What medications are used to treat kidney stones?

Medications for Kidney Stones

NSAIDs (diclofenac, ibuprofen, or metamizole) are the first-line medication for acute kidney stone pain, while alpha-blockers (tamsulosin) are the primary medical expulsive therapy for stones >5 mm in the distal ureter. 1

Acute Pain Management

For immediate pain relief during renal colic, NSAIDs are superior to opioids and should be used at the lowest effective dose. 1 NSAIDs reduce the need for additional analgesia compared to opioids, though they carry cardiovascular and gastrointestinal risks and may impair renal function in patients with low glomerular filtration rate. 1

• Opioids are second-line analgesics when NSAIDs are contraindicated or ineffective. 1, 2
• If opioids are required, avoid pethidine due to high rates of vomiting and need for additional analgesia; instead use hydromorphone, pentazocine, or tramadol. 1, 2

Medical Expulsive Therapy (MET)

Alpha-blockers are the preferred agents for facilitating stone passage, with 29% more patients passing stones compared to controls. 1

• Tamsulosin is most effective for ureteral stones >5 mm in the distal ureter. 1, 2
• Tamsulosin, terazosin, and doxazosin appear equally effective, though tamsulosin has been most studied. 1
• Nifedipine provides only marginal benefit (9% improvement, not statistically significant) and is not recommended as first-line MET. 1

Stone Type-Specific Medical Management

Calcium Stones (Most Common - 61% of stones)

Thiazide diuretics are recommended for patients with high urinary calcium and recurrent calcium stones. 2, 3

• Potassium citrate should be offered to patients with low urinary citrate and recurrent calcium stones. 2
• Allopurinol is indicated for recurrent calcium oxalate stones with hyperuricosuria and normal urinary calcium. 2

Uric Acid Stones (12% of stones)

Potassium citrate is first-line therapy to raise urinary pH to approximately 6.0, which can dissolve existing stones. 2

• Oral chemolysis with alkalinization (using citrate or sodium bicarbonate to achieve pH 7.0-7.2) shows 80.5% success rate, with only 15.7% requiring further intervention. 1
• Allopurinol should NOT be routinely used as first-line therapy, as most uric acid stones result from low urinary pH rather than hyperuricosuria. 2
• When allopurinol is used, fluid intake must be sufficient to yield at least 2 liters daily urinary output to avoid xanthine calculi formation. 4

Cystine Stones (Rare)

First-line therapy combines increased fluid intake (at least 4 liters daily), sodium restriction (≤2,300 mg/day), protein restriction, and urinary alkalinization with potassium citrate to pH 7.0. 2, 5, 6

• Tiopronin (cystine-binding thiol drug) should be offered to patients unresponsive to dietary modifications and alkalinization, or those with large recurrent stone burdens. 2, 5
• Tiopronin is preferred over D-penicillamine due to better efficacy and fewer adverse events. 5

Emergency Situations

In cases of sepsis and/or anuria with obstructed kidney, urgent decompression via percutaneous nephrostomy or ureteral stenting is mandatory. 1, 2

• Collect urine for culture before and after decompression. 1
• Administer antibiotics immediately and adjust based on antibiogram results. 1
• Delay definitive stone treatment until sepsis resolves. 1, 2

Monitoring and Follow-up

Obtain a 24-hour urine specimen within six months of initiating treatment to assess response. 2, 5, 6

• After initial follow-up, obtain annual 24-hour urine specimens, or more frequently depending on stone activity. 2
• Perform periodic blood testing to assess for adverse effects in patients on pharmacological therapy. 2, 6
• Repeat stone analysis when available, especially in patients not responding to treatment. 2, 6

Critical Pitfalls to Avoid

• Do not use allopurinol as first-line for uric acid stones - alkalinization with potassium citrate is superior. 2
• Do not restrict dietary calcium - this may worsen oxaluria and increase osteoporosis risk. 7
• Do not use pethidine as first-choice opioid due to high vomiting rates. 1, 2
• In patients with renal impairment receiving allopurinol, use lower doses (100 mg daily or 300 mg twice weekly) and monitor closely, as oxipurinol half-life is greatly prolonged. 4
• Avoid nephrotoxic medications in patients with acute kidney injury or at risk for kidney injury. 2