NEOPASALATE
Clinical safety rating: caution
Comprehensive clinical and safety monograph for NEOPASALATE (NEOPASALATE).
Para-aminosalicylic acid (PAS) competitively inhibits the conversion of aminobenzoic acid to dihydrofolate, thereby inhibiting Mycobacterium tuberculosis growth.
| Metabolism | Hepatic metabolism via N-acetylation (N-acetyltransferase) and renal excretion of metabolites and unchanged drug. |
| Excretion | Primarily renal (≥80% as unchanged drug and acetylated metabolite); minor fecal elimination (<5%). |
| Half-life | Terminal elimination half-life is 2.5–4.5 hours in adults, prolonged in renal impairment. |
| Protein binding | Approximately 50–70% bound to plasma albumin. |
| Volume of Distribution | 0.2–0.3 L/kg, indicating distribution primarily in extracellular fluid. |
| Bioavailability | Oral: 70–80%; intravenous: 100%. |
| Onset of Action | Oral: 1–2 hours; intravenous: immediate (minutes). |
| Duration of Action | 6–8 hours for bacteriostatic effect; requires multiple daily dosing for sustained action. |
4-6 g orally twice daily; maximum 12 g/day.
| Dosage form | TABLET |
| Renal impairment | GFR 30-60 mL/min: reduce dose by 50%; GFR <30 mL/min: contraindicated. |
| Liver impairment | Child-Pugh A: no adjustment; Child-Pugh B: reduce dose by 50%; Child-Pugh C: contraindicated. |
| Pediatric use | 50-75 mg/kg/day orally divided every 6-8 hours; maximum 4 g/day. |
| Geriatric use | Initiate at lowest adult dose; monitor renal function; adjust based on creatinine clearance. |
| 1st trimester | Consult provider |
| 2nd trimester | Consult provider |
| 3rd trimester | Consult provider |
Clinical note
Comprehensive clinical and safety monograph for NEOPASALATE (NEOPASALATE).
| Breastfeeding | Excreted into breast milk in small amounts; M/P ratio unknown. Potential for infant gastrointestinal disturbance and hemolytic anemia in G6PD-deficient infants. Use with caution; monitor infant for adverse effects. |
| Teratogenic Risk | NEOPASALATE (sodium aminosalicylate) is classified as FDA Pregnancy Category C. First trimester: Limited human data; animal studies show fetal harm at high doses. Second/third trimesters: Potential for maternal and fetal toxicity including hemolytic anemia, methemoglobinemia, and hypoglycemia. Avoid use unless benefit outweighs risk. |
■ FDA Black Box Warning
None
| Serious Effects |
Hypersensitivity to para-aminosalicylic acid or any component of the formulation; severe renal impairment (CrCl < 30 mL/min).
| Precautions | May cause severe hypersensitivity reactions including Stevens-Johnson syndrome; hepatotoxicity; hemolytic anemia in G6PD deficiency; GI intolerance. |
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| Fetal Monitoring |
| Monitor maternal CBC, LFTs, renal function, and G6PD status. Fetal ultrasound for growth restriction if used long-term. Newborn assessment for hemolytic anemia and methemoglobinemia. |
| Fertility Effects | No specific human data; animal studies suggest no significant effect on fertility at therapeutic doses. |