Article Randomized Clinical Trial of Sodium Polystyrene Sulfonate For
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Article Randomized Clinical Trial of Sodium Polystyrene Sulfonate for the Treatment of Mild Hyperkalemia in CKD Laurence Lepage,* Anne-Claude Dufour,* Jessica Doiron,* Katia Handfield,* Katherine Desforges,* Robert Bell,* | Michel Valle´e,†‡ Michel Savoie,* Sylvie Perreault,§ Louis-Philippe Laurin,†‡ Vincent Pichette,†‡ ¶ and | Jean-Philippe Lafrance† ¶ *Department of Pharmacy and Abstract †Division of Background and objectives Hyperkalemia affects up to 10% of patients with CKD. Sodium polystyrene sulfonate Nephrology, has long been prescribed for this condition, although evidence is lacking on its efficacy for the treatment of mild Maisonneuve- hyperkalemia over several days. This study aimed to evaluate the efficacy of sodium polystyrene sulfonate in the Rosemont Hospital, Montreal, Canada; treatment of mild hyperkalemia. ‡ Department of Medicine, §Faculty of Design, setting, participants, & measurements In total, 33 outpatients with CKD and mild hyperkalemia Pharmacy, and (5.0–5.9 mEq/L) in a single teaching hospital were included in this double–blind randomized clinical trial. ¶Department of We randomly assigned these patients to receive either placebo or sodium polystyrene sulfonate of 30 g orally Pharmacology, University of one time per day for 7 days. The primary outcome was the comparison between study groups of the mean Montreal, Montreal, difference of serum potassium levels between the day after the last dose of treatment and baseline. Canada; and | Maisonneuve- Results The mean duration of treatment was 6.9 days. Sodium polystyrene sulfonate was superior to placebo in Rosemont Hospital the reduction of serum potassium levels (mean difference between groups, 21.04 mEq/L; 95% confidence in- Research Center, Montreal, Canada terval, 21.37 to 20.71). A higher proportion of patients in the sodium polystyrene sulfonate group attained normokalemia at the end of their treatment compared with those in the placebo group, but the difference did not Correspondence: Dr. reach statistical significance (73% versus 38%; P=0.07). There was a trend toward higher rates of electrolytic Jean-Philippe disturbances and an increase in gastrointestinal side effects in the group receiving sodium polystyrene sulfonate. Lafrance, Division of Nephrology, Conclusions Sodium polystyrene sulfonate was superior to placebo in reducing serum potassium over 7 days in Maisonneuve- Rosemont Hospital, patients with mild hyperkalemia and CKD. 5415 Boulevard de Clin J Am Soc Nephrol 10: 2136–2142, 2015. doi: 10.2215/CJN.03640415 l’Assomption, Montreal, Quebec, Canada H1T 2M4. Email: jean-philippe. Introduction with the lack of strong data on its efficacy affect clini- [email protected] Hyperkalemia affects up to 10% of patients suffering cians’ willingness to use SPS as a first-line treatment of from CKD and up to 42% of patients with an eGFR,20 hyperkalemia (10). ml/min per 1.73 m2 (1). Hyperkalemia can cause fatal Efficacy of SPS in the treatment of chronic hyper- cardiac arrhythmias and has been associated with in- kalemia was evaluated in a retrospective observational creased mortality in patients with CKD (2–4). Reduc- study in 14 patients with CKD and cardiovascular dis- tion of dietary intake, modification of contributing ease taking medication affecting the renin-angiotensin medications, and use of cation-exchange resins are system (11). The small sample size and the lack of con- presently the cornerstone of treatment of mild chronic trol group made it difficult to differentiate the effect of hyperkalemia (5–8). Sodium polystyrene sulfonate SPS from that of other factors, such as dietary restric- (SPS) is a cation-exchange resin that was approved by tions and medication changes. Our double–blind, ran- the US Food and Drug Administration (FDA) in 1958, domized, placebo–controlled trial aimed to evaluate the 4yearsbeforetheKefauver–Harris Drug Amendments use of SPS in the treatment of mild hyperkalemia in were passed to ensure drug efficacy and safety. Conse- outpatients with CKD. quently, data on SPS in the treatment of mild hyper- kalemia are insufficient, especially when used over several days in a population of patients with CKD. Materials and Methods SPS has historically been used combined with sorbitol. Study Design In September of 2009, the FDA released a black box The study was conducted at the nephrology and pre- warning about the increased risk of intestinal necrosis dialysis outpatient clinics of Maisonneuve-Rosemont with this combination (9). This new warning along Hospital between February and September of 2014, 2136 Copyright © 2015 by the American Society of Nephrology www.cjasn.org Vol 10 December, 2015 Clin J Am Soc Nephrol 10: 2136–2142, December, 2015 Sodium Polystyrene