Head-to-head clinical analysis & difference comparison: details on mechanism of action, dosing, half-life, interactions, and maternal-fetal safety.
FENTANYL vs ACTIQ
Clinician-reviewed, head-to-head comparison of mechanism, dosing, pharmacokinetics, and safety profiles.
Last clinically reviewed: July 2026 · OpiCalc Medical Review Team
Fentanyl is a synthetic opioid that primarily acts as a μ-opioid receptor agonist. It binds to μ-opioid receptors in the central nervous system (CNS), leading to G-protein-coupled receptor activation, inhibition of adenylate cyclase, decreased c AMP production, and modulation of ion channels (e.g., increased potassium efflux, decreased calcium influx). This results in hyperpolarization of neurons and reduced neurotransmitter release, producing analgesia, sedation, and euphoria. Fentanyl also has high lipid solubility, allowing rapid CNS penetration and a fast onset of action.
Opioid agonist; binds to mu-opioid receptors in the CNS, altering pain perception and response.
Anesthesia adjunct (induction and maintenance),Analgesia during anesthesia (e.g., for surgery, mechanical ventilation),Management of acute pain (e.g., procedural sedation),Treatment of breakthrough pain in opioid-tolerant patients (via transmucosal formulations),Patient-controlled analgesia (PCA),Epidural or intrathecal analgesia (off-label),Prehospital analgesia for trauma (off-label)
Management of breakthrough pain in cancer patients aged 16 and older who are already receiving and tolerant to opioid therapy for their underlying persistent cancer pain
25-100 mcg IV every 1-2 hours as needed; 50-100 mcg IM every 1-2 hours; transdermal patch: 12.5-100 mcg/h every 72 hours; transmucosal: 200-1600 mcg as single dose.
200 mcg transmucosally, titrated upward as needed; initial dose for opioid-tolerant patients is 200 mcg, with additional doses possible after 15 minutes if needed. Maximum 4 doses per episode. At least 4 hours between episodes.
Terminal elimination half-life is 3–12 hours (mean ~7 hours) in adults; prolonged in elderly, hepatic impairment, or with continuous infusion due to context-sensitive half-life.
Terminal half-life 0.83–2 hours (mean 1.3 h) in adults; note that context: transmucosal absorption leads to rapid onset but short duration; half-life is not correlated with clinical effect due to oral transmucosal route and rapid redistribution.
Fentanyl undergoes extensive hepatic metabolism primarily via CYP3A4 N-dealkylation to norfentanyl (inactive) and other minor metabolites. Approximately 75% of the dose is excreted as metabolites in urine (primarily norfentanyl) and about 9% in feces. Less than 7% is excreted unchanged in urine. The terminal half-life is 3–12 hours, influenced by factors such as hepatic function and age.
Primarily hepatic via CYP3A4 to inactive metabolites (norfentanyl, despropionylfentanyl, hydroxyfentanyl) and other metabolites; <7% excreted unchanged in urine.
Primarily hepatic metabolism to norfentanyl and other inactive metabolites; renal excretion of metabolites accounts for ~75% of the dose (10% unchanged), with ~9% excreted in feces.
Primarily renal as metabolites (about 75% as metabolites, <10% unchanged). Fecal excretion accounts for <9%. Biliary excretion is minor.
~80–85% bound primarily to albumin and alpha-1-acid glycoprotein.
Fentanyl is 80–85% bound to plasma proteins (primarily albumin and α1-acid glycoprotein).
Vd: 3–8 L/kg (mean ~4 L/kg), indicating extensive tissue distribution and high lipophilicity.
Approximately 4 L/kg (range 3–6 L/kg); large Vd indicates extensive tissue distribution and redistribution contributing to short duration.
Transdermal: ~92%; Transmucosal (buccal): ~50%; Oral transmucosal lozenge: ~33%; Intranasal: ~50–70%; Oral (swallowed): very low due to first-pass metabolism (~30% but variable).
