Head-to-head clinical analysis & difference comparison: details on mechanism of action, dosing, half-life, interactions, and maternal-fetal safety.
DILAUDID vs ALFENTA
Clinician-reviewed, head-to-head comparison of mechanism, dosing, pharmacokinetics, and safety profiles.
Last clinically reviewed: July 2026 · OpiCalc Medical Review Team
Dilaudid (hydromorphone) is a full opioid agonist with high affinity for mu-opioid receptors, producing analgesia by mimicking endogenous endorphins and enkephalins. It also activates kappa and delta opioid receptors to a lesser extent.
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.
Management of moderate to severe pain in opioid-tolerant patients requiring an around-the-clock analgesic for an extended period,Off-label: acute pain management, preanesthetic medication, cough suppression
Induction and maintenance of anesthesia,Analgesic supplement during surgical procedures,Intravenous use for monitored anesthesia care (MAC)
Initial: 2-4 mg orally every 4-6 hours as needed; or 1-2 mg intramuscularly, subcutaneously, or intravenously every 4-6 hours as needed.
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.
2.5-3.5 hours (terminal); prolonged in hepatic/renal impairment
Terminal elimination half-life: 90–111 minutes (1.5–1.85 hours); prolonged in hepatic impairment.
Primarily hepatic via glucuronidation; major metabolites: hydromorphone-3-glucuronide (H3G, active) and hydromorphone-6-glucuronide (H6G); minor pathways: N-demethylation to norhydromorphone; CYP450 involvement minimal.
Hepatic via CYP3A4 to inactive metabolites; major metabolite is desmethylalfentanil (inactive).
Primarily renal (90% as hydromorphone-3-glucuronide and parent drug); <1% biliary/fecal
Primarily renal (urinary) elimination as metabolites; approximately 80% recovered in urine, 20% in feces.
~20% (primarily albumin)
Approximately 92% bound, primarily to alpha-1 acid glycoprotein and albumin.
1.2-1.7 L/kg; indicates extensive tissue distribution
0.5–1.0 L/kg; reflects moderate tissue distribution; higher Vd in neonates and elderly.
Oral: 50-60% (first-pass); IM: ~100%; Rectal: ~50-60%
Intravenous: 100%; intramuscular: approximately 90%; intrathecal: approximately 10% (due to systemic absorption following spinal administration).
e GFR 30-60 m L/min: Administer 75% of usual dose; e GFR <30 m L/min: Administer 50% of usual dose; avoid in severe impairment.
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 class A: No adjustment; Child-Pugh class B: Reduce dose by 25-50%; Child-Pugh class C: Avoid use or reduce dose by 50-75%.
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.
Children >12 years: 2-4 mg orally every 4-6 hours; 0.1-0.2 mg/kg intramuscularly/subcutaneously/intravenously every 4-6 hours (max single dose 4 mg).
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.
Initiate at 25-50% of adult dose; increase cautiously; monitor for respiratory depression, sedation, and constipation.
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.
Risk of respiratory depression, particularly in opioid-naive patients and those with respiratory compromise; risk of addiction, abuse, and misuse; risk of neonatal opioid withdrawal syndrome with prolonged use during pregnancy; risk of fatal overdose when used with benzodiazepines or CNS depressants.
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.
Respiratory depression (especially with concurrent CNS depressants); addiction potential; risk of opioid-induced hyperalgesia; severe hypotension; adrenal insufficiency; androgen deficiency; impairment of mental/physical abilities; risk of serotonin syndrome with serotonergic drugs; risk of severe hypotension in hypovolemic patients; caution in elderly, cachectic, or debilitated patients.
Respiratory depression; abuse potential; hypotension; bradycardia; muscle rigidity; serotonin syndrome with concurrent serotonergic drugs; adrenal insufficiency; risk of withdrawal with prolonged use.
Significant respiratory depression; acute or severe bronchial asthma (in unmonitored settings); known or suspected gastrointestinal obstruction (e.g., paralytic ileus); hypersensitivity to hydromorphone or any excipients; concurrent use of monoamine oxidase inhibitors (MAOIs) or within 14 days.
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 grapefruit juice as it may increase hydromorphone levels via CYP3A4 inhibition. High-fat meals may delay absorption of immediate-release formulations but do not significantly alter overall exposure. Maintain adequate fluid and fiber intake to prevent constipation.
No known interactions with food. However, grapefruit juice may increase alfentanil serum concentrations due to CYP3A4 inhibition; avoid concurrent consumption.
First trimester: Limited human data; animal studies show no consistent teratogenicity. Second and third trimesters: Chronic use may cause fetal opioid dependence and neonatal abstinence syndrome (NAS). High doses near term may cause neonatal respiratory depression.
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.
Hydromorphone is excreted into breast milk in low concentrations. M/P ratio approximately 0.8-1.0 (estimated). Relative infant dose <2% of maternal weight-adjusted dose. Monitor infant for sedation, respiratory depression, and withdrawal. Use with caution, especially in preterm or compromised infants.
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 increases clearance and volume of distribution for hydromorphone; dose may need to be increased or given more frequently, especially in the third trimester. Titrate to effect while avoiding excessive sedation. Postpartum, clearance returns to prepregnancy levels; reduce dose accordingly.
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.
Dilaudid (hydromorphone) is 5–10 times more potent than morphine. Use with caution in opioid-naive patients; start at low doses. Avoid in patients with significant respiratory depression, paralytic ileus, or acute asthma. Monitor for signs of hypotension, especially in hypovolemic patients. May cause histamine release with pruritus, but less than morphine. For breakthrough pain, immediate-release oral solution provides fastest oral onset. Not recommended for chronic pain without careful reassessment. Reversal with naloxone, but short infusion may be needed due to longer duration.
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.
Do not crush, chew, or break extended-release tablets; swallow whole.,Avoid alcohol and other CNS depressants (benzodiazepines, sedatives) as they increase risk of severe drowsiness, respiratory depression, coma, and death.,Do not drive or operate heavy machinery until you know how this medication affects you.,Store securely out of sight and reach of children; dispose of unused medication via take-back program or mixing with unpalatable substance and trashing.,Take exactly as prescribed; do not increase dose or frequency without consulting your doctor.,Common side effects include drowsiness, dizziness, constipation, nausea, and vomiting. Laxatives and hydration may help constipation.,Seek emergency help if you have trouble breathing, slow heartbeat, severe dizziness, or fainting.,Tell all healthcare providers you are taking this medication before any surgery or procedure.,Do not stop suddenly without doctor guidance to avoid withdrawal symptoms (anxiety, sweating, diarrhea, muscle aches).
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.
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 DILAUDID vs ALFENTA, answered by our medical review team.
DILAUDID is a Opioid Analgesic that works by Dilaudid (hydromorphone) is a full opioid agonist with high affinity for mu-opioid receptors, producing analgesia by mimicking endogenous endorphins and enkephalins. It also activates kappa and delta opioid receptors to a lesser extent.. 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 DILAUDID and ALFENTA depend on the specific clinical indication. These are both Opioid Analgesic agents and are not directly interchangeable by dose. A physician or clinical pharmacist should guide any therapeutic switching decisions.
The standard adult dose of DILAUDID is: Initial: 2-4 mg orally every 4-6 hours as needed; or 1-2 mg intramuscularly, subcutaneously, or intravenously every 4-6 hours as needed.. 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 DILAUDID 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. DILAUDID is classified as Category C. First trimester: Limited human data; animal studies show no consistent teratogenicity. Second and third trimesters: Chronic use may cause fetal opioid dependence and neonatal absti. 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.