Head-to-head clinical analysis & difference comparison: details on mechanism of action, dosing, half-life, interactions, and maternal-fetal safety.
APOMORPHINE HYDROCHLORIDE vs ALFENTA
Clinician-reviewed, head-to-head comparison of mechanism, dosing, pharmacokinetics, and safety profiles.
Last clinically reviewed: July 2026 · OpiCalc Medical Review Team
Non-ergoline dopamine agonist with high affinity for D2 and D3 receptors, moderate affinity for D4, D5, and adrenergic receptors; activates striatal dopamine receptors to improve motor function.
μ-opioid receptor agonist that activates G-protein coupled receptors to inhibit adenylate cyclase, decreasing c AMP production, leading to reduced neuronal excitability and pain transmission.
FDA: Acute treatment of hypomobility episodes ('off' episodes) in Parkinson disease,Off-label: Refractory erectile dysfunction, treatment of levodopa-induced dyskinesias, depression
Induction and maintenance of anesthesia,Analgesic supplement during surgical procedures,Intravenous use for monitored anesthesia care (MAC)
Subcutaneous injection: 0.2 m L (2 mg) test dose, then 0.2-0.6 m L (2-6 mg) as needed for acute hypomobility episodes; maximum single dose 0.6 m L (6 mg). Sublingual: 2-10 mg sublingually as needed, not more than every 2 hours, maximum 30 mg/day. Continuous subcutaneous infusion: 0.5-2.0 mg/hour via infusion pump.
Intravenous: Initial dose 8-20 mcg/kg (0.5-1 min) then 0.5-3 mcg/kg/min or 3-5 mcg/kg q5-20min. For short procedures: 8-20 mcg/kg. For longer procedures: 50-75 mcg/kg followed by 0.5-3 mcg/kg/min.
Terminal elimination half-life is 40–60 minutes in adults with normal renal function; prolonged to 3–6 hours in end-stage renal disease.
Terminal elimination half-life: 90–111 minutes (1.5–1.85 hours); prolonged in hepatic impairment.
Hepatic via CYP3A4, CYP2C9, and CYP2C19; main metabolite is apomorphine-8-O-sulfate; first-pass effect with rapid clearance.
Hepatic via CYP3A4 to inactive metabolites; major metabolite is desmethylalfentanil (inactive).
Approximately 90% of an intravenous dose is excreted in urine within 24 hours, primarily as unchanged drug and sulfate conjugates. Biliary/fecal excretion is minimal (<5%).
Primarily renal (urinary) elimination as metabolites; approximately 80% recovered in urine, 20% in feces.
Approximately 90–99% bound, primarily to albumin.
Approximately 92% bound, primarily to alpha-1 acid glycoprotein and albumin.
1.8–2.5 L/kg, indicating extensive tissue distribution.
0.5–1.0 L/kg; reflects moderate tissue distribution; higher Vd in neonates and elderly.
Subcutaneous: 100% (absolute); sublingual: 16–18%; oral: <1% due to extensive first-pass metabolism.
Intravenous: 100%; intramuscular: approximately 90%; intrathecal: approximately 10% (due to systemic absorption following spinal administration).
No dose adjustment for mild to moderate impairment. Severe impairment (GFR <15 m L/min): avoid use as apomorphine is renally eliminated and accumulation may occur; use with caution and reduce dose if necessary at GFR 15-29 m L/min.
No specific dose adjustment is recommended for renal impairment; however, alfentanil is primarily metabolized in the liver and its pharmacokinetics are not significantly altered in renal failure.
Child-Pugh A and B: no dose adjustment necessary. Child-Pugh C: pharmacokinetics not studied; use with caution and monitor closely.
In hepatic impairment (Child-Pugh class A, B, C): Reduce dose by 50% and titrate carefully due to prolonged elimination half-life. Consider lower initial doses and extended dosing intervals.
Safety and efficacy not established; no pediatric dosing recommendations.
Children (1-12 years): Induction of anesthesia: 10-20 mcg/kg IV; maintenance: 5-10 mcg/kg IV or infusion 0.5-1 mcg/kg/min. For neonates and infants: Dose individualization required; titrate to effect.
Elderly patients may be more sensitive to neuropsychiatric effects; initiate at low end of dosing range (e.g., 1-2 mg subcutaneously) and titrate slowly; monitor for hypotension and falls.
Elderly patients (>65 years): Reduce initial dose by 30-50% and administer slowly. Due to decreased clearance and increased sensitivity, lower infusion rates (e.g., 0.3-0.5 mcg/kg/min) may be needed.
None.
Risk of respiratory depression, particularly in elderly or debilitated patients. Concomitant use with benzodiazepines or other CNS depressants may cause profound sedation, respiratory depression, coma, and death.
