Adult: For the prevention of nephrolithiasis due to severe homozygous cystinuria in combination with high fluid intake, alkali, or diet modification, particularly in patients who are not responsive to these measures alone: 800 mg daily in 3 divided doses. Adjust dose to maintain urinary cystine concentration of <250 mg/L. Average dose: 1,000 mg daily. Initiate a lower dose in patients with history of severe d-penicillamine toxicity. Dosage recommendations may vary among individual products and between countries (refer to specific product or local guidelines). Child: For the prevention of nephrolithiasis due to severe homozygous cystinuria in combination with high fluid intake, alkali, or diet modification, particularly in patients who are not responsive to these measures alone: Patients weighing ≥20 kg: Initially, 15 mg/kg daily in 3 divided doses. Adjust dose to maintain urinary cystine concentration of <250 mg/L. Max: 50 mg/kg daily. Initiate a lower dose in patients with history of severe d-penicillamine toxicity. Dosage recommendations may vary among individual products and between countries (refer to specific product or local guidelines).
Administration
Tiopronin delayed-release: May be taken with or without food. Tiopronin immediate-release: Should be taken on an empty stomach.
Special Precautions
Patient with proteinuria; history of severe d-penicillamine toxicity. Children and elderly. Pregnancy. Breastfeeding is not recommended.
Adverse Reactions
Significant: Proteinuria including nephrotic syndrome and membranous nephropathy, thrombocytopenia, leucopenia without eosinophilia, pemphigus, hypersensitivity reactions (e.g. drug fever, rash, fever, arthralgia, lymphadenopathy). Blood and lymphatic system disorders: Anaemia. Cardiac disorders: Chest pain. Gastrointestinal disorders: Nausea, diarrhoea, vomiting, abdominal pain, ageusia, dysgeusia, oral mucosa ulcer. General disorders and administration site conditions: Fatigue, asthenia, peripheral oedema. Investigations: Decreased eGFR. Metabolism and nutrition disorders: Dehydration, anorexia. Musculoskeletal and connective tissue disorders: Back pain, myalgia. Nervous system disorders: Dizziness, headache, dysgeusia. Reproductive system and breast disorders: Impotence. Respiratory, thoracic and mediastinal disorders: Cough. Skin and subcutaneous tissue disorders: Urticaria, ecchymosis, wrinkling of skin, pruritus. Potentially Fatal: Rarely, Goodpasture syndrome, myasthenia gravis.
Monitor renal function; urinalysis and 24-hour urinary protein at baseline and every 3-6 months; urinary cystine 1 month after starting therapy and every 3 months thereafter; stone formation (e.g. X-ray, ultrasound); CBC with differential and LFTs. Assess for signs of infection and urinary or gastrointestinal symptoms.
Food Interaction
May increase bioavailability with alcohol.
Action
Description: Overview: Tiopronin, an active reducing agent, is a sulfhydryl compound and chelator with properties similar to penicillamine. Mechanism of Action: Tiopronin undergoes thiol-disulfide exchange with cystine, forming a more water-soluble tiopronin-cystine disulfide. Pharmacodynamics: The conversion of cystine via thiol-disulfide exchange into the more soluble tiopronin-cystine disulfide reduces the concentration of sparingly soluble cystine in the urine, thereby preventing cystine stone formation. The decrement in urinary cystine concentration caused by tiopronin is dose-dependent. In addition, tiopronin has a rapid onset and offset of action, showing a fall in urinary cystine on the 1st day of treatment and a rise on the 1st day after withdrawal. Onset: Rapid. Pharmacokinetics: Absorption: Absorbed from the gastrointestinal tract. Time to peak plasma concentration (median): Immediate-release tab: 1 hour (range: 0.5-2.1 hours). Delayed-release tab (intact tab): 3 hours (range: 1-6 hours). Delayed-release tab (crushed/mixed in applesauce): 1 hour (range: 0.5-2 hours). Excretion: Via urine (48% within 4 hours; 78% within 72 hours).
Chemical Structure
Tiopronin Source: National Center for Biotechnology Information. PubChem Compound Summary for CID 5483, Tiopronin. https://pubchem.ncbi.nlm.nih.gov/compound/Tiopronin. Accessed Nov. 27, 2025.
G04BX16 - tiopronin ; Belongs to the class of other urologicals.
References
Brayfield A, Cadart C (eds). Tiopronin. Martindale: The Complete Drug Reference [online]. London. Pharmaceutical Press. https://www.medicinescomplete.com. Accessed 23/10/2025.Thiola Tablet, Sugar Coated (Mission Pharmacal Company). DailyMed. Source: U.S. National Library of Medicine. https://dailymed.nlm.nih.gov/dailymed. Accessed 23/10/2025.Tiopronin Tablet, Delayed Release (BioComp Pharma, Inc.). DailyMed. Source: U.S. National Library of Medicine. https://dailymed.nlm.nih.gov/dailymed. Accessed 23/10/2025.Tiopronin. Gold Standard Drug Database in ClinicalKey [online]. Elsevier Inc. https://www.clinicalkey.com. Accessed 28/10/2025.Tiopronin. UpToDate Lexidrug, Lexi-Drugs Multinational Online. Waltham, MA. UpToDate, Inc. https://online.lexi.com. Accessed 23/10/2025.
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