ROWASA

Clinical safety rating: caution

Comprehensive clinical and safety monograph for ROWASA (ROWASA).

How it works

5-aminosalicylic acid (5-ASA) inhibits prostaglandin and leukotriene synthesis, reduces neutrophil chemotaxis, and scavenges reactive oxygen species, thereby exerting anti-inflammatory effects on the colonic mucosa.

What the body does with it

Metabolism	Primarily acetylated in the intestinal mucosa and liver to N-acetyl-5-ASA by N-acetyltransferase 1 (NAT1).
Excretion	Renal: approximately 78% (primarily N-acetyl-5-ASA and unchanged 5-ASA). Fecal: approximately 20% (unabsorbed drug). Biliary: negligible (<1%).
Half-life	Terminal elimination half-life of mesalamine (5-ASA) is approximately 0.5-2 hours; N-acetyl-5-ASA half-life is 5-10 hours. Rectal administration prolongs local retention without altering systemic half-life.
Protein binding	Mesalamine: approximately 40% bound to plasma proteins. N-acetyl-5-ASA: about 80% bound.
Volume of Distribution	Apparent Vd after IV administration: approximately 0.2 L/kg; reflects limited tissue distribution and primarily extracellular fluid.
Bioavailability	Rectal suspension: systemic bioavailability 10-35% (due to local absorption and first-pass metabolism). Oral formulations (not relevant for ROWASA, but for context: 20-30% for delayed-release). Intravenous: 100%.
Onset of Action	Rectal suspension: clinical improvement may be noted within 3-21 days. Rectal suppository: onset typically within 1-2 weeks.
Duration of Action	Duration of clinical effect is dose- and regimen-dependent; rectal formulations provide local effect lasting up to 24 hours. Maintenance therapy typically requires daily or twice-daily dosing.

Classification & Brands

Dosing & administration

Rectal suspension enema: 4 g (60 mL) once daily at bedtime, retained for at least 8 hours. Rectal suppository: 500 mg twice daily (one in the morning and one at bedtime).

Dosage form	SUPPOSITORY
Renal impairment	Contraindicated in patients with pre-existing renal impairment. For GFR <50 mL/min: avoid use. GFR 50-80 mL/min: caution, monitor renal function. GFR >80 mL/min: no adjustment needed.
Liver impairment	Child-Pugh A: no adjustment. Child-Pugh B: use with caution, monitor for hepatotoxicity. Child-Pugh C: not recommended due to lack of data.
Pediatric use	Not FDA-approved for pediatric use. Off-label: 5-10 years: rectal suspension 2 g (30 mL) once daily; >10 years: 4 g (60 mL) once daily. Safety and efficacy not fully established.
Geriatric use	Use with caution due to higher risk of renal impairment. Monitor renal function and dose adjust accordingly. Observe for increased susceptibility to adverse effects (e.g., colitis exacerbation).

Use during pregnancy

1st trimester	Consult provider
2nd trimester	Consult provider
3rd trimester	Consult provider

Clinical note

Comprehensive clinical and safety monograph for ROWASA (ROWASA).

Breastfeeding	Mesalamine is excreted into breast milk in low concentrations (M/P ratio 0.22-0.36). Considered compatible with breastfeeding, but monitor infant for diarrhea or allergic reactions. Alternative drug (sulfasalazine) may cause kernicterus in jaundiced neonates; mesalamine preferred.
Teratogenic Risk	Pregnancy Category B. No evidence of teratogenicity in human studies, but risk cannot be ruled out. First trimester: low risk; second and third trimesters: associated with neonatal renal dysfunction if used near term due to mesalamine's theoretical risk of interstitial nephritis.

Warnings & precautions

■ FDA Black Box Warning

None

Side Effect Profile

Common Effects	Stomach pain epigastric pain Flatulence Headache Vomiting Diarrhea Nausea Abdominal pain Rash
Serious Effects

Absolute Contraindications

["Hypersensitivity to mesalamine, salicylates, or any component of the formulation.","Patients with known renal impairment (severe)."]