Oral transmucosal: 50% (range 47–54%) relative to IV; variable and enhanced by rapid absorption through buccal mucosa.
GFR 30-50: use with caution, consider dose reduction by 25-50%; GFR <30: avoid or initiate at 50% of usual dose and titrate slowly; anuric patients: significant accumulation, consider alternative.
No specific GFR-based dose adjustment recommended; use with caution in severe renal impairment (Cr Cl < 30 m L/min) and consider dose reduction due to potential accumulation.
Child-Pugh A: no adjustment; Child-Pugh B: reduce dose by 50%; Child-Pugh C: avoid or use with extreme caution, reduce dose by 75%.
Child-Pugh Class A/B: No adjustment. Child-Pugh Class C: Reduce initial dose to 100 mcg and titrate slowly; monitor closely for prolonged effects.
IV: 1-2 mcg/kg every 2-4 hours; transdermal: not recommended in opioid-naïve children <2 years, start at 12.5 mcg/h if >50 kg; transmucosal: 5-15 mcg/kg as single dose.
Not approved for pediatric use; safety and efficacy not established in patients under 16 years.
Start at 50% of usual adult dose, titrate cautiously by 25% increments; avoid transdermal in opioid-naïve elderly; monitor for respiratory depression and cognitive impairment.
Initiate at 100 mcg transmucosally; titrate slowly due to increased sensitivity and risk of respiratory depression. Monitor for adverse effects.
WARNING: RISK OF RESPIRATORY DEPRESSION, ADDICTION, ABUSE, AND MISUSE; LIFE-THREATENING RESPIRATORY DEPRESSION; ACCIDENTAL EXPOSURE; NEONATAL OPIOID WITHDRAWAL SYNDROME; INTERACTION WITH ALCOHOL; RISKS FROM CONCOMITANT USE WITH BENZODIAZEPINES OR OTHER CNS DEPRESSANTS; and RISK OF MEDICATION ERRORS (especially with transmucosal formulations).
Risk of respiratory depression, addiction, abuse, and misuse; accidental ingestion can be fatal; concomitant use with benzodiazepines or CNS depressants may cause profound sedation, respiratory depression, coma, and death; not for use in opioid non-tolerant patients; risk of neonatal opioid withdrawal syndrome with prolonged use during pregnancy; serious, life-threatening, or fatal respiratory depression may occur even at recommended doses.
Life-threatening respiratory depression: risk dose-dependent; monitor respiratory function, especially during initiation and dose escalation.,Addiction, abuse, and misuse: can occur even at recommended doses; screen patients for risk.,Neonatal opioid withdrawal syndrome: prolonged use during pregnancy can result in withdrawal in the newborn.,Interaction with CNS depressants: concomitant use with benzodiazepines or alcohol may cause profound sedation, respiratory depression, coma, and death.,Accidental exposure: especially with transdermal patches; can be fatal.,Risks from use in patients with head injury or increased intracranial pressure: may obscure neurological signs.,Severe hypotension: in patients with compromised blood volume or concomitant use of drugs that depress blood pressure.,Bradycardia and heart block: use with caution in patients with bradyarrhythmias.,Seizures: may exacerbate seizure disorders.,Serotonin syndrome: when used with serotonergic drugs.,Adrenal insufficiency: with prolonged use.,Severe injection site reactions: with injectable formulations.,Risk of medication errors: especially with different formulations (e.g., transdermal vs. transmucosal).
Risk of respiratory depression; addiction, abuse, and misuse; interactions with CNS depressants; serotonin syndrome; adrenal insufficiency; severe hypotension; seizures; withdrawal; use in patients with head injuries, increased intracranial pressure, biliary tract disease, pancreatitis; risk of choking with lozenge; oral mucosal irritation; dental caries; hypokalemia; hyponatremia; use in elderly, cachectic, or debilitated patients.
