Dosing and uses of Lotronex (alosetron)
Adult dosage forms and strengths
tablet
- 0.5mg
- 1mg
Irritable Bowel Syndrome
Indicated only for women with severe diarrhea-predominant IBS who have: chronic IBS symptoms (generally lasting 6 months or longer), had anatomic or biochemical abnormalities of GI tract excluded, and not responded adequately to conventional therapy
Initial 0.5 mg PO q12hr for 4 weeks; if well tolerated, but inadequate control of IBS symptoms, increase up to 1 mg q12hr; discontinue if no improvement after 4 weeks
Renal Impairment
Dose adjustment not studied in the manufacturer's labeling
Hepatic Impairment
Moderate impairment (Child-Pugh score < 9): Use caution
Severe dysfunction (Child-Purgh score ≥ 10): Contraindicated
Pediatric dosage forms and strengths
Not recommended
Lotronex (alosetron) adverse (side) effects
>10%
Constipation (29%)
1-10%
Abdominal pain (7%)
Nausea (6%)
Headache (≥3%)
GI discomfort and pain (5%)
Fatigue (≥3%)
Gastroenteritis (>3%)
Abdominal distention (2%)
Flatulence (1-3%)
Regurgitation and reflux (2%)
Abdominal distension (2%)
Hemorrhoids (2%)
Urinary tract infection (≥3%)
Muscle spasm (≥3%)
Cough (≥3%)
Nasopharyngitis (≥3%)
<1%
Ischemic colitis
Anxiety
Bone pain
Colitis
Diverticulitis
Cholecystitis
GI impaction
GI spasms
GI ulceration
Warnings
Black box warnings
Infrequent but serious GI adverse reactions (eg, ischemic colitis, serious complications of constipation) reported; some have resulted in hospitalization and, rarely, blood transfusion, surgery, or death
In order to prescribe, physicians must be enrolled in Prescribing Program for Lotronex (see cautions)
Indicated only for women with severe diarrhea-predominant irritable bowel syndrome that has not responded adequately to conventional therapy
Discontinue immediately in patients who develop constipation or symptoms of ischemic colitis; do not resume in those who develop ischemic colitis
Contraindications
Hypersensitivity
Rectal bleeding, history of chronic or severe current constipation
History of ischemic colitis, intestinal obstruction, stricture, toxic megacolon, GI perforation or adhesion, thrombophlebitis, history of or current Crohn's disease or ulcerative colitis
Coadministration with apomorphine; combination reported to cause profound hypotension and loss of consciousness
Inability to comply with the Patient-Physician Agreement for Lotronex
Severe hepatic impairment
Impaired intestinal circulation
Concomitant administration with fluvoxamine
Thrombocytopenia
Cautions
Discontinue if inadequate control after 4 weeks of q12hr dosing
Discontinue immediately if symptoms of constipation or ischemic colitis occurs
Risk of complications from constipation higher in the elderly
Use with caution in breast-feeding women
Use caution in mild-to-moderate hepatic impairment
Withdrawn from U.S. market in Nov. 2000 due to cases of severe ischemic colitis, obstructed or ruptured bowel, and death; reinstated in June 2002 on a limited basis
Physicians must enroll in GlaxoSmithKline's Prescribing Program for Lotronex 1-888-825-5249 or www.lotronex.com
Pregnancy and lactation
Pregnancy category: B
Lactation: Not known whether drug distributed into breast milk, use caution
Pregnancy categories
A: Generally acceptable. Controlled studies in pregnant women show no evidence of fetal risk.
B: May be acceptable. Either animal studies show no risk but human studies not available or animal studies showed minor risks and human studies done and showed no risk.
C: Use with caution if benefits outweigh risks. Animal studies show risk and human studies not available or neither animal nor human studies done.
D: Use in LIFE-THREATENING emergencies when no safer drug available. Positive evidence of human fetal risk.
X: Do not use in pregnancy. Risks involved outweigh potential benefits. Safer alternatives exist.
NA: Information not available.
Pharmacology of Lotronex (alosetron)
Mechanism of action
5-HT3 receptor antagonist; modulates enteric nervous system
Pharmacokinetics
Half-life: 1.5 hr
Peak plasma time: 0.5-1.7 hr
Bioavailability: 50-60%, food decreases absorption
Protein bound: 82%
Vd: 65-95 L
Excretion: Urine (74%); feces (11%)
Metabolites: 6-hydroxyl metabolite, 6-O-glucuronide metabolite, bis-oxidized dicarbonyl metabolite, N-demethylated alosetron [all are inactive]
Metabolism
- Extensively undergoes first-pass metabolism
- Metabolized by Cytochrome (CYP) P450: CYP2C9 (30%), 3A4 (18%), 1A2 (10%), and non-CYP mediated phase I metabolism (11%)
Clearance
- Renal: 94 mL/min
- Total body: 1190 mL/min
