1. Clinical Overview
Paracetamol (Acetaminophen) 120mg/5ml is a widely used, non-prescription oral suspension analgesic and antipyretic. It is a first-line agent for the management of mild to moderate pain and fever across all age groups, particularly favored in pediatric populations due to its palatable liquid formulation, precise dosing, and established safety profile when used as directed. It acts centrally by inhibiting prostaglandin synthesis in the hypothalamus and peripherally through weak inhibition of cyclooxygenase enzymes.
| Onset | Duration | Bioavailability |
|---|---|---|
| Oral: 30 to 60 minutes | Approximately 4 to 6 hours | Approximately 85-98% |
2. Mechanism of Action
The exact mechanism is complex and not fully elucidated. Paracetamol's analgesic and antipyretic effects are primarily mediated centrally in the brain and spinal cord. It is a weak inhibitor of prostaglandin (PG) synthesis in peripheral tissues but a potent inhibitor in the central nervous system. It is believed to act on the cyclooxygenase (COX) pathway, with a preferential inhibition of the COX-2 isoform, especially in an environment of low peroxide tone (like the brain). It also modulates the endogenous cannabinoid and serotonergic systems, contributing to its pain-relieving effects.
3. Indications & Uses
- Management of mild to moderate pain (e.g., headache, toothache, musculoskeletal pain)
- Reduction of fever (pyrexia) in all age groups
4. Dosage & Administration
Adult Dosage: Not the primary strength for adults. For reference, adult dose is 325-650 mg every 4-6 hours or 500-1000 mg every 6-8 hours. Max 4g/day.
Administration: Shake the bottle well before use. Use only the calibrated measuring cup, dropper, or oral syringe provided. Do not use a household teaspoon. Can be taken with or without food. If stomach upset occurs, take with food. Do not mix with other liquids unless advised. Rinse measuring device after use.
5. Side Effects
Common side effects may include:
- Nausea
- Epigastric discomfort/pain
6. Drug Interactions
| Drug | Effect | Severity |
|---|---|---|
| Warfarin and other Coumarin Anticoagulants | Chronic high-dose paracetamol (>2g/day for several days) may potentiate anticoagulant effect, increasing INR and risk of bleeding. | Major |
| Isoniazid | Increases the formation of toxic metabolite NAPQI via CYP2E1 induction, raising risk of hepatotoxicity, especially in fast acetylators. | Major |
| Enzyme Inducers (Phenobarbital, Phenytoin, Carbamazepine, Rifampicin) | Increase metabolism via CYP450 pathway, increasing NAPQI formation and risk of hepatotoxicity, particularly with overdose. | Major |
| Probenecid | Inhibits glucuronidation, may slightly increase and prolong paracetamol levels. | Moderate |
| Metoclopramide, Domperidone | May increase absorption rate of paracetamol. | Minor |
| Cholestyramine | Reduces absorption of paracetamol if taken within 1 hour. Administer at least 1 hour apart. | Moderate |
| Other Hepatotoxic Drugs (e.g., high-dose NSAIDs, Antitubercular drugs, Azole antifungals, Statins) | Additive risk of liver damage. | Major |
| Alcohol (Chronic, heavy use) | Induces CYP2E1, depletes glutathione, significantly increases risk of severe hepatotoxicity even at therapeutic doses. | Major |
| Fluvoxamine | Inhibits metabolism, may increase paracetamol levels. | Moderate |
7. Patient Counselling
- DO use the measuring device (cup/syringe) provided with the medicine. Do not use kitchen spoons.
- DO shake the bottle well before each use.
- DO check the concentration (120mg/5ml) and calculate the dose based on your child's weight.
- DO NOT give more than 5 doses in 24 hours.
- DO NOT use with other medicines containing paracetamol (e.g., cold & flu combinations).
- DO NOT use for more than 3 days for fever or 5 days for pain without consulting a doctor.
- DO store the medicine out of reach of children, in a cool, dry place.
- DO inform your doctor if the child is taking any other medication.
8. Toxicology & Storage
Overdose: Stage 1 (0-24 hrs): Nausea, vomiting, anorexia, malaise, pallor, diaphoresis. Stage 2 (24-72 hrs): Resolution of GI symptoms; right upper quadrant pain/tenderness; elevated liver enzymes (AST/ALT), bilirubin, PT/INR; oliguria. Stage 3 (72-96 hrs): Peak hepatotoxicity: jaundice, coagulopathy, hypoglycemia, hepatic encephalopathy, acute kidney injury, possible death from multi-organ failure. Stage 4 (4 days-2 weeks): Recovery in survivors.
Storage: Store at a temperature not exceeding 30°C, in a cool, dry place. Protect from light. Keep the bottle tightly closed. Do not freeze. Keep out of reach and sight of children. Discard any unused suspension 1 month after opening the bottle (check manufacturer's instructions as some brands recommend 3 months).