ACTRON
Clinical safety rating: caution
Comprehensive clinical and safety monograph for ACTRON (ACTRON).
Acetaminophen (paracetamol) is a non-opioid analgesic and antipyretic. Its mechanism is not fully understood but involves inhibition of cyclooxygenase (COX) enzymes in the central nervous system, reducing prostaglandin synthesis. It also modulates the endocannabinoid system and serotonergic pathways.
| Metabolism | Primarily metabolized in the liver via glucuronidation (UGT1A1, UGT1A6, UGT1A9), sulfation (SULT1A1, SULT1A3), and oxidation (CYP2E1, CYP3A4) to form the toxic metabolite N-acetyl-p-benzoquinone imine (NAPQI), which is detoxified by glutathione. |
| Excretion | Renal: 90% as unchanged drug; biliary/fecal: 10% as metabolites. |
| Half-life | Terminal elimination half-life 2-4 hours; prolonged to 6-12 hours in elderly or renal impairment (CrCl <30 mL/min). |
| Protein binding | >99% bound to albumin. |
| Volume of Distribution | 0.1-0.2 L/kg; indicates limited extravascular distribution. |
| Bioavailability | Oral: 70-90% (first-pass metabolism minimal); IV: 100%. |
| Onset of Action | Oral: 30 minutes; IV: 1-2 minutes. |
| Duration of Action | 3-6 hours; may be extended with sustained-release formulation. |
Oral: 400 mg every 4-6 hours as needed for pain; maximum 1200 mg/day.
| Dosage form | TABLET |
| Renal impairment | GFR <30 mL/min: Avoid use. GFR 30-50 mL/min: Reduce dose to 50% of normal, maximum 600 mg/day. |
| Liver impairment | Child-Pugh Class B: Reduce dose by 50%; maximum 600 mg/day. Child-Pugh Class C: Contraindicated. |
| Pediatric use | Children ≥12 years: 400 mg orally every 6-8 hours as needed; maximum 1200 mg/day. Children <12 years: Not recommended. |
| Geriatric use | Initiate at 200 mg every 6-8 hours; maximum 600 mg/day due to increased risk of gastrointestinal bleeding and renal impairment. |
| 1st trimester | Consult provider |
| 2nd trimester | Consult provider |
| 3rd trimester | Consult provider |
Clinical note
Comprehensive clinical and safety monograph for ACTRON (ACTRON).
| Breastfeeding | Excreted in breast milk; M/P ratio 0.15. Low oral bioavailability to infant; considered compatible with breastfeeding. Monitor infant for sedation or feeding problems. |
| Teratogenic Risk | First trimester: Based on animal studies and limited human data, possible increased risk of cardiovascular and neural tube defects. Second/third trimester: Risk of premature closure of ductus arteriosus and oligohydramnios with prolonged use. Avoid after 30 weeks gestation. |
| Fetal Monitoring |
■ FDA Black Box Warning
Acetaminophen has been associated with cases of acute liver failure, sometimes resulting in liver transplant and death. Most cases involve use of acetaminophen at doses exceeding 4000 mg per day, often involving more than one acetaminophen-containing product.
| Serious Effects |
Severe hepatic impairment or active liver disease. Known hypersensitivity to acetaminophen or any component of the formulation.
| Precautions | Hepatotoxicity: risk increased with chronic alcohol use, liver disease, or use of other acetaminophen-containing products. Avoid exceeding 4000 mg/day. Severe skin reactions: Stevens-Johnson syndrome, toxic epidermal necrolysis, acute generalized exanthematous pustulosis. Hypersensitivity reactions: anaphylaxis. |
| Food/Dietary | Avoid alcohol; may increase risk of GI bleeding. No specific food restrictions, but taking with food can reduce gastrointestinal irritation. Maintain adequate hydration to prevent renal impairment. |
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| Maternal: Blood pressure, renal function, hepatic function, and signs of bleeding. Fetal: Ultrasound for ductus arteriosus patency and amniotic fluid index if used beyond 30 weeks. |
| Fertility Effects | Reversible impairment of spermatogenesis in males; no conclusive human data on female fertility. Use of NSAIDs may interfere with ovulation. |
| Clinical Pearls | ACTRON (ketorolac tromethamine) is a nonsteroidal anti-inflammatory drug (NSAID) for short-term management of moderate to severe acute pain, typically not exceeding 5 days due to risk of GI bleeding, renal impairment, and cardiovascular events. Avoid in patients with active peptic ulcer disease, bleeding diathesis, or advanced renal disease. Monitor renal function and signs of bleeding. Use lowest effective dose for shortest duration. May cause bronchospasm in aspirin-sensitive asthma. |
| Patient Advice | Take with food or milk to reduce stomach upset. · Do not take for more than 5 days as prescribed; longer use increases risk of serious side effects. · Avoid alcohol while taking this medication to lower risk of stomach bleeding. · Report any signs of bleeding (e.g., black stools, vomiting blood), unusual bruising, or decreased urination. · Do not take with other NSAIDs (e.g., ibuprofen, naproxen) or aspirin without consulting your doctor. · Inform your doctor about all medications, especially blood thinners (e.g., warfarin) and diuretics. · If you have asthma, be aware of potential bronchospasm; seek immediate help if you have breathing trouble. · Not recommended during pregnancy, especially in the third trimester. |