Hypersensitivity to fentanyl or any component of the formulation,Significant respiratory depression (in unmonitored settings or without resuscitative equipment),Acute or severe bronchial asthma,Paralytic ileus (known or suspected),Concurrent use of monoamine oxidase inhibitors (MAOIs) or within 14 days of such therapy,Use in opioid-naive patients for transmucosal immediate-release fentanyl (due to risk of fatal respiratory depression),Acute abdomen (relative contraindication; may obscure diagnosis)
Significant respiratory depression; acute or severe bronchial asthma in an unmonitored setting or without resuscitative equipment; known or suspected paralytic ileus; hypersensitivity to fentanyl or any component; opioid non-tolerant patients; management of acute or postoperative pain including headache/migraine, dental pain, or emergency department use.
Avoid grapefruit and grapefruit juice as they can increase fentanyl levels via CYP3A4 inhibition. No other significant food interactions. Maintain adequate hydration to prevent constipation.
No significant food interactions. Grapefruit juice may increase fentanyl levels, but specific studies with ACTIQ are lacking. Avoid alcohol, as it may increase sedation and respiratory depression risk.
First trimester: Limited data; no major malformations reported. Second and third trimesters: Chronic maternal use may lead to neonatal opioid withdrawal syndrome. High doses near term may cause respiratory depression and neonatal abstinence syndrome.
FDA Pregnancy Category C. First trimester: limited human data; animal studies show increased resorptions and fetal growth restriction. Second/third trimester: chronic use may cause neonatal opioid withdrawal syndrome; avoid use during labor due to risk of neonatal respiratory depression.
Fentanyl is excreted into breast milk. Milk-to-plasma ratio is approximately 0.4. Avoid use in lactating women who are poor metabolizers or receive high doses due to risk of infant sedation and respiratory depression.
Excreted in breast milk; M/P ratio not established. Limited data suggest low levels, but risk of infant sedation and respiratory depression. Avoid use while breastfeeding unless potential benefit outweighs risk.
Clearance of fentanyl is increased during pregnancy, particularly in the third trimester. Dose adjustments may be required; consider increasing dose or frequency. Monitor for efficacy and adjust as needed.
Due to increased plasma volume and hepatic metabolism in pregnancy, dose requirements may increase; adjust based on clinical response and tolerance. Avoid use during labor and delivery due to risk of neonatal respiratory depression; short-term use preferred.
Fentanyl is 50-100 times more potent than morphine. Due to high lipophilicity, onset of analgesia is rapid (within 30 seconds IV) but duration is short. Avoid bolus dosing in opioid-naive patients due to risk of chest wall rigidity. Transdermal patches are not indicated for acute pain due to slow onset and prolonged effect. Monitor for respiratory depression, especially in elderly and those with sleep apnea. Tolerance and physical dependence develop with chronic use. Naloxone is the reversal agent.
ACTIQ is a transmucosal immediate-release fentanyl formulation indicated for breakthrough cancer pain in opioid-tolerant patients. Initiate with the lowest strength (200 mcg) and titrate upward. Avoid use in opioid-naive patients due to risk of fatal respiratory depression. Place the unit between cheek and lower gum, not sublingually. Instruct patient not to bite or suck the unit. Monitor for sedation and respiratory depression. Multiple units may be used per episode if needed, but wait at least 4 hours before next episode. Dispose of partially used units by flushing down toilet.
Do not drive or operate heavy machinery until you know how fentanyl affects you.,Take exactly as prescribed; do not increase dose or frequency without doctor approval.,Avoid alcohol and other CNS depressants as they increase risk of severe drowsiness and respiratory depression.,Store fentanyl patches and other formulations safely out of reach of children and pets; used patches should be folded and flushed down toilet.,Do not share this medication with others; it can cause fatal overdose.,Seek emergency medical help if you experience slow/shallow breathing, extreme drowsiness, or difficulty waking up.,Do not stop abruptly; withdrawal symptoms may occur. Taper under medical supervision.
