Testosterone Enanthate FDA Approval History

What Is the FDA-Approved Status of Testosterone Enanthate?

Testosterone enanthate holds a longstanding FDA approval for male hypogonadism and, in females, for metastatic mammary cancer. The reference listed drug is Delatestryl (Endo Pharmaceuticals), though multiple generic formulations carry their own approved NDAs or ANDAs. Approval predates the modern clinical-trial framework, so the 1953 NDA was supported by clinical experience and pharmacokinetic data rather than a randomized controlled trial.

NDA 005-454 and the 1953 Approval

The original approval in 1953 designated testosterone enanthate as a long-acting injectable ester of testosterone suspended in sesame oil. The chemical structure, a 17-beta ester bond extending the half-life to approximately 4 to 5 days, allowed intramuscular dosing every 2 to 4 weeks rather than the daily injections required by testosterone propionate. The FDA's Center for Drug Evaluation and Research (CDER) lists the full NDA documentation in the Drugs@FDA database.

Approved Indications as of 2025

The current prescribing information, accessible via the FDA label repository, lists two approved indications:

1. Male hypogonadism (primary and hypogonadotropic), replacement therapy in males with confirmed deficiency by clinical features and at least two morning serum testosterone measurements below the normal range.
2. Metastatic mammary cancer, palliation of androgen-responsive advanced or metastatic breast cancer in females who are 1 to 5 years post-menopause.

Off-label uses, including gender-affirming hormone therapy and delayed puberty, carry clinical precedent but are outside the labeled indications reviewed by the FDA.

The Full Regulatory Timeline: 1953 to Present

Understanding how the FDA has updated this drug's status over seven decades helps prescribers, pharmacists, and patients interpret the current label in context. The regulatory record reflects evolving knowledge about cardiovascular risk, abuse potential, and accurate testosterone measurement.

1953 to 1990: Establishment and Early Post-Market Period

Between 1953 and the early 1990s, the testosterone enanthate label changed little. Prescribing was guided largely by endocrinologist consensus, and formal post-market surveillance systems were less structured than today. The FDA MedWatch program was not established until 1993, which created a gap in systematic adverse-event collection for drugs approved before that year.

Generic manufacturers began filing ANDAs through this period. Each generic approval required demonstration of bioequivalence to the reference listed drug, measured by comparable area-under-the-curve (AUC) and peak serum testosterone (Cmax) values in pharmacokinetic studies. The FDA's bioequivalence guidance for modified-release and extended-release androgens can be reviewed at FDA Guidance Documents.

1990 to 2014: Growing Awareness of Cardiovascular Signals

By the early 2000s, observational data were accumulating about potential cardiovascular effects of testosterone therapy in older men. The FDA Sentinel System, launched in 2008, gave regulators a new tool for active post-market surveillance using electronic health record and insurance claims data covering tens of millions of patients. Early Sentinel queries on testosterone products flagged signals around myocardial infarction and stroke in men initiating therapy. [1]

2014: The Cardiovascular Warning and FDA Safety Review

January 31, 2014 marks the most consequential label update in the drug's modern history. The FDA issued a Drug Safety Communication warning that testosterone therapy should not be used for age-related low testosterone ("low T") that is not accompanied by documented androgen deficiency syndrome. The communication cited two studies:

• A 2010 trial by Basaria et al. (N=209), published in the New England Journal of Medicine, reported a higher rate of adverse cardiovascular events in testosterone-treated older men with mobility limitations compared with placebo. [2]
• A 2013 retrospective cohort study by Vigen et al. (JAMA, N=8,709) found that testosterone therapy was associated with increased risk of death, myocardial infarction, and stroke in men with low testosterone undergoing coronary angiography. [3]

The label revision added a boxed warning-adjacent statement directing clinicians to confirm hypogonadism biochemically before initiating therapy. Serum testosterone must be measured on at least two occasions in the morning under fasting conditions, and the diagnosis requires both low levels and clinical symptoms consistent with deficiency.

2015: Schedule III Rescheduling and Abuse/Dependence Language

Congress had placed anabolic steroids, including testosterone esters, in Schedule III under the Anabolic Steroid Control Act of 1990. The 2015 class-wide label revision strengthened the abuse, dependence, and withdrawal language across all FDA-approved testosterone products, including enanthate formulations. The updated label language, viewable at Drugs@FDA, states explicitly that testosterone is subject to misuse and abuse, that withdrawal symptoms including depression and fatigue may occur upon discontinuation, and that patients with a history of substance use disorder should be prescribed with heightened caution. [4]

2018: Label Harmonization and Venous Thromboembolism Warning

A further update in 2018 added language about venous thromboembolism (VTE). The FDA required all testosterone product manufacturers to add a warning that cases of deep vein thrombosis and pulmonary embolism have been reported in patients using testosterone, and that treatment should be discontinued in cases of confirmed VTE. The biological mechanism under discussion involves testosterone's effect on erythropoiesis, which increases hematocrit and blood viscosity. Hematocrit above 54% is listed as a monitoring threshold in the current label. [5]

What Does the Current Testosterone Enanthate Label Say?

