ASACOL HD
Clinical safety rating: caution
Comprehensive clinical and safety monograph for ASACOL HD (ASACOL HD).
Mesalamine, the active ingredient, is a 5-aminosalicylic acid (5-ASA) derivative that acts locally in the colon to reduce inflammation by inhibiting prostaglandin production and leukotriene synthesis, likely through scavenging free radicals and blocking cytokine release.
| Metabolism | Primarily metabolized in the liver via acetylation to N-acetyl-5-aminosalicylic acid; minor metabolism by gut flora and intestinal mucosa. |
| Excretion | Primarily renal excretion of acetyl-5-ASA (about 80% of absorbed dose) and unchanged 5-ASA; minor fecal elimination (<20%). |
| Half-life | Terminal elimination half-life is 5-10 hours for 5-ASA and 5-10 hours for acetyl-5-ASA; clinically, it supports twice-daily dosing. |
| Protein binding | 5-ASA is approximately 40-50% bound to plasma proteins; the acetyl metabolite is about 80% bound. |
| Volume of Distribution | Approximately 0.6-1.0 L/kg; indicates distribution into total body water, with minimal penetration into tissues beyond the gastrointestinal tract. |
| Bioavailability | Oral (delayed-release): ~20-30% of a single dose is absorbed; the majority of the dose remains in the colon for local effect. |
| Onset of Action | Oral (delayed-release): 2-4 days for symptomatic improvement; full therapeutic effect may take up to 2-4 weeks. |
| Duration of Action | The duration is approximately 12-24 hours per dose; continuous daily dosing is required for maintenance of remission. |
2 tablets (1600 mg) once daily with or without food.
| Dosage form | TABLET, DELAYED RELEASE |
| Renal impairment | Severe renal impairment (GFR <30 mL/min): contraindicated. Moderate impairment (GFR 30–60 mL/min): caution, monitor renal function. |
| Liver impairment | No specific Child-Pugh adjustments exist; use caution in severe hepatic impairment due to limited data. |
| Pediatric use | Safety and efficacy not established in pediatric patients. |
| Geriatric use | No specific adjustments; monitor renal function and consider lower starting doses in elderly with renal impairment. |
| 1st trimester | Consult provider |
| 2nd trimester | Consult provider |
| 3rd trimester | Consult provider |
Clinical note
Comprehensive clinical and safety monograph for ASACOL HD (ASACOL HD).
| Breastfeeding | Mesalamine and its metabolite N-acetyl-5-aminosalicylic acid are excreted in human milk in low concentrations; M/P ratio approximately 0.3 for mesalamine; considered compatible with breastfeeding; caution in infants with sulfasalazine allergy. |
| Teratogenic Risk | FDA Pregnancy Category B; no evidence of teratogenicity in animal studies; first trimester: low risk based on human data but FDA notes unknown risk; second and third trimesters: no documented fetal harm, but use only if clearly needed. |
| Fetal Monitoring |
■ FDA Black Box Warning
None
| Serious Effects |
["Hypersensitivity to mesalamine, salicylates, or any component of the formulation","Severe hepatic impairment"]
| Precautions | ["Renal impairment (including minimal change nephropathy and interstitial nephritis)","Mesalamine-induced acute intolerance syndrome (cramping, abdominal pain, bloody diarrhea)","Hypersensitivity reactions (including myocarditis and pericarditis)","Hepatic failure risk in patients with pre-existing liver disease","Photosensitivity","Risk of worsening colitis in some patients"] |
| Food/Dietary | No known food interactions; may be taken with or without meals. Avoid alcohol if it worsens gastrointestinal symptoms. |
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| Monitor maternal renal function and complete blood count periodically; fetal assessment: standard prenatal care; consider ultrasound if signs of fetal distress. |
| Fertility Effects | No known adverse effects on fertility in human studies; animal studies show no impairment. |
| Clinical Pearls |
| Asacol HD (mesalamine) is formulated for delayed release in the colon; do not substitute with other mesalamine products due to differences in pharmacokinetics. Monitor renal function at baseline and periodically, as mesalamine can cause interstitial nephritis. Encourage patients to swallow tablets whole; do not cut, crush, or chew. Discontinue if signs of acute intolerance syndrome (cramping, abdominal pain, bloody diarrhea, fever, headache, rash). |
| Patient Advice | Take Asacol HD exactly as prescribed; swallow tablets whole with or without food. · Do not crush, chew, or break tablets; the coating protects the medication until it reaches your colon. · If you miss a dose, take it as soon as you remember, unless it is almost time for your next dose; do not double up. · Report any new or worsening symptoms like severe stomach pain, cramping, bloody diarrhea, fever, or rash immediately. · Drink plenty of fluids to stay hydrated, but no specific food restrictions apply. · Regular blood tests (e.g., kidney function) are needed while on this medication. · Store at room temperature, away from moisture and heat. |