Drug Interactions between HalfLytely and Bisacodyl and pexidartinib

ADJUST DOSING INTERVAL: By increasing gastric pH, antacids may reduce the resistance of the enteric coating of bisacodyl tablets, resulting in earlier release of bisacodyl and gastric irritation and dyspepsia.

MANAGEMENT: The administration of antacids and bisacodyl should be separated by at least one hour.

ADJUST DOSING INTERVAL: Coadministration with acid-reducing agents may significantly decrease the bioavailability and therapeutic effects of pexidartinib. The proposed mechanism is a pH-dependent reduction in drug dissolution and/or absorption. Concomitant administration of esomeprazole, a proton pump inhibitor, decreased pexidartinib peak plasma concentration (Cmax) and systemic exposure (AUC) by 55% and 50%, respectively. The effect of coadministration with an H2-receptor antagonist or locally-acting antacids on pexidartinib pharmacokinetics is unknown.

MANAGEMENT: If acid-suppression therapy is required, pexidartinib may be administered 2 hours before or 2 hours after taking a locally-acting antacid, or if using an H2-receptor antagonist, administer pexidartinib at least 2 hours before or 10 hours after taking the H2-receptor antagonist. Concomitant use of pexidartinib with proton pump inhibitors should be avoided.

GENERALLY AVOID: Concomitant use of stimulant laxatives (e.g., bisacodyl, sodium picosulfate) may increase the risk of serious gastrointestinal adverse effects associated with certain osmotic laxatives (e.g., polyethylene glycol (PEG), oral sulfate solution), such as colonic mucosal ulcerations or ischemic colitis. There have been isolated case reports of ischemic colitis occurring with the use of PEG-based bowel cleansing products in combination with higher dosages of bisacodyl (usually greater than 10 mg). Bisacodyl can cause colonic ischemia due to transient reduction in splanchnic blood flow. When administered in conjunction with an osmotic laxative such as PEG, increased intramural pressure secondary to increased peristalsis may lead to ischemic colitis and perforation.

MANAGEMENT: The manufacturers for some osmotic bowel cleansing products recommend avoiding the concurrent use of stimulant laxatives. However, stimulant laxatives, in particular bisacodyl and sodium picosulfate, are sometimes used with PEG in certain bowel cleansing regimens to help reduce dose volume and improve patient tolerability and acceptance. Please consult individual product labeling for specific recommendations and guidance. Patients using osmotic bowel cleansing products and stimulant laxatives who present with sudden abdominal pain, rectal bleeding, or other symptoms of ischemic colitis should be evaluated promptly.