olsalazine
Brand: Dipentum
Prototype: mesalamine
Drug Class: aminosalicylate (5-ASA dimer prodrug)
Drug Family: GI agent
Subclass: colonic 5-ASA prodrug
Organ Systems: gastrointestinal
Mechanism of Action
Dimer of two 5-ASA molecules linked by an azo bond. Colonic bacteria cleave the azo bond, releasing two molecules of 5-ASA locally in the colon, where they inhibit inflammatory mediator production and mucosal inflammation.
COX and lipoxygenase pathways in colonic mucosa
Indications
- maintenance of remission in ulcerative colitis in patients intolerant to sulfasalazine
Contraindications
- hypersensitivity to salicylates
- renal impairment
Adverse Effects
Common
- diarrhea (10–20% — more frequent than other 5-ASA agents)
- abdominal pain
- nausea
- headache
Serious
- renal toxicity
- hepatotoxicity
- pericarditis (rare)
Pharmacokinetics (ADME)
| Absorption | minimal systemic absorption; acts locally |
| Distribution | colonic |
| Metabolism | azo bond cleaved by colonic bacteria to yield two 5-ASA molecules |
| Excretion | fecal |
| Half-life | ~0.9 hours (olsalazine); ~0.5–1.5 hours (5-ASA) |
| Onset | days to weeks |
| Peak | weeks |
| Duration | continuous |
| Protein Binding | >99% |
| Vd | low |
Drug Interactions
| Drug / Agent | Mechanism | Severity |
|---|---|---|
| azathioprine / 6-MP | TPMT inhibition by 5-ASA increases 6-MP toxicity | major |
| warfarin | 5-ASA may increase anticoagulant effect | moderate |
Nursing Considerations
- Diarrhea is the most common adverse effect and may be dose-limiting; administer in divided doses with food to reduce incidence.
- Monitor renal function periodically; aminosalicylates carry risk of interstitial nephritis.
- Educate patients this is a maintenance medication and should not be stopped without consulting the prescriber.
- Monitor CBC and LFTs periodically; report jaundice, fatigue, or pallor.
Clinical Pearls
- Olsalazine produces more watery diarrhea than other aminosalicylates, likely due to colonic secretory effects of the dimer before cleavage; taking with food reduces this problem.
- Specifically indicated for patients who cannot tolerate sulfasalazine, offering equivalent efficacy without the sulfa-related side effects.
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.