TheraRadar
Data updated: May 26, 2026

TIOPRONIN

Cystine Disulfide Reduction
Renal Approved 2021-04-26

Tiopronin helps patients with severe homozygous cystinuria by preventing the formation of cystine stones. It is used for adults and children 9 years of age and older who have not responded sufficiently to high fluid intake, alkali, and diet modifications alone. This medication works as a reducing and complexing thiol to supplement these other preventative strategies.

Source: FDA Label • AMNEAL • Reducing and Complexing Thiol

How TIOPRONIN Works

This drug works by lowering the concentration of cystine in the urine until it is below its solubility limit. It acts as a reducing agent that undergoes a chemical exchange with cystine to form a water-soluble disulfide, which reduces the amount of insoluble cystine available to form stones.

Source: FDA Label
5
Indications
--
Phase 3 Trials
5
Years on Market

Details

Status
Discontinued
First Approved
2021-04-26
Routes
ORAL
Dosage Forms
TABLET, DELAYED RELEASE, TABLET

Companies

Active Ingredient: TIOPRONIN

TIOPRONIN Approval History

2022
2023
2024
2025
2026
Original
New Indication
New Form
Label Update
10 FDA actions from 2021 to 2025
Aug 2025 SUPPL
Mfg · Manufacturing (CMC)
Jul 2024 ORIGINAL
Update
Aug 2023 ORIGINAL
Update

What TIOPRONIN Treats

2 indications

TIOPRONIN is approved for 2 conditions since its original approval in 2021. These indications span multiple therapeutic areas including oncology, immunology, and more.

  • Cystine Stone Formation
  • Cystinuria
Source: FDA Label

TIOPRONIN Competitive Set

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Filters applied: drops same-active-ingredient (505(b)(2) reformulations), route-mismatch (topical vs systemic), and cross-therapeutic-area matches in same-indication rings.

Drugs Similar to TIOPRONIN

3 of 6

FDA-approved drugs for similar conditions. Compare mechanisms and indications to understand treatment alternatives.

VENXXIVA
TIOPRONIN
2 shared
TORRENT
Shared indications:
Cystine Stone FormationCystinuria
DEPEN
PENICILLAMINE
1 shared
Viatris
Shared indications:
Cystinuria
PENICILLAMINE
PENICILLAMINE
1 shared
INVAGEN PHARMS
Shared indications:
Cystinuria
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Clinical Trial Registry

2 trials
Trial Sponsor ID Phase Status Title
NCT01095731 results posted AAAA8597 1R01FD003728-01 Ph 2 completed The Effects of Tiopronin on 3-Aminopropanal Level & Neurologic Outcome After Aneurysmal Subarachnoid Hemorrhage
NCT03663855 results posted 18-00642 Ph 2 completed Effect of Increasing Doses of Tiopronin on Cystine Capacity in Patients With Cystinuria
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Active Pipeline

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Ongoing clinical trials by development phase

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Key Completed Trials

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Completed studies with published results, ranked by significance

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Trial Timeline

Full development history with FDA approval milestones

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Understanding FDA Approval Types
Count Type What it means
- ORIG Original approval - drug first enters market
- SUPPL - Efficacy New indication (new disease/condition approved)
- SUPPL - Labeling Label text changes (warnings, dosing updates)
- SUPPL - Manufacturing Production changes (new facility)
- SUPPL - Chemistry Formulation changes (new dosage strength)

Green lines in the timeline show ORIG and Efficacy approvals - the clinically meaningful milestones.

TIOPRONIN FDA Label Details

Indications & Usage

TIOPRONIN is indicated for the treatment of Cystine Stone Formation; Cystinuria.

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Data Sources

Data sourced from official FDA and NIH databases. Click links to verify on original sources.