Restricted dispensing

Alosetron

LOTRONEX

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Pronunciation: al-OE-se-tron (LOE-tro-nex)

Alosetron ballicule: receptor binding, kinetics and half-life diagram — Mechanism of action: Alosetron ballicule

Alosetron LOTRONEX mascot mnemonic cartoon — Visual mnemonic: Alosetron mascot
**“Low Tronic is a loose Tronic”**
approved for severely loose stools ( diarrhea-predominant IBS) in women
5-HT3 antagonist color theme (ondansetron, alosetron)

What it is5-HT3 antagonist; severe diarrhea-predominant IBS in women.

Why this oneIt can reduce pain, urgency, and stool frequency after conventional treatment has failed.

What limits itIschemic colitis and dangerous constipation complications restrict prescribing and require immediate discontinuation for warning symptoms.

Alosetron molecular structure (skeletal formula) — Molecular structure: Alosetron

FDA-approved for

IBS-D in women (2000)

FDA label

Read the full label on DailyMed ↗

BOXED WARNING Serious GI reactions (ischemic colitis, serious complications of constipation) causing hospitalization and rarely transfusion, surgery, death; only for women with severe diarrhea-predominant IBS refractory to conventional therapy—discontinue immediately if constipation or ischemic colitis.

FDA dosing	Population	Start	Target	Max
Severe diarrhea-predominant IBS (refractory)	Adult women	0.5 mg BID	0.5 mg QD–BID	1 mg BID

Titration May increase to 1 mg BID after 4 weeks if well tolerated but inadequate control.

Renal No adjustment needed

Hepatic Contraindicated in severe impairment; use with caution in mild–moderate.

Instructions

Take with or without food.
Discontinue immediately if constipation or signs of ischemic colitis (rectal bleeding, bloody diarrhea, new/worsening abdominal pain); do not resume if ischemic colitis occurs.
If constipated, stop until it resolves; may restart at 0.5 mg QD.

Available strengths

tab 0.5, 1 mg

Contraindications

Constipation (do not initiate)
History of chronic/severe constipation or its sequelae; intestinal obstruction, stricture, toxic megacolon, GI perforation/adhesions; ischemic colitis; impaired intestinal circulation, thrombophlebitis, or hypercoagulable state; Crohn's disease or ulcerative colitis; diverticulitis
Severe hepatic impairment
Concomitant fluvoxamine

Cautions

Serious complications of constipation (obstruction, ileus, impaction, toxic megacolon, bowel ischemia; rarely perforation/death); higher risk in elderly, debilitated, or on GI-motility-lowering drugs
Ischemic colitis—evaluate promptly; do not resume treatment

Adverse reactions

Constipation (dose-related, ~29% at 1 mg BID)
Abdominal discomfort/pain
Nausea
GI discomfort/pain

Pregnancy Insufficient human data; no adverse developmental effects in animal studies.

Lactation No human data; present in rat milk—monitor breastfed infant for severe constipation and blood in stools.

Cost

Alosetron (LOTRONEX)

What pharmacies pay · NADAC 9/30/26

Strength		#/mo	generic $/mo	CostPlus
0.5 mg	tab	60 BID	$121.12	offered
1 mg	tab	60 BID	$205.19	offered

Generic entry2015

⚠ BOXED WARNING

Ischemic colitis and serious complications of constipation

Classes and tags

Clinical profile

Therapeutic safety burden3 / 4

Overdose danger1 / 4

Weight-gain liability0 / 4

Sedation liability0 / 4

QT / Torsades0 / 4

Direct muscarinic antagonism0 / 4

Embryofetal risk1 / 4

Legacy pregnancy categoryUnknown / historical label unavailable

Defining liabilityGenerally tolerated at therapeutic doses; clinically important risks are agent-specific and increase with interactions or organ impairment.