COLAZAL

Clinical safety rating: caution

Comprehensive clinical and safety monograph for COLAZAL (COLAZAL).

How it works

Balsalazide is a prodrug that is converted in the colon by bacterial azoreductases to mesalamine (5-aminosalicylic acid), which inhibits cyclooxygenase and lipoxygenase pathways, reducing prostaglandin and leukotriene synthesis, and scavenges reactive oxygen species, thereby decreasing colonic inflammation.

What the body does with it

Metabolism	Primarily metabolized in the colon by bacterial azoreductases to mesalamine and 4-aminobenzoyl-beta-alanine. Mesalamine undergoes hepatic and intestinal metabolism via N-acetyltransferase to N-acetyl-5-aminosalicylic acid. Minor renal excretion of parent drug.
Excretion	Primarily excreted in feces as balsalazide (prodrug) and its active metabolite, mesalamine (5-ASA). Minimal renal excretion (<1% unchanged). Biliary excretion of metabolites is negligible.
Half-life	Balsalazide: approximately 0.5-1 hour. Mesalamine (active): approximately 0.5-1.5 hours. The clinical effect is prolonged due to local activity in the colon. Systemic half-life is short; elimination is rapid.
Protein binding	Balsalazide: approximately 99% bound to plasma proteins. Mesalamine: approximately 40-50% bound to plasma proteins, primarily albumin.
Volume of Distribution	Balsalazide: Vd approximately 8-12 L (0.1-0.2 L/kg). Mesalamine: Vd approximately 7-10 L (0.1-0.15 L/kg). The small Vd reflects limited extravascular distribution; drug remains largely in the colonic lumen and local tissues.
Bioavailability	Oral balsalazide: approximately 10-15% systemically absorbed as mesalamine after colonic bacterial cleavage. The prodrug itself has negligible bioavailability (<1%) due to poor absorption. Most is activated in the colon.
Onset of Action	Oral: clinical improvement may be seen within 3 to 21 days; full therapeutic effect often requires 2 to 4 weeks. Rectal (not applicable; no rectal formulation). Onset is delayed due to colonic delivery and local action.
Duration of Action	Duration of clinical effect is typically 8 to 12 hours for local colonic concentrations. Dosing is twice daily (750 mg per capsule) for maintenance of remission. Duration is limited by drug metabolism and clearance.

Classification & Brands

Dosing & administration

1.5 g (3 capsules) orally twice daily for ulcerative colitis; 3 capsules (0.75 g each) three times daily for Crohn's disease (off-label). Total daily dose: 3 g.

Dosage form	CAPSULE
Renal impairment	Contraindicated in severe renal impairment (eGFR <30 mL/min/1.73 m²). For eGFR 30-50: reduce dose by 50%; for eGFR 50-80: monitor renal function; no adjustment for eGFR >80.
Liver impairment	No specific adjustment recommended. Use caution in severe hepatic impairment (Child-Pugh C) as balsalazide is prodrug requiring colonic bacterial activation; systemic exposure may be altered.
Pediatric use	Children ≥5 years: 2.25 g/day (6 capsules) in divided doses (e.g., 0.75 g three times daily) for ulcerative colitis. Weight-based: 36-47 kg: 1.5 g/day; 48-59 kg: 2.25 g/day; ≥60 kg: 3 g/day.
Geriatric use	Initiate at lower end of dosing range (e.g., 1.5 g/day) due to age-related renal decline. Monitor renal function closely; adjust per renal function. Avoid in eGFR <30.

Use during pregnancy

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

Clinical note

Comprehensive clinical and safety monograph for COLAZAL (COLAZAL).

Breastfeeding	Balsalazide is excreted into human breast milk in low concentrations. The milk-to-plasma ratio is unknown. Due to potential for adverse effects in nursing infants (diarrhea, bloody stools), caution is advised. Consider the developmental and health benefits of breastfeeding along with the mother's clinical need for colazal.
Teratogenic Risk	Pregnancy Category B. No evidence of teratogenicity in animal studies; limited human data. Risk of fetal harm cannot be ruled out; use only if clearly needed. First trimester: avoid unless essential. Second and third trimesters: no known increased risk of malformations, but monitor for potential neonatal effects such as diarrhea or allergic reactions.

Warnings & precautions

■ FDA Black Box Warning

None

Side Effect Profile

Serious Effects

Absolute Contraindications

["Hypersensitivity to balsalazide, mesalamine, salicylates, or any component of the formulation","History of severe allergic reaction to sulfasalazine or mesalamine"]

Clinical Precautions

Precautions	["Renal impairment: Monitor renal function; risk of interstitial nephritis","Hepatic impairment: Potential hepatotoxicity","Gastrointestinal: May cause exacerbation of colitis or rectal bleeding","Hypersensitivity: Severe allergic reactions including Stevens-Johnson syndrome","Use in children aged 5-17 years: Safety established only for mild to moderate active UC"]
Food/Dietary	No significant food interactions. However, taking with food may reduce gastrointestinal irritation. No specific dietary restrictions required.

