Fiber 6 (bran/guar gum/fiber/cellulose/psyllium seed/kelp/apple pectn)

Bulk-forming laxatives are usually administered 1-3 times daily. To reduce the risk of esophageal obstruction in patients receiving large (e.g., the maximum daily dosage recommended by the manufacturer) dosages of bulk-forming laxatives, these laxatives should be administered in divided doses instead of a single daily dose. The usual dosages for the individual bulk-forming laxatives are below; for dosages in children younger than the ages listed, a physician should be consulted.

Bulk-forming laxatives are administered orally. Commercially available powders, flakes, granules, tablets, and liquids should be dissolved and/or diluted according to the instructions of the manufacturer. In the treatment of constipation, at least one full glass (250 mL) of liquid should be administered with each laxative dose. When used to increase the bulk of stools in patients with chronic, watery diarrhea, one manufacturer suggests that one-third of a glass (80 mL) of liquid be administered with each dose.

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There are no contraindication interactions for this drug.

Severe Interaction: Action is required to reduce the risk of severe adverse interaction.

Agents That Affect Iodide/Radioactive Iodide

SEVERITY LEVEL: 2-Severe Interaction: Action is required to reduce the risk of severe adverse interaction.

MECHANISM OF ACTION: Many compounds can affect iodide protein binding and alter iodide pharmacokinetics and pharmacodynamics.(1)

CLINICAL EFFECTS: Compounds that affect iodide pharmacokinetics and pharmacodynamics may impact the effectiveness of radioactive iodide.(1)

PREDISPOSING FACTORS: Compounds that affect iodide pharmacokinetics and pharmacodynamics are expected to have the most impact during therapy using radioactive iodide. Diagnostic procedures would be expected to be impacted less.

PATIENT MANAGEMENT: Discuss the use of agents that affect iodide pharmacokinetics and pharmacodynamics with the patient's oncologist.(1) Because indocyanine green contains sodium iodide, the iodine-binding capacity of thyroid tissue may be reduced for at least one week following administration. Do not perform radioactive iodine uptake studies for at least one week following administration of indocyanine green.(2) The manufacturer of iopamidol states administration may interfere with thyroid uptake of radioactive iodine and decrease therapeutic and diagnostic efficacy. Avoid thyroid therapy or testing for up to 6 weeks post administration of iopamidol.(3)

DISCUSSION: Many agents interact with radioactive iodine. The average duration of effect is: anticoagulants - 1 week antihistamines - 1 week anti-thyroid drugs, e.g: carbimazole, methimazole, propylthiouracil - 3-5 days corticosteroids - 1 week iodide-containing medications, e.g: amiodarone - 1-6 months expectorants - 2 weeks Lugol solution - 3 weeks saturated solution of potassium iodine - 3 weeks vitamins - 10-14 days iodide-containing X-ray contrast agents - up to 1 year lithium - 4 weeks phenylbutazone - 1-2 weeks sulfonamides - 1 week thyroid hormones (natural or synthetic), e.g.: thyroxine - 4 weeks tri-iodothyronine - 2 weeks tolbutamide - 1 week topical iodide - 1-9 months (1)

Agents That Affect Iodide/Sodium Iodide I 131

SEVERITY LEVEL: 2-Severe Interaction: Action is required to reduce the risk of severe adverse interaction.

MECHANISM OF ACTION: Many compounds can affect iodide protein binding and alter iodide pharmacokinetics and pharmacodynamics.(1,2)

CLINICAL EFFECTS: Compounds that affect iodide pharmacokinetics and pharmacodynamics may impact the effectiveness of radioactive iodide.(1,2)

PREDISPOSING FACTORS: Compounds that affect iodide pharmacokinetics and pharmacodynamics are expected to have the most impact during therapy using radioactive iodide. Diagnostic procedures would be expected to be impacted less.

PATIENT MANAGEMENT: Discuss the use of agents that affect iodide pharmacokinetics and pharmacodynamics with the patient's oncologist.(1,2) Because indocyanine green contains sodium iodide, the iodine-binding capacity of thyroid tissue may be reduced for at least one week following administration. Do not perform radioactive iodine uptake studies for at least one week following administration of indocyanine green.(3) The manufacturer of iopamidol states administration may interfere with thyroid uptake of radioactive iodine and decrease therapeutic and diagnostic efficacy. Avoid thyroid therapy or testing for up to 6 weeks post administration of iopamidol.(4)

DISCUSSION: Many agents interact with radioactive iodine. The average duration of effect is: anticoagulants - 1 week antihistamines - 1 week anti-thyroid drugs, e.g: carbimazole, methimazole, propylthiouracil - 3-5 days corticosteroids - 1 week iodide-containing medications, e.g: amiodarone - 1-6 months expectorants - 2 weeks Lugol solution - 3 weeks saturated solution of potassium iodine - 3 weeks vitamins - 10-14 days iodide-containing X-ray contrast agents - up to 1 year lithium - 4 weeks phenylbutazone - 1-2 weeks sulfonamides - 1 week thyroid hormones (natural or synthetic), e.g.: thyroxine - 4 weeks tri-iodothyronine - 2 weeks tolbutamide - 1 week topical iodide - 1-9 months (1,2)

Laxatives/Trofinetide

SEVERITY LEVEL: 2-Severe Interaction: Action is required to reduce the risk of severe adverse interaction.

