Head-to-head clinical analysis & difference comparison: details on mechanism of action, dosing, half-life, interactions, and maternal-fetal safety.
DANAZOL vs PREGNYL
Clinician-reviewed, head-to-head comparison of mechanism, dosing, pharmacokinetics, and safety profiles.
Last clinically reviewed: July 2026 · OpiCalc Medical Review Team
Danazol is a synthetic androgen derived from ethisterone that suppresses pituitary-ovarian axis by inhibiting gonadotropin release, leading to decreased estrogen and progesterone levels. It also has weak androgenic and progestational activity.
Human chorionic gonadotropin (h CG) acts as a luteinizing hormone (LH) agonist, binding to LH receptors in the gonads, stimulating testosterone production in males and ovulation in females.
FDA: Treatment of endometriosis, fibrocystic breast disease, hereditary angioedema,Off-label: Idiopathic thrombocytopenic purpura, precocious puberty, gynecomastia
FDA: Treatment of prepubertal cryptorchidism,FDA: Induction of ovulation and pregnancy in anovulatory infertile women,Off-label: Hypogonadotropic hypogonadism in males,Off-label: Assisted reproductive technology (ART) protocols
300-600 mg orally twice daily; maximum 800 mg/day
Intramuscular injection: 5,000-10,000 IU once weekly for 4-9 weeks for ovulation induction; 1,000-2,000 IU three times weekly for spermatogenesis.
Terminal elimination half-life is 4-4.5 hours; clinical context: requires multiple daily dosing to maintain therapeutic levels.
Terminal elimination half-life: 23–24 hours; clinically, supports daily or every-other-day dosing; peak effect may lag due to prolonged absorption
Primarily hepatic: undergoes oxidation and conjugation via CYP3A4, with metabolites excreted in urine and feces.
Primarily renal metabolism and excretion; limited hepatic metabolism.
Primarily hepatic metabolism; approximately 60% excreted in feces, 30% in urine as metabolites.
Renal: 10-20% as unchanged drug; hepatic metabolism to inactive metabolites; fecal excretion negligible (<5%)
Highly protein bound: 97-99%, primarily to albumin.
~80% bound primarily to albumin; minor binding to sex hormone-binding globulin (SHBG)
Approximately 1.5 L/kg; indicates extensive distribution into tissues, exceeding total body water.
0.5–0.7 L/kg; moderately distributed into extracellular fluid; penetrates gonadal tissues
Oral bioavailability is approximately 100% due to extensive absorption, but first-pass metabolism reduces systemic availability to about 70-80%.
Intramuscular: ~100%; Subcutaneous: comparable (~95-100%); Oral: <5% (not used)
No adjustment required for GFR ≥10 m L/min; avoid use in GFR <10 m L/min due to fluid retention risk
No specific guidelines; use with caution in severe renal impairment (Cr Cl <30 m L/min) due to limited data.
Child-Pugh A: no adjustment; Child-Pugh B: reduce dose by 50%; Child-Pugh C: contraindicated
No specific guidelines for Child-Pugh; use with caution in severe hepatic impairment.
2-5 mg/kg/dose orally twice daily; maximum 400 mg/day
Not indicated for prepubertal children; for delayed puberty in males: 1,000-2,000 IU intramuscularly 2-3 times weekly for 3-6 months.
Start at low end of adult dose, titrate cautiously due to increased risk of fluid retention and thromboembolism
No specific recommendations; use lowest effective dose due to potential increased sensitivity and comorbidities.
Danazol may cause thrombotic events, including pulmonary embolism and thrombophlebitis. It is contraindicated in patients with a history of thrombosis.
No FDA black box warning.
Hepatotoxicity (monitor LFTs), pseudotumor cerebri (benign intracranial hypertension), androgenic effects (hirsutism, acne, voice deepening), lipid changes (decreased HDL, increased LDL), thromboembolic events, and premature closure of epiphyses in children.
Ovarian hyperstimulation syndrome (OHSS) in women,Arterial thromboembolism,Precocious puberty in males,Fluid retention,Ovarian enlargement or cyst rupture
Pregnancy, lactation, porphyria, severe hepatic/renal/cardiac disease, undiagnosed abnormal genital bleeding, history of thromboembolic disorders, androgen-dependent tumors.
Hypersensitivity to h CG or any component,Premature epiphyseal closure in males,Androgen-dependent neoplasia (e.g., prostate cancer),Undiagnosed uterine bleeding,Ovarian cyst or enlargement due to polycystic ovarian syndrome (PCOS),Active thromboembolic disorders
Take with food or milk to minimize gastrointestinal irritation. Avoid grapefruit juice as it may alter drug metabolism. Limit alcohol consumption due to increased risk of hepatotoxicity.
No known clinically significant food interactions. Maintain usual diet unless advised otherwise by physician.
Danazol is contraindicated in pregnancy. First trimester exposure is associated with virilization of female fetus including clitoromegaly, labioscrotal fusion, and urogenital sinus abnormalities. Risk in second and third trimesters is also significant due to androgenic effects; fetal growth restriction and preterm birth may occur. No safe gestational period exists.
Pregny (h CG) is not indicated for use during pregnancy. h CG is used to induce ovulation and is not continued after conception. In animal studies, high doses have shown fetal abnormalities, but human data are insufficient. First trimester: No direct fetal risk from therapeutic use as it is discontinued before implantation. Second/Third trimester: Not used. Overall, classified as FDA Pregnancy Category X for ovulation induction (contraindicated in pregnancy) but no teratogenic risk if discontinued before conception.
Danazol is excreted in human milk; M/P ratio not determined. Potential for adverse effects in breastfed infant (e.g., androgenization). Use is contraindicated during breastfeeding due to risk of virilization and other hormonal effects.