Risk of hypotension, syncope, and orthostatic hypotension,Severe nausea and vomiting (pretreat with antiemetic),Potential for hallucination, dyskinesia, and impulse control disorders,Do not mix with serotonin 5-HT3 antagonists (e.g., ondansetron) due to severe hypotension,Use caution in patients with cardiovascular disease, hypotension, or renal impairment
Respiratory depression; abuse potential; hypotension; bradycardia; muscle rigidity; serotonin syndrome with concurrent serotonergic drugs; adrenal insufficiency; risk of withdrawal with prolonged use.
Concurrent use with serotonin 5-HT3 antagonists (e.g., ondansetron),Hypersensitivity to apomorphine or sulfite-containing products,Severe asthma or sulfite allergy
Hypersensitivity to alfentanil or any component; significant respiratory insufficiency; severe asthma; paralytic ileus; concurrent use of MAOIs (or within 14 days); acute or postoperative pain management in children (except for procedural sedation).
Avoid alcohol: may increase drowsiness and hypotension. Grapefruit juice: may increase risk of QT prolongation. No specific food interactions; maintain normal diet but monitor for changes in blood pressure.
No known interactions with food. However, grapefruit juice may increase alfentanil serum concentrations due to CYP3A4 inhibition; avoid concurrent consumption.
Apomorphine hydrochloride is a dopamine agonist indicated for Parkinson's disease. Limited human pregnancy data; animal studies show fetotoxicity and teratogenicity at doses near maternal toxic doses. FDA Pregnancy Category C. First trimester: Avoid use unless benefit outweighs risk. Second/third trimester: No established safety; potential fetal effects include altered dopamine receptor development. Postnatal: Risk of neonatal withdrawal if used near term.
Alfentanil, a short-acting opioid analgesic, is classified as FDA Pregnancy Category C. No well-controlled studies in pregnant women exist. In animal studies, no teratogenic effects were observed at clinically relevant doses; however, high doses caused embryotoxicity and increased fetal mortality. Trimester-specific risks: First trimester - potential for minor malformations based on limited human data; second trimester - possible risk if used chronically; third trimester - prolonged use may lead to neonatal respiratory depression, withdrawal syndrome, or opioid dependence. Use only if benefits outweigh risks.
No data on apomorphine excretion in human milk. M/P ratio unknown. Due to potential for serious adverse reactions in breastfeeding infants (e.g., somnolence, hypotension, dyskinesia), breastfeeding is not recommended during therapy.
Alfentanil is excreted into human breast milk in low concentrations. The milk-to-plasma (M/P) ratio is approximately 0.3. Estimated infant dose is <1% of maternal weight-adjusted dose, which is considered clinically insignificant. However, due to potential for neonatal opioid effects, caution is advised; monitor infant for drowsiness, respiratory depression, and feeding difficulties. Consider alternative analgesics with established safety profiles, such as acetaminophen or ibuprofen, for lactation.
Pregnancy can alter apomorphine pharmacokinetics due to increased plasma volume, renal blood flow, and hepatic metabolism. No specific dose adjustment guidelines exist. Use lowest effective dose with careful titration. Monitor for reduced efficacy or increased adverse effects (e.g., hypotension, nausea).
Pregnancy can alter pharmacokinetics of alfentanil. Increased plasma volume and distribution may require higher doses to achieve same effect, while decreased plasma protein binding may increase free fraction, potentiating effects. Alpha-1-acid glycoprotein levels change in pregnancy, affecting binding. In third trimester, clearance may be increased by up to 50% due to enhanced hepatic metabolism. Therefore, dose adjustments may be needed: consider starting at low dose and titrating to effect, with close monitoring. For intravenous administration, typical adult doses (5-20 μg/kg) may need adjustments; no standard pregnancy-specific dosing exists. Use the lowest effective dose for the shortest duration. In labor, avoid high doses prior to delivery due to risk of neonatal respiratory depression.
Administer subcutaneously; avoid intravenous use due to risk of hemolytic anemia and hypotension. Onset is rapid (5-15 minutes) with short duration (1 hour). Use an antiemetic (e.g., domperidone or trimethobenzamide) for 3 days before starting to prevent nausea. Do not use with 5-HT3 antagonists (e.g., ondansetron) due to profound hypotension. Monitor for dyskinesia, orthostatic hypotension, and QT prolongation. Avoid in patients with dementia, psychosis, or severe respiratory depression; caution in hepatic/renal impairment. Test dose (0.2-0.5 m L) is required before first prescription.
Alfentanil is a potent, rapid-onset, short-acting opioid analgesic used primarily for induction and maintenance of anesthesia. Due to its high protein binding (90%) and rapid redistribution, it has a shorter duration of action than fentanyl, making it suitable for brief, painful procedures. It undergoes hepatic metabolism via CYP3A4, so concomitant use with CYP3A4 inhibitors like ketoconazole or erythromycin can prolong its effects. Use caution in elderly or hypovolemic patients due to increased risk of hypotension. Naloxone reverses respiratory depression. Alfentanil is 5-10 times less potent than fentanyl.
