Head-to-head clinical analysis & difference comparison: details on mechanism of action, dosing, half-life, interactions, and maternal-fetal safety.
ANDROID 5 vs ALFENTANIL
Clinician-reviewed, head-to-head comparison of mechanism, dosing, pharmacokinetics, and safety profiles.
Last clinically reviewed: July 2026 · OpiCalc Medical Review Team
Androgen receptor agonist; stimulates protein synthesis and growth of androgen-sensitive tissues.
Alfentanil is a potent, short-acting synthetic opioid analgesic that primarily acts as a mu-opioid receptor agonist. It binds to mu-opioid receptors in the central nervous system, leading to G-protein coupled activation of inwardly rectifying potassium channels and inhibition of voltage-gated calcium channels, resulting in hyperpolarization and reduced neurotransmitter release. This produces analgesia, sedation, and respiratory depression.
Testosterone replacement therapy for male hypogonadism,Off-label: delayed puberty in males
Analgesic adjunct during general anesthesia,Induction of anesthesia,Maintenance of anesthesia for short surgical procedures,Off-label: Procedural sedation in monitored settings
2.5-10 mg orally once daily in the morning for androgen replacement therapy in adult males.
Initial IV bolus of 5-20 mcg/kg; maintenance infusion of 0.5-1.5 mcg/kg/min; incremental boluses of 5-10 mcg/kg as needed. Induction of anesthesia: 50-100 mcg/kg IV.
Terminal elimination half-life is 3.5–5.5 hours; clinical effects may persist for several days due to active metabolites.
Terminal elimination half-life: 90–111 minutes (1.5–1.85 hours). Clinically, context-sensitive half-time is short (~40 min after 3-hour infusion) due to rapid redistribution and metabolism.
Hepatic via CYP3A4 and CYP2B6; undergoes first-pass metabolism.
Alfentanil is primarily metabolized by hepatic cytochrome P450 enzymes, mainly CYP3A4, through oxidative N-dealkylation and O-demethylation to inactive metabolites.
Primarily renal: ~90% as glucuronide and sulfate conjugates, 6% as unchanged drug; ~5% fecal via bile.
Primarily hepatic metabolism via CYP3A4; <1% excreted unchanged in urine; metabolites (mainly noralfentanil) excreted renally. Biliary/fecal excretion of metabolites accounts for ~30%.
98% bound to sex hormone-binding globulin (SHBG) and albumin.
~92% bound primarily to alpha-1-acid glycoprotein (AAG) and albumin.
Vd approximately 1.0 L/kg; indicates extensive tissue distribution, especially to reproductive organs and bone marrow.
Vd: 0.4–1.0 L/kg (mean ~0.75 L/kg). Moderate Vd reflecting rapid distribution to tissues, especially brain and muscle.
Oral: 15–25% due to first-pass metabolism; buccal or transdermal: higher, but not commercially available for this formulation.
IV: 100%. IM: ~90%. Epidural: ~30–50% due to local uptake and redistribution. No significant oral bioavailability.
No specific dose adjustment required based on GFR; caution in severe impairment (Cr Cl <30 m L/min) due to potential fluid retention.
GFR 10-50 m L/min: administer with caution, consider dose reduction of 25-50%; GFR <10 m L/min: reduce dose by 50% and extend dosing interval.
Contraindicated in Child-Pugh class B and C cirrhosis due to hepatotoxicity risk; in class A, use with caution and monitor liver function.
Child-Pugh class A: no adjustment needed; Child-Pugh class B: reduce dose by 50%; Child-Pugh class C: reduce dose by 75%.
Not recommended for use in children as it may cause premature epiphyseal closure and virilization; limited data.
Initial IV bolus of 5-20 mcg/kg; maintenance infusion of 0.5-2 mcg/kg/min. For neonates, reduce dose by 30-50% due to immature clearance.
Increased risk of prostatic hyperplasia and carcinoma; use lowest effective dose with regular prostate monitoring.
Reduce initial IV bolus by 30-50% to 3-10 mcg/kg; titrate carefully; monitor for prolonged sedation and respiratory depression.
Warning: Prolonged use may cause virilization in women, premature epiphyseal closure, and increased risk of prostatic hypertrophy/carcinoma.
