Balsalazide
5-ASA
Aminosalicylates (5-ASA)
A prodrug that carries mesalazine (5-ASA) to the colon, where bacteria release it. Used for mild to moderate active ulcerative colitis.
Quick facts
- Group
- Aminosalicylates (5-ASA)
- Target
- Local anti-inflammatory action of mesalazine on the colonic mucosa (cyclooxygenase and lipoxygenase products)
- Key effects
- Headache · Abdominal pain · Respiratory infection
- Monitor
- Renal function before · Blood counts
- ATC
- A07EC04
No doses: the clinician sets them by the current guideline.
Mechanism of action
Balsalazide is mesalazine joined by an azo bond to an inert carrier. It passes the stomach and small bowel intact; in the colon bacterial azoreductases split it into mesalazine and the carrier, which is barely absorbed. Mesalazine acts on the colonic epithelium; it probably reduces production of prostaglandins and leukotrienes, which are increased in ulcerative colitis.
- Balsalazide reaches the colon intact
- Colonic bacteria cut the azo bond and release mesalazine
- Mesalazine calms mucosal inflammation locally
Indications
- Mildly to moderately active ulcerative colitis in adults and children aged 5 years and older Ulcerative colitis →
Adverse effects
Common
- Headache
- Abdominal pain, diarrhoea, nausea, vomiting
- Respiratory infection
- Joint pain
Contraindications
- Hypersensitivity to salicylates, aminosalicylates, balsalazide or its metabolites
Key interactions
- NSAIDs and other nephrotoxic drugs
- Higher risk of kidney injury; renal function is checked
- Azathioprine or mercaptopurine
- Higher risk of blood disorders; blood counts are checked
- Urinary normetanephrine tests
- Falsely high results with some laboratory methods
What is monitored
- Renal function before and during treatment
- Blood counts, especially in older patients
- Worsening colitis symptoms
Administration and safety
- Capsules are swallowed whole; if needed they can be opened onto applesauce, which may stain teeth or tongue.
- Can be taken with or without food; good fluid intake is encouraged.
- Avoided in pyloric stenosis or other upper GI obstruction.
Pregnancy and breastfeeding
Published data on mesalazine in pregnancy have not shown a reliable link with birth defects or miscarriage; active ulcerative colitis itself carries risks.
Nursing care
- Ask about aspirin or salicylate allergy and kidney disease before starting.
- Check creatinine at baseline and periodically.
- Teach that cramping, bloody diarrhoea, fever or rash may be drug intolerance, not just a flare, and must be reported.
- Advise sun protection if the skin is sensitive.
Pharmacokinetics
- Absorption
- Low and variable systemic absorption of balsalazide and its metabolites
- Metabolism
- Split by colonic bacteria; mesalazine is then acetylated
Test yourself
Think of the answer, then tap the question to see it.
How is balsalazide activated?
Colonic bacterial azoreductases split it and release mesalazine.
Which organ function is checked before and during treatment?
Kidney function.
Why can mesalazine intolerance be missed?
Its cramping, bloody diarrhoea and fever look like a colitis flare.
Connections
← Back to the class: Aminosalicylates (5-ASA)
Educational content on how drugs work; not a prescribing guide and no substitute for a health professional's advice. No doses are given.
Sources: DailyMed - BALSALAZIDE DISODIUM capsule (DailyMed (U.S. National Library of Medicine), 2023); Balsalazide: MedlinePlus Drug Information (MedlinePlus (U.S. National Library of Medicine), 2026); ATCDDD - ATC/DDD Index (WHO Collaborating Centre for Drug Statistics Methodology, 2026).
Spotted a mistake?We are always improving for the community. Tell us what is wrong and our team will review it.Report a mistake
Representative model, for educational purposes only.