The prescribing information as last revised in 2018 governs current clinical use. Every prescriber should read the full label; the summary below covers the sections most relevant to monitoring and safety.

Dosing and Administration

The labeled dose range is 50 to 400 mg administered by deep intramuscular injection every 2 to 4 weeks. Most clinical practice guidelines from the American Urological Association and the Endocrine Society have moved toward shorter intervals (every 7 to 14 days) with lower per-injection doses to reduce peak-to-trough fluctuation, though this is not reflected in the FDA label itself. The Endocrine Society's 2018 Clinical Practice Guideline on Testosterone Therapy notes that wide serum testosterone fluctuation from longer dosing intervals may worsen symptoms and complicate monitoring. [6]

Contraindications

The current label lists the following absolute contraindications:

• Known or suspected carcinoma of the prostate or male breast
• Pregnancy (Category X; testosterone is teratogenic)
• Hypersensitivity to sesame oil or any component of the formulation
• Women who are or may become pregnant

Warnings and Precautions: A Section-by-Section Review

Cardiovascular risk. The label requires clinicians to weigh benefit versus risk in men with pre-existing cardiovascular disease, given the signals identified in the 2014 FDA safety review. Whether testosterone therapy causes cardiovascular events or merely correlates with them in sick populations remains debated. The T-Trials (N=788 men aged 65 or older with unequivocally low testosterone), published in NEJM 2016, showed that testosterone treatment over 1 year significantly increased coronary artery plaque volume compared with placebo, a finding that raised concern even though the trial was not powered to detect clinical events. [7]

Polycythemia. Hematocrit must be measured at baseline, at 3 months, and then annually. Dose reduction or treatment interruption is required if hematocrit exceeds 54%.

Sleep apnea. The label notes that testosterone may worsen pre-existing obstructive sleep apnea, particularly in obese patients. Screening with the STOP-BANG questionnaire before initiating therapy is consistent with guideline recommendations.

Hepatic effects. Although hepatotoxicity is a well-documented risk with 17-alpha-alkylated oral androgens, injectable esters including enanthate bypass first-pass hepatic metabolism. The label still advises monitoring liver enzymes periodically in long-term users.

Lipid effects. High-density lipoprotein (HDL) cholesterol may decrease with testosterone therapy. A meta-analysis of 51 trials published in JAMA Internal Medicine found mean HDL reductions of approximately 4.7 mg/dL in testosterone-treated men. [8]

Post-Market Surveillance: What Has Emerged Since Approval?

The FDA's active surveillance infrastructure has grown substantially since 1953, and testosterone products have been among the more closely monitored drug classes since 2014.

FDA Sentinel Data and Pharmacovigilance

The FDA Sentinel System has conducted multiple targeted queries on testosterone products. One 2017 analysis examining Medicare and commercial insurance data found no statistically significant increase in acute myocardial infarction risk in testosterone users compared with age-matched non-users after adjusting for confounders, a result that partially contradicted earlier observational signals. [1] The conflicting findings across observational studies reflect the challenge of confounding by indication: men prescribed testosterone often have comorbidities such as obesity, type 2 diabetes, and metabolic syndrome that independently raise cardiovascular risk.

The T-Trials: The Largest Placebo-Controlled Dataset in Older Men

The Testosterone Trials (T-Trials) remain the most rigorous post-market randomized dataset for testosterone therapy in older men. Seven coordinated trials enrolled 788 men aged 65 or older with serum testosterone below 275 ng/dL. Results published in NEJM 2016 showed:

• The sexual function trial: testosterone gel (titrated to normal range) improved sexual activity, desire, and erectile function compared with placebo (P<0.001 for composite endpoint). [7]
• The physical function trial: no significant improvement in walking distance with testosterone versus placebo.
• The bone trial: testosterone significantly increased volumetric bone mineral density and estimated bone strength.
• The coronary artery plaque sub-study: testosterone increased non-calcified plaque volume by a mean of 41 mm³ more than placebo (P=0.002), raising the cardiovascular concern that ultimately influenced the FDA's ongoing monitoring posture. [7]

The table below summarizes the T-Trials outcomes most relevant to the FDA's post-market safety posture:

| T-Trials Sub-Study | N | Primary Outcome | Result vs. Placebo | |---|---|---|---| | Sexual function | 470 | PDAS composite score | Significantly improved | | Physical function | 474 | 6-minute walk distance | No significant difference | | Bone density | 211 | Volumetric BMD (spine) | Significantly increased | | Coronary artery plaque | 170 | Non-calcified plaque volume | Increased by 41 mm³ (P=0.002) |

MedWatch Reports and FAERS Data

The FDA Adverse Event Reporting System (FAERS), searchable at FDA FAERS, contains thousands of reports involving testosterone products. The most frequently reported adverse events include polycythemia, acne, injection-site reactions, mood changes, and sexual dysfunction upon discontinuation. FAERS data are hypothesis-generating rather than confirmatory; they do not establish causation without controlled comparisons.