Risk of respiratory depression: Alfentanil can cause severe, life-threatening, or fatal respiratory depression. Monitor for respiratory depression, especially during initiation or following dose increases. Accidental ingestion of even one dose can be fatal. Concomitant use with central nervous system depressants (e.g., benzodiazepines, alcohol) may increase risk. Alfentanil is an opioid agonist and a Schedule II controlled substance with high potential for abuse and addiction.
Monitor liver function, lipid profile, and prostate-specific antigen; risk of edema in patients with cardiac disease; avoid use in patients with sleep apnea.
Respiratory depression: Potentially fatal; monitor oxygenation and ventilation.,Abuse potential: Schedule II controlled substance; risk of addiction, abuse, and diversion.,Concomitant use with CNS depressants: Increases risk of profound sedation, respiratory depression, coma, and death; limit use or monitor closely.,Geriatric and cachectic patients: Increased sensitivity; reduce initial dose.,Hepatic impairment: Alfentanil clearance is reduced in patients with cirrhosis; consider dose adjustment.,Bradycardia and hypotension: Use with caution in patients with hypovolemia or reduced cardiac reserve.,Serotonin syndrome: Risk with concurrent serotonergic drugs (e.g., MAOIs, SSRIs, triptans); monitor for symptoms.,Withdrawal: Prolonged use may lead to physical dependence; taper dose gradually.
Known or suspected prostate cancer; breast cancer in males; hypersensitivity to androgens; pregnancy and lactation.
Hypersensitivity to alfentanil, fentanyl, or any opioid,Significant respiratory depression (e.g., acute asthma, COPD in acute exacerbation),Acute or severe bronchial asthma,Suspected or known paralytic ileus,MAO inhibitor use within 14 days (serotonin syndrome risk),Myasthenia gravis (relative contraindication due to risk of respiratory muscle weakness),Morbid obesity with sleep apnea (relative contraindication; increased risk of respiratory depression)
Avoid grapefruit and grapefruit juice as they may increase drug levels. Limit salt intake to reduce fluid retention. Alcohol may increase risk of liver toxicity.
No significant food interactions known. Avoid grapefruit and grapefruit juice as they may inhibit CYP3A4 metabolism, potentially prolonging effects.
Pregnancy Category X. ANDROID 5 (oxandrolone) is contraindicated in pregnancy due to teratogenic effects including masculinization of female fetus, clitoral enlargement, and labial fusion. Risk is highest during first trimester but applies throughout gestation.
Alfentanil is an opioid analgesic; limited human data. No clear evidence of major malformations, but third trimester use may cause neonatal opioid withdrawal syndrome (NOWS). Avoid prolonged use or high doses near term; use during labor may cause respiratory depression in neonate.
Excretion into human milk is unknown. Due to potential for androgenic effects in nursing infants, breastfeeding is not recommended. No M/P ratio available.
Alfentanil is excreted into breast milk in very low concentrations; estimated relative infant dose is low (<2% of maternal weight-adjusted dose). M/P ratio not determined in humans. Compatible with breastfeeding with caution; monitor infant for drowsiness, feeding difficulties.
Not applicable; contraindicated in pregnancy. No dose adjustment recommendations exist for pregnant patients.
Pregnancy can alter alfentanil pharmacokinetics: increased volume of distribution, decreased plasma clearance, prolonged elimination half-life. Dose reduction may be needed for prolonged use; titrate to effect. During labor, use smallest effective dose.
Android 5 (methyltestosterone) is an androgenic anabolic steroid used for hypogonadism and delayed puberty. Monitor liver function due to hepatotoxicity. Use with caution in elderly due to increased risk of prostatic hypertrophy and carcinoma. Can cause fluid retention in patients with cardiac, renal, or hepatic disease. Avoid in patients with breast cancer or known or suspected prostate cancer.
Alfentanil is a potent, short-acting synthetic opioid (4-5 times more potent than fentanyl) with rapid onset (1-2 min) and brief duration (5-10 min). Primarily used for induction and maintenance of anesthesia, especially in short procedures. Requires careful monitoring of respiratory depression and chest wall rigidity, particularly during rapid IV administration. Hepatic metabolism (CYP3A4) affected by liver disease; reduce dose. Decrease dose in elderly and hypovolemic patients. Not recommended for chronic pain due to short half-life.
