potassium

(K) [po-tas´e-um]

a chemical element, atomic number 19, atomic weight 39.102. (See Appendix 6.) In combination with other minerals in the body, potassium forms alkaline salts that are important in body processes and play an essential role in maintenance of the acid-base and water balance in the body. All body cells, especially muscle tissue, require a high content of potassium. A proper balance between sodium, calcium, and potassium in the blood plasma is necessary for proper cardiac function.

Since most foods contain a good supply of potassium, potassium deficiency (hypokalemia) is unlikely to be caused by an unbalanced diet. Possible causes include cushing's syndrome (due to an adrenal gland disorder) and fanconi's syndrome (the result of a congenital kidney defect). The cause could also be an excessive dose of cortisone, prolonged vomiting or diarrhea, or thiazide diuretics, which are administered for treatment of hypertension. Signs of potassium deficiency can include weakness and lethargy, rapid pulse, nausea, diarrhea, and tingling sensations.

If the body absorbs enough potassium but the element is not distributed properly, various disorders may develop. Thus an abnormally low content of potassium in the blood may result in an intermittent temporary paralysis of the muscles, known as familial periodic paralysis.

Potassium deficiency can be treated by administration of potassium supplements. There is a large variety of these preparations. Some are liquids, some are powders to be dissolved in liquids, and some are slow-release tablets that dissolve in the intestine. All can cause gastrointestinal irritation. For many persons on diuretic therapy for hypertension, potassium deficiency can be avoided by increasing their consumption of potassium-containing foods, such as bananas, dates, prunes, and raisins, and potassium supplements are not needed. Potassium supplements are never given to patients receiving potassium-sparing diuretics such as amiloride, spironolactone, or triamterene. If the difficulty lies in the body's use of potassium, treatment is concerned with the primary cause of the deficiency.

Homeostatic balance of potassium. Through the functions of resorption and excretion, the kidneys are the best regulator of potassium balance in the extracellular fluids. From Malarkey and McMorrow, 2000.

potassium acetate an electrolyte replenisher and systemic and urinary alkalizer.

potassium bicarbonate an electrolyte replenisher, antacid, and urinary alkalizer.

potassium bitartrate a compound administered rectally as a suppository with sodium bicarbonate to produce carbon dioxide, which promotes defecation by distending the rectal ampulla; administered for relief of constipation, and evacuation of the colon before surgical or diagnostic procedures or childbirth.

potassium chloride a compound used orally or intravenously as an electrolyte replenisher.

potassium citrate a systemic and urinary alkalizer, electrolyte replenisher, and diuretic.

dibasic potassium phosphate the dipotassium salt, K₂HPO₄; used alone or in combination with other phosphate compounds as an electrolyte replenisher.

potassium gluconate an electrolyte replenisher used in the prophylaxis and treatment of hypokalemia.

potassium guaiacolsulfonate an expectorant.

potassium iodide an expectorant, antithyroid agent, and antifungal.

monobasic potassium phosphate the monopotassium salt, KH₂PO₄; used as a buffering agent in pharmaceutical preparations and, alone or in combination with other phosphate compounds, as an electrolyte replenisher and urinary acidifier and for prevention of kidney stones.

potassium permanganate a topical antiinfective and oxidizing agent, and an antidote for many poisons.

potassium phosphate a compound combining potassium and phosphoric acid, usually dibasic potassium phosphate.

potassium sodium tartrate a compound used as a saline cathartic.

potassium bicarbonate

Pharmacologic class: Mineral, electrolyte

Therapeutic class: Electrolyte replacement, nutritional supplement

Pregnancy risk category C

Action

Maintains acid-base balance, isotonicity, and electrophysiologic balance throughout body tissues; crucial to nerve impulse transmission and contraction of cardiac, skeletal, and smooth muscle. Also essential for normal renal function and carbohydrate metabolism.

Availability

Tablets for effervescent oral solution: 25 mEq

Indications and dosages

➣ To prevent potassium depletion

Adults: Dosage highly individualized. Usual dosage is 25 mEq/day P.O. in divided doses.

➣ To treat potassium depletion

Adults: 50 to 100 mEq/day P.O. in divided doses, not to exceed a maximum daily dosage of 150 mEq

Contraindications

• Hypersensitivity to tartrazine or alcohol (with some products)

• Acute dehydration

• Heat cramps

• Hyperkalemia

• Hyperkalemic familial periodic paralysis

• Severe renal impairment

• Severe hemolytic reaction

• Severe tissue trauma

• Untreated Addison's disease

• Concurrent use of potassium-sparing diuretics, angiotensin-converting enzyme (ACE) inhibitors, or salt substitutes containing potassium

Precautions

Use cautiously in:

• cardiac disease, renal impairment, diabetes mellitus, hypomagnesemia

• pregnant or breastfeeding patients

• children (safety and efficacy not established).

Administration

• Ensure that patient is adequately hydrated and urinating before starting therapy.

• Give with meals and a full glass of water or juice to minimize GI upset.

• Be aware that potassium preparations aren't interchangeable.

• Know that dosages are expressed in mEq of potassium and that potassium bicarbonate contains 10 mEq potassium/g.

Adverse reactions

CNS: confusion, unusual fatigue, restlessness, asthenia, flaccid paralysis, paresthesia

CV: ECG changes, hypotension, heart block, arrhythmias, cardiac arrest

GI: nausea, vomiting, diarrhea, abdominal discomfort, flatulence

Metabolic: hyperkalemia

Musculoskeletal: weakness and heaviness of legs

Interactions

Drug-drug. ACE inhibitors, potassium-sparing diuretics, other potassium-containing preparations: increased risk of hyperkalemia

Drug-diagnostic tests. Potassium: increased level

Drug-food. Salt substitutes containing potassium: increased risk of hyperkalemia

Drug-herbs. Dandelion: increased risk of hyperkalemia

Licorice: decreased response to potassium

Patient monitoring

• Monitor renal function, fluid intake and output, and potassium, creatinine, and blood urea nitrogen levels.

☞ Be aware that potassium is contraindicated in patients with severe renal impairment and must be used with extreme caution (if at all) in patients with any degree of renal impairment, because of risk of life-threatening hyperkalemia.

• Assess vital signs. Check ECG for arrhythmias.

• Monitor neurologic status. Stay alert for neurologic complications.

Patient teaching

• Instruct patient to dissolve tablets thoroughly in 4 to 8 oz of cold water or juice and to sip solution over 5 to 10 minutes with a meal.

• Advise patient to minimize GI upset by eating small, frequent servings of food and drinking plenty of fluids.

• Tell patient to report nausea, vomiting, confusion, numbness and tingling, unusual tiredness or weakness, or a heavy feeling in legs.

• Instruct patient to avoid salt substitutes.

• As appropriate, review all other significant and life-threatening adverse reactions and interactions, especially those related to the drugs, tests, foods, and herbs mentioned above.

po·tas·si·um bi·car·bon·ate

used as a diuretic to decrease the acidity of the urine and as an electrolyte replenisher.

potassium bicarbonate

A compound, KHCO₃, in the form of a white powder or colorless crystals, used in baking powder and in medicine as an antacid and in the treatment of potassium deficiency.

po·tas·si·um bi·car·bon·ate

(pŏ-tasē-ŭm bī-kahrbŏ-nāt)

Agent used as diuretic to decrease acidity of urine.