What medications are used to treat renal stones?

Medications for Renal Stones

NSAIDs (diclofenac, ibuprofen, or metamizole) are first-line treatment for acute renal colic pain, while medical management depends on stone type: alpha-blockers for stone passage, potassium citrate for uric acid and calcium stones with hypocitraturia, and thiazide diuretics for calcium stones with hypercalciuria. 1

Acute Pain Management

NSAIDs are superior to opioids for renal colic because they reduce the need for additional analgesia, have fewer side effects, and carry no risk of dependence. 1, 2, 3

• Specific NSAID options: diclofenac 50-75 mg IM, ibuprofen, or metamizole at the lowest effective dose 1
• Opioids are second-line: Use hydromorphone, pentazocine, or tramadol only when NSAIDs are contraindicated or ineffective; avoid pethidine due to high vomiting rates (20% versus 6% with NSAIDs) 1, 3
• Critical caveat: NSAIDs may impair renal function in patients with reduced glomerular filtration rate, heart failure, renal artery stenosis, dehydration, or concurrent nephrotoxic drugs 1, 4
• Never use NSAIDs during pregnancy; morphine is safer in this population 4

Medical Expulsive Therapy (MET)

Alpha-blockers provide the greatest benefit for ureteral stones >5 mm in the distal ureter and should be offered to patients amenable to conservative management. 1, 2

• Conservative management is appropriate for uncomplicated ureteral stones up to 10 mm (AUA) or 6 mm (EAU) 5
• Maximum duration of conservative treatment is 4-6 weeks from initial presentation 5, 6

Stone Type-Specific Medical Management

Calcium Stones

Thiazide diuretics are first-line for calcium stone formers with hypercalciuria because they lower urinary calcium excretion and reduce stone recurrence. 1, 2, 5

Potassium citrate should be offered to calcium stone formers with hypocitraturia (low or low-normal 24-hour urinary citrate excretion) as it is a potent inhibitor of calcium phosphate crystallization. 1, 2, 7

• Potassium citrate is preferred over sodium citrate because sodium increases urinary calcium excretion 1, 5
• Allopurinol is indicated for calcium oxalate stones with hyperuricosuria (>800 mg/day) and normal urinary calcium, not for routine use 1, 2
• Combination therapy with thiazide diuretics and potassium citrate can be used for persistent stone formation 5

Uric Acid Stones

Potassium citrate is first-line therapy for uric acid stones to achieve urinary alkalinization with target pH 7.0-7.2 (EAU) or 6.0 (AUA). 1, 2, 7

• Patients must monitor urine pH and adjust medication accordingly 1
• Success rate of oral chemolysis is approximately 80.5%, with 15.7% requiring further intervention 1, 8
• Do not use allopurinol as first-line therapy because most uric acid stone formers have low urinary pH rather than hyperuricosuria as the predominant risk factor 1, 2, 6

Cystine Stones

First-line therapy includes increased fluid intake, sodium and protein restriction, and urinary alkalinization with potassium citrate to achieve pH 7.0. 1, 2

• Cystine-binding thiol drugs (tiopronin) are second-line for patients unresponsive to dietary modifications and alkalinization, or those with large recurrent stone burdens 1, 2
• Tiopronin is preferred over d-penicillamine due to better efficacy and fewer adverse events 1

Emergency Situations Requiring Urgent Intervention

In cases of sepsis and/or anuria with obstructed kidney, urgent decompression via percutaneous nephrostomy or ureteral stenting is mandatory. 1, 2, 6

• Delay definitive stone treatment until sepsis resolves 1, 6
• Collect urine for antibiogram testing before and after decompression 1, 6
• Administer antibiotics immediately and adjust based on culture results 1, 6

Follow-up and Monitoring

Obtain a 24-hour urine specimen for stone risk factors within 6 months of initiating treatment, then annually or more frequently depending on stone activity. 1, 2, 5

• Perform periodic blood testing to assess for adverse effects in patients on pharmacological therapy 2, 5
• Obtain repeat stone analysis when available, especially in patients not responding to treatment 2, 5

Critical Pitfalls to Avoid

• Do not prescribe allopurinol as first-line for uric acid stones; alkalinization with potassium citrate is correct 1, 2, 6
• Do not use supplemental calcium; dietary calcium is preferred as supplemental calcium may increase stone formation risk 5
• Do not neglect stone type determination before initiating medical therapy, as treatment differs significantly 2, 5
• Do not use NSAIDs in patients with significantly reduced renal function without careful monitoring 1, 6
• Do not extend conservative management beyond 6 weeks without reassessment 5, 6