Dosing and uses of Canasa, Rowasa (mesalamine rectal)
Adult dosage forms and strengths
rectal suppository
- 1g (Canasa)
rectal suspension enema
- 4g/60mL (Rowasa)
Active Ulcerative Colitis
Indicated for treatment of active, mild-to-moderate distal ulcerative colitis, including ulcerative proctosigmoiditis and ulcerative proctitis
Rowasa: 60 mL PR qHS for 3-6 weeks, retain for 8 hr
Ulcerative Proctitis
Indicated for treatment of active ulcerative proctitis
Canasa: Insert one (1 g) rectal suppository PR qHS for 3-6 weeks, retain for 1-3 hr or longer if possible
Other Indications & Uses
Off-label: Crohn disease
Pediatric dosage forms and strengths
Safety and efficacy not established
Ulcerative Colitis (Orphan)
Canasa: Treatment of pediatric ulcerative colitis
Orphan indication sponsor
- Axcan Pharma US, Inc; 22 Iverness Parkway; Birmingham, AL 35242
Canasa, Rowasa (mesalamine rectal) adverse (side) effects
1-10%
Dizziness (3%)
Rectal pain (1.8%)
Fever (1.2%)
Rash (1.2%)
Acne (1.2%)
Colitis (1.2%)
Warnings
Contraindications
Hypersensitivity to mesalamine or salicylates
Active PUd
Severe renal failure
Breastfeeding
Rectal suspension: history of sulfite hypersensitivity
Adolescents with chicken pox or flu-like symptoms (risk of Reye syndrome)
Cautions
Sulfasalazine hypersensitivity, renal insufficiency, coagulation abnormalities, pyloric stenosis
Rare instances of pericarditis reported with mesalamine containing products; investigate any chest pain or dyspnea
Acute intolerance syndrome characterized by cramping, acute abdominal pain, and bloody diarrhea, sometimes fever, headache and a rash; in such cases prompt withdrawal is required
Follow instruction for use for rectal suppository and enema
For maximum benefit, retain rectal suppository for 1-3 hr; retain rectal suspension for 8 hr
Hepatic failure may occur, particularly with pre-existing liver impairment
May lead to falsely elevated test results when measuring urinary normetanephrine by liquid chromatography with electrochemical detection, because of the similarity in the chromatograms of normetanephrine and mesalamine’s main metabolite, N-acetyl aminosalicylic acid
Pregnancy and lactation
Pregnancy category: B
Lactation: Unknown whether distributed in breast milk, caution advised
Pregnancy categories
A: Generally acceptable. Controlled studies in pregnant women show no evidence of fetal risk.
B: May be acceptable. Either animal studies show no risk but human studies not available or animal studies showed minor risks and human studies done and showed no risk.
C: Use with caution if benefits outweigh risks. Animal studies show risk and human studies not available or neither animal nor human studies done.
D: Use in LIFE-THREATENING emergencies when no safer drug available. Positive evidence of human fetal risk.
X: Do not use in pregnancy. Risks involved outweigh potential benefits. Safer alternatives exist.
NA: Information not available.
Pharmacology of Canasa, Rowasa (mesalamine rectal)
Mechanism of action
Anti-inflammatory agent; mesalamine (5-aminosalicylic acid [5-ASA]) is the active component of sulfasalazine; specific MOA unknown, but thought to inhibit prostaglandin, TNF, and leukotriene synthesis/release in colon
Absorption
Suspension enema: Poor systemic absorption
Rectal suppository: Systemic absorption 15-38%
Peak plasma concentration: 353 ng/mL (mean concentration after 6 days)
Metabolism
Active drug, 5-aminosalicylic acid (5-ASA), is rapidly acetylated in colon wall and liver, independent of patient acetylator status, into N-acetyl-5-aminosalicylic acid (inactive)
Elimination
Half-life
- Rectal: 1.5-5 hr
- Metabolite (N-acetyl-5-salycylic acid): 6 hr
Excretion
- Suspension enema: Principally excreted in feces during subsequent bowel movements; 10-30% in urine
- Suppository: 80-90% in urine as metabolite
