Urocit®-K is a citrate salt of potassium. Its empirical formula is K3C6H507 · H20.
Urocit®-K yellowish to tan, oral wax-matrix tablets, contain 5 mEq (540 mg) potassium citrate, 10 mEq (1080 mg) potassium citrate and 15 mEq (1620 mg) potassium citrate each. Inactive ingredients include carnauba wax and magnesium stearate.
Dosage forms and strengths
- 5 mEq tablets are uncoated, tan to yellowish in color, modified ball shaped, with MPC 600 debossed on one side and blank on the other
- 10 mEq tablets are uncoated, tan to yellowish in color, elliptical shaped, with 610 debossed on one side and MISSION on the other
- 15 mEq tablets are uncoated, tan to yellowish in color, modified rectangle shaped, with M15 debossed on one side and blank on the other
Clinical pharmacology
Mechanism of action
When Urocit®-K is given orally, the metabolism of absorbed citrate produces an alkaline load. The induced alkaline load in turn increases urinary pH and raises urinary citrate by augmenting citrate clearance without measurably altering ultrafilterable serum citrate. Thus, Urocit®-K therapy appears to increase urinary citrate principally by modifying the renal handling of citrate, rather than by increasing the filtered load of citrate. The increased filtered load of citrate may play some role, however, as in small comparisons of oral citrate and oral bicarbonate, citrate had a greater effect on urinary citrate.
In addition to raising urinary pH and citrate, Urocit®-K increases urinary potassium by approximately the amount contained in the medication. In some patients, Urocit®-K causes a transient reduction in urinary calcium.
The changes induced by Urocit®-K produce urine that is less conducive to the crystallization of stone-forming salts (calcium oxalate, calcium phosphate and uric acid). Increased citrate in the urine, by complexing with calcium, decreases calcium ion activity and thus the saturation of calcium oxalate. Citrate also inhibits the spontaneous nucleation of calcium oxalate and calcium phosphate (brushite).
The increase in urinary pH also decreases calcium ion activity by increasing calcium complexation to dissociated anions. The rise in urinary pH also increases the ionization of uric acid to the more soluble urate ion.
Urocit®-K therapy does not alter the urinary saturation of calcium phosphate, since the effect of increased citrate complexation of calcium is opposed by the rise in pH-dependent dissociation of phosphate. Calcium phosphate stones are more stable in alkaline urine.
In the setting of normal renal function, the rise in urinary citrate following a single dose begins by the first hour and lasts for 12 hours. With multiple doses the rise in citrate excretion reaches its peak by the third day and averts the normally wide circadian fluctuation in urinary citrate, thus maintaining urinary citrate at a higher, more constant level throughout the day. When the treatment is withdrawn, urinary citrate begins to decline toward the pre-treatment level on the first day.
The rise in citrate excretion is directly dependent on the Urocit®-K dosage. Following long-term treatment, Urocit®-K at a dosage of 60 mEq/day raises urinary citrate by approximately 400 mg/day and increases urinary pH by approximately 0.7 units.
In patients with severe renal tubular acidosis or chronic diarrheal syndrome where urinary citrate may be very low (<100 mg/day), Urocit®-K may be relatively ineffective in raising urinary citrate. A higher dose of Urocit®-K may therefore be required to produce a satisfactory citraturic response. In patients with renal tubular acidosis in whom urinary pH may be high, Urocit®-K produces a relatively small rise in urinary pH.
Urocit®-K is a prescription form of potassium citrate. It helps restore the chemicals in urine that stop crystals from forming, and reduces the formation of the two most common types of kidney stones: calcium oxalate and uric acid stones.
Important Safety Information
Urocit®-K is not for everyone. It has not been tested on children, pregnant women, or women who are breastfeeding, and it is unknown whether Urocit®-K can affect reproductive capacity, unborn children, or breast milk content. You should not take Urocit®-K if you are pregnant, may become pregnant, or are currently breastfeeding, unless your doctor has discussed the risks with you and determined that it is necessary.
Certain drugs can interact with Urocit®-K and lead to increased gastrointestinal (GI) irritation. Drug interactions can also lead to hyperkalemia, an excess of potassium in your blood that could lead to cardiac arrest or death. These serious and possibly fatal conditions can develop rapidly with no noticeable symptoms. Always talk to your doctor about any medications you are taking before starting a prescription of Urocit®-K.
If you have hyperkalemia, or any condition that puts you at risk for the condition or prevents your body from processing potassium normally, do not take Urocit®-K because it could lead to cardiac arrest. Conditions that may put you at risk include kidney failure, uncontrolled diabetes, severe dehydration, strenuous physical exercise if you're unconditioned, extensive tissue breakdown, or adrenal insufficiency (when your adrenal glands do not produce the correct amount of chemicals needed to regulate the function of your organs).
Do not take Urocit®-K if you have an active urinary tract infection, peptic ulcer disease, or conditions that slow or prevent the tablet from passing through your GI tract, such as compression of the esophagus, delayed gastric emptying, or narrowing or blockage of your intestines.
Take Urocit®-K only as directed. Do not crush, chew, or suck on the tablets, and check with your doctor if you experience any trouble swallowing tablets or if they seem to get stuck in your throat.
To ensure your safety during your prescription, your doctor may perform regular blood tests and EKGs (which analyze the electrical activity in your heart).
Some patients taking Urocit®-K may develop minor GI side effects such as abdominal discomfort, vomiting, diarrhea, loose bowel movements or nausea. To reduce these effects, take each dose of Urocit®-K with meals or snacks, or talk to your doctor about reducing the amount of your dosage.
If you experience severe vomiting, abdominal pain, tarry stools, or other signs of intestinal bleeding, stop taking Urocit®-K and see your doctor right away. These could be signs of a serious condition such as a perforated or blocked bowel.
To report negative side effects, contact Mission Pharmacal Company at 1-800-298-1087 or the FDA at 1-800-FDA-1088 or www.fda.gov/medwatch.
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