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Pregnancy Category: B
Pharmacologic: five ht3 antagonists
ClassificationTherapeutic: anti irritable bowel syndrome agents
Pharmacologic: five ht3 antagonists
Treatment of severe diarrhea-predominant irritable bowel syndrome (IBS) in women who have chronic symptoms (≥6 mo), no other GI pathology, and have had no response to conventional therapy.
5-HT3 receptors are non-selective cation channels responsible for regulation of visceral pain, colonic transit, and GI secretions. Alosetron inhibits the activation of these channels.
Increased colonic transit time without affecting orocecal transit time resulting in decreased pain/discomfort and diarrhea associated with IBS.
Absorption: 50–60% absorbed following oral administration.
Distribution: 65–95 L.
Protein Binding: 82% bound to plasma proteins.
Metabolism and Excretion: Extensively metabolized by the liver; 13% excreted unchanged in urine.
Half-life: 1.5 hr.
Time/action profile (pain/discomfort, diarrhea)
|PO||within 1–2 wk||up to 6 wk||1 wk†|
Contraindicated in: Hypersensitivity; Constipation; History of chronic/severe constipation or complications due to constipation; History of GI obstruction, stricture, toxic megacolon, perforation, and/or adhesions; History of ischemic colitis, ↓ intestinal circulation, thrombophlebitis, or coagulation defects; History of Crohn’s disease/ulcerative colitis/diverticulitis; Severe hepatic impairment; Concurrent use of fluvoxamine; Patients unable to understand or comply with Patient Acknowledgement Form.
Use Cautiously in: Men – safety not established; Mild-moderate hepatic impairment; Patients who are elderly, debilitated, or taking medications that ↓ GI motility; Obstetric / Lactation / Pediatric: Safety not established.
Adverse Reactions/Side Effects
- acute ischemic colitis (life-threatening)
- toxic megacolon (life-threatening)
- constipation (most frequent)
- abdominal discomfort
- abdominal distention
- GI viral infections
- regurgitation or reflux
Drug-Drug interactionFluvoxamine can ↑ levels; concurrent use contraindicated).Amiodarone, cimetidine, ciprofloxacin, clarithromycin, itraconazole, ketoconazole, ofloxacin, protease inhibitors, telithromycin, and voriconazole may ↑ levels; use concomitantly with caution.
Oral (Adults) Women—0.5 mg twice daily.
Tablets: 0.5 mg, 1 mg
- Monitor patient for signs of constipation or ischemic colitis (new or worsening abdominal pain, bloody diarrhea, blood in stool) throughout therapy. Patients should not start taking alosetron if they are constipated.
- Discontinue therapy immediately if patient develops constipation or signs/symptoms of ischemic colitis.
Potential Nursing DiagnosesDiarrhea (Indications)
Risk for constipation (Side Effects)
Deficient knowledge, related to medication regimen (Patient/Family Teaching)
- Do not confuse Lotronex with Protonix.
- Alosetron should only be prescribed by physicians enrolled in GlaxoSmithKline’s Prescribing Program for Alosetron.
- Oral: Administer 0.5 mg twice daily for 4 wk. If constipation occurs after initiation of therapy, discontinue until constipation resolves, then restart at 0.5 mg once daily (if constipation recurs at this dose, discontinue therapy). If IBS symptoms are not controlled after 4 wk, no constipation has occurred and patient tolerates either 0.5 mg once or twice daily, dose may be increased to 1 mg twice daily. If symptoms are not controlled after 4 wk of 1 mg twice, discontinue alosetron.
- Can be administered with or without food; however, administration with food may decrease absorption by 25%.
- Instruct patient to take alosetron exactly as directed. If a dose is missed, skip the dose and return to regular schedule; do not double doses. Counsel patients about the risks and benefits of alosetron and the impact of IBS symptoms on their life. Patients should read the Medication Guide before starting alosetron and each time they refill their prescription. The Patient-Physician Agreement should be signed, with the original in the patient’s chart and a copy to the patient, prior to initiating therapy.
- Caution patient to stop taking alosetron and report constipation or signs of ischemic colitis to health care professional immediately. Immediately contact health care professional again if constipation does not resolve after discontinuation of alosetron. Alosetron should be resumed only after constipation has resolved and on the advice of their health care professional. Treatment with alosetron should not be resumed in patients who develop ischemic colitis.
- Increased colonic transit time without affecting orocecal transit time resulting in decreased pain, discomfort, and diarrhea associated with IBS.