What Is Urocit-K XR? Uses, Dosage, and What You Need to Know in 2026

Urocit-K XR is the brand name for potassium citrate extended-release tablets — a prescription medication used primarily to prevent kidney stones and treat renal tubular acidosis. If you've just been prescribed this drug or are trying to understand what a family member was prescribed, this guide covers everything you need to know.

What Is Urocit-K XR?

Urocit-K XR (generic name: potassium citrate extended release) is a citrate salt of potassium manufactured by Mission Pharmacal. It was first approved by the FDA in 1985 and is classified as a urinary pH modifier. In plain terms, it makes the urine less acidic — which prevents certain types of kidney stones from forming or growing.

The "XR" in Urocit-K XR stands for extended release. Unlike immediate-release potassium supplements that deliver a large dose at once, the wax-matrix extended-release tablet delivers potassium citrate gradually over several hours, which is easier on the digestive system and maintains more consistent urinary pH throughout the day.

What Is Urocit-K XR Used For?

Urocit-K XR has three FDA-approved indications:

Hypocitraturic calcium oxalate nephrolithiasis: Kidney stones made of calcium oxalate that form because the urine doesn't contain enough citrate (a natural stone inhibitor). This is the most common use.

Uric acid lithiasis (with or without calcium stones): Kidney stones made of uric acid, which form in overly acidic urine. Raising urinary pH dissolves existing uric acid stones and prevents new ones.

Renal tubular acidosis (RTA) with calcium stones: A kidney condition in which the kidneys can't properly acidify the urine, leading to metabolic acidosis and calcium stone formation.

Available Strengths and Dosage Forms

Urocit-K XR is available in three tablet strengths:

5 mEq (540 mg potassium citrate): Tan to yellowish, modified ball shaped, "MPC 600" on one side

10 mEq (1080 mg potassium citrate): Tan to yellowish, elliptical, "610" on one side, "MISSION" on the other

15 mEq (1620 mg potassium citrate): Tan to yellowish, modified rectangle, "M15" on one side

How Much Do You Take? (Typical Dosing)

Your dose depends on how severe your hypocitraturia is, as measured by a 24-hour urine test:

Severe hypocitraturia (urinary citrate < 150 mg/day): 60 mEq/day — typically 30 mEq twice daily or 20 mEq three times daily

Mild to moderate hypocitraturia (urinary citrate > 150 mg/day): 30 mEq/day — typically 15 mEq twice daily or 10 mEq three times daily

Maximum dose: 100 mEq/day (doses above this have not been studied)

The goal of treatment is to raise urinary citrate above 320 mg/day (ideally 640 mg/day) and raise urinary pH to 6.0–7.0. Your doctor will adjust your dose based on follow-up 24-hour urine tests every four months.

How to Take Urocit-K XR Correctly

Always take with food or within 30 minutes after a meal or bedtime snack

Swallow tablets whole — do not crush, cut, or chew

Drink at least 2 liters of water per day

Follow a low-sodium diet (limit to 2,000 mg sodium per day)

Do not stop taking without talking to your doctor — missing doses allows stone-forming conditions to return

Who Should Not Take Urocit-K XR?

Urocit-K XR is contraindicated in patients with:

Hyperkalemia or conditions predisposing to high potassium (chronic kidney disease, uncontrolled diabetes, adrenal insufficiency)

Delayed gastric emptying, intestinal obstruction, or esophageal stricture

Active peptic ulcer disease

Active urinary tract infection with urea-splitting organisms

Significant kidney impairment (GFR < 0.7 mL/kg/min)

For a detailed look at side effects and warnings, see our guide: Urocit-K XR Side Effects: What to Expect and When to Call Your Doctor.

If you have a prescription and need help finding Urocit-K XR in stock near you, medfinder can check pharmacies in your area.