1. Clinical Overview
Tegaserod is a selective serotonin 5-HT4 receptor partial agonist used primarily for the treatment of Irritable Bowel Syndrome with Constipation (IBS-C) in women under 65 years of age. It enhances gastrointestinal motility and reduces visceral sensitivity. In India, its use is strictly controlled due to cardiovascular safety concerns.
| Onset | Duration | Bioavailability |
|---|---|---|
| Within 1-2 hours for initial effects on motility; symptomatic relief for IBS-C may take 1-4 weeks. | Approximately 8-12 hours. | Approximately 10% (due to significant first-pass metabolism). |
2. Mechanism of Action
Tegaserod acts as a partial agonist at serotonin 5-HT4 receptors in the gastrointestinal tract. This activation stimulates the peristaltic reflex, enhances intestinal secretion, and reduces visceral sensitivity. It accelerates orocecal transit and colonic transit time in patients with constipation-predominant IBS.
3. Indications & Uses
- Irritable Bowel Syndrome with Constipation (IBS-C) in women < 65 years of age.
4. Dosage & Administration
Adult Dosage: 6 mg orally twice daily, before the morning and evening meals.
Administration: Take tablet with a glass of water on an empty stomach, at least 30 minutes before a meal (breakfast and dinner). Do not take with food as it significantly reduces absorption. If a dose is missed, skip it and take the next dose at the regular time. Do not double the dose.
5. Side Effects
Common side effects may include:
- Headache
- Diarrhea (usually mild and transient)
- Abdominal pain
- Nausea
- Flatulence
- Dizziness
6. Drug Interactions
| Drug | Effect | Severity |
|---|---|---|
| Fluoxetine, Paroxetine, Sertraline (SSRIs) | Theoretical risk of serotonin syndrome, though low. Monitor for CNS effects. | Moderate |
| Warfarin | No significant pharmacokinetic interaction observed, but monitor INR as a precaution due to tegaserod's protein binding. | Low |
| Digoxin | Tegaserod may slightly decrease the bioavailability of digoxin. Monitor digoxin levels and clinical response. | Moderate |
| Oral Contraceptives | No clinically significant interaction reported. | Low |
| Theophylline | No significant pharmacokinetic interaction. | Low |
| Other 5-HT4 agonists (e.g., Prucalopride) | Additive pharmacodynamic effects; concurrent use not recommended. | High |
7. Patient Counselling
- DO take the tablet on an empty stomach, 30 minutes before breakfast and dinner.
- DO report any new or worsening abdominal pain, bloody diarrhea, or rectal bleeding immediately.
- DO inform all your doctors you are taking tegaserod, especially before any new prescription.
- DO maintain adequate fluid intake if you experience diarrhea.
- DONT take the medicine with food.
- DONT take if you are 65 years or older.
- DONT take if you have a history of heart problems, stroke, or mini-strokes (TIA).
- DONT start this medicine without a thorough discussion of risks and benefits with your doctor.
8. Toxicology & Storage
Overdose: Expected to be an extension of its pharmacological effects: severe diarrhea, abdominal cramps, hypotension, dizziness, and headache. Single doses up to 100 mg have been reported with increased incidence of these effects.
Storage: Store at room temperature (15°C to 30°C). Protect from light and moisture. Keep out of reach of children. Do not use after the expiry date printed on the pack.