ASACOL
Clinical safety rating: caution
Comprehensive clinical and safety monograph for ASACOL (ASACOL).
Asacol (mesalamine) is an aminosalicylate that exerts anti-inflammatory effects in the colon via inhibition of prostaglandin and leukotriene synthesis, particularly by blocking cyclooxygenase and lipoxygenase pathways, and by scavenging reactive oxygen species. It also inhibits cytokine production and reduces mucosal inflammation.
| Metabolism | Mesalamine is primarily metabolized in the liver and colonic mucosa to N-acetyl-5-aminosalicylic acid via N-acetyltransferase 1 (NAT1) and N-acetyltransferase 2 (NAT2). A portion is also acetylated in the gut wall. The parent drug and its metabolite are excreted in feces (mostly as mesalamine) and urine (mainly as N-acetyl-5-aminosalicylic acid). |
| Excretion | Renal (80% as 5-ASA and N-acetyl-5-ASA), fecal (20%) |
| Half-life | Terminal half-life: 0.6-1.4 hours for 5-ASA; 6-12 hours for N-acetyl-5-ASA. Clinical context: short t1/2 necessitates multiple daily dosing for sustained colonic exposure. |
| Protein binding | 5-ASA: ~43% bound to albumin; N-acetyl-5-ASA: ~73% bound to albumin |
| Volume of Distribution | 5-ASA: 0.2-0.3 L/kg; N-acetyl-5-ASA: 0.1-0.2 L/kg. Clinical meaning: low Vd indicates limited extravascular distribution, primarily local colonic action. |
| Bioavailability | Oral (delayed-release): ~28% (systemic from colonic absorption). Rectal: ~10-20% (systemic). Note: local colonic bioavailability is high but systemic is low. |
| Onset of Action | Oral (delayed-release): 3-5 hours (colonic levels). Rectal (suppository/enema): 1-3 hours for local effect. |
| Duration of Action | Oral: 24 hours with multiple daily doses. Rectal: 8-12 hours for enema; 12-24 hours for suppository. Clinical notes: continuous dosing required for maintenance of remission. |
| Action Class | 5- Aminosalicylic acid (5-ASA) |
| Brand Substitutes | Tidocol 400mg Tablet, Mezakool 400mg Tablet, Zemakool Tablet, Walasa 400mg Tablet, Mesalacure 400mg Tablet |
800 mg orally three times daily or 1600 mg three times daily for 6 weeks; maintenance: 1.6 g daily in divided doses.
| Dosage form | TABLET, DELAYED RELEASE |
| Renal impairment | GFR 30-50 mL/min: reduce dose by 50%; GFR <30 mL/min: contraindicated. |
| Liver impairment | Child-Pugh A: no adjustment; Child-Pugh B or C: contraindicated due to risk of nephrotoxicity. |
| Pediatric use | Weight ≥40 kg: same as adult; 17-39 kg: 800 mg twice daily; <17 kg: not recommended. |
| Geriatric use | No specific dose adjustment, but monitor renal function; use lowest effective dose due to age-related renal decline. |
| 1st trimester | Consult provider |
| 2nd trimester | Consult provider |
| 3rd trimester | Consult provider |
Clinical note
Comprehensive clinical and safety monograph for ASACOL (ASACOL).
| Breastfeeding | Mesalamine (5-ASA) is excreted into breast milk in low concentrations (M/P ratio approximately 0.1-0.4). No adverse effects reported in nursing infants. Use with caution; monitor for diarrhea in infant. |
| Teratogenic Risk | FDA Pregnancy Category B. No evidence of teratogenicity in animal studies. Limited human data; risk of congenital anomalies not increased in first trimester exposure. No known fetal risks in second or third trimesters. Inflammatory bowel disease activity should be controlled to reduce adverse pregnancy outcomes. |
■ FDA Black Box Warning
None
| Serious Effects |
Hypersensitivity to mesalamine, salicylates, or any component of the formulation; hypersensitivity to sulfasalazine (cross-reactivity possible); severe renal impairment (CrCl <30 mL/min).
| Precautions | Renal impairment (monitor renal function), mesalamine-induced acute intolerance syndrome (cramping, abdominal pain, bloody diarrhea, fever, headache, rash), hypersensitivity reactions (including myocarditis and pericarditis), hepatic toxicity, and exacerbation of symptoms in patients with inflammatory bowel disease. Avoid use in patients with severe renal impairment (CrCl <30 mL/min). |
| Food/Dietary | No specific food interactions reported. However, a high-fiber diet may potentially affect absorption; maintain consistent dietary habits. |
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| Fetal Monitoring |
| Monitor maternal disease activity. No specific fetal monitoring required; standard prenatal care. Assess renal function in mother and infant due to potential nephrotoxicity. |
| Fertility Effects | No known adverse effects on fertility in human studies. Mesalamine does not impair spermatogenesis or oocyte function. Disease control may improve fertility outcomes. |
| Clinical Pearls | ASACOL (mesalamine) is a delayed-release formulation designed to release the active drug in the terminal ileum and colon. It is used for induction and maintenance of remission in mild-to-moderate ulcerative colitis. Avoid concurrent administration with antacids, which can prematurely dissolve the coating. Monitor renal function regularly due to potential interstitial nephritis. Discontinue if acute intolerance syndrome (cramping, abdominal pain, bloody diarrhea, fever) occurs. |
| Patient Advice | Swallow tablets whole; do not crush, break, or chew. · Take with or without food, but consistently with respect to meals. · Drink plenty of fluids to prevent dehydration. · Report any unusual bleeding, bruising, or signs of kidney problems (e.g., swelling, fatigue). · Avoid antacids within 2 hours of taking this medication. · Store at room temperature away from moisture and heat. |