Adverse effects from normal use of KCl are typically related to the administration route. The FDA notes particular adverse effects for each administration route. In general, oral formulations most commonly correlate with GI irritation, including vomiting and diarrhoea. Tablet and capsule forms may cause ulcerative/stenotic lesions with prolonged exposure to GI surfaces. Injectable KCl formulations have the potential to cause injection site complications (eg phlebitis, erythema, thrombosis, etc.). Also, rapid injection of KCl can precipitate mild hyperkalaemia. This review discusses the symptoms of hyperkalaemia in the Toxicity section.
As KCl is used to increase body potassium content, its use with other drugs that achieve this outcome is contraindicated. Examples of such medications include potassium-sparing diuretics, non-steroidal anti-inflammatory drugs, and angiotensin-converting enzyme inhibitors. Certain medical conditions involve hyperkalaemia as part of their pathophysiologies. KCl use in these cases is contraindicated. Examples of notable conditions that involve hyperkalaemia include type IV renal tubular acidosis, chronic kidney disease, and leakage from cell breakdown (eg rhabdomyolysis, tumour lysis syndrome).
Given the narrow normal range of serum potassium, careful monitoring is a requirement when utilising KCl. For hospitalised patients receiving oral KCl, serum potassium checks should occur at least daily to determine treatment effectiveness. Patients treated with intravenous KCl may require more frequent checking, especially if the serum potassium level addressed is below 2.5mEq/L. The use of continuous cardiac monitoring can aid in correlating symptoms with telling electrocardiogram changes (eg peaked T-waves in hyperkalaemia, flattened T-waves in hypokalaemia).
KCl toxicity is primarily a discussion of hyperkalaemia. Like hypokalaemia, the potentially fatal complication of hyperkalaemia is cardiac arrhythmia. The risk for cardiac arrhythmia is significant at serum potassium levels greater than 6-6.5mEq/L. Other manifestations of symptomatic hyperkalaemia include ascending muscle weakness and GI disturbance (eg nausea, local mucosal necrosis).
Enhancing healthcare team outcomes
When making decisions regarding KCl use, input from the entire multidisciplinary healthcare team can prove valuable. The prescribing clinician needs to determine whether oral or IV administration is warranted for the patient's condition. Pharmacists can assist with dosing, particularly at times when intravenous KCl infusion rates merit careful consideration. Nurses can monitor minute-to-minute vital signs and correlate them with symptom development.
Source: National Institutes of Health: StatPearls: Potassium Chloride. Robert S. McMahon; Khalid Bashir.