Human chorionic gonadotropin (h CG) is normally present in breast milk in low concentrations. Exogenous h CG is likely excreted into breast milk, but the M/P ratio is not established. Due to lack of data and potential for adverse effects in the infant (e.g., hormonal disruption), breastfeeding is not recommended during therapy. The manufacturer advises discontinuing breastfeeding or avoiding the drug.
Danazol is contraindicated in pregnancy; no dose adjustment recommendations exist. If inadvertently used during pregnancy, discontinue immediately and monitor for fetal effects. Pharmacokinetic changes in pregnancy are not studied; dose modifications are not applicable due to contraindication.
Pregny is contraindicated in pregnancy. No dose adjustment is applicable as it is discontinued prior to conception. There are no pharmacokinetic data for pregnancy, but the drug is not used during gestation.
Monitor liver function tests; androgenic effects (acne, hirsutism, voice deepening) may occur; use with caution in patients with cardiac or renal impairment; may potentiate warfarin; effective for hereditary angioedema prophylaxis; check pregnancy test before initiation due to teratogenicity.
Pregnyl (h CG) is used to trigger final follicular maturation and ovulation in assisted reproduction. Monitor for ovarian hyperstimulation syndrome (OHSS); consider withholding h CG if estradiol >4000 pg/m L or >20 follicles per ovary. Administer exactly 36 hours before oocyte retrieval. Intramuscular injection into gluteal muscle; rotate sites if repeated doses.
Do not take if pregnant or planning pregnancy; use effective contraception.,Report symptoms of liver toxicity (jaundice, dark urine, abdominal pain) immediately.,Avoid alcohol as it may increase hepatotoxicity risk.,May cause weight gain, acne, or voice changes; report if bothersome.,Take with food to reduce GI upset.,Use sunscreen due to photosensitivity risk.,Do not discontinue abruptly; taper under medical supervision.
Use Pregnyl exactly as prescribed to trigger ovulation; timing is critical for egg retrieval.,Report severe pelvic pain, bloating, nausea, or rapid weight gain (possible OHSS) immediately.,Avoid pregnancy tests during treatment as h CG may cause false positive.,May cause injection site pain or swelling; apply warm compress if needed.,Do not discontinue without consulting your fertility specialist.
"Formestane, an aromatase inhibitor, reduces estrogen synthesis, while danazol, a synthetic androgen, possesses weak androgenic and anabolic activity. Concomitant use may lead to additive fluid retention due to danazol's mineralocorticoid-like effects and formestane's potential to cause fluid retention through estrogen withdrawal. This can result in peripheral edema, hypertension, or exacerbation of heart failure in susceptible patients."
"Danazol, a synthetic androgen with weak androgenic activity, may reduce the therapeutic efficacy of vildagliptin, a dipeptidyl peptidase-4 (DPP-4) inhibitor used for glycemic control in type 2 diabetes. The proposed mechanism involves danazol-induced activation of cytochrome P450 enzymes (particularly CYP3A4) and potential upregulation of glucagon counter-regulatory pathways, leading to increased vildagliptin clearance and diminished inhibition of DPP-4. Clinically, this interaction may result in elevated postprandial glucose levels and reduced HbA1c reduction, compromising glycemic management."
"Danazol, an androgenic steroid, can induce hepatic microsomal enzymes, particularly CYP2C9, which accelerates the metabolism of glipizide, a sulfonylurea antidiabetic agent. This increased clearance reduces glipizide's plasma concentrations, diminishing its insulinotropic effect and potentially leading to hyperglycemia and loss of glycemic control in patients with type 2 diabetes mellitus."
No interactions on record
Explore head-to-head clinical comparisons of other medications in the same therapeutic classes.
Common clinical questions about DANAZOL vs PREGNYL, answered by our medical review team.
DANAZOL is a Androgen/Antigonadotropin that works by Danazol is a synthetic androgen derived from ethisterone that suppresses pituitary-ovarian axis by inhibiting gonadotropin release, leading to decreased estrogen and progesterone levels. It also has weak androgenic and progestational activity.. PREGNYL is a Gonadotropin Hormone that works by Human chorionic gonadotropin (h CG) acts as a luteinizing hormone (LH) agonist, binding to LH receptors in the gonads, stimulating testosterone production in males and ovulation in females.. They differ in pharmacokinetic profiles, FDA-approved indications, and side effect profiles.
Potency comparisons between DANAZOL and PREGNYL depend on the specific clinical indication. These are agents from distinct pharmacological classes and are not directly interchangeable by dose. A physician or clinical pharmacist should guide any therapeutic switching decisions.
The standard adult dose of DANAZOL is: 300-600 mg orally twice daily; maximum 800 mg/day. The standard adult dose of PREGNYL is: Intramuscular injection: 5,000-10,000 IU once weekly for 4-9 weeks for ovulation induction; 1,000-2,000 IU three times weekly for spermatogenesis.. Dosing should always be individualized based on indication, renal and hepatic function, age, and other patient factors.
No direct drug-drug interaction has been formally documented between DANAZOL and PREGNYL in current clinical databases. However, individual patient risk factors including other medications, organ function, and comorbidities should always be evaluated by a qualified healthcare provider.
The maternal-fetal safety profiles differ. DANAZOL is classified as Category C. Danazol is contraindicated in pregnancy. First trimester exposure is associated with virilization of female fetus including clitoromegaly, labioscrotal fusion, and urogenital sinus. PREGNYL is classified as Category C. Pregny (hCG) is not indicated for use during pregnancy. hCG is used to induce ovulation and is not continued after conception. In animal studies, high doses have shown fetal abnorm. Always consult a maternal-fetal medicine specialist before taking either drug during pregnancy or lactation.