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Class: Anti-inflammatory Agents
VA Class: GA900
Chemical Name: 5-[[4-[[(2-carboxyethyl)amino]carbonyl]-phenyl]azo]-2-hydroxybenzoic acid disodium dihydrate
Molecular Formula: C17H13N3Na2O6•2H2O
CAS Number: 150399-21-6
Brands: Colazal

Medically reviewed by on Apr 21, 2022. Written by ASHP.


Anti-inflammatory agent with GI tract activity; prodrug of mesalamine.

Uses for Balsalazide

Ulcerative Colitis

Management of active, mild to moderate ulcerative colitis.

Crohn’s Disease

May be beneficial in the management of Crohn's disease involving the colon.

Balsalazide Dosage and Administration


Oral Administration

Administer orally 3 times daily.


Available as balsalazide disodium; dosage expressed in terms of the salt.

Daily dosage of 6.75 g is equivalent to mesalamine 2.4 g.


Ulcerative Colitis

2.25 g (three 750-mg capsules) 3 times daily for 8 weeks. Some patients may require up to 12 weeks of therapy.

Crohn’s Disease

2–6 g daily may be used.

Prescribing Limits


Safety and efficacy not established beyond 12 weeks.

Cautions for Balsalazide


  • Known hypersensitivity to salicylates, balsalazide or its metabolites, or any ingredient in the formulation.


Major Toxicities

GI Effects

Exacerbation of preexisting symptoms of ulcerative colitis has been reported rarely.

General Precautions

Gastric Retention

Potential for prolonged gastric retention of basalazide capsules in patients with pyloric stenosis.

Sodium Content

Each g of balsalazide disodium (as commercially available 750-mg capsules) provides approximately 5 mEq (115 mg) of sodium.

Specific Populations


Category B.


Not known whether balsalazide is distributed into milk. Caution if used in nursing women.

Pediatric Use

Safety and efficacy not established in children <18 years of age.

Geriatric Use

Insufficient experience in patients >65 years of age to determine whether geriatric patients respond differently than younger adults.

Hepatic Impairment

Safety and efficacy not established in patients with hepatic impairment.

Renal Impairment

Safety and efficacy not established in patients with renal impairment. Use with caution in patients with renal impairment or a history of renal disease, since renal toxicity has been reported in patients receiving other mesalamine preparations.

Common Adverse Effects

Headache, abdominal pain, diarrhea, nausea, vomiting, respiratory infection, arthralgia, flatulence, fatigue.

Interactions for Balsalazide

Specific Drugs




Anti-infectives, oral

Potential for interference with bacterial metabolism and release of mesalamine in the colon

Theoretical; no formal interaction studies to date

Immunosuppressive agents (azathioprine, mercaptopurine)

Potential for interference with metabolism of immunosuppressive agents by thiopurine methyltransferase

Balsalazide Pharmacokinetics



Absolute bioavailability undetermined in healthy individuals; absorption very limited and variable.

Systemic exposure (based on mean AUC) in ulcerative colitis patients receiving 1.5 g twice daily for 1 year is up to 60 times greater than that in healthy individuals receiving the same dosage.


Plasma Protein Binding




Azo-linkage is cleaved in the colon by intestinal flora to form mesalamine and 4-aminobenzoyl-β-alanine.

Elimination Route

In healthy individuals, excreted principally in feces as metabolites (65%) and unchanged drug (<1%); also excreted in urine as N-acetylated metabolites (up to 25%) and unchanged drug (<1%).

In ulcerative colitis patients in remission after 1 year of balsalazide therapy, excreted in urine as N-acetylated metabolites (20–25%), mesalamine (<4%), and unchanged drug (<1%); fecal elimination not studied.





25°C (may be exposed to 15–30°C).


  • Prodrug with little or no pharmacologic activity until cleaved to form mesalamine (active moiety) and 4-aminobenzoyl-β-alanine.

  • Exerts local (not systemic) anti-inflammatory effects in the GI tract.

  • May reduce inflammation in the colon by inhibiting cyclooxygenase and lipoxygenase, which catalyze the formation of prostaglandin precursors (endoperoxides) and of leukotrienes and hydroxyeicosatetraenoic acids, respectively, from arachidonic acid and/or its metabolites.

Advice to Patients

  • Importance of women informing clinicians if they are or plan to become pregnant or plan to breast-feed.

  • Importance of informing clinicians of existing or contemplated concomitant therapy, including prescription and OTC drugs.

  • Importance of informing patients of other important precautionary information. (See Cautions.)


Excipients in commercially available drug preparations may have clinically important effects in some individuals; consult specific product labeling for details.

Please refer to the ASHP Drug Shortages Resource Center for information on shortages of one or more of these preparations.

Balsalazide Disodium


Dosage Forms


Brand Names




750 mg



AHFS DI Essentials™. © Copyright 2022, Selected Revisions May 1, 2006. American Society of Health-System Pharmacists, Inc., 4500 East-West Highway, Suite 900, Bethesda, Maryland 20814.

† Use is not currently included in the labeling approved by the US Food and Drug Administration.

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