Head-to-head clinical analysis & difference comparison: details on mechanism of action, dosing, half-life, interactions, and maternal-fetal safety.
DICLOFENAC vs ACTIQ
Clinician-reviewed, head-to-head comparison of mechanism, dosing, pharmacokinetics, and safety profiles.
Last clinically reviewed: July 2026 · OpiCalc Medical Review Team
Diclofenac inhibits cyclooxygenase (COX) enzymes, primarily COX-2, reducing prostaglandin synthesis, thereby exerting analgesic, anti-inflammatory, and antipyretic effects.
Opioid agonist; binds to mu-opioid receptors in the CNS, altering pain perception and response.
Ankylosing spondylitis,Osteoarthritis,Rheumatoid arthritis,Acute migraine (oral formulation),Mild to moderate acute pain (off-label),Dysmenorrhea (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
Oral: 50 mg twice daily or 75 mg twice daily; maximum 150 mg/day. Topical: apply 4 times daily. IM: 75 mg once daily.
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 ~2 h (diclofenac immediate-release); enterohepatic recirculation may produce secondary peaks. Clinical context: Short half-life requires multiple daily dosing for sustained effect.
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.
Primarily hepatic via CYP2C9 (major) and CYP3A4 (minor); undergoes glucuronidation. Metabolites include 4'-hydroxydiclofenac, 5-hydroxydiclofenac, and 3'-hydroxydiclofenac.
Primarily hepatic via CYP3A4 to inactive metabolites (norfentanyl, despropionylfentanyl, hydroxyfentanyl) and other metabolites; <7% excreted unchanged in urine.
Renal (65% as metabolites, <1% unchanged); biliary/fecal (35% as metabolites).
Primarily renal as metabolites (about 75% as metabolites, <10% unchanged). Fecal excretion accounts for <9%. Biliary excretion is minor.
>99% bound primarily to serum albumin.
Fentanyl is 80–85% bound to plasma proteins (primarily albumin and α1-acid glycoprotein).
0.1-0.2 L/kg (low distribution, reflects high protein binding). Clinical meaning: Limited extravascular distribution; primarily remains in vascular space.
Approximately 4 L/kg (range 3–6 L/kg); large Vd indicates extensive tissue distribution and redistribution contributing to short duration.
Oral immediate-release: ~50% due to extensive first-pass metabolism; Topical: <10% systemic; Ophthalmic: minimal; IV: 100%.
Oral transmucosal: 50% (range 47–54%) relative to IV; variable and enhanced by rapid absorption through buccal mucosa.
GFR >30 m L/min: no adjustment. GFR 15-30 m L/min: use with caution, reduce dose, avoid if possible. GFR <15 m L/min: contraindicated.
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: contraindicated.
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.
Children ≥1 year: oral 0.5-1 mg/kg/dose twice daily; maximum 3 mg/kg/day or 150 mg/day. Children ≥14 years: same as adult.
Not approved for pediatric use; safety and efficacy not established in patients under 16 years.
Start at lowest effective dose, e.g., 25-50 mg/day oral; increase cautiously. Avoid NSAIDs in advanced age due to GI and renal risks.
Initiate at 100 mcg transmucosally; titrate slowly due to increased sensitivity and risk of respiratory depression. Monitor for adverse effects.
Nonsteroidal anti-inflammatory drugs (NSAIDs) cause an increased risk of serious cardiovascular thrombotic events, including myocardial infarction and stroke, which can be fatal. This risk may increase with duration of use. Patients with cardiovascular disease or risk factors for cardiovascular disease may be at greater risk. Diclofenac is contraindicated for the treatment of perioperative pain in the setting of coronary artery bypass graft (CABG) surgery.
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.
Cardiovascular risk: increased risk of thrombotic events, hypertension, and heart failure.,Gastrointestinal risk: increased risk of serious GI adverse events including bleeding, ulceration, and perforation.,Renal toxicity: monitor renal function in patients with preexisting renal disease, dehydration, or concomitant nephrotoxic agents.,Hepatic toxicity: elevated liver enzymes; rare cases of severe hepatic reactions.,Anaphylactoid reactions: can occur in patients with or without known NSAID hypersensitivity.,Fluid retention and edema: use with caution in patients with hypertension or heart failure.,Skin reactions: serious cutaneous adverse reactions such as Stevens-Johnson syndrome and DRESS.,Hematologic: prolonged bleeding time; use with caution in patients with coagulation disorders.
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.
