Methods for assaying D-penicillamine in a clinical setting.

Area of Science:

• Pharmacology
• Analytical Chemistry
• Biochemistry

Background:

• Penicillamine is a drug used to treat various conditions, including rheumatoid arthritis and Wilson's disease.
• Accurate quantification of penicillamine and its metabolites is crucial for pharmacokinetic studies and therapeutic drug monitoring.
• Traditional amino acid analysis methods have limitations in detecting penicillamine due to its reactive thiol group.

Purpose of the Study:

• To analyze penicillamine disulfides using advanced analytical techniques.
• To report pharmacokinetic studies of penicillamine in patients on established treatment regimens.
• To determine the concentrations of free penicillamine and its disulfide forms in human plasma.

Main Methods:

• Automatic amino acid analysis was employed for initial analysis.
• High-performance liquid chromatography (HPLC) with an electrochemical detector was used for preferred detection.
• Gas chromatography (GC) with a flame ionization detector (FID) was also utilized for analysis.

Main Results:

• Plasma concentrations of free penicillamine in patients varied between 4 and 20 microM.
• Concentrations of penicillamine disulfides were 3-4 times higher than free penicillamine.
• Significant quantities of penicillamine were found to be bound to plasma and tissue proteins.

Conclusions:

• HPLC and GC are superior detection methods for penicillamine analysis compared to ninhydrin-based methods.
• Pharmacokinetic studies reveal substantial variability in free penicillamine plasma levels.
• Penicillamine exists predominantly as disulfide forms and protein-bound conjugates in vivo.