Only use ACTIQ if you are already taking regular around-the-clock opioid pain medicine and are tolerant to opioids.,Do not use ACTIQ for short-term pain like after surgery, headache, or dental pain.,Place the unit in your cheek pouch, not under your tongue. Do not chew or suck it.,If you need more than 4 units per day, contact your doctor as your dose may need adjustment.,Store ACTIQ in a safe place away from children, as accidental ingestion can be fatal.,Dispose of unused or partially used units by flushing them down the toilet.
"Metaraminol, a direct-acting alpha-adrenergic agonist, can reduce the serum concentration of fentanyl, a potent opioid analgesic, likely through enhanced hepatic metabolism or altered renal clearance. This interaction may lead to diminished analgesic efficacy of fentanyl, requiring higher doses to achieve pain control and potentially increasing the risk of opioid withdrawal symptoms. Clinically, patients receiving both drugs may exhibit inadequate pain relief or unexpected opioid tolerance."
"The concomitant use of pergolide, a dopamine receptor agonist, and fentanyl, a μ-opioid receptor agonist, may result in additive central nervous system depression, leading to increased sedation, respiratory depression, and potential for coma or death. Pergolide can also potentiate the hypotensive effects of opioids, resulting in orthostatic hypotension and syncope. Additionally, both drugs can prolong the QTc interval, increasing the risk of torsades de pointes and sudden cardiac death."
"The combination of glycopyrronium, an anticholinergic agent, and fentanyl, a potent mu-opioid receptor agonist, can result in additive anticholinergic effects, specifically severe constipation, urinary retention, and central nervous system depression, leading to delirium or cognitive impairment in susceptible patients. Additionally, fentanyl-induced gastrointestinal hypomotility is exacerbated by glycopyrronium, increasing the risk of paralytic ileus. Clinically, patients may present with prolonged QTc interval, decreased gastrointestinal motility, and exacerbated sedation, particularly in elderly or renally impaired individuals."
No interactions on record
Explore head-to-head clinical comparisons of other medications in the same therapeutic classes.
Common clinical questions about FENTANYL vs ACTIQ, answered by our medical review team.
FENTANYL is a Opioid Agonist that works by Fentanyl is a synthetic opioid that primarily acts as a μ-opioid receptor agonist. It binds to μ-opioid receptors in the central nervous system (CNS), leading to G-protein-coupled receptor activation, inhibition of adenylate cyclase, decreased c AMP production, and modulation of ion channels (e.g., increased potassium efflux, decreased calcium influx). This results in hyperpolarization of neurons and reduced neurotransmitter release, producing analgesia, sedation, and euphoria. Fentanyl also has high lipid solubility, allowing rapid CNS penetration and a fast onset of action.. ACTIQ is a Opioid Analgesic that works by Opioid agonist; binds to mu-opioid receptors in the CNS, altering pain perception and response.. They differ in pharmacokinetic profiles, FDA-approved indications, and side effect profiles.
Potency comparisons between FENTANYL and ACTIQ 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 FENTANYL is: 25-100 mcg IV every 1-2 hours as needed; 50-100 mcg IM every 1-2 hours; transdermal patch: 12.5-100 mcg/h every 72 hours; transmucosal: 200-1600 mcg as single dose.. The standard adult dose of ACTIQ is: 200 mcg transmucosally, titrated upward as needed; initial dose for opioid-tolerant patients is 200 mcg, with additional doses possible after 15 minutes if needed. Maximum 4 doses per episode. At least 4 hours between episodes.. 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 FENTANYL and ACTIQ 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. FENTANYL is classified as Category D/X. First trimester: Limited data; no major malformations reported. Second and third trimesters: Chronic maternal use may lead to neonatal opioid withdrawal syndrome. High doses near t. ACTIQ is classified as Category C. FDA Pregnancy Category C. First trimester: limited human data; animal studies show increased resorptions and fetal growth restriction. Second/third trimester: chronic use may cause. Always consult a maternal-fetal medicine specialist before taking either drug during pregnancy or lactation.