Known hypersensitivity to diclofenac or any component of the formulation,History of asthma, urticaria, or other allergic-type reactions after taking aspirin or other NSAIDs,Perioperative pain in the setting of CABG surgery,Active GI bleeding,Severe uncontrolled heart failure,Advanced renal disease (unless dialysis is ongoing),Third trimester of pregnancy
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 alcohol as it increases risk of GI bleeding. Take with food or milk to minimize GI irritation. No specific food restrictions, but high-fat meals may delay absorption.
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: Increased risk of spontaneous abortion and congenital malformations (cardiac defects, gastroschisis) due to prostaglandin synthesis inhibition. Second trimester: Risk of oligohydramnios and fetal renal impairment with prolonged use. Third trimester: Avoid after 30 weeks gestation; risk of premature closure of ductus arteriosus, persistent pulmonary hypertension of the newborn, and oligohydramnios.
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.
Excreted in breast milk in low amounts; M/P ratio not reported. Use with caution; avoid in breastfeeding mothers with infants with thrombocytopenia or platelet dysfunction. Consider risk of infant renal impairment.
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.
No dose adjustment recommended for pharmacokinetic changes; however, use at lowest effective dose for shortest duration. Avoid in third trimester due to fetal risks. Consider alternative analgesics in all trimesters.
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.
Diclofenac is a potent NSAID with a short half-life, making it suitable for acute pain but requiring frequent dosing. It carries a higher risk of cardiovascular events compared to other NSAIDs; caution in patients with hypertension or heart disease. Enteric-coated formulations may delay onset but reduce GI irritation. Intravenous formulation allows for rapid analgesia but requires monitoring for hypertension and fluid retention. Diclofenac can cause elevation of liver enzymes; monitor LFTs with long-term use. It is available in combination with misoprostol to reduce GI ulcer risk.
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.
Take with food or milk to reduce stomach upset.,Avoid alcohol while taking this medication to lower risk of stomach bleeding.,Do not take with other NSAIDs (e.g., ibuprofen, naproxen) or aspirin without consulting doctor.,Report signs of stomach bleeding (black/tarry stools, vomit that looks like coffee grounds) or chest pain immediately.,May cause dizziness or drowsiness; avoid driving until you know how this drug affects you.,Limit sun exposure and use sunscreen as this drug may increase sun sensitivity.,Do not use in third trimester of pregnancy as it may harm the unborn baby.,Store at room temperature away from moisture and heat.
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.
"Ximelagatran, an oral direct thrombin inhibitor, increases the risk of bleeding when coadministered with diclofenac, a nonsteroidal anti-inflammatory drug (NSAID). The combination potentiates anticoagulant activity through additive inhibition of platelet aggregation and thrombin-mediated coagulation, elevating the risk of gastrointestinal hemorrhage and other serious bleeding events. Patients, particularly those with renal impairment or advanced age, require close monitoring for signs of bleeding."
"Acebutolol, a cardioselective beta-blocker, may attenuate the antihypertensive effect of diclofenac, a nonsteroidal anti-inflammatory drug (NSAID). Diclofenac inhibits cyclooxygenase, reducing prostaglandin synthesis, which can lead to sodium retention and increased vascular resistance, thereby counteracting the blood pressure-lowering effects of acebutolol. This interaction may result in diminished blood pressure control, potentially requiring dose adjustments of antihypertensive therapy."
"Enzalutamide, a potent CYP3A4 inducer, significantly reduces the exposure of diclofenac, a CYP2C9 substrate, by increasing its hepatic metabolism. This interaction can lead to subtherapeutic diclofenac concentrations, thereby diminishing its analgesic and anti-inflammatory efficacy. Clinically, patients may experience inadequate pain control or exacerbation of inflammatory conditions, such as arthritis, when these agents are coadministered."
No interactions on record
Explore head-to-head clinical comparisons of other medications in the same therapeutic classes.
Common clinical questions about DICLOFENAC vs ACTIQ, answered by our medical review team.
DICLOFENAC is a NSAID that works by Diclofenac inhibits cyclooxygenase (COX) enzymes, primarily COX-2, reducing prostaglandin synthesis, thereby exerting analgesic, anti-inflammatory, and antipyretic effects.. 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 DICLOFENAC 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 DICLOFENAC is: Oral: 50 mg twice daily or 75 mg twice daily; maximum 150 mg/day. Topical: apply 4 times daily. IM: 75 mg once daily.. 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 DICLOFENAC 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. DICLOFENAC is classified as Category D/X. First trimester: Increased risk of spontaneous abortion and congenital malformations (cardiac defects, gastroschisis) due to prostaglandin synthesis inhibition. Second trimester: R. 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.