Tenapanor

Pharmacology

Mechanism of Action

Tenapanor is a sodium/hydrogen exchanger 3 inhibitor, which acts locally to reduce sodium absorption from the small intestine and colon. Reduced sodium absorption results in increased intestinal lumen water secretion, accelerating intestinal transit time, and softening stool consistency. Tenapanor also decreases intestinal permeability and visceral hypersensitivity in animal models, which may reduce abdominal pain.

Pharmacokinetics/Pharmacodynamics

Absorption

Minimal.

Metabolism

Hepatic via CYP3A4/5 primarily to inactive metabolite M1.

Excretion

Feces (65% as unchanged drug); urine (~9% as metabolites).

Protein Binding

~99%.

Use: Labeled Indications

Irritable bowel syndrome with constipation: Treatment of irritable bowel syndrome with constipation in adults.

Contraindications

Patients <6 years of age; known or suspected mechanical GI obstruction.

Dosage and Administration

Dosing: Adult

Irritable bowel syndrome with constipation: Oral: 50 mg twice daily.

Missed dose: If a dose is missed, skip the missed dose and administer the next dose at the regular time. Do not administer 2 doses at the same time.

Dosing: Geriatric

Refer to adult dosing.

Dosing: Adjustment for Toxicity

Severe diarrhea: Discontinue treatment.

Administration

Oral: Administer immediately prior to breakfast or the first meal of the day and immediately prior to dinner.

Storage

Store at 20°C to 25°C (68°F to 77°F) in original container; protect from moisture. Do not subdivide, repackage, or remove desiccant from bottle.

Drug Interactions

There are no known significant interactions.

Adverse Reactions

>10%: Gastrointestinal: Diarrhea (15% to 16%)

1% to 10%:

Central nervous system: Dizziness (2%)

Gastrointestinal: Flatulence (3%), severe diarrhea (3%), abdominal distension (2% to 3%), abnormal bowel sounds (<2%)

Hematologic & oncologic: Rectal hemorrhage (<2%)

Warnings/Precautions

Concerns related to adverse effects:

• Diarrhea: May cause diarrhea; discontinue and rehydrate if severe diarrhea occurs.

Disease-related concerns:

• Renal impairment: May increase the risk for adverse reactions, including diarrhea and hyperkalemia (requiring hospitalization).

Special populations:

• Risk of serious dehydration in pediatric patients: [US Boxed Warning]: Tenapanor is contraindicated in patients <6 years of age; in nonclinical studies in young juvenile rats (approximate human age equivalent of <2 years of age), administration of tenapanor caused decreased body weight and deaths presumed to be due to dehydration. Avoid use of tenapanor in patients 6 to <12 years of age; safety and effectiveness of tenapanor have not been established in patients <18 years of age.

Monitoring Parameters

Frequency of bowel movements; signs and symptoms of dehydration in patients with diarrhea; serum potassium in patients with renal impairment.

Pregnancy

Pregnancy Considerations

Tenapanor has limited systemic absorption following oral administration. Use during pregnancy is not expected to result in significant exposure to the fetus.

Patient Education

What is this drug used for?

• It is used to treat irritable bowel syndrome with constipation (IBS-C).

Frequently reported side effects of this drug

• Diarrhea
• Passing gas
• Dizziness

Other side effects of this drug: Talk with your doctor right away if you have any of these signs of:

• Abdominal swelling
• Signs of a significant reaction like wheezing; chest tightness; fever; itching; bad cough; blue skin color; seizures; or swelling of face, lips, tongue, or throat.

Note: This is not a comprehensive list of all side effects. Talk to your doctor if you have questions.

Consumer Information Use and Disclaimer: This information should not be used to decide whether or not to take this medicine or any other medicine. Only the healthcare provider has the knowledge and training to decide which medicines are right for a specific patient. This information does not endorse any medicine as safe, effective, or approved for treating any patient or health condition. This is only a brief summary of general information about this medicine. It does NOT include all information about the possible uses, directions, warnings, precautions, interactions, adverse effects, or risks that may apply to this medicine. This information is not specific medical advice and does not replace information you receive from the healthcare provider. You must talk with the healthcare provider for complete information about the risks and benefits of using this medicine.