Lidocaine/potassium chloride Disease Interactions

Antiarrhythmic agents can induce severe hypotension (particularly with IV administration) or induce or worsen congestive heart failure (CHF). Patients with primary cardiomyopathy or inadequately compensated CHF are at increased risk. Antiarrhythmic agents should be administered cautiously and dosage and/or frequency of administration modified in patients with hypotension or adequately compensated CHF. Alternative therapy should be considered unless these conditions are secondary to cardiac arrhythmia.

Lidocaine is rapidly and extensively metabolized by the liver. Less than 10% is eliminated unchanged in the urine. Several inactive and two active forms (MEGX and GX) have been identified. MEGX and GX exhibit antiarrhythmic and convulsant properties. GX accumulates during prolonged intravenous lidocaine infusion. The pharmacokinetic disposition of lidocaine is altered by changes in hepatic function, including hepatic blood flow. Therapy with lidocaine should be administered cautiously and dosing modifications for repeated or loading and maintenance doses may be necessary. Clinical monitoring of cardiac (continuous ECG) is required and serum metabolite concentrations and monitoring hepatic function are recommended.

Lidocaine is primarily eliminated by the kidney. Less than 10% is eliminated unchanged in the urine. Two active metabolites (MEGX and GX) have been identified that exhibit antiarrhythmic and convulsant properties. GX accumulates during prolonged intravenous lidocaine infusion. Serum concentrations of lidocaine and the active metabolites are increased and the half-life prolonged in patients with renal impairment. Therapy with lidocaine should be administered cautiously and dosing modified for repeated or maintenance doses in patients with compromised renal function. Clinical monitoring of cardiac function (continual ECG) is required and serum metabolite concentrations and monitoring renal function are recommended.

Seizures have occurred during lidocaine therapy and have been associated with the rapid administration of a large intravenous doses or accumulation of active metabolites with maintenance therapy. Therapy with lidocaine should be administered cautiously to patients with or predisposed to seizure disorders. Clinical monitoring of cardiac (continuous ECG) is required, and serum metabolite concentrations are recommended.

The use of lidocaine is contraindicated in patients with Stokes-Adam syndrome, Wolff-Parkinson White syndrome, or second- or third-degree AV block in the absence of a functional artificial pacemaker, or congenital QT prolongation.

Potassium chloride liquid suspension contains the stool softener, docusate sodium, as a dispersing agent. Clinical studies with potassium chloride liquid suspension indicate that minor changes in stool consistency may be common though usually well tolerated. However, patients may rarely experience diarrhea or cramping abdominal pain. Patients with severe or chronic diarrhea or who are dehydrated ordinarily should not be prescribed potassium chloride liquid suspension.

Administration of potassium salts in severe dehydration may predispose to renal impairment. Therapy with potassium salts should be administered cautiously in patients with acute dehydration (e.g., due to severe or prolonged diarrhea or heat stress). Close monitoring of serum potassium concentrations is recommended, as potentially fatal hyperkalemia can develop rapidly and is often asymptomatic, manifested only by an increased potassium level (6.5 to 8 mEq/L) and characteristic electrocardiographic changes (peaking of T waves, loss of P waves, depression of ST segment, prolongation of the QT interval). Late manifestations include muscle paralysis and cardiovascular collapse from cardiac arrest (9 to 12 mEq/L). Continuous or serial electrocardiography may be appropriate in some patients during replacement therapy, particularly if given intravenously.

Administration of potassium salts may precipitate attacks in familial hyperkalemic periodic paralysis or paramyotonia congenita. Therapy with potassium preparations should be administered cautiously in patients with these conditions.

