balsalazide
Brand: Colazal, Giazo
Prototype: mesalamine
Drug Class: aminosalicylate (5-ASA prodrug)
Drug Family: GI agent
Subclass: colonic 5-ASA prodrug
Organ Systems: gastrointestinal
Mechanism of Action
Prodrug of mesalamine (5-aminosalicylic acid) linked to an inert carrier (4-aminobenzoyl-beta-alanine) by an azo bond, which is cleaved by colonic bacteria to release active 5-ASA locally. 5-ASA suppresses inflammatory mediators in the colonic mucosa without significant systemic absorption.
COX and lipoxygenase pathways in colonic mucosa
Indications
- mild to moderately active ulcerative colitis
Contraindications
- hypersensitivity to salicylates or balsalazide
- renal impairment (use with caution)
Adverse Effects
Common
- headache
- nausea
- abdominal pain
- diarrhea
- fatigue
Serious
- renal toxicity (nephrotoxicity — class effect)
- hepatotoxicity (rare)
- pericarditis
- pancreatitis (rare)
Pharmacokinetics (ADME)
| Absorption | minimal systemic absorption; active 5-ASA released in colon |
| Distribution | primarily local colonic distribution |
| Metabolism | azo bond cleaved by colonic bacteria; 5-ASA acts locally; absorbed 5-ASA undergoes N-acetylation |
| Excretion | primarily fecal; minor renal |
| Half-life | ~1 hour (5-ASA) |
| Onset | days to weeks |
| Peak | weeks |
| Duration | continuous dosing |
| Protein Binding | >99% (5-ASA if absorbed) |
| Vd | low |
Drug Interactions
| Drug / Agent | Mechanism | Severity |
|---|---|---|
| nephrotoxic agents | additive renal toxicity risk | moderate |
| azathioprine or 6-MP | aminosalicylates inhibit TPMT, increasing 6-MP/azathioprine toxicity | major |
Nursing Considerations
- Monitor renal function (BUN, creatinine) before and periodically during therapy; aminosalicylates carry a class risk of renal impairment.
- Administer with food to improve tolerability; capsules may be opened and sprinkled on food for patients with dysphagia.
- Assess for and report symptoms of pericarditis (chest pain, fever, dyspnea) or exacerbation of colitis.
- Educate patients that maintenance therapy reduces relapse risk in UC; non-compliance is a major risk factor for disease flare.
Clinical Pearls
- Balsalazide delivers a high concentration of 5-ASA to the colon with minimal systemic exposure, making it well-tolerated and appropriate for long-term maintenance of UC remission.
- Azathioprine and 6-mercaptopurine levels must be carefully monitored if combined with balsalazide, as 5-ASA inhibits TPMT (thiopurine methyltransferase), increasing risk of myelosuppression.
Safety Profile
Pregnancy use-with-caution
Lactation use-with-caution
Renal Adjustment Required
Hepatic Adjustment Not required
TDM Not required
Concordance Terms
Cross-referenced clinical concepts — click any term to see all content where it appears.