MEASURIN
Clinical safety rating: caution
Comprehensive clinical and safety monograph for MEASURIN (MEASURIN).
Measurin is an aspirin preparation that irreversibly inhibits cyclooxygenase (COX-1 and COX-2), thereby reducing prostaglandin and thromboxane synthesis. This results in analgesic, antipyretic, anti-inflammatory, and antiplatelet effects.
| Metabolism | Measurin is rapidly hydrolyzed to salicylic acid in the gastrointestinal tract and liver. Salicylic acid is primarily metabolized in the liver via conjugation with glycine (to form salicyluric acid) and glucuronic acid, and oxidation to gentisic acid and other metabolites. Major enzymes: UGTs, CYP2E1 (minor). |
| Excretion | Renal excretion of salicylate and its metabolites (salicyluric acid, salicyl phenolic glucuronide, salicyl acyl glucuronide, gentisic acid) accounts for >90% of elimination; minor biliary/fecal excretion (<5%) occurs. |
| Half-life | Plasma elimination half-life is 2-3 hours at low doses (antiplatelet) and increases to 15-30 hours at anti-inflammatory doses due to saturation of hepatic metabolism; clinical context: higher doses require longer dosing intervals to avoid accumulation. |
| Protein binding | Highly bound to albumin (80-90%); binding is saturable at high concentrations. |
| Volume of Distribution | 0.1-0.2 L/kg; low Vd indicates limited extravascular distribution; increased in acidosis or hypoalbuminemia. |
| Bioavailability | Oral: 80-100% (immediate-release); delayed-release forms have reduced rate but complete extent of absorption. |
| Onset of Action | Oral: Analgesic effect begins 30-60 minutes; anti-inflammatory effect begins 1-2 hours; antiplatelet effect occurs within 1 hour (irreversible COX-1 inhibition). |
| Duration of Action | Analgesic/antipyretic: 3-4 hours; anti-inflammatory: up to 12 hours; antiplatelet: 7-10 days (lifespan of platelet). |
325-650 mg orally every 4-6 hours as needed; maximum 4 g/day.
| Dosage form | TABLET, EXTENDED RELEASE |
| Renal impairment | GFR 10-50 mL/min: avoid use or extend dosing interval to 6-8 hours; GFR <10 mL/min: contraindicated. |
| Liver impairment | Child-Pugh A: no adjustment; Child-Pugh B: reduce dose by 50% and monitor; Child-Pugh C: contraindicated. |
| Pediatric use | 10-15 mg/kg/dose orally every 4-6 hours; maximum 75 mg/kg/day or 4 g/day. |
| Geriatric use | Initiate at lowest effective dose; consider 325 mg every 6-8 hours due to increased risk of GI bleeding and renal impairment. |
| 1st trimester | Consult provider |
| 2nd trimester | Consult provider |
| 3rd trimester | Consult provider |
Clinical note
Comprehensive clinical and safety monograph for MEASURIN (MEASURIN).
| Breastfeeding | Aspirin enters breast milk; M/P ratio ~0.05-0.1. Avoid due to risk of Reye's syndrome and platelet dysfunction in infant. Occasional low doses may be compatible with monitoring. |
| Teratogenic Risk | Measurin (aspirin) is contraindicated in the third trimester due to risk of premature closure of ductus arteriosus and oligohydramnios. In first and second trimesters, increased risk of gastroschisis and cardiac defects. Avoid high doses near term. |
| Fetal Monitoring |
■ FDA Black Box Warning
Reye's syndrome: Aspirin should not be used in children or teenagers with viral infections because of the risk of Reye's syndrome.
| Serious Effects |
Hypersensitivity to aspirin or NSAIDs; active peptic ulcer disease; bleeding disorders (e.g., hemophilia); severe hepatic or renal impairment; children with viral infections (Reye's syndrome risk); third trimester of pregnancy; history of asthma induced by NSAIDs.
| Precautions | Risk of gastrointestinal bleeding, ulcers, and perforation; increased bleeding risk (especially with alcohol, anticoagulants); Reye's syndrome in children with viral illness; hypersensitivity reactions including asthma and anaphylaxis; impaired renal function; avoid use during late pregnancy (may cause premature closure of ductus arteriosus and increase risk of hemorrhage). |
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| Monitor fetal ultrasound for ductus arteriosus flow and amniotic fluid index. Maternal bleeding time, platelet count, and signs of gastrointestinal bleeding. Neonatal monitoring for bruising and bleeding. |
| Fertility Effects | Aspirin may inhibit prostaglandin synthesis, potentially delaying ovulation or impairing implantation. Reversible effect. |