The use of potassium salts is contraindicated in patients with hyperkalemia, since a further increase in serum potassium concentration in such patients can lead to cardiac arrhythmias or arrest. Potassium therapy should be administered cautiously in patients with conditions predisposing to hyperkalemia, such as chronic renal failure, systemic acidosis, acute dehydration, hypoaldosteronism (e.g., due to primary adrenal insufficiency or congenital adrenal enzyme deficiency), uncontrolled diabetes mellitus, and extensive tissue breakdown (e.g., due to severe burns, intravascular hemolysis, tumor lysis syndrome, or rhabdomyolysis). Close monitoring of serum potassium concentrations is recommended, as potentially fatal hyperkalemia can develop rapidly and is often asymptomatic, manifested only by an increased potassium level (6.5 to 8 mEq/L) and characteristic electrocardiographic changes (peaking of T waves, loss of P waves, depression of ST segment, prolongation of the QT interval). Late manifestations include muscle paralysis and cardiovascular collapse from cardiac arrest (9 to 12 mEq/L). Continuous or serial electrocardiography may be appropriate in some patients during replacement therapy, particularly if given intravenously.

The use of potassium salts is contraindicated in patients with severe renal impairment characterized by oliguria, anuria, or azotemia. Since potassium is excreted by the kidney, the administration of potassium salts in such patients, particularly by the intravenous route, may produce hyperkalemia and cardiac arrhythmias or arrest. Therapy with potassium salts should be administered cautiously in patients with diminished renal function or other conditions which impairs potassium excretion (e.g. adrenal insufficiency). Close monitoring of serum potassium concentrations is recommended, as potentially fatal hyperkalemia can develop rapidly and is often asymptomatic, manifested only by an increased potassium level (6.5 to 8 mEq/L) and characteristic electrocardiographic changes (peaking of T waves, loss of P waves, depression of ST segment, prolongation of the QT interval). Late manifestations include muscle paralysis and cardiovascular collapse from cardiac arrest (9 to 12 mEq/L). Continuous or serial electrocardiography may be appropriate in some patients during replacement therapy, particularly if given intravenously.

The use of all solid oral formulations of potassium is contraindicated in patients with arrested or delayed gastrointestinal (GI) transit, whether due to structural, pathological, or pharmacological causes. Potassium is irritating to the GI mucosa and may cause ulcerative and/or stenotic lesions during prolonged physical contact. Based on spontaneous adverse reaction reports, the frequency of small bowel lesions associated with enteric-coated preparations of potassium chloride is 40 to 50 per 100,000 patient-years, while that for wax matrix controlled-release formulations is less than one per 100,000 patient years. Esophageal ulceration has also been reported following administration of controlled-release formulations of potassium chloride in cardiac patients with esophageal compression due to enlarged left atrium. Potassium supplementation should be administered as a liquid preparation or as an aqueous suspension in patients with esophageal obstruction and/or delayed gastrointestinal transit time.

Because of ulcerogenic effects, oral potassium should be administered cautiously in patients with peptic ulcers or other upper gastrointestinal diseases associated with inflammation, bleeding, or perforation. Patients should be advised not to crush, chew, or break potassium tablets or capsules, and to take them with meals and a full glass of water or other liquid. Potassium liquids should be diluted prior to consumption.

Electrolyte imbalance can alter the therapeutic effectiveness of antiarrhythmic agents. Hypokalemia and hypomagnesemia can reduce the effectiveness of antiarrhythmic agents. In some cases, these disorders can exaggerate the degree of QTc prolongation and increase the potential for torsade de pointes. Hyperkalemia can potentiate the toxic effects of antiarrhythmic agents. Electrolyte imbalance should be corrected prior to initiating antiarrhythmic therapy. Clinical monitoring of cardiac function and electrolyte concentrations is recommended.

Hypokalemia in patients with metabolic acidosis should be treated with an alkalinizing potassium salt (i.e. acetate, bicarbonate, citrate, or gluconate) rather than potassium chloride, since alkali therapy helps to promote cellular uptake of potassium. Close monitoring of acid-base balance, serum electrolytes, electrocardiogram, and clinical status is recommended.