Drug Interactions between RoxyBond and sodium polystyrene sulfonate

GENERALLY AVOID: Alcohol may potentiate the central nervous system (CNS) depressant effects of opioid analgesics including oxycodone. Concomitant use may result in additive CNS depression and impairment of judgment, thinking, and psychomotor skills. In more severe cases, hypotension, respiratory depression, profound sedation, coma, or even death may occur.

GENERALLY AVOID: Grapefruit juice may increase the plasma concentrations of oxycodone. The proposed mechanism is inhibition of CYP450 3A4-mediated metabolism of oxycodone by certain compounds present in grapefruit, resulting in decreased formation of metabolites noroxycodone and noroxymorphone and increased formation of oxymorphone due to a presumed shifting of oxycodone metabolism towards the CYP450 2D6-mediated route. In 12 healthy, nonsmoking volunteers, administration of a single 10 mg oral dose of oxycodone hydrochloride on day 4 of a grapefruit juice treatment phase (200 mL three times a day for 5 days) increased mean oxycodone peak plasma concentration (Cmax), systemic exposure (AUC) and half-life by 48%, 67% and 17% (from 3.5 to 4.1 hours), respectively, compared to administration during an equivalent water treatment phase. Grapefruit juice also decreased the metabolite-to-parent AUC ratio of noroxycodone by 44% and that of noroxymorphone by 45%. In addition, oxymorphone Cmax and AUC increased by 32% and 56%, but the metabolite-to-parent AUC ratio remained unchanged. Pharmacodynamic changes were modest and only self-reported performance was significantly impaired after grapefruit juice. Analgesic effects were not affected.

MANAGEMENT: Patients should not consume alcoholic beverages or use drug products that contain alcohol during treatment with oxycodone. Any history of alcohol or illicit drug use should be considered when prescribing oxycodone, and therapy initiated at a lower dosage if necessary. Patients should be closely monitored for signs and symptoms of sedation, respiratory depression, and hypotension. Due to a high degree of interpatient variability with respect to grapefruit juice interactions, patients treated with oxycodone may also want to avoid or limit the consumption of grapefruit and grapefruit juice.

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: 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.