Ineffectiveness of ascorbic acid therapy in nephropathic cystinosis

Area of Science:

• Biochemistry
• Pediatric Nephrology
• Clinical Pharmacology

Background:

• Cystinosis is a rare genetic disorder characterized by lysosomal accumulation of cystine.
• High concentrations of ascorbic acid reduce free cystine in cultured cells, suggesting a potential therapeutic avenue.

Purpose of the Study:

• To evaluate the efficacy and safety of ascorbic acid in children with cystinosis.
• To determine if vitamin C supplementation improves outcomes for pediatric patients with this metabolic disorder.

Main Methods:

• A double-blind, placebo-controlled clinical trial involving 64 cystinotic children.
• Patients were randomized to receive either ascorbic acid (200 mg/kg/day) or a placebo.
• The study was terminated early due to lack of efficacy and emerging safety concerns.

Main Results:

• No evidence of benefit from ascorbic acid treatment was observed.
• A higher proportion of patients on ascorbic acid experienced adverse events, including death, dialysis, or transplantation (8 out of 11 early withdrawals).
• Serum creatinine levels increased at a faster rate in the ascorbic acid group compared to the placebo group (0.53 vs. 0.24 mg/dL/year).

Conclusions:

• Ascorbic acid is not beneficial for treating cystinosis in children.
• The use of ascorbic acid in cystinosis patients may be associated with increased risks of adverse events and renal deterioration.