Head-to-head clinical analysis & difference comparison: details on mechanism of action, dosing, half-life, interactions, and maternal-fetal safety.
ACTIQ vs CHEMET
Clinician-reviewed, head-to-head comparison of mechanism, dosing, pharmacokinetics, and safety profiles.
Last clinically reviewed: July 2026 · OpiCalc Medical Review Team
Opioid agonist; binds to mu-opioid receptors in the CNS, altering pain perception and response.
Chelates heavy metals, particularly lead, mercury, and arsenic, by forming soluble complexes that are excreted renally. Acts as an antidote by binding to toxic metals and reducing their tissue concentrations.
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
Treatment of acute and chronic lead poisoning,Treatment of mercury poisoning,Treatment of arsenic poisoning,Diagnostic chelation challenge test
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.
10-20 mg/kg orally every 8 hours for 5 days; maximum single dose 1250 mg.
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.
Terminal elimination half-life: 1.6–3.5 hours (mean 2.1 h) in adults with normal renal function; prolonged in renal impairment (up to 20 h).
Primarily hepatic via CYP3A4 to inactive metabolites (norfentanyl, despropionylfentanyl, hydroxyfentanyl) and other metabolites; <7% excreted unchanged in urine.
Metabolized in liver to disulfide dimers; undergoes enterohepatic circulation; primarily excreted renally as metabolites and unchanged drug.
Primarily renal as metabolites (about 75% as metabolites, <10% unchanged). Fecal excretion accounts for <9%. Biliary excretion is minor.
Renal: 80–90% as unchanged drug and metabolites (primarily as chelated complexes); biliary/fecal: <10%.
Fentanyl is 80–85% bound to plasma proteins (primarily albumin and α1-acid glycoprotein).
Approximately 80% bound to plasma proteins, primarily albumin.
Approximately 4 L/kg (range 3–6 L/kg); large Vd indicates extensive tissue distribution and redistribution contributing to short duration.
0.5–0.8 L/kg, indicating distribution mainly in extracellular fluid; limited intracellular penetration.
Oral transmucosal: 50% (range 47–54%) relative to IV; variable and enhanced by rapid absorption through buccal mucosa.
20–40% after oral administration due to first-pass metabolism and limited absorption.
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.
GFR 50-80 m L/min: same dose every 12 hours. GFR 10-49 m L/min: same dose every 24 hours. GFR <10 m L/min: same dose every 48 hours.
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.
No specific recommendations; caution in severe hepatic impairment (Child-Pugh C) due to potential toxicity.
Not approved for pediatric use; safety and efficacy not established in patients under 16 years.
Children >1 year: 10-20 mg/kg/dose orally every 8 hours for 5 days; maximum 1250 mg/dose.
Initiate at 100 mcg transmucosally; titrate slowly due to increased sensitivity and risk of respiratory depression. Monitor for adverse effects.
Consider starting at lower end of dosing range (10 mg/kg) due to potential renal impairment; adjust per renal function.
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.
None
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.
May cause nephrotoxicity; monitor renal function,May cause hypersensitivity reactions, including fever, rash, and anaphylaxis,Monitor for neutropenia; obtain CBC before and during therapy,Use caution in patients with hepatic impairment or glucose-6-phosphate dehydrogenase (G6PD) deficiency,May chelate essential minerals (e.g., zinc, copper); monitor levels with prolonged use,Not recommended for routine use in asymptomatic lead poisoning with low blood lead levels
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.
Hypersensitivity to dimercaprol or any component of the formulation,Hepatic failure (except severe heavy metal poisoning),Concurrent use with iron (increases nephrotoxicity); avoid iron therapy within 24 hours,Pregnancy (if not life-saving indication due to risk of teratogenicity),Peanut allergy (formulation contains peanut oil)
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.
No specific food interactions reported. However, due to gastrointestinal side effects (nausea, vomiting), it is advisable to maintain small, frequent meals. Avoid alcohol.
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.
FDA Pregnancy Category C. First trimester: No adequate studies, but animal studies show fetal resorption at maternally toxic doses, risk cannot be excluded. Second and third trimesters: No specific teratogenicity, but may cause anemia in fetus due to maternal chelation of essential metals. Avoid use unless clearly needed.
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 human data on excretion in breast milk. M/P ratio unknown. Caution due to potential for infant exposure and chelation of trace elements; consider benefit-risk. Avoid breastfeeding during therapy and for 2 weeks after last dose.
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.
No specific dose adjustments recommended for pregnancy. Increased plasma volume in pregnancy may alter pharmacokinetics, but studies not performed. Use lowest effective dose; monitor therapeutic response and toxicity closely.
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.
Chelation therapy with dimercaprol (CHEMET) should be initiated within 4 hours of arsenic or mercury exposure for maximal efficacy. Administer only via deep intramuscular injection, never intravenously. Monitor renal function and urine output closely, as dimercaprol can cause nephrotoxicity. Alkalinize urine to p H 7.5-8.5 to decrease renal precipitation of metal-drug complexes. Use with caution in patients with glucose-6-phosphate dehydrogenase deficiency due to risk of hemolysis. Contraindicated in patients with peanut allergy (vehicle is peanut oil).
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.
This medication is given as a shot into a muscle, usually in the buttock. It may cause pain at the injection site.,You may experience a metallic taste, nausea, vomiting, headache, or burning sensation in the mouth or throat.,Drink plenty of fluids unless otherwise instructed to help flush metals from your body.,Avoid alcohol during treatment and for at least 48 hours after the last dose.,Report any signs of allergic reaction (rash, itching, difficulty breathing) or dark urine immediately.
No interactions on record
No interactions on record
Explore head-to-head clinical comparisons of other medications in the same therapeutic classes.
Common clinical questions about ACTIQ vs CHEMET, answered by our medical review team.
ACTIQ is a Opioid Analgesic that works by Opioid agonist; binds to mu-opioid receptors in the CNS, altering pain perception and response.. CHEMET is a Chelating agent that works by Chelates heavy metals, particularly lead, mercury, and arsenic, by forming soluble complexes that are excreted renally. Acts as an antidote by binding to toxic metals and reducing their tissue concentrations.. They differ in pharmacokinetic profiles, FDA-approved indications, and side effect profiles.
Potency comparisons between ACTIQ and CHEMET 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 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.. The standard adult dose of CHEMET is: 10-20 mg/kg orally every 8 hours for 5 days; maximum single dose 1250 mg.. 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 ACTIQ and CHEMET 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. 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. CHEMET is classified as Category C. FDA Pregnancy Category C. First trimester: No adequate studies, but animal studies show fetal resorption at maternally toxic doses, risk cannot be excluded. Second and third trimes. Always consult a maternal-fetal medicine specialist before taking either drug during pregnancy or lactation.