CANASA
Clinical safety rating: caution
Comprehensive clinical and safety monograph for CANASA (CANASA).
Mesalamine (5-aminosalicylic acid) is an anti-inflammatory agent that inhibits prostaglandin and leukotriene synthesis, scavenges reactive oxygen species, and inhibits cytokine production and nuclear factor-kappa B (NF-κB) activation in colonic mucosa.
| Metabolism | Metabolized via N-acetylation to N-acetyl-5-aminosalicylic acid by N-acetyltransferase 1 (NAT1) in the liver and colonic epithelium; also metabolized by the gut microbiome. |
| Excretion | Renal (approximately 20-30% as unchanged drug and metabolites, primarily N-acetyl-5-aminosalicylic acid); biliary/fecal (the remainder, with extensive enterohepatic circulation). |
| Half-life | Terminal elimination half-life of mesalamine is approximately 0.5-2 hours; however, the N-acetyl metabolite has a half-life of 5-10 hours. Due to the sustained-release formulation, clinical effects persist beyond the plasma half-life. |
| Protein binding | Mesalamine is approximately 40-50% bound to plasma proteins, primarily albumin. The N-acetyl metabolite is about 15-20% bound. |
| Volume of Distribution | Apparent volume of distribution is approximately 0.15-0.3 L/kg, indicating limited systemic distribution and primarily local action in the gastrointestinal tract. |
| Bioavailability | Rectal administration: approximately 15-30% of the dose is systemically absorbed; the remainder acts locally in the colon. Oral mesalamine formulations have lower systemic bioavailability (20-30%) due to extensive first-pass metabolism. |
| Onset of Action | Rectal administration: clinical improvement may be seen within 3-21 days for ulcerative colitis. |
| Duration of Action | With CANASA (mesalamine) rectal suppositories, the duration of clinical effect is approximately 24 hours, supporting once-daily dosing. The sustained-release formulation allows for prolonged local exposure. |
Mesalamine 1000 mg rectally once daily at bedtime, or 500 mg rectally twice daily (morning and evening). Administered as suppository for ulcerative colitis.
| Dosage form | SUPPOSITORY |
| Renal impairment | CrCl 30-90 mL/min: No adjustment recommended. CrCl <30 mL/min: Avoid use due to risk of mesalamine accumulation and nephrotoxicity. Not studied in ESRD. |
| Liver impairment | No specific guidelines exist; use caution in severe hepatic impairment (Child-Pugh C) due to limited data. |
| Pediatric use | Not FDA-approved for pediatric use. Off-label dosing: 25-50 mg/kg/day divided every 6-8 hours, but safety and efficacy not established. |
| Geriatric use | No specific dose adjustment; monitor renal function closely due to age-related decline, consider lower starting dose or increased interval. |
| 1st trimester | Consult provider |
| 2nd trimester | Consult provider |
| 3rd trimester | Consult provider |
Clinical note
Comprehensive clinical and safety monograph for CANASA (CANASA).
| Breastfeeding | Mesalamine and its metabolite N-acetyl-5-ASA are excreted in breastmilk in low concentrations. M/P ratio for mesalamine is approximately 0.45. Diarrhea reported in some breastfed infants; weigh benefits of breastfeeding against potential risk. Consider monitoring infant for loose stools. |
| Teratogenic Risk | Pregnancy Category B. First trimester: No evidence of teratogenicity in animal studies; human data limited but not suggestive of increased malformation risk. Second and third trimesters: Potential for oligohydramnios and fetal renal impairment with high doses; monitor amniotic fluid index if used near term. |
■ FDA Black Box Warning
None.
| Serious Effects |
["Hypersensitivity to mesalamine, salicylates, or any component of the formulation","History of hypersensitivity to sulfasalazine"]
| Precautions | ["Renal impairment (including nephrotic syndrome, interstitial nephritis, and renal failure) requires monitoring of renal function.","Patients with pre-existing renal disease, concomitant nephrotoxic drugs, or hypovolemia at increased risk.","Mesalamine-induced acute intolerance syndrome (cramping, abdominal pain, bloody diarrhea, sometimes fever, headache, rash) may occur and requires discontinuation.","Hepatic failure, particularly in patients with pre-existing liver disease, has been reported.","Blood dyscrasias (agranulocytosis, aplastic anemia, thrombocytopenia) have been reported; monitor CBC if signs of infection or bleeding occur.","Sulfasalazine allergy: cross-sensitivity possible in patients allergic to sulfasalazine."] |
| Food/Dietary | No specific food interactions. Take with or without food. Avoid alcohol if it exacerbates gastrointestinal symptoms. |
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| Fetal Monitoring | Maternal: Renal function, CBC with differential, liver enzymes. Fetal: Ultrasound for amniotic fluid volume and fetal renal anatomy if used in second/third trimester, especially at high doses. |
| Fertility Effects | No known adverse effects on human fertility. Animal studies show no impairment of fertility at clinically relevant doses. |
| Clinical Pearls | Canasa (mesalamine) is a rectal suppository for active ulcerative colitis, limited to distal disease. Administer after bowel movement for retention. May cause staining of stools. Avoid in patients with salicylate allergy or severe renal impairment. Monitor renal function periodically. |
| Patient Advice | Use the suppository after a bowel movement to ensure retention. · Wash hands before and after insertion. · Lie on your side for 15-20 minutes after insertion to allow melting. · Do not use if foil wrap is damaged or missing. · Contact your doctor if rectal bleeding worsens or if you experience severe abdominal pain. · Store at room temperature, away from heat and moisture. |