POTASSIUM-CIT- potassium citrate tablet, extended release
1 INDICATIONS AND USAGE
1.1 Renal Tubular Acidosis (RTA) with Calcium Stones
Potassium citrate is indicated for the management of renal tubular acidosis [see Clinical Studies (14.1)].
1.2 Hypocitraturic Calcium Oxalate Nephrolithiasis of any Etiology
Potassium citrate is indicated for the management of Hypocitraturic calcium oxalate nephrolithiasis [see Clinical Studies (14.2)].
1.3 Uric Acid Lithiasis with or without Calcium Stones
Potassium citrate is indicated for the management of Uric acid lithiasis with or without calcium stones [see Clinical Studies (14.3)].
2 DOSAGE AND ADMINISTRATION
2.1 Dosing Instructions
Treatment with extended release potassium citrate should be added to a regimen that limits salt intake (avoidance of foods with high salt content and of added salt at the table) and encourages high fluid intake (urine volume should be at least two liters per day). The objective of treatment with potassium citrate extended-release tablets is to provide potassium citrate in sufficient dosage to restore normal urinary citrate (greater than 320 mg/day and as close to the normal mean of 640 mg/day as possible), and to increase urinary pH to a level of 6.0 or 7.0.
Monitor serum electrolytes (sodium, potassium, chloride and carbon dioxide), serum creatinine and complete blood counts every four months and more frequently in patients with cardiac disease, renal disease or acidosis. Perform electrocardiograms periodically. Treatment should be discontinued if there is hyperkalemia, a significant rise in serum creatinine or a significant fall in blood hematocrit or hemoglobin.
2.2 Severe Hypocitraturia
In patients with severe hypocitraturia (urinary citrate < 150 mg/day), therapy should be initiated at a dosage of 60 mEq /day (30 mEq two times/day or 20 mEq three times/day with meals or within 30 minutes after meals or bedtime snack). Twenty-four hour urinary citrate and/or urinary pH measurements should be used to determine the adequacy of the initial dosage and to evaluate the effectiveness of any dosage change. In addition, urinary citrate and/or pH should be measured every four months. Doses of potassium citrate extended-release tablets greater than 100 mEq/day have not been studied and should be avoided.
2.3 Mild to Moderate Hypocitraturia
In patients with mild to moderate hypocitraturia (urinary citrate > 150 mg/day) therapy should be initiated at 30 mEq/day (15 mEq two times/day or 10 mEq three times/day with meals or within 30 minutes after meals or bedtime snack). Twenty-four hour urinary citrate and/or urinary pH measurements should be used to determine the adequacy of the initial dosage and to evaluate the effectiveness of any dosage change. Doses of potassium citrate extended-release tablet greater than 100 mEq/day have not been studied and should be avoided.
3 DOSAGE FORMS AND STRENGTHS
- 5 mEq tablets are uncoated, tan to yellowish speckled in color, round shaped, with E34 debossed on one side and plain on the other side.
- 10 mEq tablets are uncoated, tan to yellowish speckled in color, elliptical shaped, with E35 debossed on one side and plain on the other side.
- 15 mEq tablets are uncoated, tan to yellowish speckled in color, modified rectangle shaped, with E36 debossed on one side and plain on the other side.
Potassium citrate extended-release tablets is contraindicated:
- In patients with hyperkalemia (or who have conditions predisposing them to hyperkalemia), as a further rise in serum potassium concentration may produce cardiac arrest. Such conditions include: chronic renal failure, uncontrolled diabetes mellitus, acute dehydration, strenuous physical exercise in unconditioned individuals, adrenal insufficiency, extensive tissue breakdown or the administration of a potassium-sparing agent (such as triamterene, spironolactone or amiloride).
- In patients in whom there is cause for arrest or delay in tablet passage through the gastrointestinal tract, such as those suffering from delayed gastric emptying, esophageal compression, intestinal obstruction or stricture, or those taking anticholinergic medication.
- In patients with peptic ulcer disease because of its ulcerogenic potential.
- In patients with active urinary tract infection (with either urea-splitting or other organisms, in association with either calcium or struvite stones). The ability of potassium citrate extended-release tablet to increase urinary citrate may be attenuated by bacterial enzymatic degradation of citrate. Moreover, the rise in urinary pH resulting from potassium citrate extended-release tablet therapy might promote further bacterial growth.
- In patients with renal insufficiency (glomerular filtration rate of less than 0.7 ml/kg/min), because of the danger of soft tissue calcification and increased risk for the development of hyperkalemia.
5 WARNINGS AND PRECAUTIONS
In patients with impaired mechanisms for excreting potassium, potassium citrate administration can produce hyperkalemia and cardiac arrest. Potentially fatal hyperkalemia can develop rapidly and be asymptomatic. The use of potassium citrate in patients with chronic renal failure, or any other condition which impairs potassium excretion such as severe myocardial damage or heart failure, should be avoided. Closely monitor for signs of hyperkalemia with periodic blood tests and ECGs.
5.2 Gastrointestinal Lesions
Solid dosage forms of potassium chlorides have produced stenotic and/or ulcerative lesions of the small bowel and deaths. These lesions are caused by a high local concentration of potassium ions in the region of the dissolving tablets, which injured the bowel. In addition, perhaps because wax-matrix preparations are not enteric-coated and release some of their potassium content in the stomach, there have been reports of upper gastrointestinal bleeding associated with these products. The frequency of gastrointestinal lesions with wax-matrix potassium chloride products is estimated at one per 100,000 patient-years. Experience with potassium citrate is limited, but a similar frequency of gastrointestinal lesions should be anticipated.
If there is severe vomiting, abdominal pain or gastrointestinal bleeding, potassium citrate should be discontinued immediately and the possibility of bowel perforation or obstruction investigated.
6 ADVERSE REACTIONS
6.1 Postmarketing Experience
Some patients may develop minor gastrointestinal complaints during potassium citrate therapy, such as abdominal discomfort, vomiting, diarrhea, loose bowel movements or nausea. These symptoms are due to the irritation of the gastrointestinal tract, and may be alleviated by taking the dose with meals or snacks, or by reducing the dosage. Patients may find intact matrices in their feces.
7 DRUG INTERACTIONS
7.1 Potential Effects of Potassium Citrate on Other Drugs
Potassium-sparing Diuretics: Concomitant administration of potassium citrate and a potassium-sparing diuretic (such as triamterene, spironolactone or amiloride) should be avoided since the simultaneous administration of these agents can produce severe hyperkalemia.
7.2 Potential Effects of Other Drugs on Potassium Citrate
Drugs that slow gastrointestinal transit time: These agents (such as anticholinergics) can be expected to increase the gastrointestinal irritation produced by potassium salts.
7.3 Renin-Angiotensin-Aldosterone System Inhibitors
Drugs that inhibit the renin-angiotensin-aldosterone system (RAAS) including angiotensin converting enzyme (ACE) inhibitors, angiotensin receptor blockers (ARBs), spironolactone, eplerenone, or aliskiren produce potassium retention by inhibiting aldosterone production. Closely monitor potassium in patients receiving concomitant RAAS therapy.
7.4 Nonsteroidal Anti-Inflammatory Drugs (NSAIDs)
NSAIDs may produce potassium retention by reducing renal synthesis of prostagladin E and impairing the renin-angiotensin system. Closely monitor potassium in patients on concomitant NSAIDs.
8 USE IN SPECIFIC POPULATIONS
Animal reproduction studies have not been conducted. It is also not known whether potassium citrate can cause fetal harm when administered to a pregnant woman or can affect reproduction capacity. Potassium citrate should be given to a pregnant woman only if clearly needed.
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