Kidney Stones - Medications

Allopurinol. Allopurinol (Lupurin, Zyloprim) is very effective in reducing high levels of uric acid and may be helpful for patients with uric acid stones. It should be noted that allopurinol will not prevent calcium stones from forming. There is also a slight risk for xanthine stones with this drug.

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The drug's side effects, experienced by 3% to 5% of patients, include diarrhea, headache, and fever. More severe complications include blood disorders that may produce fatigue, bleeding, or bruising. About 2% of patients experience an allergic reaction to allopurinol that causes a rash. In rare cases, the rash can become severe and widespread enough to be life threatening. Allergic individuals who had experienced only a mild rash may be able to build up their tolerance for the drug by undergoing a desensitization process. The drug may also increase the risk for cataracts.

Some patients experience an allergic reaction to allopurinol, which can be fatal. Because allopurinol reduces uric acid levels rapidly, it may trigger an attack of gout in susceptible people. To prevent this, patients should take a nonsteroidal anti-inflammatory (NSAID) for two or three months. One study recommended indomethacin, although many NSAIDs are available. (Aspirin, which is also an NSAID, should not be taken, since it increases uric acid levels.) Patients should discuss the appropriate drug with their doctor.

Medications for Struvite Stones

Before any medical treatment is given for struvite stones, they must be completely removed with surgery. They do not respond well to standard stone-crushing procedures (lithotripsy) so major surgery may be necessary. (New procedures may be helpful.)

Antibiotics for Eliminating Infection. The first medical line of defense against struvite (magnesium ammonium phosphate) stones are on-going antibiotics to keep the urine free of bacteria that cause urinary tract infections. Careful follow-up afterward and testing urine for acidity is extremely important. (A high pH indicates low acidity and an increased risk of infection.)

Acetohydroxamic Acid (AHA). Acetohydroxamic acid or AHA (Lithostat) is beneficial when used with long-term antibiotics. AHA blocks the enzymes released by the bacteria and has been effective in preventing stones even when bacteria are present. Side effects, however, can be severe. The drug reduces iron stores in the body, so anemia is a common problem. Iron supplements may be needed. Other side effects include nausea and vomiting, depression, anxiety, rash, persistent headache, and, rarely, small blood clots in the legs. Experts recommend this drug only for patients with healthy kidneys who have chronic diseases caused by these specific struvite-causing organisms. Alcohol should be avoided. Pregnant women should not take it.