Patiromer (Veltassa), approved in October 2015, is a novel oral potassium binder used in the treatment of hyperkalemia. Due to its delayed onset of action, it is not indicated for emergent correction of life-threatening hyperkalemia.1
Patients with heart failure, diabetes or kidney disease benefit from renin-angiotensin-aldosterone system (RAAS) inhibitors, however the risk of hyperkalemia from these medications may limit their use.2 Drug therapy management becomes complicated by requirements for frequent laboratory monitoring. Elevated potassium levels are associated with electrocardiographic changes and cardiac arrhythmias. Additionally, patients with chronic kidney disease (CKD) are often predisposed to chronic hyperkalemia. Patiromer may be used to treat chronic hyperkalemia in such patients.
The Study Evaluating the Efficacy and Safety of Patiromer for the Treatment of Hyperkalemia (OPAL-HK) was a two-part, single-blind, phase 3 study evaluating the safety and efficacy of patiromer.3 It included 237 patients with stage 3 or 4 CKD who were receiving RAAS inhibitor therapy, and who had serum potassium levels of 5.1 mmol/L to 6.5 mmol/L. In the initial treatment phase of the study, all patients received patiromer, and the mean change in serum potassium levels after 4 weeks was -1.01 + 0.03 mmol/L (95% CI -1.07 to -0.95, P < 0.001). Patients who met target range at week 4 were eligible for the withdrawal phase of the study. Patients were randomized to continue to receive their study dose of patiromer or placebo. Sixty percent of patients in the placebo group compared to 15% of patients in the patiromer group experienced a recurrent episode of hyperkalemia through week 8 of the withdrawal phase (P < 0.001). Overall, the study showed that hyperkalemic patients with chronic kidney disease on RAAS inhibitor therapy experienced a significant decrease in both serum potassium values and recurrence of hyperkalemia with patiromer compared to placebo.
Mechanism of Action
Patiromer is a cation-exchange polymer that binds potassium in the colon.4 This leads to increased fecal excretion of potassium and a reduction in serum potassium levels. Patiromer contains two elements: a potassium-binding polymer and a calcium sorbitol substance. When the polymer removes potassium, it exchanges it with calcium to maintain the electrolyte balance. Patiromer may also bind to magnesium.
Dosage, Costs, Pharmacokinetics
The initial recommended dose is 8.4 g orally once daily with food.1,5 Doses should be titrated at least one week apart in increments of 8.4 g until the desired serum potassium level is achieved. The maximum daily dose is 25.2 g. Patiromer is a dry powder that must be reconstituted with approximately 3 ounces of water and be consumed immediately.1,5 It should not be heated or mixed with heated foods or liquids. It should be stored in the refrigerator. Once removed from refrigeration, it must be used within 3 months (stored at room temperature). A 30-day supply of 8.4 g/day is approximately $595.00 (wholesale acquisition cost).6
Patiromer acts locally and is not systemically absorbed.4 It is excreted in the feces. No dosage adjustments are required for renal or hepatic impairment.1, 5 Use during pregnancy or breastfeeding is not expected to affect the fetus or child since it is not absorbed systemically.1, 5
Drug Interactions & Side Effects
Although no formal drug interaction studies have been performed in humans, in vitro studies indicate that patiromer binds with many oral medications.1 Patiromer has a boxed warning for the risk of decreased absorption and efficacy of other oral medications, and therefore should be administered 6 hours before or after administration of other oral medications.
Patiromer was well tolerated in clinical trials. The most common adverse effects were mild to moderate gastrointestinal problems, including constipation, diarrhea, nausea, abdominal discomfort, and flatulence.1,4,5 In addition to the risk of hypokalemia, patiromer also binds magnesium and subsequently may cause hypomagnesemia.1,5 Potassium and magnesium should be regularly monitored during patiromer therapy. Additionally, patiromer should not be used in patients with severe constipation, bowel obstruction or motility disorders, since patiromer may not be effective in these patients and may worsen these conditions.1, 5
1. Prescribing information, Voltas. Relapse, Inc.
2. Henneman A, et al. Emerging therapies for the management of chronic hyperkalemia in the ambulatory care setting. Am J Health Syst Pharm. 2016;73(2):33-44.
3. Weir MR, et al. Patiromer in patients with kidney disease and hyperkalemia receiving RAAS Inhibitors. N Engl J Med. 2015;372(3):211-221.
4. Li L, et al. Mechanism of action and pharmacology of patiromer, a nonabsorbed cross-linked polymer that lowers serum potassium concentrations in patients with hyperkalemia. J Cardiovasc Pharmacol Ther. 2016. pii: 1074248416629549.
5. Lexicomp Online, 2016.
6. Micromedex 2.0. Redbook online. Truven Health Analytics. http://www-micromedexsolutions-com.db.usciences.edu/
Amber Dow is a 2016 doctor of pharmacy candidate at the Philadelphia College of Pharmacy, University of the Sciences. Alice Lim is an ambulatory care pharmacist at the Philadelphia College of Pharmacy, University of the Sciences and her practice site is at the Michael J. Crescent VA Medical Center in Philadelphia.