Mesalamine and olsalazine are cornerstone drugs in the treatment of ulcerative colitis, belonging to the 5-aminosalicylic acid (5-ASA) family. This guide explains how these drugs work, when to use each, correct dosing, comparisons, and common mistakes—written for students, clinicians, and informed patients.
What Are Mesalamine and Olsalazine?
Mesalamine (5-ASA)
Mesalamine is the active anti-inflammatory compound that acts locally on the intestinal mucosa to reduce inflammation in ulcerative colitis.
Common brand names:
1. AsacolOlsalazine
Olsalazine is a prodrug that is converted by colonic bacteria into two molecules of mesalamine, delivering 5-ASA directly to the colon.
Brand name:
Dipentum
Drug Class: 5-Aminosalicylic Acid (5-ASA)
Both drugs belong to the 5-ASA class, which is considered first-line therapy for mild to moderate ulcerative colitis.
Related entities:
1. Ulcerative colitisMechanism of Action
Mesalamine
Mesalamine works topically in the gut by:
- Inhibiting cyclooxygenase (COX) and lipoxygenase
- Reducing prostaglandins and leukotrienes
- Decreasing TNF-α and inflammatory cytokines
- Scavenging free radicals
Result: Reduced mucosal inflammation and symptom control
Olsalazine
- Olsalazine reaches the colon intact
- Colonic bacteria split it into two mesalamine molecules
- Acts locally, minimizing systemic absorption
Clinical Uses
Mesalamine Uses
- Mild to moderate ulcerative colitis
- Induction and maintenance of remission
- Proctitis and distal colitis (via suppository/enema)
Olsalazine Uses
- Maintenance of remission in ulcerative colitis
- Alternative in patients intolerant to sulfasalazine
Not effective in Crohn’s disease involving small intestine
Dosage and Formulations
Mesalamine Dosage
| Form | Typical Dose |
|---|---|
| Oral tablets/capsules | 2–4.8 g/day in divided doses |
| Suppository (proctitis) | 1 g rectally once daily |
| Enema (left-sided colitis) | 4 g rectally at night |
Olsalazine Dosage
| Indication | Dose |
|---|---|
| UC maintenance | 500 mg twice daily |
Response time: 2–6 weeks
How to Take These Drugs
1. Match formulation to disease location
- Rectal disease → suppository/enema
- Extensive disease → oral ± rectal
Side Effects
Common Side Effects (Both)
- Nausea
- Abdominal pain
- Headache
- Flatulence
Olsalazine-Specific
Watery diarrhea (dose-limiting, common)Rare but Serious
- Interstitial nephritis
- Pancreatitis
- Worsening colitis
- Blood dyscrasias (rare)
Monitor renal function every 6–12 months
Contraindications & Warnings
1. Severe renal impairment- Liver disease
- Elderly patients
- Pregnancy (generally safe, but monitor)
Mesalamine vs Olsalazine
| Feature | Mesalamine | Olsalazine |
|---|---|---|
| Type | Active drug | Prodrug |
| Diarrhea risk | Low | High |
| Formulations | Oral + rectal | Oral only |
| UC severity | Mild–moderate | Maintenance |
| Patient tolerance | Better | Lower |
Common Mistakes
❌ Using oral drug alone for proctitis
✅ Add rectal mesalamine
❌ Stopping after symptom relief
✅ Continue for maintenance
❌ Ignoring kidney monitoring
✅ Check creatinine regularly
❌ Using olsalazine in active diarrhea
✅ Prefer mesalamine
FAQs
Is mesalamine a steroid?
No. It is a non-steroidal anti-inflammatory drug acting locally in the gut.
Can mesalamine cure ulcerative colitis?
No cure—but it induces and maintains remission effectively.
Why does olsalazine cause diarrhea?
Due to colonic secretion stimulation during conversion to mesalamine.
Is mesalamine safe long-term?
Yes, with renal monitoring.
Can mesalamine be used in pregnancy?
Generally safe, but use under medical supervision.
