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) facilitate stone passage for stones >5 mm, and long-term prevention depends on stone type: thiazides for hypercalciuria, potassium citrate for hypocitraturia, and urinary alkalinization for uric acid stones. 1, 2, 3

Acute Pain Management

For immediate pain relief:

• NSAIDs are superior to opioids for renal colic, reducing the need for additional analgesia while minimizing side effects 1, 3
• Use the lowest effective dose due to cardiovascular and gastrointestinal risks, particularly in patients with reduced kidney function 1, 3
• Reserve opioids as second-line when NSAIDs are contraindicated or ineffective 1, 3
• If opioids are necessary, avoid pethidine due to high vomiting rates; instead use hydromorphone, pentazocine, or tramadol 1, 3

Medical Expulsive Therapy (MET)

For facilitating stone passage:

• Alpha-blockers (tamsulosin) are strongly recommended for stones >5 mm in the distal ureter 1, 2, 3
• Greatest benefit occurs with distal ureteral stones amenable to conservative management 1
• Conservative management is appropriate for uncomplicated stones up to 10 mm (AUA) or 6 mm (EAU) 2
• Maximum duration of conservative treatment should be 4-6 weeks from initial presentation 2

Stone-Specific Prevention Medications

Calcium Stones (Most Common - 61% of all stones)

For hypercalciuria (high urinary calcium):

• Thiazide diuretics are the standard therapy 1, 2, 3
• Effective dosages: hydrochlorothiazide 25 mg twice daily or 50 mg once daily, chlorthalidone 25 mg once daily, or indapamide 2.5 mg once daily 1
• Must continue sodium restriction (≤100 mEq/day) to maximize hypocalciuric effect and limit potassium wasting 1
• Potassium supplementation (citrate or chloride) may be needed 1

For hypocitraturia (low urinary citrate):

• Potassium citrate is first-line therapy 1, 2, 3, 4
• Dosage typically ranges from 30-100 mEq per day, usually 20 mEq three times daily 4
• Potassium citrate is preferred over sodium citrate because sodium increases urinary calcium excretion 1, 2
• Particularly important for calcium phosphate stone formers as citrate potently inhibits calcium phosphate crystallization 1, 2

For hyperuricosuria with normal urinary calcium:

• Allopurinol reduces recurrent calcium oxalate stones 1, 3
• Only use when hyperuricosuria is present with normal calcium levels 1, 3

Uric Acid Stones (12% of stones)

Primary treatment is urinary alkalinization:

• Potassium citrate is first-line therapy to raise urinary pH to approximately 6.0-6.5 2, 3, 4
• Oral chemolysis with citrate or sodium bicarbonate (target pH 7.0-7.2) can dissolve existing stones 1
• Success rate of 80.5% with oral chemolysis, though 15.7% need further intervention 1
• Do NOT use allopurinol as first-line therapy - most uric acid stone formers have low urinary pH rather than hyperuricosuria as the predominant problem 3
• Patients should monitor urine pH and adjust medication accordingly 1

Cystine Stones (Rare but Challenging)

Stepwise approach:

• First-line: Potassium citrate to raise urinary pH to approximately 7.0 3
• Combine with sodium restriction (≤100 mEq or 2,300 mg daily) and protein limitation 1
• Target urine volume >4 liters daily to decrease cystine concentration below 250 mg/L 1
• Second-line: Cystine-binding thiol drugs (tiopronin) for patients unresponsive to dietary modifications and alkalinization, or those with large recurrent stone burdens 3

Brushite (Calcium Phosphate) Stones

Specific considerations:

• Potassium citrate for hypocitraturia or elevated urine pH 2
• Thiazide diuretics for hypercalciuria 2
• Combination therapy can be used for persistent stone formation 2

Emergency Situations

For sepsis and/or anuria with obstruction:

• Urgent decompression via percutaneous nephrostomy or ureteral stenting is mandatory 1, 3
• Collect urine for culture before and after decompression 1
• Start antibiotics immediately, adjust based on antibiogram results 1
• Delay definitive stone treatment until sepsis resolves 1, 3

Monitoring and Follow-up

Essential monitoring parameters:

• Obtain 24-hour urine specimen within 6 months of initiating treatment to assess response 2, 3, 5
• Subsequently obtain annually or more frequently depending on stone activity 2, 3, 5
• Perform periodic blood testing to assess for adverse effects of pharmacological therapy 2, 3
• Repeat stone analysis when available, especially in non-responders 2, 3

Critical Pitfalls to Avoid

• Never prescribe allopurinol as first-line for uric acid stones - alkalinization with potassium citrate is correct 3
• Never use sodium citrate instead of potassium citrate - sodium increases urinary calcium excretion 1, 2
• Never prescribe thiazides without sodium restriction - this undermines the hypocalciuric effect 1
• Never ignore stone type - treatment must be tailored to stone composition 2, 3
• Never use supplemental calcium over dietary calcium - supplements may increase stone formation risk 2
• Never forget to check kidney function before NSAIDs - they can worsen renal function in patients with low GFR 1