Head-to-head clinical analysis & difference comparison: details on mechanism of action, dosing, half-life, interactions, and maternal-fetal safety.
ACEPHEN vs BAL
Clinician-reviewed, head-to-head comparison of mechanism, dosing, pharmacokinetics, and safety profiles.
Last clinically reviewed: July 2026 · OpiCalc Medical Review Team
ACEPHEN (acetaminophen) is a para-aminophenol derivative with analgesic and antipyretic activity. Its mechanism involves inhibition of cyclooxygenase (COX) enzymes in the central nervous system, particularly COX-2, reducing prostaglandin synthesis. It has weak peripheral COX inhibition and minimal anti-inflammatory effect.
Chelating agent that forms stable complexes with heavy metals (e.g., arsenic, mercury, lead) by binding to their sulfhydryl groups, facilitating renal excretion.
Mild to moderate pain,Fever
Arsenic poisoning,Mercury poisoning,Lead poisoning (adjunct to edetate calcium disodium),Acute gold poisoning,Wilson's disease (investigational)
325-650 mg orally every 4-6 hours as needed; maximum 4 g/day.
3-5 mg/kg IM every 4 hours for 2 days, then every 6 hours for 1 day, then every 12 hours for 10 days.
Terminal elimination half-life: 1.0-1.5 hours in adults with normal renal function. Prolonged to 2-5 hours in hepatic impairment or elderly; requires dose adjustment in severe hepatic disease.
Terminal elimination half-life is approximately 6.8 hours (range 4–13 hours). In patients with impaired renal function, half-life may be prolonged.
Acetaminophen is primarily metabolized in the liver via glucuronidation (UGT1A1, UGT1A6, UGT1A9) and sulfation (SULT1A1, SULT1A3). A minor fraction is oxidized by cytochrome P450 enzymes (CYP2E1, CYP1A2, CYP3A4) to a reactive toxic metabolite (NAPQI), which is normally detoxified by conjugation with glutathione.
Primarily hepatic; undergoes oxidation and conjugation; metabolites excreted renally.
Renal: 90-95% as unchanged drug; tubular secretion and glomerular filtration. Biliary/fecal: <5%.
Primarily renal; approximately 80% of a dose is excreted in urine as unchanged drug and metabolites within 24 hours. Biliary/fecal elimination accounts for less than 5%.
Approximately 10-20% bound to serum albumin; extensive tissue binding.
BAL is extensively bound to plasma proteins, primarily albumin, with protein binding >90%.
Apparent Vd: 0.5-0.7 L/kg (30-40 L in a 70 kg adult). Distributions into CSF and breast milk.
Volume of distribution is approximately 3.5 L/kg, indicating extensive distribution into tissues, including brain and intracellular spaces.
Oral: 85-90% (first-pass metabolism minimal). Rectal: approximately 70-80% of oral bioavailability.
BAL is not administered orally due to poor absorption and gastrointestinal irritation. Given intravenously, bioavailability is 100%. Intramuscular bioavailability is similar but with slower absorption.
GFR 10-50 m L/min: 650 mg every 6 hours; GFR <10 m L/min: 650 mg every 8 hours.
GFR 10-50 m L/min: reduce frequency to every 6-8 hours; GFR <10 m L/min: reduce frequency to every 8-12 hours.
Child-Pugh Class A: no adjustment; Child-Pugh Class B: maximum 2 g/day; Child-Pugh Class C: maximum 1 g/day.
Child-Pugh A: no adjustment; Child-Pugh B: reduce dose by 25%; Child-Pugh C: reduce dose by 50% and monitor for hepatotoxicity.
10-15 mg/kg/dose orally every 4-6 hours; maximum 75 mg/kg/day or 4 g/day, whichever is less.
3-5 mg/kg IM every 4 hours for 2 days, then every 6 hours for 1 day, then every 12 hours for 10 days; maximum 100 mg per dose.
Start at lowest effective dose (325 mg every 6 hours); avoid exceeding 3 g/day unless closely monitored.
Start at 3 mg/kg IM every 6 hours; adjust based on renal function, monitor for hypotension and pain at injection site.
Acetaminophen has been associated with cases of acute liver failure, at times resulting in liver transplant and death. Most of the cases of liver injury are associated with the use of acetaminophen at doses that exceed 4,000 milligrams per day, and often involve more than one acetaminophen-containing product.
None.
Risk of severe liver injury with doses >4000 mg/day; use caution with hepatic impairment, chronic alcoholism, malnutrition, or concomitant hepatotoxic drugs; avoid exceeding recommended dose; limit use to 10 days for pain or 3 days for fever unless directed by physician; serious skin reactions (Stevens-Johnson syndrome, toxic epidermal necrolysis) have occurred.
