Allopurinol therapy and cataractogenesis in humans

Area of Science:

• Ophthalmology
• Pharmacology
• Biochemistry

Background:

• Allopurinol is a common antihyperuricemic agent for gout treatment.
• Lens opacities (cataracts) have been anecdotally linked to long-term allopurinol use in younger patients.
• The mechanism of this potential cataractogenesis remains unclear.

Purpose of the Study:

• To investigate the potential of allopurinol to cause cataracts.
• To determine if allopurinol can bind to lens proteins and become phototoxic.

Main Methods:

• High-resolution phosphorescence spectroscopy was used to analyze human cataracts from patients on allopurinol.
• In vitro experiments exposed normal human lenses to allopurinol and UV radiation.
• In vivo experiments administered allopurinol to rats followed by UV exposure.

Main Results:

• The characteristic allopurinol triplet spectrum was detected in all three human cataracts analyzed.
• Identical spectra were observed in human lenses incubated with allopurinol and exposed to UV radiation.
• Rat lenses treated with allopurinol and UV also showed similar spectral evidence of photobinding.

Conclusions:

• Allopurinol can be photobound within both human and rat lenses.
• These findings suggest a plausible mechanism for allopurinol-induced cataract formation.
• Further research is warranted to confirm the clinical significance of allopurinol's cataractogenic potential.