|CAS number||, R|
|PubChem||, R, S|
|ChemSpider||, R , S|
|Jmol-3D images||Image 1
|Molar mass||163.19 g mol−1|
|Appearance||White, opaque crystals|
93-98 °C, 366-371 K, 199-208 °F
|GHS signal word||WARNING|
|GHS hazard statements||H302|
|LD50||1,300 mg kg−1 (oral, rat)|
|Related alkanoic acids|
| (what is: / ?)
Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa)
Tiopronin (trade name Thiola) is a prescription thiol drug used to control the rate of cystine precipitation and excretion in the disease cystinuria. Due to the rarity of the disorder, tioronin falls under the classification of an orphan drug.
Tiopronin is used primarily for cystinuria and is well known in the cystinuric community. Depending on the severity of a person's cystinuria, tiopronin may be taken for life, possibly starting in early childhood.
Side effects 
Tiopronin may present a wide variety of side effects, but side effects are usually limited and subside over time with continued usage. Due to the rarity of the disease cystinuria, tiopronin has not been studied substantially.