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

☞ 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.

☞ Don't administer drug if patient is constipated.

☞ 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

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

Patient teaching

☞ 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.

☞ 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.