Lotronex

Action

Inhibits activation of nonselective cation channels, resulting in modulation of enteric nervous system

Availability

Tablets: 0.5 mg, 1 mg

Indications and dosages

➣ Women with severe, diarrhea-predominant irritable bowel syndrome (IBS) who have chronic symptoms not caused by anatomic or biochemical abnormalities and who are unresponsive to conventional therapy

Adult women: Initially, 0.5 mg P.O. b.i.d. If after 4 weeks dose is well tolerated but doesn't adequately control IBS, may increase to 1 mg P.O. b.i.d.; therapy should be discontinued in patients not responding to 1 mg P.O. b.i.d. after 4 weeks.

Contraindications

• Concurrent use of fluvoxamine

• Severe hepatic impairment

• Current constipation or history of chronic or severe constipation

• History of complications related to constipation

• History of intestinal obstruction, stricture, toxic megacolon, GI perforation, or adhesion

• History of ischemic colitis, impaired intestinal circulation, thrombophlebitis, or hypercoagulable state

• Current Crohn's disease or ulcerative colitis, active diverticulitis, or history of these disorders

• Inability to understand or comply with patient-physician agreement for drug

Precautions

Use cautiously in:

• hepatic insufficiency

• moderate CYP/A2 inhibitors, such as quinolone antibiotics and cimetidine (avoid use)

• elderly patients

• pregnant or breastfeeding patients

• children.

Administration

See Before administering, know that drug is approved with the following marketing restrictions: Ensure that patient understands that drug has serious risks, patient reads and signs patient-physician agreement, and patient follows directions in accompanying medication guide.

• Know that anatomical and biochemical abnormalities of GI tract should be ruled out before drug therapy starts.

• Give with or without food.

See Don't administer drug if patient is constipated.

See Stop therapy immediately if patient develops constipation or signs or symptoms of ischemic colitis.

Adverse reactions

CNS: anxiety, malaise

CV: increased blood pressure, extrasystoles, tachyarrhythmias, arrhythmias

GI: nausea; constipation; GI pain, discomfort, or spasms; abdominal distention; regurgitation or gastroesophageal reflux; hemorrhoids; decreased salivation; dyspepsia; ischemic colitis; GI perforation; small-bowel mesenteric ischemia

GU: urinary frequency

Hematologic: hemorrhage

Respiratory: breathing disorders

Skin: sweating, urticaria

Other: fatigue, cramps, disturbed temperature regulation

Interactions

Drug-drug. CYP450 inducers or inhibitors: altered alosetron clearance

Fluvoxamine: increased alosetron concentration and half-life

Drug-diagnostic tests. Blood glucose, calcium, phosphate: increased or decreased level

Patient monitoring

See Monitor patient closely for adverse reactions, especially such GI reactions as constipation and signs or symptoms of ischemic colitis.

Patient teaching

See Make sure patient knows about drug's marketing restrictions, which stipulate that she understands drug has serious risks, that she reads and signs patient-physician agreement, and that she follows directions in accompanying medication guide.

• Tell patient to take drug exactly as prescribed, with or without food.

See Instruct patient to contact prescriber immediately if she develops constipation or symptoms of insufficient blood flow to bowel (such as new or worsening pain in bowels or bloody bowel movements).

• As appropriate, review all other significant and life-threatening adverse reactions and interactions, especially those related to the drugs and tests mentioned above.