Tiopronin

Brand Names: Venxxiva

Drug Class: Reducing and Complexing Thiol

Overview

11 DESCRIPTION VENXXIVA (tiopronin) delayed-release tablets are a reducing and cystine-binding thiol drug (CBTD) for oral use. Tiopronin is N‑(2‑Mercaptopropionyl) glycine and has the following structure: Tiopronin has the empirical formula C 5 H 9 NO 3 S and a molecular weight of 163.19. In this drug product tiopronin exists as a dl racemic mixture.

Mechanism of Action

12 CLINICAL PHARMACOLOGY 12.1 Mechanism of Action The goal of therapy is to reduce urinary cystine concentration below its solubility limit. Tiopronin is an active reducing agent which undergoes thiol-disulfide exchange with cystine to form a mixed disulfide of tiopronin-cysteine. From this reaction, a water-soluble mixed disulfide is formed and the amount of sparingly soluble cystine is reduced. 12.2 Pharmacodynamics The decrement in urinary cystine produced by tiopronin is generally proportional to the dose. A reduction in urinary cystine of 250 to 350 mg/day at tiopronin dosage of 1 g/day, and a decline of approximately 500 mg/day at a dosage of 2 g/day, might be expected.

Indications

  • 1 INDICATIONS AND USAGE VENXXIVA is indicated, in combination with high fluid intake, alkali, and diet modification, for the prevention of cystine stone formation in adults and pediatric patients 9 years of age and older with severe homozygous cystinuria, who are not responsive to these measures alone. Additional pediatric use information is approved for Mission Pharmacal Company’s Thiola EC (tiopronin delayed-release) tablets. However, due to Mission Pharmacal Company’s marketing exclusivity rights, this drug product is not labeled with that information.

Common Doses

  • 800 mg
  • 000 mg
  • 15 mg
  • 50 mg

Dosage

2 DOSAGE AND ADMINISTRATION The recommended initial dosage in adult patients is 800 mg/day. In clinical studies, the average dosage was about 1,000 mg/day. ( 2.1 ) The recommended initial dosage in pediatric patients 9 years of age and older is 15 mg/kg/day. Avoid dosages greater than 50 mg/kg per day in pediatric patients. ( 5.1 , 8.4 ) Measure urinary cystine 1 month after initiation of VENXXIVA and every 3 months thereafter. ( 2.3 ) Administer VENXXIVA in 3 divided doses at the same times each day, without food. ( 2.1 ) 2.

Contraindications

  • 4 CONTRAINDICATIONS VENXXIVA is contraindicated in patients with hypersensitivity to tiopronin or any other components of VENXXIVA [see Warnings and Precautions ( 5.2 )] . Hypersensitivity to tiopronin or any component of VENXXIVA ( 4 )

Side Effects

  • 6 ADVERSE REACTIONS The following adverse reactions are discussed in greater detail in other sections of the labeling: Proteinuria [see Warnings and Precautions ( 5.1 )] Hypersensitivity [see Warnings and Precautions ( 5.2 )] Most common adverse reactions (≥10%) are nausea, diarrhea or soft stools, oral ulcers, rash, fatigue, fever, arthralgia, proteinuria, and emesis. ( 6 ) To report SUSPECTED ADVERSE REACTIONS, contact Cycle Pharmaceuticals Ltd at 1-857-437-3969 or FDA at 1-800-FDA-1088 or www.fda.gov/medwatch. 6.

Interactions

  • 7 DRUG INTERACTIONS 7.1 Alcohol Tiopronin is released faster from VENXXIVA in the presence of alcohol and the risk for adverse events associated with VENXXIVA when taken with alcohol is unknown. Avoid alcohol consumption 2 hours before and 3 hours after taking VENXXIVA [see Clinical Pharmacology ( 12.3 )] .