INDOCIN SR
Clinical safety rating: caution
Comprehensive clinical and safety monograph for INDOCIN SR (INDOCIN SR).
Indomethacin is a nonsteroidal anti-inflammatory drug (NSAID) that inhibits cyclooxygenase (COX-1 and COX-2) enzymes, reducing synthesis of prostaglandins, which mediate inflammation, pain, and fever. It also has a direct effect on renal blood flow and platelet aggregation.
| Metabolism | Hepatic metabolism via O-demethylation and N-deacylation; undergoes enterohepatic recirculation. Metabolites are excreted in urine and bile. |
| Excretion | Approximately 50% renal (as unchanged drug and metabolites, primarily glucuronide conjugates), 33% biliary/fecal. Indomethacin undergoes enterohepatic recirculation. |
| Half-life | Terminal half-life is 4.5 hours (range 2.6-11.2 hours) in young adults; prolonged in elderly (up to 16 hours) and in patients with renal or hepatic impairment. |
| Protein binding | Approximately 90-99% bound primarily to albumin. |
| Volume of Distribution | 0.1-0.3 L/kg (low Vd, indicating extensive protein binding and limited extravascular distribution). |
| Bioavailability | Oral (sustained release): Approximately 100% (complete absorption) but with slower rate; bioavailability comparable to immediate-release. |
| Onset of Action | Oral (sustained release): 1-2 hours for analgesic/anti-inflammatory effect; may take days for full anti-inflammatory effect in chronic conditions. |
| Duration of Action | Oral (sustained release): 8-12 hours for analgesic effect; anti-inflammatory effect may persist longer with repeated dosing. |
| Molecular Weight | 357.79 |
75 mg orally once daily, extended-release capsules.
| Dosage form | CAPSULE, EXTENDED RELEASE |
| Renal impairment | Contraindicated if GFR < 30 mL/min. For GFR 30-59 mL/min: reduce dose to 75 mg every other day or use alternative agent. |
| Liver impairment | Child-Pugh A: no adjustment. Child-Pugh B: use with caution, reduce dose by 50% (e.g., 75 mg every other day). Child-Pugh C: avoid use. |
| Pediatric use | Not recommended for pediatric use; safety and efficacy not established. |
| Geriatric use | Initiate at lowest effective dose; typical dose 75 mg once daily; avoid if CrCl <30 mL/min; monitor for GI bleeding and renal function. |
| 1st trimester | Avoid; risk of spontaneous abortion and congenital malformations (particularly cardiovascular) increased. |
| 2nd trimester | Avoid; may cause oligohydramnios and fetal renal dysfunction. |
| 3rd trimester | Contraindicated; premature closure of ductus arteriosus, persistent pulmonary hypertension, oligohydramnios. |
Clinical note
Comprehensive clinical and safety monograph for INDOCIN SR (INDOCIN SR).
| Placental transfer | Active; crosses placenta rapidly, achieving fetal serum concentrations similar to maternal. |
| Breastfeeding | Excreted into breast milk in low amounts; use caution, especially in infants with hypersensitivity or thrombocytopenia. |
| Lactation Rating |
■ FDA Black Box Warning
Nonsteroidal anti-inflammatory drugs (NSAIDs) cause an increased risk of serious cardiovascular thrombotic events, including myocardial infarction and stroke, which can be fatal. This risk may occur early in treatment and may increase with duration of use. NSAIDs are contraindicated in the setting of coronary artery bypass graft (CABG) surgery.
| Serious Effects |
Hypersensitivity to indomethacin or NSAIDsHistory of asthma, urticaria, or allergic-type reactions after aspirin/NSAIDsActive peptic ulcer disease or GI bleedingPerioperative pain in setting of coronary artery bypass graft (CABG) surgeryAdvanced renal diseaseProctitis or bleeding (for rectal formulation)
| Precautions | Cardiovascular: increased risk of thrombotic events, hypertension, fluid retention, Gastrointestinal: bleeding, ulceration, perforation (especially in elderly), Renal: decreased renal blood flow, papillary necrosis, renal failure, Hepatic: elevated liver enzymes, hepatic necrosis, Hematologic: inhibition of platelet aggregation, prolonged bleeding time, Central nervous system: headache, dizziness, depression, psychiatric disturbances, Ocular: blurry vision, corneal deposits, retinal changes, Skin: exfoliative dermatitis, Stevens-Johnson syndrome, Pregnancy: avoid in third trimester due to premature closure of ductus arteriosus |
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| L2 (Probably Compatible) |
| Teratogenic Risk | First trimester: Limited data; theoretical risk of miscarriage and cardiac defects based on prostaglandin inhibition. Second trimester: Avoid due to risk of oligohydramnios and premature closure of ductus arteriosus after 20 weeks. Third trimester: Contraindicated after 30 weeks due to risk of premature ductus arteriosus closure, oligohydramnios, and neonatal complications (persistent pulmonary hypertension, renal impairment). |
| Fetal Monitoring | Monitor fetal heart rate, amniotic fluid index via ultrasound starting at 20 weeks gestation; perform ductal Doppler if exposure after 28 weeks. Assess maternal renal function and blood pressure regularly. |
| Fertility Effects | Reversible inhibition of prostaglandin synthesis can delay or prevent ovulation; may impair implantation. Effects resolve upon discontinuation. |
| Food/Dietary | Take with food or milk to minimize gastrointestinal irritation. Avoid alcohol as it increases the risk of GI bleeding. No specific food restrictions beyond general avoidance of high-fat meals that may slow absorption. |
| Clinical Pearls | INDOCIN SR (indomethacin) is a nonsteroidal anti-inflammatory drug (NSAID) with potent analgesic and antipyretic properties. It is more likely to cause central nervous system (CNS) side effects (e.g., headache, dizziness, confusion) than other NSAIDs, especially in the elderly. Use with caution in patients with renal impairment, as it reduces renal blood flow and can cause acute kidney injury. Monitor for gastrointestinal (GI) bleeding, as it is a potent inhibitor of COX-1. The sustained-release formulation allows for twice-daily dosing, but should not be crushed or chewed. |
| Patient Advice | Take with food or milk to reduce stomach upset. · Avoid alcohol and aspirin while taking this medication to lower the risk of stomach bleeding. · Report any signs of bleeding (e.g., black/tarry stools, vomiting blood, unusual bruising) or CNS effects (e.g., severe headache, confusion, visual changes) to your healthcare provider immediately. · Do not crush, chew, or break the sustained-release capsules; swallow them whole. · Stay hydrated and avoid taking this medication if you are dehydrated or have kidney problems. |