Slow-K Side Effects
Generic name: potassium chloride
Note: This document contains side effect information about potassium chloride. Some of the dosage forms listed on this page may not apply to the brand name Slow-K.
Some side effects of Slow-K may not be reported. Always consult your doctor or healthcare specialist for medical advice. You may also report side effects to the FDA.
For the Consumer
Applies to potassium chloride: oral capsule extended release, oral liquid, oral powder for reconstitution, oral tablet, oral tablet extended release
Get emergency medical help if you have any of these signs of an allergic reaction while taking potassium chloride (the active ingredient contained in Slow-K) hives; difficulty breathing; swelling of your face, lips, tongue, or throat.
Stop using this medication and call your doctor at once if you have any of these serious side effects:
confusion, anxiety, feeling like you might pass out;
extreme thirst, increased urination;
muscle weakness or limp feeling;
numbness or tingly feeling in your hands or feet, or around your mouth;
severe stomach pain, ongoing diarrhea or vomiting;
black, bloody, or tarry stools; or
coughing up blood or vomit that looks like coffee grounds.
Less serious side effects of potassium chloride may include:
mild nausea or upset stomach;
mild or occasional diarrhea;
slight tingling in your hands or feet; or
appearance of a potassium chloride tablet in your stool.
This is not a complete list of side effects and others may occur. Call your doctor for medical advice about side effects.
For Healthcare Professionals
Applies to potassium chloride: compounding powder, intravenous solution, oral capsule extended release, oral granule extended release, oral liquid, oral powder for reconstitution, oral tablet, oral tablet extended release
Metabolic side effects have been reported rarely and have usually resulted from hyperkalemia. The risk of hyperkalemia is relatively high in patients with preexisting renal insufficiency.
Signs of hyperkalemia include muscle weakness, including frank skeletal muscle and diaphragm paralysis, cardiac arrhythmias, and ECG changes. Common ECG changes associated with hypokalemia include loss of P waves, wide QRS complexes, decreased rate, and conduction disturbances. If toxicity is suspected or documented, potassium should be stopped immediately. While monitoring the ECG, a combination of dextrose and insulin in a ratio of 3 g of dextrose for every 1 unit of insulin may be administered. Sodium bicarbonate 50 to 100 mEq and calcium gluconate 10% intravenously may be helpful if acidosis is present. Potassium-binding resins or dialysis may be necessary in serious cases.
A 74-year-old woman receiving chronic intermittent hemodialysis treatment three times a week for 5 months developed cardiopulmonary arrest secondary to severe hyperkalemia on two separate occasions. The patient had a history of nephrolithiasis, hypertension, renal vascular disease, and chronic obstructive pulmonary disease (30-year history of smoking). A potassium-containing salt substitute was a probable cause.
The Boston Collaborative Drug Surveillance Program monitored 16,048 consecutive patients. of whom 4,921 (31%) had received potassium chloride (KCl). Adverse reactions were reported in 5.8%, the most common being hyperkalemia
Hyperkalemia is significantly more likely after intravenous administration and in elderly patients with uremia who receive high doses.
Gastrointestinal (GI) side effects have been reported from orally administered potassium chloride (the active ingredient contained in Slow-K) They have included bad taste or aftertaste, nausea (10% to 30%), abdominal pain (20%), diarrhea (25%), dyspepsia or "heartburn" (5% to 20%) and GI ulceration. They have rarely included gastric or small bowel obstruction associated with the use of solid preparations.
In a large, retrospective study of 104,908 patients, the reported incidence of upper GI tract bleeding was 0.3% to 0.4%, depending on the type of KCl preparation. The risk of GI bleeding was approximately 30% lower with use of a microencapsulated KCl preparation compared with a wax-matrix preparation.
All solid KCl preparations can cause erosive damage to the GI mucosa, especially when they are administered in high doses with an anticholinergic agent. Anticholinergic agents increase GI transit (and potassium-mucosa contact) time.
The incidence of small bowel ulceration associated with encapsulated or wax-matrix KCl is relatively low, averaging less than 1 per 100,000 patient-years. The incidence of small bowel lesions associated with enteric-coated KCl is higher, averaging 40 to 50 per 100,000 patient-years.
Patients at higher risk of GI lesions include the elderly, the immobile and those with scleroderma, diabetes mellitus, mitral valve replacement, cardiomegaly or esophageal stricture. These problems were so much more common with the use of enteric-coated KCl, this form of the drug was withdrawn from the market in 1965.
The pathogenesis of potassium-induced ulceration is not known, but may be direct mucosal injury or induction of local mesenteric vascular insufficiency.
Nearly half of all patients complain of a bad taste or aftertaste.
Liquid KCl may be a better choice for patients with a history of esophageal stenosis or left atrial enlargement.
Local side effects related to intravenous administration have included phlebitis or erythema at the injection site and pain with infusion.
Local reactions related to intravenous administration of KCl occur in up to 25% of patients. Diluting 40 mEq or less of KCl in 1 liter or more of intravenous solution and administering this concentration in no less than 1 hour is strongly recommended to reduce the likelihood of these problems. If the clinical situation is not critical and the patient's serum K+ is 2.5 mEq/L or more, an infusion rate not to exceed 10 mEq/hour is recommended.
Limited data show that infusion pain was significantly less common among patients when KCl (in D5W) was infused with 50 mg of lidocaine compared with KCl infusions without lidocaine.
A single case of paraplegia following epidural injection of 15 mL of 15% KCl and bupivacaine has been reported. The patient suffered permanent neurologic damage, which was thought to be due to the high extracellular concentration of potassium in the injection. Potassium salts are not routinely used as adjuvants to local anesthetics.
Nervous system side effects have included a single report of paraplegia following epidural injection.
Hypersensitivity side effects have been reported rarely. They have included a single case of contact dermatitis.
Dermatologic side effects have rarely included skin rash.
More Slow-K resources
- Slow-K Prescribing Information (FDA)
- Potassium Chloride Prescribing Information (FDA)
- Epiklor Prescribing Information (FDA)
- Glu-K Advanced Consumer (Micromedex) - Includes Dosage Information
- K-Tab Prescribing Information (FDA)
- Klor-Con extended-release tablets MedFacts Consumer Leaflet (Wolters Kluwer)
- Klor-Con Prescribing Information (FDA)
- Klor-Con M10 controlled-release tablets MedFacts Consumer Leaflet (Wolters Kluwer)
- Klor-con powder MedFacts Consumer Leaflet (Wolters Kluwer)
- Klor-con Consumer Overview
- Klotrix Prescribing Information (FDA)
- Micro-K Prescribing Information (FDA)
- Micro-K extended-release capsules MedFacts Consumer Leaflet (Wolters Kluwer)
- Rum-K liquid MedFacts Consumer Leaflet (Wolters Kluwer)
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