DICLOFENAC SODIUM
Clinical safety rating: avoid
ACE inhibitors and ARBs may have diminished antihypertensive effect Increases risk of serious cardiovascular thrombotic events and GI bleeding.
Non-selective COX-1 and COX-2 inhibitor, reducing prostaglandin synthesis via inhibition of cyclooxygenase, leading to anti-inflammatory, analgesic, and antipyretic effects.
| Metabolism | Primarily hepatic via CYP2C9 and other CYP enzymes; undergoes glucuronidation. Minor renal clearance. |
| Excretion | Approximately 65% renal as glucuronide conjugates and inactive metabolites, ~20% biliary/fecal. Less than 1% unchanged in urine. |
| Half-life | Terminal elimination half-life approximately 2 hours (range 1.3–3.1 h). Short half-life requires frequent dosing; no accumulation with normal dosing intervals. |
| Protein binding | Greater than 99.5% bound to albumin. |
| Volume of Distribution | Approximately 0.12–0.17 L/kg (total Vd at steady state 0.12–0.17 L/kg). Low Vd indicates minimal tissue distribution; primarily confined to plasma and extracellular fluid. |
| Bioavailability | Oral: 50–60% (first-pass metabolism); rectally: approximately 50–70% (similar to oral); intramuscular: 90–100%; topical: 6–10% (systemic absorption, but local concentrations higher); ophthalmic: minimal systemic absorption (<0.5%). |
| Onset of Action | Oral: 30 minutes (analgesic); topical: 2–4 hours; ophthalmic: 30 minutes; rectal: 30–60 minutes; intramuscular: 15–30 minutes. |
| Duration of Action | Oral: 4–6 hours (immediate-release); topical: 6–8 hours; ophthalmic: 4–6 hours; rectal: 4–8 hours; gastrointestinal and renal adverse effects may persist longer. |
| Molecular Weight | 318.13 |
| Action Class | NSAID's- Non-Selective COX 1&2 Inhibitors (acetic acid) |
| Brand Substitutes | Diclonir Injection, 3D Injection, Powerflam Injection, Recoflam Injection, Iconac Injection, Walkfree Injection, NAC -AQ Injection, Vivian Plus 75mg Injection, Dilona Aqua 75mg Injection, Vivogesic AQ 75mg Injection |
Oral: 50 mg two to three times daily; maximum 150 mg/day. Topical: 1% gel applied four times daily. Rectal: 100 mg suppository once daily.
| Dosage form | SOLUTION/DROPS |
| Renal impairment | eGFR 30-59 mL/min: No adjustment needed; monitor renal function. eGFR <30 mL/min: Contraindicated. Hemodialysis: Not recommended. |
| Liver impairment | Child-Pugh A: No adjustment. Child-Pugh B: Use caution; reduce dose by 50%. Child-Pugh C: Contraindicated. |
| Pediatric use | For children ≥1 year: Oral suspension 0.5-1 mg/kg/dose two to three times daily; maximum 3 mg/kg/day. For juvenile idiopathic arthritis: 1-2 mg/kg/day divided two to three times daily. Not recommended in children <1 year. |
| Geriatric use | Start at lowest effective dose (e.g., 50 mg once daily); use for shortest duration. Avoid in patients with high GI or cardiovascular risk. Monitor renal function and electrolytes. |
| 1st trimester | Avoid use; associated with increased risk of miscarriage and congenital malformations (particularly cardiac). NSAIDs cross placenta; risk of oligohydramnios and premature ductus arteriosus closure. |
| 2nd trimester | Use with caution; may cause oligohydramnios due to fetal renal effects. Avoid prolonged use. |
| 3rd trimester | Contraindicated; risk of premature closure of ductus arteriosus, oligohydramnios, and fetal renal impairment. |
Clinical note
ACE inhibitors and ARBs may have diminished antihypertensive effect Increases risk of serious cardiovascular thrombotic events and GI bleeding.
| FDA category | Positive |
| Placental transfer | Crosses the placenta in measurable amounts; fetal concentrations reach approximately 30-50% of maternal serum levels. |
■ FDA Black Box Warning
Increased risk of serious cardiovascular thrombotic events (including MI and stroke) and serious GI adverse events (including bleeding, ulceration, and perforation of stomach/intestines). Contraindicated in CABG surgery.
| Serious Effects |
Hypersensitivity to diclofenac or other NSAIDsActive peptic ulcer disease or gastrointestinal bleedingHistory of asthma, urticaria, or allergic-type reactions after taking aspirin or other NSAIDsSevere heart failure (NYHA class III/IV)Coronary artery bypass graft (CABG) surgery perioperative painThird trimester of pregnancyRenal impairment (CrCl <30 mL/min)
| Precautions | Cardiovascular risk (HTN, CHF, edema), GI risk (bleeding, ulcers), renal toxicity, hepatic toxicity, anaphylactoid reactions, skin reactions (including SJS/TEN), and hematologic effects (anemia). Use lowest effective dose for shortest duration. |
| Food/Dietary | Avoid concurrent use with alcoholic beverages. Taking with food may reduce gastrointestinal irritation, but does not prevent NSAID-induced ulcers. No specific food restrictions, but maintain adequate hydration to minimize renal risk. |
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| Breastfeeding |
| Transfer into breast milk is low; however, diclofenac has a long half-life and may accumulate in infants. Use with caution, especially in neonates or infants with compromised renal function. Alternative analgesics (e.g., ibuprofen) preferred due to shorter half-life. |
| Lactation Rating | L3 (Moderately Safe) |
| Teratogenic Risk | Category C in first and second trimesters; Category D in third trimester. Risk of premature ductus arteriosus closure and oligohydramnios in third trimester. Avoid after 30 weeks gestation. |
| Fetal Monitoring | Monitor maternal renal function, blood pressure, and signs of bleeding. Fetal ultrasound for ductus arteriosus and amniotic fluid volume if used in third trimester. |
| Fertility Effects | Reversible inhibition of ovulation and implantation; may delay conception. Use in women trying to conceive is not recommended. |
| Clinical Pearls | Diclofenac sodium is a non-selective NSAID with strong analgesic and anti-inflammatory effects, often used for acute musculoskeletal pain. It carries a boxed warning for cardiovascular thrombotic events, especially in patients with known CV disease or risk factors. Avoid use in patients with active GI bleeding or peptic ulcer disease. For topical formulations, absorption is minimal but caution is still advised in patients on anticoagulants. Monitor renal function in elderly or dehydrated patients. Onset of action is rapid (30-60 min) for oral formulations. |
| Patient Advice | Take with food or milk to reduce stomach upset. · Do not take with other NSAIDs (e.g., ibuprofen, naproxen) or aspirin unless directed by your doctor. · Seek immediate medical attention for signs of heart attack (chest pain, shortness of breath) or stroke (weakness on one side, slurred speech). · Avoid alcohol while taking this medication. · Tell your doctor if you have a history of stomach ulcers, bleeding problems, high blood pressure, or kidney disease. · Use the lowest effective dose for the shortest duration possible. · For topical gel: apply to intact skin only, avoid contact with eyes, and do not cover with bandages or heat packs. |