What is Tiopronin

Tiopronin is an oral agent, also known as alpha-mercaptopropionylglycine (alpha-MPG), that is used to prevent cystine kidney stones.

It is used for the prevention of nephrolithiasis due to severe homozygous cystinuria in combination with high fluid intake, alkali, and diet modification in adult and pediatric patients who are not responsive to these measures alone.

Similar to d-penicillamine, tiopronin forms a more water-soluble complex with cystine, resulting in a decrease in the amount of sparingly soluble cystine in the urine.

Compared to d-penicillamine, tiopronin is associated with fewer and less severe adverse reactions.

However, serious adverse reactions and toxicity related to tiopronin are more likely to appear if the patient has a history of toxicity to d-penicillamine.

Brand Name

  • Thiola
  • Thiola EC


  • cystinuria
  • nephrolithiasis

For the prevention of cystine nephrolithiasis due to severe homozygous cystinuria, in combination with high fluid intake, alkali, and diet modification in patients who are not responsive to these measures alone

Side Effects

  1. abdominal pain
  2. anemia
  3. anorexia
  4. arthralgia
  5. asthenia
  6. back pain
  7. chest pain (unspecified)
  8. cough
  9. dehydration
  10. diarrhea
  11. dizziness
  12. dysgeusia
  13. dyspepsia
  14. dysphagia
  15. ecchymosis
  16. elevated hepatic enzymes
  17. eructation
  18. fatigue
  19. fever
  20. flank pain
  21. flatulence
  22. gastroesophageal reflux
  23. glomerulonephritis
  24. headache
  25. heart failure
  26. hyperhidrosis
  27. hypoesthesia
  28. impotence (erectile dysfunction)
  29. jaundice
  30. lymphadenopathy
  31. malaise
  32. musculoskeletal pain
  33. myalgia
  34. nausea
  35. nephrotic syndrome
  36. oral ulceration
  37. pemphigus
  38. peripheral edema
  39. proteinuria
  40. pruritus
  41. rash
  42. renal failure (unspecified)
  43. skin irritation
  44. urticaria
  45. vertigo
  46. vomiting
  47. weakness
  48. weight gain
  49. xerosis
  50. xerostomia

Monitoring Parameters

  • CBC with differential
  • LFTs
  • serum creatinine/BUN
  • urinalysis
  • urinary cystine concentrations


  • breast-feeding
  • children
  • infants
  • neonates
  • pregnancy
  • proteinuria


  • Ethanol

Ethanol: (Moderate) Avoid alcohol consumption 2 hours before and 3 hours after taking tiopronin EC. Tiopronin is released faster from tiopronin EC in the presence of alcohol; the risk for adverse events associated with tiopronin EC when taken with alcohol is unknown. 


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