Uric Acid Stones Medication
- Author: Sahar Fathallah-Shaykh, MD; Chief Editor: Craig B Langman, MD more...
Medication Summary
The overall goal of medical treatment is to dissolve formed stones and prevent new stones from forming.
Citrate or bicarbonate is used to alkalinize the urine. Uric acid has 4 ionizable hydrogen ions (positions 1, 3, 7, and 9). Only the hydrogen ion on position 9 (pKa = 5.8) is ionizable at physiologic pH. Sodium urate is 15 times more soluble than uric acid. When pH levels equal the pKa (5.8), uric acid and sodium urate are present in equal quantities. As pH levels increase, the ratio of sodium urate to uric acid increases. At a pH level of 6.8, 10 times more sodium urate is present than uric acid; whereas, at a pH level of 7.8, 100 times more sodium urate is present than uric acid.
Uric acid–lowering agents
Class Summary
These agents are used to decrease the production of uric acid, thus lowering the serum and urine concentration of uric acid.
Allopurinol (Zyloprim)
Decreases the production of uric acid from nucleic acid breakdown. Inhibits xanthine oxidase, the enzyme that synthesizes uric acid from hypoxanthine. Reduces the synthesis of uric acid without disrupting the biosynthesis of vital purines.
Alkalinizing agents
Class Summary
These agents are used to alkalinize the urine and increase the solubility of uric acid.
Sodium citrate and citric acid (Bicitra)
Citrate is metabolized to bicarbonate. Several mixtures of citrate with sodium or potassium or both are available as alkalinizing agents. With normal hepatic function, 1 mEq of citrate is converted to 1 mEq of bicarbonate.
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| Neonates* | Children | Adults | |||||||||
| 29-33 wk | 34-37 wk | 38-40 wk | 3-4 y | 5-9 y | 10-14 y | 40-44 y | |||||
| Male | Female | Male | Female | Male | Female | Male | Female | ||||
| Serum uric acid (mg/dL) | 7.71±2.65 | 6.04±2.19 | 5.19±1.57 | 3.45±1.01 | 3.44±0.8 | 3.63±1.04 | 3.71±0.92 | 4.28±1.19 | 4.09±1.2 | 5.134±1.25 | 4.25±1.1 |
| Uric acid excretion (mg/dL GFR†) | 4.8±2.23 | 2.81±0.93 | 1.69±0.84 | 0.34±0.11 | 0.403±0.095 | ||||||
| Uric acid excretion (mg/kg/d) | N/A | N/A | 19.6 | 13.5±3.75 (3 y) | 11.5±3.75 (7 y) | 9±3.75 (12 y) | 10 | ||||
| Fractional excretion of uric acid (%) | 61.24±12.21 | 44.52±15.23 | 38.19±13.61 | 12±3.75 (3 y) | 10±3 (7 y) | 7.6±3.75 (12 y) | 7±1.6 | ||||
| *Gestational ages † Glomerular filtration rate | |||||||||||
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