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Hong Kong Journal of Emergency Medicine A case of slow-release potassium chloride overdose
An 86-year-old gentleman was brought to the emergency department after a massive overdose of slow-release potassium chloride and indapamide. The initial serum potassium was 6.8 mmol/L. His abdominalX-ray did not reveal any radio-opaque drugs. Whole bowel irrigation was commenced shortly afterpresentation. There was no rebound of hyperkalaemia and his stay in the acute hospital was short. Slow-release potassium overdose is uncommonly reported in the medical literature; such poisoning in the elderlyhas not been reported. Previous case reports are summarised and the management of this uncommon poisoningis discussed. (Hong Kong j.emerg.med. 2007;14:169-173) Keywords: Aged, delayed-action preparations, irrigation, poisoning, potassium
Slow-release potassium chloride (Slow-K) is a commonly prescribed potassium supplement. The hypertension and regular follow-up in a government elderly is the major group of patients consuming this outpatient clinic (GOPD), was suspected to have early drug. Overdose of slow-release potassium (SRP) is dementia and was referred to the memory clinic.
rarely encountered in our practice. In case of massive Currently, he was on indapamide (Natrilix) 2.5 mg overdose of Slow-K, it is important to manage the daily and slow-release potassium chloride (Slow-K, hyperkalaemia. Gastrointestinal decontamination in 600 mg or 8 mmol per tablet) 2 tablets per day. In SRP overdose is also of paramount importance.
March 2007, he was followed up three days beforeattending our department and was given a total of41 tablets of Natrilix and 82 tablets of Slow-K. One Correspondence to: day before attending our department, his daughter- Wan Chi Keung, MRCSEd(A&E), FHKCEM, FHKAM(Emergency Medicine)
Queen Mary Hospital, Accident & Emergency Department, 102
in-law found that only a few tablets of the drugs were Pokfulam Road, Hong Kong left. He was brought to the GOPD and was immediately referred to our department. He was Tong Hon Kuan, FRCSEd, FHKCEM, FHKAM(Emergency Medicine) estimated to have ingested at least 30 tablets of Hong Kong j. emerg. med. „ Vol. 14(3) „ Jul 2007 indapamide and 70 tablets of slow-release potassium reasons and the need of the rehabilitation program for chloride (approximately 8 mmol potassium chloride/ his poor mobility.
kg of body weight).
On presentation, he had no discomfort and denied any suicidal idea. His general condition was fair. However,he was mildly dehydrated and looked tired. He was fully Indapamide is a common anti-hypertensive drug for conscious and afebrile. The blood pressure was 112/66 the elderly. It is a thiazide diuretic with the side effect mmHg and the pulse rate was 86 beats per minute.
of hypokalaemia, so potassium supplement is usually Venous blood was sampled immediately (Table 1). The given concurrently. The toxic dose of indapamide has potassium level was 6.8 mmo/L. The electrocardiogram not been established. Toxicity of indapamide is showed no features of hyperkalaemia. According to the primarily associated with fluid and electrolyte loss that computer record, the renal function test done four months should be corrected with appropriate intravenous or before this consultation was normal (urea 7.1 mmol/L, creatinine 89 umol/L).
SRP overdose has been uncommonly reported in the He was managed in our resuscitation room. The literature. An extensive medical literature search from hyperkalaemia was treated with 10 ml 10% calcium 1966 to 2007 revealed only 10 case reports with the gluconate, 100 ml 8.4% sodium bicarbonate, insulin description of a total of 13 patients of SRP overdose and dextrose infusion (Actrapid HM 8 units in 50 ml D50 over 1 hour).