Monitor renal function and serum electrolytes during therapy.,Can cause hypertension, tachycardia, and myocardial ischemia; use cautiously in cardiovascular disease.,May induce hemolytic anemia in patients with G6PD deficiency.,Injection site reactions and sterile abscesses may occur.,Iron deficiency is a known adverse effect due to iron chelation.
Hypersensitivity to acetaminophen or any component of the formulation; severe hepatic impairment or active liver disease.
Hypersensitivity to BAL or any component.,Hepatic insufficiency (unless benefit outweighs risk).,Iron poisoning (forms toxic complex).,Concurrent use with cadmium or selenium (increased toxicity).
Alcohol: increased risk of hepatotoxicity. Avoid concurrent use. Food: no significant interaction, but taking with food may reduce minor gastrointestinal irritation.
Avoid alcohol and caffeine. Maintain adequate hydration. No specific food restrictions, but ensure iron-rich foods are avoided if concurrent iron poisoning suspected (though BAL not indicated for iron).
Pregnancy Category C. First trimester: potential risk of neural tube defects and orofacial clefts (limited human data, animal studies show embryotoxicity). Second and third trimesters: NSAID exposure associated with oligohydramnios, premature ductus arteriosus constriction, and fetal renal impairment. Avoid in third trimester.
Insufficient human data; animal studies suggest potential teratogenicity at high doses. Avoid in first trimester unless benefit outweighs risk.
Excreted into breast milk in low concentrations (M/P ratio approximately 0.10). Considered compatible with breastfeeding; however, use lowest effective dose for shortest duration given potential for neonatal adverse effects (e.g., thrombocytopenia, renal dysfunction).
BAL (dimercaprol) is excreted into breast milk; M/P ratio unknown. Limited data; exercise caution and consider temporary cessation of breastfeeding during therapy.
No standard dose adjustments recommended; however, due to increased plasma volume and metabolism in pregnancy, higher doses may be required to achieve therapeutic effect. Avoid near term.
No specific dose adjustments recommended in pregnancy; monitor for increased volume of distribution and potential need for higher doses if toxicity persists.
ACEPHEN (acetaminophen) is commonly used for mild to moderate pain and fever. Avoid exceeding 4 g/day in adults to prevent hepatotoxicity. In patients with hepatic impairment, reduce maximum daily dose to 2 g. Consider acetylcysteine for overdose. Onset of action is 15-30 minutes orally.
BAL (dimercaprol) is used as a chelating agent for heavy metal poisoning, particularly arsenic, lead, and mercury. Administer deep IM only; avoid IV due to risk of hemolysis. Monitor blood pressure closely as hypertension can occur. Contraindicated in peanut allergy due to peanut oil vehicle. Administer with alkaline urine to protect kidneys.
Do not exceed 4000 mg (4 grams) in 24 hours.,Avoid drinking alcohol while taking this medication.,Do not combine with other products containing acetaminophen.,Take with food if stomach upset occurs.,Seek immediate medical help if you experience symptoms of liver damage: yellowing of skin/eyes, dark urine, severe abdominal pain.
This medication is given as an injection into a muscle.,You may experience a metallic taste, headache, or nausea.,Report any signs of allergic reaction such as rash or difficulty breathing.,Avoid alcohol while on this medication.,Do not drive or operate heavy machinery until you know how this drug affects you.
No interactions on record
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Explore head-to-head clinical comparisons of other medications in the same therapeutic classes.
Common clinical questions about ACEPHEN vs BAL, answered by our medical review team.
ACEPHEN is a Non-Opioid Analgesic that works by ACEPHEN (acetaminophen) is a para-aminophenol derivative with analgesic and antipyretic activity. Its mechanism involves inhibition of cyclooxygenase (COX) enzymes in the central nervous system, particularly COX-2, reducing prostaglandin synthesis. It has weak peripheral COX inhibition and minimal anti-inflammatory effect.. BAL is a Chelating Agent that works by Chelating agent that forms stable complexes with heavy metals (e.g., arsenic, mercury, lead) by binding to their sulfhydryl groups, facilitating renal excretion.. They differ in pharmacokinetic profiles, FDA-approved indications, and side effect profiles.
Potency comparisons between ACEPHEN and BAL 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 ACEPHEN is: 325-650 mg orally every 4-6 hours as needed; maximum 4 g/day.. The standard adult dose of BAL is: 3-5 mg/kg IM every 4 hours for 2 days, then every 6 hours for 1 day, then every 12 hours for 10 days.. 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 ACEPHEN and BAL 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. ACEPHEN is classified as Category C. Pregnancy Category C. First trimester: potential risk of neural tube defects and orofacial clefts (limited human data, animal studies show embryotoxicity). Second and third trimest. BAL is classified as Category C. Insufficient human data; animal studies suggest potential teratogenicity at high doses. Avoid in first trimester unless benefit outweighs risk.. Always consult a maternal-fetal medicine specialist before taking either drug during pregnancy or lactation.