MECHANISM OF ACTION: Trofinetide commonly causes diarrhea of mild to moderate severity. Laxatives may increase the incidence or severity of diarrhea.(1)

CLINICAL EFFECTS: Concurrent use of laxatives with trofinetide may increase the risk of severe diarrhea.(1)

PREDISPOSING FACTORS: None determined.

PATIENT MANAGEMENT: Patients should stop laxatives before starting trofinetide. If diarrhea occurs, consider anti-diarrheal treatment and monitor hydration status. If severe diarrhea or dehydration occurs, interrupt, reduce dose, or discontinue trofinetide.(1)

DISCUSSION: In clinical trials, 85% of patients on trofinetide developed diarrhea. Concurrent use of laxatives may increase this risk.(1)

Laxatives; Stool Softeners/Tenapanor

SEVERITY LEVEL: 2-Severe Interaction: Action is required to reduce the risk of severe adverse interaction.

MECHANISM OF ACTION: Tenapanor commonly causes diarrhea of mild to moderate severity. Laxatives and stool softeners may increase the incidence or severity of diarrhea.(1)

CLINICAL EFFECTS: Concurrent use of laxatives or stool softeners with tenapanor may increase the risk of severe diarrhea.(1)

PREDISPOSING FACTORS: None determined.

PATIENT MANAGEMENT: The US manufacturer of tenapanor states that patients should be instructed to avoid stool softeners and laxatives with tenapanor. If severe diarrhea occurs, tenapanor should be discontinued.(1)

DISCUSSION: In clinical trials, 43-53% of CKD patients on dialysis treated with tenapanor developed diarrhea. Diarrhea usually occurred soon after treatment initiation and was severe in 5% of patients.(1)

Moderate Interaction: Assess the risk to the patient and take action as needed.

Bulk Forming Laxatives/Clozapine

SEVERITY LEVEL: 3-Moderate Interaction: Assess the risk to the patient and take action as needed.

MECHANISM OF ACTION: Clozapine has potent anticholinergic properties and inhibits serotonin receptors, including 5-HT3.(1-4) Both of these properties may cause inhibition of gastrointestinal (GI) smooth muscle contraction, resulting in decreased peristalsis.(3,4) If fluid intake is inadequate, bulk forming laxatives can increase the risk of gastrointestinal obstruction.(1-6)

CLINICAL EFFECTS: Concurrent use of clozapine and bulk forming laxatives with inadequate fluid intake may increase the risk of constipation (common) and serious bowel complications (uncommon), including complete bowel obstruction, fecal impaction, paralytic ileus and intestinal ischemia or infarction.(1-6)

PREDISPOSING FACTORS: The risk for serious bowel complications is higher with increasing age, higher frequency of constipation, and in patients on higher doses of clozapine or multiple anticholinergic agents.(1,5)

PATIENT MANAGEMENT: Concurrent use of bulk forming laxatives with clozapine may be used with caution in patients who can maintain adequate fluid intake. Evaluate the patient's bowel function regularly. If patient is unable to maintain adequate fluid intake and use bulk forming laxatives as prescribed, avoid the use of bulk forming laxatives with clozapine.(1-6) Monitor for symptoms of constipation and GI hypomotility, including having bowel movements less than three times weekly or less than usual, difficulty having a bowel movement or passing gas, nausea, vomiting, and abdominal pain or distention.(2) Consider a prophylactic laxative in those with a history of constipation or bowel obstruction.(2) Review patient medication list for anticholinergic agents which may have additive effects on decreased GI motility. When possible, decrease the dosage or number of prescribed anticholinergic agents, particularly in the elderly. Counsel the patient about the importance of maintaining adequate hydration. Encourage regular exercise and eating a high-fiber diet.(2)

DISCUSSION: The concurrent use of clozapine and bulk forming laxatives has not been studied. Use of bulk forming laxatives with inadequate fluid intake has been associated with gastrointestinal obstruction.

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• Appendicitis
• Esophageal obstruction
• Gastrointestinal obstruction
• Ileus

• Dysphagia

• Fecal incontinence

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Rare or Very Rare

• Allergic dermatitis
• Anaphylaxis
• Bronchospastic pulmonary disease
• Conjunctivitis
• Esophageal obstruction
• Gastrointestinal obstruction
• Intestinal impaction
• Pruritus of skin
• Rhinitis
• Skin rash
• Urticaria

There are no less severe adverse reactions for this drug.

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