The main concerns of SRP overdose are the potentially Although activated charcoal is believed to be ineffective life-threatening hyperkalaemia and gastrointestinal in the adsorption of potassium salts, it was still given for suspected co-ingestion. The chest X-ray was haemorrhage and stricture.12,13 SRP is less irritating but unremarkable and the abdominal X-ray revealed no more likely to cause hyperkalaemia than immediate radio-opaque drugs. After resuscitation, he was closely release preparations because vomiting may not occur.
monitored in the intensive care unit (ICU). In view of In adults with normal renal function, hyperkalaemia the significant hyperkalaemia and the potentially fatal may occur if the potassium load exceeds the maximal dose of potassium exposure, whole bowel irrigation excretory capacity. An acute ingestion of 2-2.5 mEq/kg (mmol/kg) may result in hyperkalaemia.14 The decontamination. The serum potassium level dropped absorption of Slow-K takes place in the small bowel to 4.6 mmol/L one hour later. There was no rebound over 3-4 hours in therapeutic doses; however of hyperkalaemia afterwards. He was transferred out hyperkalaemia may develop rapidly after a massive to the general medical ward the next day and then overdose. Illingworth and Proudfoot reported the death transferred to a convalescent hospital on Day 5. He of a 26-year-old man who presented to the hospital ran an uneventful course in the convalescent hospital 3.5 hours after ingestion of 24 grams of slow-release and was discharged home one month later. The long potassium chloride. His peak potassium level was stay in the convalescent hospital was due to social 9.3 mmol/L.4 Saxena reported a 46-year-old woman Table 1. Results of the initial venous blood gas
Na (mmol/L)
K (mmol/L)
PCO (kPa)
HCO (mmol/L)
Base excess (mmol/L)
Wan et al./Slow-release potassium chloride overdose Table 2. Summary of previous case reports of slow-release potassium overdose
Age (year)/
Amount of
Peak serum
KCl (grams)
10.8 ocular fluid Geluk & Braitberg9 27 F Alprazolam, Ibuprofen who developed cardiac arrest within one hour of considered to be remaining in the stomach. Performing ingestion of 60 grams of SRP with peak potassium lavage is not without risk. Apart from mechanical trauma and risk of aspiration, the procedure may affectcardiorespiratory function.16 Illingworth and Proudfoot Apart from the acute management of hyperkalaemia, reported the death of a 26-year-old man who had gastrointestinal decontamination may be beneficial in ingested 24 grams of SRP and developed cardiac arrest SRP overdose. From Table 2, seven out of the 13 with asystole during gastric lavage.4 The second patients had received decontamination. One patient problem is technical difficulty. The tablet size of Slow- received both gastric lavage and activated charcoal.6 K is large with a diameter of 13 mm. In order to ensure Three received gastric lavage only.4,5 Another patient the passage of one whole tablet of Slow-K, the internal received both gastric lavage and WBI.11 Two received diameter of the lavage tube should be at least 40 solely WBI.10,11 Although data suggest that activated French.10 The passage of such a large tube in small sized charcoal cannot adsorb potassium effectively as it is patients may be considered risky.
ionic and small in nature, it may be useful in case of co-ingestion.14,15 Gastric lavage is another option for Whole bowel irrigation involves the use of polyethylene gastrointestinal decontamination if the drugs are still glycol electrolyte solution that is commonly used Hong Kong j. emerg. med. „ Vol. 14(3) „ Jul 2007 nowadays for bowel preparation prior to investigation significant. However, it could be postulated that the and surgery of the bowel. WBI is considered useful in peak serum potassium might be higher if he did not managing overdose of substances that are poorly take any indapamide. Whole bowel irrigation with adsorbed by activated charcoal. WBI can be applied polyethylene glycol electrolyte solution was reasonable in the management of various drugs including iron, after commencing treatment for the hyperkalaemia.
lead, zinc sulphate, sustained release theophylline, The patient was discharged to general medical ward sustained release verapamil and can also be used to from the ICU the next day and had no rebound of remove illegal drugs from "body packers".17-19 There were only two previous case reports mentioning the use of WBI in three cases of SRP overdose.
However, the patients were young. Whitaker et alreported a 30-month-old child who had ingested an unknown amount of Slow-K.10 The abdominal X-rayof this patient showed at least 32 tablets in the We reported a case of massive overdose of slow-release gastrointestinal tract. WBI was performed resulting in potassium and described the use of WBI in its a significant reduction of radio-opaque tablets as shown management. Whole bowel irrigation appears to be one in the subsequent film. The peak serum potassium was of the alternatives of gastrointestinal decontamination 9.2 mmol/L. The patient survived and developed no for the management of SRP overdose in the elderly.
complication of his gastrointestinal tract after eightmonths of follow up. Su et al reported the use of WBIin two patients. In this report, the first patient was a 50-year-old woman who had ingested 75 grams ofpotassium chloride. Abdominal X-ray showed tablets Wilcox CS. Metabolic and adverse effects of diuretics.
in her gastrointestinal tract. Her peak serum potassium Semin Nephrol 1999;19(6):557-68.