Clinical Tips & Counseling

Drug interactions

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COLAZAL

Clinical safety rating: caution

Comprehensive clinical and safety monograph for COLAZAL (COLAZAL).

How it works

What the body does with it

Metabolism	Primarily metabolized in the colon by bacterial azoreductases to mesalamine and 4-aminobenzoyl-beta-alanine. Mesalamine undergoes hepatic and intestinal metabolism via N-acetyltransferase to N-acetyl-5-aminosalicylic acid. Minor renal excretion of parent drug.
Excretion	Primarily excreted in feces as balsalazide (prodrug) and its active metabolite, mesalamine (5-ASA). Minimal renal excretion (<1% unchanged). Biliary excretion of metabolites is negligible.
Half-life	Balsalazide: approximately 0.5-1 hour. Mesalamine (active): approximately 0.5-1.5 hours. The clinical effect is prolonged due to local activity in the colon. Systemic half-life is short; elimination is rapid.
Protein binding	Balsalazide: approximately 99% bound to plasma proteins. Mesalamine: approximately 40-50% bound to plasma proteins, primarily albumin.
Volume of Distribution	Balsalazide: Vd approximately 8-12 L (0.1-0.2 L/kg). Mesalamine: Vd approximately 7-10 L (0.1-0.15 L/kg). The small Vd reflects limited extravascular distribution; drug remains largely in the colonic lumen and local tissues.
Bioavailability	Oral balsalazide: approximately 10-15% systemically absorbed as mesalamine after colonic bacterial cleavage. The prodrug itself has negligible bioavailability (<1%) due to poor absorption. Most is activated in the colon.
Onset of Action	Oral: clinical improvement may be seen within 3 to 21 days; full therapeutic effect often requires 2 to 4 weeks. Rectal (not applicable; no rectal formulation). Onset is delayed due to colonic delivery and local action.
Duration of Action	Duration of clinical effect is typically 8 to 12 hours for local colonic concentrations. Dosing is twice daily (750 mg per capsule) for maintenance of remission. Duration is limited by drug metabolism and clearance.

Classification & Brands

Dosing & administration

1.5 g (3 capsules) orally twice daily for ulcerative colitis; 3 capsules (0.75 g each) three times daily for Crohn's disease (off-label). Total daily dose: 3 g.

Dosage form	CAPSULE
Renal impairment	Contraindicated in severe renal impairment (eGFR <30 mL/min/1.73 m²). For eGFR 30-50: reduce dose by 50%; for eGFR 50-80: monitor renal function; no adjustment for eGFR >80.
Liver impairment	No specific adjustment recommended. Use caution in severe hepatic impairment (Child-Pugh C) as balsalazide is prodrug requiring colonic bacterial activation; systemic exposure may be altered.
Pediatric use	Children ≥5 years: 2.25 g/day (6 capsules) in divided doses (e.g., 0.75 g three times daily) for ulcerative colitis. Weight-based: 36-47 kg: 1.5 g/day; 48-59 kg: 2.25 g/day; ≥60 kg: 3 g/day.
Geriatric use	Initiate at lower end of dosing range (e.g., 1.5 g/day) due to age-related renal decline. Monitor renal function closely; adjust per renal function. Avoid in eGFR <30.

Use during pregnancy

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

Clinical note

Comprehensive clinical and safety monograph for COLAZAL (COLAZAL).

Breastfeeding	Balsalazide is excreted into human breast milk in low concentrations. The milk-to-plasma ratio is unknown. Due to potential for adverse effects in nursing infants (diarrhea, bloody stools), caution is advised. Consider the developmental and health benefits of breastfeeding along with the mother's clinical need for colazal.
Teratogenic Risk	Pregnancy Category B. No evidence of teratogenicity in animal studies; limited human data. Risk of fetal harm cannot be ruled out; use only if clearly needed. First trimester: avoid unless essential. Second and third trimesters: no known increased risk of malformations, but monitor for potential neonatal effects such as diarrhea or allergic reactions.

Warnings & precautions

■ FDA Black Box Warning

None

Side Effect Profile

Serious Effects

Absolute Contraindications

["Hypersensitivity to balsalazide, mesalamine, salicylates, or any component of the formulation","History of severe allergic reaction to sulfasalazine or mesalamine"]

Clinical Precautions

Precautions	["Renal impairment: Monitor renal function; risk of interstitial nephritis","Hepatic impairment: Potential hepatotoxicity","Gastrointestinal: May cause exacerbation of colitis or rectal bleeding","Hypersensitivity: Severe allergic reactions including Stevens-Johnson syndrome","Use in children aged 5-17 years: Safety established only for mild to moderate active UC"]
Food/Dietary	No significant food interactions. However, taking with food may reduce gastrointestinal irritation. No specific dietary restrictions required.

Clinical Tips & Counseling

Drug interactions

Loading safety data…