Adult: 33-50 kg: 15 mg/kg 4-6 hourly if needed. Max: 3 g daily. >50 kg: 1 g 4-6 hourly if needed. Max: 4 g daily. Administer by infusion over 15 minutes. Child: Full-term neonates and children <10 kg: 7.5 mg/kg as a single dose, at least 4 hourly. Max: 30 mg/kg/day; 10-33 kg: 15 mg/kg as a single dose, at least 4 hourly. Max: 2 g daily; 33-50 kg: 15 mg/kg as a single dose, at least 4 hourly. Max: 3 g daily; >50 kg: Same as adult dose.
Oral Post-immunisation pyrexia
Child: 2-3 months 60 mg as a single dose. May give 2nd dose after 4-6 hours if needed. Max: 4 doses daily.
Oral Fever, Mild to moderate pain
Adult: 0.5-1 g 4-6 hourly. Max: 4 g daily. Child: 1-2 months 30-60 mg 8 hourly. Max: 60 mg/kg/day; 3-<6 months 60 mg. 6 months to <2 years 120 mg; 2-<4 years 180 mg; 4-<6 years 240 mg; 6-<8 years 240 or 250 mg; 8-<10 years 360 or 375 mg; 10-<12 years 480 or 500 mg; 12-16 years 480 or 750mg. Administer 4-6 hourly if necessary. Max: 4 doses in 24 hours.
Rectal Fever, Mild to moderate pain
Adult: As supp: 0.5-1 g 4-6 hourly. Max: 4 g daily. Child: 3 months to <1 year 60-125 mg; 1-<5 years 125-250 mg: 5-<12 years 250-500 mg; 12-17 years 500 mg. Given 4-6 hourly if needed. Max: 4 doses/day.
Rectal Post-immunisation pyrexia
Child: 2-3 months 60 mg as a single dose. May give 2nd dose after 4-6 hours if needed.
Renal Impairment
Intravenous:
CrCl (mL/min)
Dosage
<30
Increase dosing interval to 6 hrly. Max: 3 g daily.
Hepatic Impairment
Oral: Mild to moderate pain; Fever: Dosage reduction may be needed. Recommendation: Max: ≤2-3 g daily. Intravenous:
Mild or moderate: Max: 3 g daily. Severe: Contraindicated.
Administration
May be taken with or without food.
Reconstitution
IV: Dilute with NaCl 0.9% or glucose 5% to make a concentration of not less than 1 mg/mL.
Incompatibility
Incompatible with acyclovir Na, diazepam, chlorpromazine HCl.
Contraindications
Hypersensitivity. Severe hepatic impairment or active liver disease (IV).
Special Precautions
Patient with known G6PD deficiency, alcohol dependence, chronic malnutrition or dehydration, weight <50 kg; severe hypovolaemia (IV). Renal and hepatic impairment. Children. Pregnancy and lactation.
Adverse Reactions
Significant: Thrombocytopenia, leucopenia, neutropenia, pancytopenia, methaemoglobinaemia, agranulocytosis, angioedema, pain and burning sensation at inj site. Rarely, hypotension and tachycardia. Gastrointestinal disorders: Nausea, vomiting, constipation. Nervous system disorders: Headache. Psychiatric disorders: Insomnia. Skin and subcutaneous tissue disorders: Erythema, flushing, pruritus. Potentially Fatal: Hepatotoxicity, acute renal tubular necrosis. Rarely, hypersensitivity reactions such as acute generalised exanthematous pustulosis (AGEP), Stevens-Johnson syndrome (SJS), toxic epidermal necrolysis (TEN).
Assess patient for history of liver disease or alcohol abuse.
Overdosage
Symptoms: Pallor, nausea, vomiting, anorexia, abdominal pain, metabolic acidosis, glucose metabolism abnormalities. After 12-48 hours of ingestion, liver damage may become apparent, which may lead to encephalopathy, haemorrhage, hypoglycaemia, hypotension, cerebral oedema, cardiac arrhythmia, and pancreatitis. Management: Administer activated charcoal within 1 hour of ingestion. Determine plasma paracetamol concentration ≥4 hours after ingestion. IV N-acetylcysteine may be used up to 24 hours after ingestion (most effective if given within 8 hours). As an alternative, oral methionine can also be used if vomiting is not a problem.
Drug Interactions
Decreased absorption with colestyramine. Decreased serum concentrations with rifampicin and some anticonvulsants (e.g. phenytoin, phenobarbital, carbamazepine, primidone). Enhances the anticoagulant effect of warfarin and other coumarins with prolonged use. Increased absorption with metoclopramide and domperidone. Increased serum concentration with probenecid. May increase serum concentration of chloramphenicol.
Food Interaction
Increased risk of hepatotoxicity with alcohol. Decreased serum concentration with St John’s wort.
Lab Interference
May produce false-positive test results for urinary 5-hydroxyindoleacetic acid.
Action
Description: Paracetamol exhibits analgesic action by peripheral blockage of pain impulse generation. It produces antipyresis by inhibiting the hypothalamic heat-regulating centre. Its weak anti-inflammatory activity is related to inhibition of prostaglandin synthesis in the CNS.
Synonym: acetaminophen. Onset: Oral: <1 hour. IV: 5-10 minutes (analgesia); within 30 minutes (antipyretic). Duration: Oral, IV: 4-6 hours (analgesia). IV: ≥6 hours (antipyretic). Pharmacokinetics: Absorption: Well absorbed after oral and rectal administration. Time to peak plasma concentration: Approx 10-60 minutes (oral); 15 minutes (IV); approx 2-3 hours (rectal). Distribution: Distributed into most body tissues. Crosses placenta and enters breast milk. Plasma protein binding: Approx 10-25%. Metabolism: Mainly metabolised in the liver via glucuronic and sulfuric acid conjugation. N-acetyl-p-benzoquinone imine (NAPQI), a minor metabolite produced by CYP2E1 and CYP3A4, is further metabolised via conjugation with glutathione in the liver and kidneys. Excretion: Mainly via urine (<5% as unchanged drug; 60-80% as glucuronide metabolites and 20-30% as sulphate metabolites). Elimination half-life: Approx 1-3 hours.
Chemical Structure
Paracetamol Source: National Center for Biotechnology Information. PubChem Database. Acetaminophen, CID=1983, https://pubchem.ncbi.nlm.nih.gov/compound/Acetaminophen (accessed on Jan. 22, 2020)
Storage
Tab/cap/susp/solution: Store between 20-25°C. Do not freeze. Protect from light and moisture. Rectal Supp: Store between 2-25°C. Do not freeze.
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