Potassium Phosphate, Monobasic and Sodium Phosphate, Monobasic, Anhydrous

INDICATONS AND USAGE K-PHOS® No. 2 is a highly effective urinary acidifier for use in patients with elevated urinary pH. This product helps keep calcium soluble and reduces odor and rash caused by ammoniacal urine. Also, by acidifying the urine, it increases the antibacterial activity of methenamine mandelate and methenamine hippurate.

DOSAGE AND ADMINISTRATION One tablet four times daily with a full glass of water. When the urine is difficult to acidify, administer one tablet every two hours not to exceed 8 tablets in a 24-hour period.

CONTRAINDICATIONS This product is contraindicated in patients with infected phosphate stones, in patients with severely impaired renal function (less than 30% of normal) and in the presence of hyperphosphatemia.

Drug Interactions The use of antacids containing magnesium, aluminum, or calcium in conjunction with phosphate preparations may bind the phosphate and prevent its absorption. Concurrent use of antihypertensives, especially diazoxide, guanethidine, hydralazine, methyldopa, or rauwolfia alkaloid; or corticosteroids, especially mineralocorticoids or corticotropin, with sodium phosphate may result in hypernatremia. Potassium-containing medications or potassium-sparing diuretics may cause hyperkalemia when used wi t h potassium phosphate. Patients should have serum potassium level determinations at periodic intervals. Plasma levels of salicylates may be increased since salicylate excretion is decreased in acidified urine. Administration of monobasic phosphates to patients stabilized on salicylates may lead to toxic salicylate levels.

ADVERSE REACTIONS Gastrointestinal upset (diarrhea, nausea, stomach pain and vomiting) may occur with phosphate therapy. Also, bone and joint pain (possible phosphate-induced osteomalacia) could occur. The following adverse effects may be observed (primarily from sodium or potassium): headaches; dizziness; mental confusion; seizures; weakness or heaviness of legs; unusual tiredness or weakness; muscle cramps; numbness, tingling, pain, or weakness of hands or feet; numbness or tingling around lips; fast or irregular heartbeat; shortness of breath or troubled breathing; swelling of feet or lower legs; unusual weight gain; low urine output; unusual thirst.

CLINICAL PHARMACOLOGY Phosphorus has a number of important functions in the biochemistry of the body. The bulk of the body's phosphorus is located in the bones, where it plays a key role in osteoblastic and osteoclastic activities. Enzymatically catalyzed phosphate-transfer reactions are numerous and vital in the metabolism of carbohydrate, lipid and protein, and a proper concentration of the anion is of primary importance in assuring an orderly biochemical sequence. In addition, phosphorus plays an important role in modifying steady-state tissue concentrations of calcium. Phosphate ions are important buffers of the intracellular fluid, and also play a primary role in the renal excretion of hydrogen ion. Oral administration of inorganic phosphates increases serum phosphate levels. Phosphates lower urinary calcium levels in idiopathic hypercalciuria. In general, in adults, about two thirds of the ingested phosphate is absorbed from the bowel, most of which is rapidly excreted into the urine.