Bacon C. Letter: death from accidental potassium was 9.7 mmol/L with peaked T wave shown in the poisoning in childhood. Br Med J 1974;1(5904):389- electrocardiogram. Although WBI was commenced approximately 13 hours after presentation, the Wetli CV, Davis JH. Fatal hyperkalemia from accidentaloverdose of potassium chloride. JAMA 1978;240(13): decontamination was successful. The second case was a 17-year-old teenager who presented to the emergency Illingworth RN, Proudfoot AT. Rapid poisoning with room about 10 hours after the ingestion of approximately slow-release potassium. Br Med J 1980;281(6238): 15 to 22.5 grams of potassium chloride. WBI was Colledge NR, Northridge B, Fraser DM. Survival after commenced soon after his presentation. He had a massive overdose of slow-release potassium. Scott Med shorter stay than the first case but it could be due to J 1988;33(3):279.
the lesser amount of potassium taken.11 Saxena K. Death from potassium chloride overdose.
Postgrad Med 1988;84(1):97-8, 101-2.
Steedman DJ. Poisoning with sustained release Generally speaking, potassium preparations are radio- potassium. Arch Emerg Med 1988;5(4):206-11.
opaque and may be shown up in routine radiography.20 Davey M, Kuhn M. Slow-release potassium overdose: Although the abdominal X-ray of our patient revealed is there a role for magnesium? Emerg Med 1999;11:263-71.
no radio-opaque drugs, a negative film cannot rule out Geluk M, Braitberg G. Ipecac for slow-release potassium the diagnosis as radio-opacity varies among the same poisoning: pariah or phoenix? Emerg Med 2000;12:226- medication made by different manufacturers and is also affected by the size of the patient, air contrasting the pill 10. Whitaker R, Maguire JE. Slow-release potassium overdose: clinical features and the role of whole and the arrangement of drugs within the stomach.20 bowel lavage in management. Emerg Med 2000;12: Notably, his initial hyperkalaemia (6.8 mmol/L) was Wan et al./Slow-release potassium chloride overdose 11. Su M, Stork C, Ravuri S, Lavoie T, Anguish D, Nelson 16. Thompson AM, Robins JB, Prescott LF. Changes in LS, et al. Sustained-release potassium chloride overdose.
cardiorespiratory function during gastric lavage for drug J Toxicol Clin Toxicol 2001;39(6):641-8.
overdose. Hum Toxicol 1987;6(3):215-8.
12. Ward C, Hamid S, Dow J. Gastric complication of 17. Howland MA. Antidote in depth: whole-bowel massive Slow-K overdose. Br J Surg 1987;74(6):490.
irrigation. In: Goldfrank L, Flomenbaum N, Lewin N, 13. Lambert JR, Newman A. Ulceration and stricture of Weisman R, Howland MA, Hoffman RS, editors.
the esophagus due to oral potassium chloride (slow Goldfrank's toxicologic emergencies. 6th ed. Stamford, release tablet) therapy. Am J Gastroenterol 1980;73(6): CT: Appletion and Lange; 1998. p. 538-9.
18. Tenenbein M. Whole bowel irrigation for toxic ingestions. J Toxicol Clin Toxicol 1985;23(2-3):177- International Programme on Chemical Safety. [cited 2007 Mar 13]. Available from: http://www.inchem.org/ 19. Position paper: whole bowel irrigation. J Toxicol Clin 15. Welch DW, Johnson PN, Driscoll JL. In vitro potassium 20. Savitt DL, Hawkins HH, Roberts JR. The radiopacity binding: a comparison of activated charcoal and sodium of ingested medications. Ann Emerg Med 1987;16(3): polystyrene sulfonate. Vet Hum Toxicol 1986;28:495.

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