Clinical Precautions

Precautions

["Renal impairment (including interstitial nephritis) reported; monitor renal function.","Patients with pyloric stenosis may have prolonged gastric retention.","Sulfite sensitivity (contains sulfites); may cause allergic reactions in susceptible individuals.","Exacerbation of colitis symptoms occasionally reported.","Mesalamine-induced acute intolerance syndrome (cramping, abdominal pain, bloody diarrhea) may occur."]

Clinical Tips & Counseling

Drug interactions

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ROWASA

Clinical safety rating: caution

Comprehensive clinical and safety monograph for ROWASA (ROWASA).

How it works

What the body does with it

Metabolism	Primarily acetylated in the intestinal mucosa and liver to N-acetyl-5-ASA by N-acetyltransferase 1 (NAT1).
Excretion	Renal: approximately 78% (primarily N-acetyl-5-ASA and unchanged 5-ASA). Fecal: approximately 20% (unabsorbed drug). Biliary: negligible (<1%).
Half-life	Terminal elimination half-life of mesalamine (5-ASA) is approximately 0.5-2 hours; N-acetyl-5-ASA half-life is 5-10 hours. Rectal administration prolongs local retention without altering systemic half-life.
Protein binding	Mesalamine: approximately 40% bound to plasma proteins. N-acetyl-5-ASA: about 80% bound.
Volume of Distribution	Apparent Vd after IV administration: approximately 0.2 L/kg; reflects limited tissue distribution and primarily extracellular fluid.
Bioavailability	Rectal suspension: systemic bioavailability 10-35% (due to local absorption and first-pass metabolism). Oral formulations (not relevant for ROWASA, but for context: 20-30% for delayed-release). Intravenous: 100%.
Onset of Action	Rectal suspension: clinical improvement may be noted within 3-21 days. Rectal suppository: onset typically within 1-2 weeks.
Duration of Action	Duration of clinical effect is dose- and regimen-dependent; rectal formulations provide local effect lasting up to 24 hours. Maintenance therapy typically requires daily or twice-daily dosing.

Classification & Brands

Dosing & administration

Rectal suspension enema: 4 g (60 mL) once daily at bedtime, retained for at least 8 hours. Rectal suppository: 500 mg twice daily (one in the morning and one at bedtime).

Dosage form	SUPPOSITORY
Renal impairment	Contraindicated in patients with pre-existing renal impairment. For GFR <50 mL/min: avoid use. GFR 50-80 mL/min: caution, monitor renal function. GFR >80 mL/min: no adjustment needed.
Liver impairment	Child-Pugh A: no adjustment. Child-Pugh B: use with caution, monitor for hepatotoxicity. Child-Pugh C: not recommended due to lack of data.
Pediatric use	Not FDA-approved for pediatric use. Off-label: 5-10 years: rectal suspension 2 g (30 mL) once daily; >10 years: 4 g (60 mL) once daily. Safety and efficacy not fully established.
Geriatric use	Use with caution due to higher risk of renal impairment. Monitor renal function and dose adjust accordingly. Observe for increased susceptibility to adverse effects (e.g., colitis exacerbation).

Use during pregnancy

1st trimester	Consult provider
2nd trimester	Consult provider
3rd trimester	Consult provider

Clinical note

Comprehensive clinical and safety monograph for ROWASA (ROWASA).

Breastfeeding	Mesalamine is excreted into breast milk in low concentrations (M/P ratio 0.22-0.36). Considered compatible with breastfeeding, but monitor infant for diarrhea or allergic reactions. Alternative drug (sulfasalazine) may cause kernicterus in jaundiced neonates; mesalamine preferred.
Teratogenic Risk	Pregnancy Category B. No evidence of teratogenicity in human studies, but risk cannot be ruled out. First trimester: low risk; second and third trimesters: associated with neonatal renal dysfunction if used near term due to mesalamine's theoretical risk of interstitial nephritis.

Warnings & precautions

■ FDA Black Box Warning

None

Side Effect Profile

Common Effects	Stomach pain epigastric pain Flatulence Headache Vomiting Diarrhea Nausea Abdominal pain Rash
Serious Effects

Absolute Contraindications

["Hypersensitivity to mesalamine, salicylates, or any component of the formulation.","Patients with known renal impairment (severe)."]