Take this medication exactly as prescribed; it is for on-demand treatment of 'off' episodes.,Inject under the skin (subcutaneous) as directed; do not inject into a vein or muscle.,You may feel dizzy or lightheaded when standing up; rise slowly from sitting or lying down.,Nausea is common; your doctor may prescribe an anti-nausea medicine to take before each dose.,Report any chest pain, fainting, or severe dizziness immediately.,Avoid alcohol and grapefruit juice while using this medication.,Do not change your dose or frequency without consulting your doctor.,Keep this medication away from children and pets.
This medication is given only by a healthcare professional in a hospital or surgical setting.,You may feel drowsy, dizzy, or nauseated after receiving this drug.,Report any difficulty breathing or slow heart rate to your healthcare provider immediately.,Avoid alcohol and sedatives for 24 hours after administration, as they can increase side effects.,Do not drive or operate machinery until the effects have fully worn off.
"Coadministration of morphine with palbociclib may increase plasma concentrations of palbociclib due to morphine-induced inhibition of intestinal P-glycoprotein (P-gp) efflux transporter and potential competition for CYP3A4 metabolism. This elevation can heighten the risk of palbociclib-related toxicities, including myelosuppression (neutropenia, leukopenia, anemia), hepatotoxicity, and gastrointestinal adverse effects (e.g., diarrhea, nausea). Patients should be monitored for signs of excessive palbociclib exposure and dose reductions considered if toxicity occurs."
"Morphine, a potent opioid analgesic, can inhibit the metabolism of sulfisoxazole, a sulfonamide antibiotic, by competing for hepatic glucuronidation pathways. This pharmacokinetic interaction leads to increased plasma concentrations of sulfisoxazole, potentially elevating the risk of dose-dependent adverse effects such as crystalluria, hypersensitivity reactions, and bone marrow suppression. Co-administration requires careful monitoring for sulfonamide toxicity, especially in patients with renal impairment or those receiving high-dose morphine."
"Morphine is a potent opioid analgesic that can inhibit the metabolism of isavuconazonium (prodrug of isavuconazole) via competitive inhibition of CYP3A4, the primary enzyme responsible for its activation. This leads to reduced conversion to the active antifungal isavuconazole, potentially decreasing its efficacy against invasive fungal infections. Conversely, isavuconazonium may also inhibit morphine metabolism, increasing opioid side effects such as respiratory depression, sedation, and constipation."
"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 APOMORPHINE HYDROCHLORIDE vs ALFENTA, answered by our medical review team.
APOMORPHINE HYDROCHLORIDE is a Opioid Agonist that works by Non-ergoline dopamine agonist with high affinity for D2 and D3 receptors, moderate affinity for D4, D5, and adrenergic receptors; activates striatal dopamine receptors to improve motor function.. ALFENTA is a Opioid Analgesic that works by μ-opioid receptor agonist that activates G-protein coupled receptors to inhibit adenylate cyclase, decreasing c AMP production, leading to reduced neuronal excitability and pain transmission.. They differ in pharmacokinetic profiles, FDA-approved indications, and side effect profiles.
Potency comparisons between APOMORPHINE HYDROCHLORIDE and ALFENTA 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 APOMORPHINE HYDROCHLORIDE is: Subcutaneous injection: 0.2 m L (2 mg) test dose, then 0.2-0.6 m L (2-6 mg) as needed for acute hypomobility episodes; maximum single dose 0.6 m L (6 mg). Sublingual: 2-10 mg sublingually as needed, not more than every 2 hours, maximum 30 mg/day. Continuous subcutaneous infusion: 0.5-2.0 mg/hour via infusion pump.. The standard adult dose of ALFENTA is: Intravenous: Initial dose 8-20 mcg/kg (0.5-1 min) then 0.5-3 mcg/kg/min or 3-5 mcg/kg q5-20min. For short procedures: 8-20 mcg/kg. For longer procedures: 50-75 mcg/kg followed by 0.5-3 mcg/kg/min.. 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 APOMORPHINE HYDROCHLORIDE and ALFENTA 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. APOMORPHINE HYDROCHLORIDE is classified as Category D/X. Apomorphine hydrochloride is a dopamine agonist indicated for Parkinson's disease. Limited human pregnancy data; animal studies show fetotoxicity and teratogenicity at doses near m. ALFENTA is classified as Category C. Alfentanil, a short-acting opioid analgesic, is classified as FDA Pregnancy Category C. No well-controlled studies in pregnant women exist. In animal studies, no teratogenic effect. Always consult a maternal-fetal medicine specialist before taking either drug during pregnancy or lactation.