How Do Urinary Acidifying Agents Work?

Urinary acidifying agents are medications used to dissolve certain types of stones in the kidney and bladder and to maintain acid-base balance in blood and urine. Urinary acidifying agents chemically make the stones more soluble and facilitate their excretion or removal.

Struvite stones develop in the kidney or bladder due to upper urinary tract bacterial infections. Ammonia is a bacterial waste product that makes the urine more alkaline promoting the formation of struvite stones. Struvite stones are composed mainly of magnesium, ammonium, phosphate, and calcium carbonate.

Urinary acidifying agents make struvite stones more soluble by chemically exchanging magnesium for calcium in the stones. The resultant magnesium salts are soluble in the irrigating solution. Urinary acidifying agents are not effective for dissolving other types of stones such as uric acid, cystine, and calcium oxalate stones.

Urinary acidifying agents lower serum and urine alkalinity and also supplement the deficiency in potassium and phosphorus. These chemicals regulate many physiological processes including the maintenance of acid-base balance in the body, transmission of nerve impulses, glucose utilization, muscle contraction, and enzyme activity.

Urinary acidifying agents may be administered as:

• Oral tablets
• Renal irrigating solution
  • Infused through a nephrostomy tube into the kidney
  • Instilled through a catheter into the bladder

Urinary acidifying agents are approved by the FDA, for use in the following conditions in adults:

• To irrigate and dissolve renal calculi (kidney stones)
• To dissolve bladder calculi (stones in the bladder)
• To prevent incrustation in urinary catheter
• To acidify the urine in patients with elevated urinary pH

Side effects of urinary acidifying agents may include the following:

• Transient flank pain
• Fever
• Urothelial (urinary tract lining) ulceration with or without edema
• Urinary tract infection
• Dysuria (painful urination)
• Transient hematuria (blood in urine)
• Candidiasis (Candida infection)
• Bladder irritability
• Back pain
• Nausea
• Vomiting
• Diarrhea
• Stomach pain
• Flatulence
• Ileus (temporary loss of intestinal muscle contraction)
• Hypermagnesemia (elevated magnesium in the blood)
• Hyperphosphatemia (elevated phosphate in the blood)
• Hyperkalemia (elevated potassium in the blood)
• Hypocalcemia (low calcium level in the blood)
• Elevated serum creatinine
• Phosphate intoxication
• Septicemia (infection in the blood)
• Thrombophlebitis (inflammation of a vein with blood clots)
• Local tissue necrosis (death) with extravasation (leakage of fluid out of blood vessels)
• Bradycardia (slow heartbeat)
• Arrhythmia (irregular heart rhythm)
• Hypotension (low blood pressure)
• Dyspnea (shortness of breath)
• Tetany (muscle spasm)
• Weakness

Information contained herein is not intended to cover all possible side effects, precautions, warnings, drug interactions, allergic reactions, or adverse effects. Check with your doctor or pharmacist to make sure these drugs do not cause any harm when you take them along with other medicines. Never stop taking your medication and never change your dose or frequency without consulting your doctor.

Generic and brand names of urinary acidifying agents include:

• citric acid/glucono-delta-lactone/magnesium carbonate
• KPhos Original
• NeutraPhos
• potassium acid phosphate
• Renacidin