What medications are used to treat kidney stones?

Medications for Kidney Stones

Acute Pain Management

NSAIDs (diclofenac, ibuprofen, or metamizole) are the first-line medication for acute renal colic, as they provide superior pain relief compared to opioids while reducing the need for additional analgesia. 1

• NSAIDs should be used at the lowest effective dose due to potential cardiovascular and gastrointestinal risks, and may impact renal function in patients with reduced glomerular filtration rate 1
• Opioids (hydromorphine, pentazocine, or tramadol—but NOT pethidine) are reserved as second-choice analgesics when NSAIDs are contraindicated or ineffective 1, 2
• Pethidine should be avoided as it is associated with higher rates of vomiting and greater likelihood of requiring additional analgesia 1

Medical Expulsive Therapy (MET)

Alpha-blockers (tamsulosin) are strongly recommended for conservative management of ureteral stones, particularly those >5 mm in the distal ureter. 1, 2

• MET is appropriate for uncomplicated ureteral stones up to 10 mm according to American Urological Association guidelines 2
• Maximum duration of conservative treatment should be 4-6 weeks from initial presentation 2

Stone Prevention: Calcium Stones

For calcium stones with hypercalciuria, thiazide diuretics combined with dietary sodium restriction (≤2,300 mg/day) are recommended as first-line prevention. 3, 2

• Thiazide diuretics lower urinary calcium excretion and should be continued with sodium restriction to maximize the hypocalciuric effect 3
• Monitor for hypokalemia as an adverse effect of thiazide therapy 3, 4

For calcium stones with hypocitraturia, potassium citrate therapy is recommended. 3, 2

• Potassium citrate is preferred over sodium citrate because sodium load increases urinary calcium excretion 3, 4
• Potassium citrate is a potent inhibitor of calcium phosphate crystallization 3
• Monitor for hyperkalemia as an adverse effect 3, 4
• The combination of thiazide diuretics and potassium citrate may be used when other metabolic abnormalities are adequately addressed but stone formation persists 3

For calcium stones with hyperuricosuria (>800 mg/day) and normal urinary calcium, allopurinol is recommended. 3

Stone Prevention: Uric Acid Stones

Potassium citrate is first-line therapy for uric acid stones, with a target urinary pH of approximately 6.0. 3, 2, 4, 5

• Most patients with uric acid stones have low urinary pH rather than hyperuricosuria, making urinary alkalinization more important than allopurinol 3, 4
• Oral chemolysis with citrate or sodium bicarbonate (pH 7.0-7.2) can dissolve existing uric acid stones, with an 80.5% success rate 1
• Patients should monitor their urine pH and adjust medication accordingly 1

Stone Prevention: Cystine Stones

For cystine stones, potassium citrate should be used to raise urinary pH to approximately 7.0, combined with increased fluid intake (≥4 liters/day). 3, 4

• Cystine-binding thiol drugs such as tiopronin should be offered to patients unresponsive to dietary modifications and urinary alkalinization 4
• Tiopronin is preferred over d-penicillamine due to better efficacy and fewer adverse events 4

Stone Prevention: Struvite Stones

For struvite stones, acetohydroxamic acid (AHA) may be considered as a urease inhibitor in high-risk patients or when surgery is not feasible, though extensive side effects may limit use. 3, 4

• Complete surgical removal coupled with appropriate antibiotic therapy is necessary for definitive treatment 1

Stone Prevention: Calcium Phosphate and Brushite Stones

For calcium phosphate or brushite stones with hypocitraturia, potassium citrate is first-line therapy, but exercise caution with excessive alkalinization. 3, 2

• Calcium phosphate solubility decreases at higher pH, so avoid excessive urinary alkalinization 3
• Thiazide diuretics should be offered to brushite stone formers with hypercalciuria, as they may increase the safety and efficacy of citrate therapy 2

Universal Preventive Measures

All patients should increase fluid intake to achieve urine volume of at least 2.5 liters daily. 3, 4

• For cystine stones specifically, target at least 4 liters per day to decrease urinary cystine concentration below 250 mg/L 4

Monitoring and Follow-up

Obtain a 24-hour urine specimen within 6 months of initiating treatment to assess response to therapy. 3, 2, 4

• Continue annual 24-hour urine collections for ongoing monitoring, with more frequent testing depending on stone activity 4
• Perform periodic blood testing to monitor for adverse effects: hypokalemia with thiazides and hyperkalemia with potassium citrate 3, 4
• Obtain repeat stone analysis when available, especially in patients not responding to treatment 4

Common Pitfalls to Avoid

• Do not prescribe allopurinol as first-line therapy for uric acid stones without first addressing urinary pH with potassium citrate 3, 4
• Do not use sodium citrate instead of potassium citrate, as the sodium load increases urinary calcium excretion 3, 4
• Do not neglect monitoring for medication side effects, particularly electrolyte abnormalities 3, 4
• Do not use supplemental calcium rather than dietary calcium (1,000-1,200 mg/day), as supplemental calcium may increase stone formation risk 2