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Mechanism of action paracetamol
analgesic and antipyretic. It inhibits the synthesis of prostaglandins in the CNS and blocks the generation of pain impulses at the peripheral level. It acts on the hypothalamic center that regulates temperature.
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Therapeutic indications paracetamol
– Oral or rectal: fever; pain of any etiology of mild or moderate intensity.
– IV: moderate pain and fever, short-term, when there is an urgent need or other routes are not possible.
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Paracetamol dosage
– Oral: ads.: 1g/6-8 ho ads. and children > 12 years: 500-650 mg/4-6 h; max. 4g/day. Children from 0 months: 15 mg/kg/6 h or 10 mg/kg/4 h. IR: Clcr < 10 ml/min: range min. between shots, 8 h; Clcr 10-15 mL/min, 6 hrs. Elderly, reduce dose by 25%.
– Rectal: children: 15 mg/kg every 6 h or 10 mg/kg every 4 h. Do not exceed 60 mg/kg for children weighing <25 kg and 80 mg/kg for children weighing between 25-37 kg. ads. and adolescents: 600-1,300 mg/6 h, max. 5g/day.
– IV (infusion of 15 min): dose according to patient weight:
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To avoid dose errors in neonates and children and confusion between milligrams (mg) and milliliters (ml), it is recommended that the desired volume for administration be specified in milliliters. In neonates and children, very small volumes will be required. With ≤ 10 kg do not infuse directly from the vial or bag. The volume of paracetamol to be administered will be diluted to 1/10 in a 0.9% NaCl or 5% glucose solution and will be administered as a continuous perfusion for at least 15 min. The minimum interval between each administration of IV paracetamol should be at least 4 hours and no more than 4 doses should be administered in 24 hours. In severe IR: min. interval between doses, 6 h. With ≤50 kg, dosage calculations will be made based on weight.
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Mode of administration paracetamol
N/A
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Contraindications paracetamol
hypersensitivity to paracetamol, to propacetamol hydrochloride (prodrug of paracetamol). Severe hepatocellular insufficiency. Viral hepatitis. Recent history of rectitis, anitis or rectal bleeding (only for rectal form).
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Warnings and precautions paracetamol
IH, acute hepatitis, concomitant with substances that affect liver function, dehydration due to alcohol abuse and chronic malnutrition. Chronic alcoholism; TO GO; insuf. severe cardiac; lung conditions; anemia. Asthmatics sensitive to ASA (cross reaction). In alcoholics or in case of IH: do not exceed 2 g paracetamol/day. Children < 3 years. Risk of serious skin reactions, such as acute generalized exanthematous pustulosis, s. Stevens-Johnson, and toxic epidermal necrolysis, discontinue at first sign of skin rash or any other sign of hypersensitivity. The toxic pictures associated with paracetamol can be produced both by the intake of a single overdose or by several intakes with excessive doses. IV route, caution in chronic malnutrition and dehydration.
In solutions for infusion: fetal anomalies due to overdose.
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Hepatic failure paracetamol
Contraindicated in severe hepatocellular insufficiency. Caution in case of IH do not exceed 2 g paracetamol/day and interval min. between doses, 8 h. Acceptable occasional use, but prolonged administration of high doses increases the risk of adverse effects.
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Renal failure paracetamol
Caution. Acceptable occasional use, but prolonged administration of high doses increases the risk of adverse renal effects. IR: Clcr < 10 ml/min: range min. between shots, 8 h; Clcr 10-15 mL/min, 6 hrs.
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Paracetamol interactions
increases effect (at doses > 2 g/day) of: oral anticoagulants.
Hepatotoxicity potentiated by: alcohol, isoniazid.
Decreased bioavailability and potentiation of toxicity by: anticonvulsants.
Plasma levels decreased by: estrogens.
Decreases effect of: loop diuretics, lamotrigine, zidovudine.
Action increased by: probenecid, isoniazid, propranolol.
Decreased effect by: anticholinergics, cholestyramine.
Increased absorption by: metoclopramide, domperidone.
Clearance increased by: rifampin.
May increase toxicity of: chloramphenicol.
Lab: blood: increased glucose, theophylline and ac. uric; glucose reduction by oxidase-peroxidase method. Urine: increases values of metadrenaline and ac. uric; false + in determination of ac. 5-hydroxy indole acetic acid in tests with the reagent nitrosonaphthol. Increases prothrombin time. Discontinue 3 days before pancreatic function tests with bentiromide.
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Pregnancy paracetamol
No problems have been described in humans. Although no controlled studies have been conducted, it has been shown that paracetamol crosses the placenta, so it is recommended that paracetamol not be administered except in case of necessity.
Updated safety information: There is no evidence of the prenatal use of paracetamol and the urogenital impact or neurodevelopmental alterations of the exposed child in utero.
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Breastfeeding paracetamol
Compatible. Although it is excreted in milk in small amounts, it has not been detected in the urine of infants. It can be used at therapeutic doses.
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Adverse reactions paracetamol
Rare: malaise, increased level of transaminases, hypotension, hepatotoxicity, skin rash, haematological abnormalities, hypoglycaemia, sterile pyuria.
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Paracetamol overdose
liver failure can cause death. Antidote, N-acetylcysteine: ads.: loading dose: 150 mg/kg IV slowly, or diluted in 200 mL of 5% dextrose over 15 min; maintenance: 50 mg/kg in 500 ml dextrose 5%, infus. slow over 4 h, followed by 100 mg/kg in 1,000 mL 5% dextrose, infus. slow of 16 h. In children, adjust the volume of 5% dextrose according to age and weight to avoid pulmonary vascular congestion. Discontinue when blood levels of paracetamol are < 200 mcg/ml. Max effectiveness of the antidote within 4 hours of intoxication; ineffective from 15 h.
– Oral: administer N-acetylcysteine within 10 hours. Ads., initial, 140 mg/kg + 17 doses of 70 mg/kg, one every 4 hours. Dilute each dose to 5% in cola, orange juice or water.
In solutions for infusion: fetal anomalies due to overdose (possible fetal involvement in the context of maternal paracetamol overdose).
Pregnancy
Compatible breastfeeding
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