How the FDA Label Compares to Major Clinical Guidelines

The FDA label represents the minimum regulatory floor for prescribing. Clinical practice often diverges from label language, guided by specialist society recommendations.

Endocrine Society 2018 Guideline

The Endocrine Society's 2018 guideline recommends testosterone therapy for men with classic androgen deficiency symptoms and consistently low morning serum testosterone, defined as below the normal reference range for the assay used. The guideline states: "We suggest using a total testosterone level below which most men with hypogonadism have symptoms and signs" and recommends against universal age-based prescribing. [6] This language aligns closely with the FDA's 2014 safety communication requiring documented deficiency.

American Urological Association 2018 Guideline

The AUA's 2018 guideline on testosterone deficiency, available at AUA Guidelines, states that a serum total testosterone below 300 ng/dL on two separate morning measurements, combined with symptoms, is required before initiating therapy. The AUA also specifies monitoring intervals: total testosterone at 3 to 6 months after initiation, then annually once a stable dose is achieved. [9]

Where Label and Guideline Differ

The labeled dosing interval of every 2 to 4 weeks at 50 to 400 mg per injection produces wide serum fluctuations that most clinical pharmacologists consider suboptimal. A pharmacokinetic modeling study published in the Journal of Clinical Endocrinology and Metabolism demonstrated that weekly injections of 75 to 100 mg maintain serum testosterone within the mid-normal range (400 to 700 ng/dL) with far less peak-to-trough variation than the labeled biweekly or monthly regimens. [10] The FDA has not updated the dosing section of the label to reflect this evidence, which means the weekly dosing most commonly used in TRT clinics is technically off-label despite broad guideline acceptance.

Testosterone Enanthate Safety Profile: Prescriber Reference

Safety data from the 70-year post-market period, the T-Trials, and FDA Sentinel surveillance converge on a consistent set of clinically relevant risks.

Hematologic Effects

Erythrocytosis is the most common laboratory abnormality in testosterone-treated men. Across multiple trials, hematocrit increases of 3 to 5 percentage points from baseline are typical within the first 6 months. In a cohort of 1,000 men enrolled in a large integrated health system TRT program, polycythemia (hematocrit above 52%) occurred in approximately 18% of patients within 12 months of initiating injectable testosterone. [11] Phlebotomy or dose reduction effectively corrects the elevation in most cases.

Cardiovascular Effects

The cardiovascular risk signal remains the most contested area of testosterone safety. The TRAVERSE trial (N=5,246 middle-aged and older men with hypogonadism and elevated cardiovascular risk), results published in NEJM 2023, found that testosterone therapy was non-inferior to placebo for major adverse cardiovascular events (MACE) over a mean follow-up of 33 months. [12] This is the largest cardiovascular outcomes trial for testosterone to date. The TRAVERSE results have led several specialists to argue that the 2014 FDA warning language overstates cardiovascular risk for properly selected patients.

Fertility and Hypothalamic-Pituitary Suppression

Exogenous testosterone suppresses the hypothalamic-pituitary-gonadal (HPG) axis, reducing luteinizing hormone (LH) and follicle-stimulating hormone (FSH), which in turn suppresses spermatogenesis. Azoospermia or severe oligospermia develops in most men within 3 months of starting testosterone therapy. Recovery of spermatogenesis after discontinuation may take 6 to 24 months and is not guaranteed, particularly in men who have used testosterone for several years. The American Society for Reproductive Medicine advises that men desiring future fertility should not use testosterone therapy without concurrent gonadotropin support or should consider alternative treatments such as clomiphene citrate or human chorionic gonadotropin (hCG). [13]

Injection-Site Reactions

Pain, induration, and oil emboli are documented risks of intramuscular sesame oil-based injections. Subcutaneous injection of testosterone enanthate, while not specifically labeled, has been studied as a lower-risk alternative for patients prone to injection-site reactions. A small crossover study (N=22) found comparable pharmacokinetics between IM and subcutaneous routes at equivalent doses. [14]

Regulatory Outlook: What Could Change the Label Next

The FDA's 2023 review of TRAVERSE data is expected to inform future label revisions. Regulators may soften the cardiovascular warning for patients with confirmed hypogonadism who do not have active coronary artery disease, based on the TRAVERSE non-inferiority finding. The ongoing FDA Sentinel monitoring program continues to track real-world testosterone prescribing patterns and adverse events across millions of covered lives, and any emerging signal from that system could trigger a new safety communication.

The DEA's Schedule III classification is unlikely to change in the near term. Testosterone enanthate's abuse potential in athletic and body-building contexts remains a regulatory concern independent of its therapeutic profile.

Prescribers using testosterone enanthate should verify the most current label at Drugs@FDA before initiating therapy, and should monitor patients with a minimum protocol of serum testosterone at 3 months post-initiation, hematocrit at 3 months and annually, PSA at baseline and 3 to 6 months, and lipid panel at 12 months.