Head-to-head clinical analysis & difference comparison: details on mechanism of action, dosing, half-life, interactions, and maternal-fetal safety.
ACTIQ vs AMOXICILLIN
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.
Amoxicillin is a beta-lactam antibiotic that inhibits bacterial cell wall synthesis by binding to penicillin-binding proteins (PBPs), inhibiting transpeptidase activity, and activating autolytic enzymes.
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
Upper respiratory tract infections (e.g., otitis media, sinusitis, pharyngitis/tonsillitis),Lower respiratory tract infections (e.g., community-acquired pneumonia, acute exacerbation of chronic bronchitis),Genitourinary tract infections (e.g., cystitis, urethritis),Skin and skin structure infections,Helicobacter pylori eradication (in combination with clarithromycin and a proton pump inhibitor),Lyme disease (early localized),Prophylaxis of infective endocarditis (for dental procedures in high-risk patients),Off-label: Anthrax (post-exposure prophylaxis), uncomplicated gonorrhea
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.
250-500 mg orally every 8 hours or 500-875 mg orally every 12 hours; for severe infections, up to 1 g orally every 8 hours.
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: 1-1.5 hours in normal renal function. Prolonged to 7-20 hours in end-stage renal disease.
Primarily hepatic via CYP3A4 to inactive metabolites (norfentanyl, despropionylfentanyl, hydroxyfentanyl) and other metabolites; <7% excreted unchanged in urine.
Amoxicillin is primarily metabolized by hydrolysis to penicilloic acid (inactive). It is not extensively metabolized by the liver; about 60% of an oral dose is excreted unchanged in urine.
Primarily renal as metabolites (about 75% as metabolites, <10% unchanged). Fecal excretion accounts for <9%. Biliary excretion is minor.
Renal: 60-80% unchanged via glomerular filtration and tubular secretion. Biliary: up to 20% excreted in bile. Fecal: minimal.
Fentanyl is 80–85% bound to plasma proteins (primarily albumin and α1-acid glycoprotein).
17-20% bound to serum albumin.
Approximately 4 L/kg (range 3–6 L/kg); large Vd indicates extensive tissue distribution and redistribution contributing to short duration.
0.3-0.4 L/kg. Distributes well into most body fluids and tissues, including pleural, peritoneal, and synovial fluids; limited CNS penetration unless meninges inflamed.
Oral transmucosal: 50% (range 47–54%) relative to IV; variable and enhanced by rapid absorption through buccal mucosa.
Oral: 74-92% (absorption is not food-dependent). IM: approximately 100%.
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.
Cr Cl 30-50 m L/min: 250-500 mg every 8-12 hours. Cr Cl 10-29 m L/min: 250-500 mg every 12 hours. Cr Cl <10 m L/min: 250-500 mg every 24 hours. Hemodialysis: 250-500 mg every 24 hours, supplemented during and after dialysis.
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 dose adjustment required for mild to moderate hepatic impairment. Severe hepatic impairment (Child-Pugh class C): use with caution; specific dosing guidelines not established.
Not approved for pediatric use; safety and efficacy not established in patients under 16 years.
Children >3 months: 20-40 mg/kg/day divided every 8 hours for mild to moderate infections; 40-90 mg/kg/day divided every 8-12 hours for severe infections. Maximum 3 g/day.
Initiate at 100 mcg transmucosally; titrate slowly due to increased sensitivity and risk of respiratory depression. Monitor for adverse effects.
No specific dose adjustment; monitor renal function and adjust based on Cr Cl. Caution with concurrent nephrotoxic agents.
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.
No FDA black box warning.
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 reactions including anaphylaxis have been reported; contraindicated in patients with known penicillin allergy.,Clostridium difficile-associated diarrhea (CDAD) may occur and must be considered in patients presenting with diarrhea after antibiotic use.,Serious skin reactions (e.g., Stevens-Johnson syndrome, toxic epidermal necrolysis) can occur; discontinue if rash or other allergic signs appear.,Use caution in patients with renal impairment; dosage adjustment may be necessary.,Prolonged use may result in superinfection with non-susceptible organisms.
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.
History of hypersensitivity reaction to any penicillin or beta-lactam antibiotic.,Infectious mononucleosis (increases risk of maculopapular rash).,Phenylketonuria (some formulations contain aspartame).