Take exactly as prescribed; do not increase dose or frequency without consulting your doctor.,Report any signs of liver problems: yellowing of skin or eyes, dark urine, severe stomach pain.,Women should report any signs of virilization: hoarseness, acne, menstrual changes, growth of facial hair.,Men should report any breast enlargement, changes in urination, or priapism.,Avoid driving or operating machinery if you experience dizziness or drowsiness.,Do not use if you are pregnant or planning to become pregnant.
This medication causes drowsiness and dizziness; avoid driving or operating machinery for at least 24 hours after administration.,Report any difficulty breathing, chest tightness, or feeling faint immediately.,Alfentanil is used only in hospital settings under direct supervision of healthcare professionals.,Inform your doctor if you have a history of liver disease, lung disease, or drug/alcohol abuse.,Do not consume alcohol or other sedatives while under the effects of alfentanil.
No interactions on record
"Propantheline, an anticholinergic agent, can competitively antagonize muscarinic acetylcholine receptors, potentially reducing gastrointestinal motility and secretion. Alfentanil, a mu-opioid receptor agonist, also decreases gastrointestinal motility through central and peripheral opioid receptors. Concomitant use may synergistically inhibit peristalsis, leading to severe constipation, paralytic ileus, or delayed gastric emptying, which can increase the risk of aspiration and complicate anesthesia recovery."
"Alfentanil, a potent opioid analgesic, can cause significant hypotension and respiratory depression. When combined with furosemide, a loop diuretic that reduces blood volume and vascular resistance, there is a synergistic decrease in blood pressure, which may precipitate cardiovascular collapse, especially in patients with compromised circulatory reserves. Additionally, furosemide may enhance the sedative and respiratory depressant effects of alfentanil, leading to increased risk of respiratory acidosis and altered mental status."
"Alfentanil, a potent mu-opioid receptor agonist, can enhance the bradycardic effects of nebivolol, a beta-1 selective blocker with additional nitric oxide-mediated vasodilation. The combination may lead to excessive slowing of heart rate, reduced cardiac output, and potential hemodynamic instability, particularly in patients with underlying cardiac conduction abnormalities or hypovolemia."
Explore head-to-head clinical comparisons of other medications in the same therapeutic classes.
Common clinical questions about ANDROID 5 vs ALFENTANIL, answered by our medical review team.
ANDROID 5 is a Androgen that works by Androgen receptor agonist; stimulates protein synthesis and growth of androgen-sensitive tissues.. ALFENTANIL is a Opioid Analgesic that works by Alfentanil is a potent, short-acting synthetic opioid analgesic that primarily acts as a mu-opioid receptor agonist. It binds to mu-opioid receptors in the central nervous system, leading to G-protein coupled activation of inwardly rectifying potassium channels and inhibition of voltage-gated calcium channels, resulting in hyperpolarization and reduced neurotransmitter release. This produces analgesia, sedation, and respiratory depression.. They differ in pharmacokinetic profiles, FDA-approved indications, and side effect profiles.
Potency comparisons between ANDROID 5 and ALFENTANIL 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 ANDROID 5 is: 2.5-10 mg orally once daily in the morning for androgen replacement therapy in adult males.. The standard adult dose of ALFENTANIL is: Initial IV bolus of 5-20 mcg/kg; maintenance infusion of 0.5-1.5 mcg/kg/min; incremental boluses of 5-10 mcg/kg as needed. Induction of anesthesia: 50-100 mcg/kg IV.. 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 ANDROID 5 and ALFENTANIL 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. ANDROID 5 is classified as Category C. Pregnancy Category X. ANDROID 5 (oxandrolone) is contraindicated in pregnancy due to teratogenic effects including masculinization of female fetus, clitoral enlargement, and labial. ALFENTANIL is classified as Category C. Alfentanil is an opioid analgesic; limited human data. No clear evidence of major malformations, but third trimester use may cause neonatal opioid withdrawal syndrome (NOWS). Avoid. Always consult a maternal-fetal medicine specialist before taking either drug during pregnancy or lactation.