Drug Interactions between Kalexate and Lokelma

GENERALLY AVOID: Potassium in foods can bind to the cation exchange resin and interfere with potassium removal in the treatment of hyperkalemia.

MANAGEMENT: Cation exchange resins should not be mixed with orange juice or other foods with a high potassium content.

ADJUST DOSING INTERVAL: Cation exchange resins may bind to other medications that are administered orally. Reduced systemic absorption and therapeutic efficacy may occur. Manufacturers have reported that polystyrene sulfonate exchange resins can decrease the absorption of lithium and levothyroxine. A more recent study found that sodium polystyrene sulfonate binds to many commonly prescribed oral medications. Another potassium-lowering drug, patiromer, has also been found to bind about half of the medications tested, some of which are commonly used in patients who require potassium-lowering drugs.

MANAGEMENT: To minimize the risk of interaction, patients should be advised to separate the dosing of the cation exchange resin from other orally administered medications by at least 3 hours. The dosing interval should be increased to 6 hours for patients with gastroparesis or other conditions resulting in delayed emptying of food from the stomach into the small intestine. Health care professionals should monitor blood levels and/or clinical response to the other medications when appropriate.

ADJUST DOSING INTERVAL: Because sodium zirconium cyclosilicate can transiently increase gastric pH, it may affect the absorption of coadministered medications that exhibit pH-dependent solubility. Altered efficacy or safety of these medications may occur when they are administered too close to the dosing of sodium zirconium cyclosilicate. According to the product labeling, 39 drugs were tested to determine potential interactions with sodium zirconium cyclosilicate. Drugs that did not show an in vitro interaction with sodium zirconium cyclosilicate were allopurinol, apixaban, aspirin, captopril, cyclosporine, digoxin, ethyl estradiol, lisinopril, magnesium, metformin, phenytoin, prednisone, propranolol, quinapril, spironolactone, and ticagrelor. Of the 23 drugs that showed an in vitro interaction, nine were subsequently tested in healthy volunteers. Losartan, glipizide, and levothyroxine did not demonstrate an in vivo interaction with sodium zirconium cyclosilicate. However, an increase in systemic exposure was observed for weak acids such as furosemide and atorvastatin when coadministered with sodium zirconium cyclosilicate, while a decrease in systemic exposure was observed for weak bases such as dabigatran.

MANAGEMENT: In general, concomitant oral medications should be administered at least 2 hours before or 2 hours after sodium zirconium cyclosilicate. Separation of dosing times is not needed if it has been determined that the concomitant medication does not exhibit pH-dependent solubility.

ADJUST DOSING INTERVAL: Simultaneous administration of cation-donating preparations may reduce the potassium exchange capability of cation-exchange resins due to binding of the cation to the resin.

MANAGEMENT: Patients should consider separating the times of administration of the cation-exchange resin and any cation-donating preparation (e.g., mineral supplements; antacids; products containing antacids such as didanosine buffered tablets or pediatric oral solution) by several hours if possible.

The recommended maximum number of medicines in the 'potassium-removing resins' category to be taken concurrently is usually one. Your list includes two medicines belonging to the 'potassium-removing resins' category:

• Kalexate (sodium polystyrene sulfonate)
• Lokelma (sodium zirconium cyclosilicate)

Note: In certain circumstances, the benefits of taking this combination of drugs may outweigh any risks. Always consult your healthcare provider before making changes to your medications or dosage.