ACETAMINOPHEN, PARACETAMOL

(a-seat-a-mee'noe-fen)

Abenol

, A'Cenol, Acephen, Anacin-3, Anuphen, APAP, Atasol

, Campain

, Dolanex, Exdol

, Halenol, Liquiprin, Panadol, Pedric, Robigesic

, Rounox

, Tapar, Tempra, Tylenol, Tylenol Arthritis, Valadol
Classifications: nonnarcotic analgesic, antipyretic;
Therapeutic: nonnarcotic analgesic; antipyretic
Pregnancy Category: B

Availability

80 mg, 120 mg, 125 mg, 300 mg, 325 mg, 650 mg suppositories; 80 mg, 160 mg, 325 mg, 500 mg tablets/caplets; 650 mg extended release tablets/capsules; 80 mg/0.8 mL, 80 mg/2.5 mL, 80 mg/5 mL, 120 mg/5 mL, 160 mg/5 mL, 500 mg/5 mL liquid

Action

Produces analgesia by unknown mechanism, but it is centrally acting in the CNS by increasing the pain threshold by inhibiting cyclooxygenase. Reduces fever by direct action on hypothalamus heat-regulating center with consequent peripheral vasodilation, sweating, and dissipation of heat. Unlike aspirin, has little effect on platelet aggregation, does not affect bleeding time, and produces no gastric bleeding.

Therapeutic Effect

It provides temporary analgesia for mild to moderate pain. In addition, acetaminophen lowers body temperature in individuals with a fever.

Uses

Fever reduction. Temporary relief of mild to moderate pain. Generally as substitute for aspirin when the latter is not tolerated or is contraindicated.

Contraindications

Hypersensitivity to acetaminophen or phenacetin; use with alcohol.

Cautious Use

Repeated administration to patients with anemia, G6PD deficiency, renal or hepatic disease; arthritic or rheumatoid conditions affecting children <12 y; alcoholism; malnutrition; thrombocytopenia; bone marrow depression, immunosuppression; pregnancy (category B).

Route & Dosage

Mild to Moderate Pain, Fever
Adult: PO 325–650 mg q4–6h (max: 4 g/d) PR 650 mg q4–6h (max: 4 g/d)
Child: PO 10–15 mg/kg q4–6h PR 2–5 y, 120 mg q4–6h (max: 720 mg/d); 6–12 y, 325 mg q4–6h (max: 2.6 g/d)
Neonate: PO 10–15 mg/kg q6–8h

Administration

Oral

Administer tablets or caplets whole or crushed and give with fluid of patient's choice.
Chewable tablets should be thoroughly chewed and wetted before they are swallowed.
Do not coadminister with a high carbohydrate meal; absorption rate may be significantly retarded.
Store in light-resistant containers at room temperature, preferably between 15°–30° C (59°–86° F).

Rectal

Insert suppositories beyond the rectal sphincter.

Adverse Effects (≥1%)

Body as a Whole: Negligible with recommended dosage; rash. Acute poisoning: Anorexia, nausea, vomiting, dizziness, lethargy, diaphoresis, chills, epigastric or abdominal pain, diarrhea; onset of hepatotoxicity—elevation of serum transaminases (ALT, AST) and bilirubin; hypoglycemia, hepatic coma, acute renal failure (rare). Chronic ingestion: Neutropenia, pancytopenia, leukopenia, thrombocytopenic purpura, hepatotoxicity in alcoholics, renal damage.

Diagnostic Test Interference

False increases in urinary 5-HIAA (5-hydroxyindoleacetic acid) by-product of serotonin; false decreases in blood glucose (by glucose oxidase–peroxidase procedure); false increases in urinary glucose (with certain instruments in glucose analyses); and false increases in serum uric acid (with phosphotungstate method). High doses or long-term therapy: hepatic, renal, and hematopoietic function (periodically).

Interactions

Drug: Cholestyramine may decrease acetaminophen absorption. With chronic coadministration, barbiturates, carbamazepine, phenytoin, and rifampin may increase potential for chronic hepatotoxicity. Chronic, excessive ingestion of alcohol will increase risk of hepatotoxicity.

Pharmacokinetics

Absorption: Rapid and almost complete absorption from GI tract; less complete absorption from rectal suppository. Peak: 0.5–2 h. Duration: 3–4 h. Distribution: In all body fluids; crosses placenta. Metabolism: Extensively in liver. Elimination: 90–100% of drug excreted as metabolites in urine; excreted in breast milk. Half-Life: 1–3 h.

Nursing Implications

Assessment & Drug Effects

Monitor for S&S of: hepatotoxicity, even with moderate acetaminophen doses, especially in individuals with poor nutrition or who have ingested alcohol over prolonged periods; poisoning, usually from accidental ingestion or suicide attempts; potential abuse from psychological dependence (withdrawal has been associated with restless and excited responses).

Patient & Family Education

Do not take other medications (e.g., cold preparations) containing acetaminophen without medical advice; overdosing and chronic use can cause liver damage and other toxic effects.
Do not self-medicate adults for pain more than 10 d (5 d in children) without consulting a physician.
Do not use this medication without medical direction for: fever persisting longer than 3 d, fever over 39.5° C (103° F), or recurrent fever.
Do not give children more than 5 doses in 24 h unless prescribed by physician.

Common adverse effects in italic, life-threatening effects underlined; generic names in bold; classifications in SMALL CAPS; Canadian drug name; Prototype drug

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