PARASAL SODIUM
Clinical safety rating: caution
Comprehensive clinical and safety monograph for PARASAL SODIUM (PARASAL SODIUM).
Parasal sodium is a prodrug that is converted to 5-aminosalicylic acid (5-ASA) in the colon, where it inhibits cyclooxygenase and lipoxygenase pathways, reducing prostaglandin and leukotriene synthesis, thereby exerting anti-inflammatory effects in the gastrointestinal tract.
| Metabolism | Metabolized in the intestinal wall and liver via N-acetylation by N-acetyltransferase 1 (NAT1). |
| Excretion | Primarily renal (90-95% as unchanged drug and metabolites, with 50-70% as unchanged salicylate in alkaline urine); minor biliary (2-5%) and fecal (<1%). |
| Half-life | 2-3 hours for low doses (antiplatelet effect); 15-30 hours for high doses (anti-inflammatory), increasing with dose due to saturation of hepatic metabolism. |
| Protein binding | 50-80% bound to albumin, concentration-dependent (lower binding at higher concentrations due to saturation). |
| Volume of Distribution | 0.15-0.2 L/kg (low, reflecting high protein binding and limited tissue distribution; increases in acidosis). |
| Bioavailability | Oral: 80-100% (sodium salt); rectal: 70-80%; topical: 10-20% (variable). |
| Onset of Action | Oral: 15-30 minutes (analgesic); rectal: 30-45 minutes; topical: 60 minutes (keratolytic). |
| Duration of Action | Analgesic: 3-4 hours; anti-inflammatory: 6-8 hours; antiplatelet: 7-10 days (irreversible COX-1 acetylation). |
300 mg orally twice daily
| Dosage form | TABLET |
| Renal impairment | GFR <30 mL/min: reduce dose by 50%; GFR <15 mL/min: use with caution, not recommended |
| Liver impairment | Child-Pugh A: no adjustment; Child-Pugh B: reduce dose by 50%; Child-Pugh C: avoid use |
| Pediatric use | Body weight <30 kg: 10 mg/kg twice daily; >30 kg: 300 mg twice daily |
| Geriatric use | Consider lower starting dose (150 mg twice daily) due to age-related decline in renal function; monitor closely for adverse effects |
| 1st trimester | Consult provider |
| 2nd trimester | Consult provider |
| 3rd trimester | Consult provider |
Clinical note
Comprehensive clinical and safety monograph for PARASAL SODIUM (PARASAL SODIUM).
| Breastfeeding | PAS is excreted into breast milk in low amounts. M/P ratio not established. Risk to infant is minimal, but monitor for gastrointestinal disturbances. Consider benefits and risks. |
| Teratogenic Risk | PAS (aminosalicylic acid) has not been associated with major congenital malformations in humans. However, animal studies show some fetal effects at high doses. First trimester: risk of malformations is low, but data limited. Second/third trimester: no known specific risks; use only if clearly needed. |
■ FDA Black Box Warning
None.
| Serious Effects |
["Hypersensitivity to salicylates or any component of the formulation","Severe renal impairment (e.g., GFR <30 mL/min/1.73 m²)"]
| Precautions | ["Renal impairment: Monitor renal function due to risk of nephrotoxicity","Hepatic impairment: Use with caution","Blood dyscrasias: Monitor for signs of agranulocytosis, leukopenia, or thrombocytopenia","GI adverse effects: May exacerbate colitis symptoms"] |
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| Fetal Monitoring |
| Monitor liver function tests, renal function, and CBC periodically. Assess for gastrointestinal intolerance. No specific fetal monitoring required unless co-administered with other anti-tuberculosis drugs. |
| Fertility Effects | No known adverse effects on human fertility. Animal studies show no impairment. |