinician or poison service. Severe symptoms need emergency care rather than online product identification.
References
- Norclostebol compound record. PubChem, National Library of Medicine. Chemical identity and formula.
- Norclostebol substance record. FDA Global Substance Registration System. Name, identifier and substance relationships.
- 4 chloro 19 nortestosterone acetate substance record. FDA Global Substance Registration System. Acetate names, formula and identifiers.
- Clostebol compound record. PubChem, National Library of Medicine. Separate chlorotestosterone identity.
- Nandrolone compound record. PubChem, National Library of Medicine. Separate 19 nortestosterone identity.
- Myotrophic activity of 4 substituted testosterone analogs. Proceedings of the Society for Experimental Biology and Medicine. 1957.
- Norchlorotestosterone acetate metabolism study. Chromatographia. 2004.
- Norclostebol acetate metabolites in bovine urine. Journal of Steroid Biochemistry and Molecular Biology. 2006.
- Norclostebol record. NCATS Inxight Drugs. Drug class and status fields.
- Controlled substances in alphabetical order. Drug Enforcement Administration. Current Schedule III entry, code and other names.
- Controlled drugs list. United Kingdom Home Office. Current class and schedule record.
- Controlled Drugs and Substances Act, Schedule IV. Justice Laws Website, Government of Canada.
- Steroids fact sheet. Drug Enforcement Administration. Anabolic steroid class harms and control context.
- The 2026 Prohibited List. World Anti Doping Agency. Current sport rule.
- Scientific statement on health harms from drugs used for performance. Endocrine Society.
- Diagnosis and management of anabolic androgenic steroid use. Journal of Clinical Endocrinology and Metabolism. 2019.