Sulfonate in Hyperkalemia, Lepage et al. 2137 which was the predetermined end date. The trial was were completed. The placebo was similar in taste, texture, registered on ClinicalTrials.gov (NCT 02065076) and funded and appearance to SPS. Both were supplied as individual by the Nephrology Research Axis of Maisonneuve-Rosemont doses in tinted bottles. Patients were instructed to mix Hospital, the Dean’s Circle of the Faculty of Pharmacy each dose with 150 ml water immediately before adminis- of the University of Montreal, and the Department of tration and take their study medication in the evening Pharmacy of Maisonneuve-Rosemont Hospital. The pla- starting on the day of randomization. Their final follow- cebo (carob gum and lactose; Galenova Inc.) and SPS up was scheduled the day after their last dose. (Kayexalate; Sanofi Aventis) powders were purchased Three days after randomization, investigators contacted from Galenova Inc., an independent firm, to ensure blind- patients by telephone to assess side effects using a standard- ing. Neither products contained sorbitol. Study protocol ized questionnaire. Seven days after randomization, patients was approved by the Institutional Scientific Committee returned for blood tests and completed the same side effects and Research Ethics Board. All patients provided written questionnaire as on day 3. For patients’ convenience, a 1-day informed consent. All authors declare their adherence to difference was tolerated, meaning that patients could receive the Declaration of Helsinki. between six and eight doses. They were instructed to return all bottles (including empty ones) to investigators on the day of their final follow-up to allow an objective assessment of Study Population compliance, which was also evaluated with a modified ver- Patients ages 18 years old and older with eGFR,40 ml/min sion of a validated questionnaire. per 1.73 m2 (calculated using the Modification of Diet in Although no formal diet education was part of this trial, Renal Disease four–variable equation) were assessed for all patients with CKD and hyperkalemia followed in our eligibility according to their serum potassium levels mea- nephrology and predialysis outpatient clinics routinely sured for their usual follow-up with their nephrologist and receive information on a low–potassium intake diet by a on the day of randomization (12). Patients who had taken nutritionist, and patients were instructed not to modify SPS in the 7 days before their initial visit were eligible if their diet. Average dietary intake of potassium was esti- their serum potassium level measured for their regular mated through a food diary completed by patients for 3 of follow-up was from 4.5 to 5.5 mEq/L (multiply by 1 to con- 7 study days. Compilation was done in accordance with vert to millimoles per liter) inclusively and from 5.0 to the Canadian Nutrient File from Health Canada, which 5.9 mEq/L inclusively after a 7-day washout period was exported to a Microsoft Excel database. (day of randomization). Patients who had not taken SPS in the 7 days before their initial visit were eligible if their serum potassium levels measured for their regular follow- Outcomes up and on the day of randomization were both from 5.0 to Theprimaryoutcomewasthecomparisonbetween 5.9 mEq/L inclusively. study groups of the mean difference in serum potassium Patients on dialysis were not included in this study. levels between the day after the last dose of treatment (day 7) Exclusion criteria included a change in medication affecting and baseline (day 0). Secondary outcomes were to compare potassium levels within 30 days before enrolment. Excep- the proportion of patients achieving normokalemia, de- tion was made for insulin, for which dose modifications fined as a serum potassium level of at least 3.5 mEq/L and occurring .7 days before randomization were accepted or ,5.0 mEq/L, at the end of the study period as well as if more recent modifications were not .10% of the total compare the prevalence of side effects between study daily dose up to a maximum variation of five units. Pa- groups. Specifically, nausea, vomiting, constipation, and tients with changes in dosage of angiotensin–converting diarrhea were assessed on study days 3 and 7. Addition- enzyme inhibitors (ACEIs), angiotensin receptor blockers ally, on day 7, blood tests assessed the frequency of hyper- (ARBs), or aliskiren within 60 days before randomization natremia, hypophosphatemia, hypomagnesemia, and were also excluded. For safety reasons, patients were ex- hypocalcemia. cluded if they were pregnant or breastfeeding, had a con- traindication to SPS, had a lactose intolerance, or had an Statistical Analyses episode of decompensated heart failure in the 30 days be- To detect a mean difference of serum potassium of fore enrolment. Patients with symptomatic