SODIUM P.A.S.
Clinical safety rating: caution
Comprehensive clinical and safety monograph for SODIUM P.A.S. (SODIUM P.A.S.).
Sodium P.A.S. (para-aminosalicylate) inhibits folic acid synthesis in Mycobacterium tuberculosis by competing with para-aminobenzoic acid, thereby suppressing bacterial growth.
| Metabolism | Hepatic acetylation via N-acetyltransferase (NAT2); undergoes conjugation with glycine and glucuronic acid. |
| Excretion | Primarily renal (80-90% as unchanged drug) via glomerular filtration and tubular secretion; biliary/fecal ≤10%. |
| Half-life | 0.5–1 hour (normal renal function); prolonged to ≥10 hours in renal impairment (requires dose adjustment). |
| Protein binding | 50–60% bound to serum albumin. |
| Volume of Distribution | 0.2–0.4 L/kg (suggests low tissue penetration, primarily extracellular). |
| Bioavailability | Oral: ~80–90%. IV: 100%. |
| Onset of Action | Oral: ~1–2 hours. IV: Immediate. Rectal: 2–4 hours. |
| Duration of Action | 6–12 hours (oral); sustained with impaired renal function. |
4 g orally three times daily (total 12 g/day). For intravenous administration, 4 g (10 mL of 40% solution) diluted in 250 mL of 5% dextrose or normal saline infused over 2-3 hours three times daily.
| Dosage form | TABLET |
| Renal impairment | GFR 30-50 mL/min: administer every 12 hours. GFR 10-30 mL/min: administer every 24 hours. GFR <10 mL/min: administer every 48 hours or avoid use. |
| Liver impairment | Child-Pugh Class A: no adjustment. Child-Pugh Class B: reduce dose by 50%. Child-Pugh Class C: avoid use due to risk of hepatotoxicity. |
| Pediatric use | Children: 150-300 mg/kg/day orally in 3-4 divided doses, maximum 12 g/day. Intravenous: 150-300 mg/kg/day in divided doses every 6-8 hours. |
| Geriatric use | Start at lower end of dosing range (e.g., 4 g orally twice daily) and titrate based on renal function. Monitor for electrolyte disturbances and hepatotoxicity. |
| 1st trimester | Consult provider |
| 2nd trimester | Consult provider |
| 3rd trimester | Consult provider |
Clinical note
Comprehensive clinical and safety monograph for SODIUM P.A.S. (SODIUM P.A.S.).
| Breastfeeding | PAS enters breast milk in low concentrations; M/P ratio unknown. Considered compatible with breastfeeding by American Academy of Pediatrics, but monitor infant for gastrointestinal disturbances or allergic reactions. |
| Teratogenic Risk | PAS is not associated with major congenital malformations. First trimester: no significant increase in defect risk. Second/third trimester: may increase risk of maternal hemolysis in G6PD deficiency; no direct fetal toxicity reported. Limited human data. |
| Fetal Monitoring |
■ FDA Black Box Warning
No FDA black box warning.
| Serious Effects |
["Hypersensitivity to para-aminosalicylate or any component","Severe hepatic impairment","Severe renal impairment (CrCl < 30 mL/min)"]
| Precautions | ["Hepatotoxicity, including hepatic necrosis and jaundice","Hypersensitivity reactions (drug rash, fever, eosinophilia)","Gastrointestinal intolerance (nausea, vomiting, diarrhea)","Renal impairment may require dose adjustment","Monitor liver function tests, blood counts, and renal function"] |
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| Baseline and periodic liver function tests, renal function, CBC with differential, and serum electrolytes. Monitor for signs of hemolysis in G6PD-deficient mothers. Fetal growth ultrasound if used in pregnancy. |
| Fertility Effects | No evidence of impaired fertility in animal studies or human reports. PAS does not affect gonadal function or spermatogenesis. |