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. Its use in India is restricted due to cardiovascular safety concerns, requiring careful patient selection and monitoring.
| 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 extensive first-pass metabolism). |
2. Mechanism of Action
Tegaserod acts as a partial agonist at serotonin 5-HT4 receptors in the gastrointestinal tract. This action triggers the release of sensory neurotransmitters like calcitonin gene-related peptide (CGRP) and stimulates peristaltic reflex, increases intestinal secretion, and reduces visceral sensitivity.
3. Indications & Uses
- Irritable Bowel Syndrome with Constipation (IBS-C) in women under 65 years of age
4. Dosage & Administration
Adult Dosage: 6 mg orally twice daily, before morning and evening meals. The 150mg strength is not standard; the standard dose is 6mg. If a 150mg tablet is referenced, it is an error. The correct dosage form is 6mg tablet.
Administration: Take one 6 mg tablet with a glass of water, approximately 30 minutes before the morning and evening meals. Do not take with high-fat meals 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
- Abdominal pain
- Diarrhea (usually mild, transient)
- Nausea
- Flatulence
- Dizziness
6. Drug Interactions
| Drug | Effect | Severity |
|---|---|---|
| Fluoxetine, Paroxetine, Fluvoxamine (Strong CYP2D6 Inhibitors) | Increased Tegaserod exposure (AUC) by 40-50%. Increased risk of adverse effects. | Moderate |
| Ketoconazole, Itraconazole (Strong CYP3A4 Inhibitors) | Increased Tegaserod exposure. Monitor for side effects. | Moderate |
| Rifampicin, Carbamazepine (CYP Inducers) | May decrease Tegaserod plasma concentrations, reducing efficacy. | Moderate |
| Digoxin | Tegaserod may slightly decrease the bioavailability of digoxin. Monitor digoxin levels. | Mild |
| Oral Contraceptives | No clinically significant interaction expected. | None |
7. Patient Counselling
- DO take the tablet 30 minutes before your morning and evening meals.
- DO inform your doctor immediately if you experience sudden severe diarrhea, rectal bleeding, or new/worsening abdominal pain.
- DO inform your doctor of all other medications you are taking.
- DONT take Tegaserod if you are male, or a woman aged 65 or older.
- DONT take Tegaserod with a high-fat meal.
- DONT start Tegaserod if you have a history of heart problems, stroke, or mini-stroke.
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 tolerated 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.