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 significant food interactions. Absorption is not affected by food; may be taken with meals to reduce gastrointestinal upset. Avoid concurrent alcohol consumption as it may increase risk of side effects like nausea and vomiting.
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 B. No evidence of teratogenicity in animal studies. First trimester: no increased risk of major malformations observed in large cohort studies. Second and third trimesters: use only if clearly needed; no known fetal harm, but caution due to maternal physiological changes.
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.
Amoxicillin is excreted into breast milk in small amounts (M/P ratio approximately 0.014-0.015). Considered compatible with breastfeeding; potential for diarrhea or allergic sensitization in infant, but generally safe.
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 dose adjustment required for amoxicillin in pregnancy; however, increased renal clearance and expanded plasma volume may lower serum concentrations. For severe infections, consider standard dosing with monitoring of clinical response.
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.
For streptococcal pharyngitis, amoxicillin 50 mg/kg once daily (max 1 g) is as effective as multiple daily doses and improves adherence. In penicillin-allergic patients, the cross-reactivity risk with cephalosporins is low; a cephalosporin can be used if no history of immediate-type hypersensitivity. Amoxicillin is not effective against penicillinase-producing staphylococci or most Gram-negative organisms due to beta-lactamase production. Monitor for rash in patients with infectious mononucleosis (ampicillin rash occurs more frequently, but amoxicillin also has increased risk). Dose adjustment needed for creatinine clearance <30 m L/min.
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.
Take exactly as prescribed; complete the full course even if you feel better.,Can be taken with or without food; if stomach upset occurs, take with a meal.,Swallow capsules whole; do not crush or chew; oral suspension shake well before each dose.,Skip missed dose if almost time for next; do not double dose.,Seek immediate medical help for signs of allergic reaction: hives, difficulty breathing, swelling of face/lips/tongue.,May cause diarrhea; contact doctor if watery or bloody stools.,Inform doctor if you are pregnant, planning to become pregnant, or breastfeeding.,Avoid large amounts of grapefruit juice as it may affect absorption (limited clinical significance).
No interactions on record
"Amoxicillin may reduce the metabolism of Indinavir via inhibition of CYP3A4, leading to increased plasma concentrations of Indinavir. This can elevate the risk of Indinavir-related toxicities such as nephrolithiasis, hepatotoxicity, and gastrointestinal intolerance. Patients may experience exacerbated adverse effects without a corresponding increase in antiviral efficacy."
"Amoxicillin may inhibit the CYP3A4-mediated metabolism of nicardipine, a calcium channel blocker, leading to increased plasma concentrations of nicardipine. This can potentiate vasodilation and negative chronotropic effects, resulting in an increased risk of hypotension, bradycardia, and peripheral edema. Patients, especially those with pre-existing cardiovascular conditions, should be monitored for enhanced antihypertensive effects and adverse reactions when these drugs are coadministered."
"Amoxicillin may inhibit the metabolism of bortezomib through competitive inhibition of cytochrome P450 enzymes, particularly CYP3A4 and CYP2C19, potentially leading to increased bortezomib exposure. This interaction could result in enhanced toxicity of bortezomib, including peripheral neuropathy, myelosuppression, and gastrointestinal adverse effects. Clinicians should monitor for signs of bortezomib toxicity when amoxicillin is coadministered, especially in patients with pre-existing hepatic impairment or other risk factors."
Explore head-to-head clinical comparisons of other medications in the same therapeutic classes.
Common clinical questions about ACTIQ vs AMOXICILLIN, 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.. AMOXICILLIN is a Penicillin Antibiotic that works by Amoxicillin is a beta-lactam antibiotic that inhibits bacterial cell wall synthesis by binding to penicillin-binding proteins (PBPs), inhibiting transpeptidase activity, and activating autolytic enzymes.. They differ in pharmacokinetic profiles, FDA-approved indications, and side effect profiles.
Potency comparisons between ACTIQ and AMOXICILLIN 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 AMOXICILLIN is: 250-500 mg orally every 8 hours or 500-875 mg orally every 12 hours; for severe infections, up to 1 g orally every 8 hours.. 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 AMOXICILLIN 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. AMOXICILLIN is classified as Category A/B. FDA Pregnancy Category B. No evidence of teratogenicity in animal studies. First trimester: no increased risk of major malformations observed in large cohort studies. Second and th. Always consult a maternal-fetal medicine specialist before taking either drug during pregnancy or lactation.