pH-dependent secretion of procainamide into saliva

Area of Science:

• Pharmacokinetics
• Analytical Chemistry

Background:

• Procainamide is an antiarrhythmic drug.
• Monitoring drug levels is crucial for effective treatment.

Purpose of the Study:

• To investigate the relationship between serum and saliva procainamide concentrations.
• To assess factors influencing this relationship, such as saliva pH.

Main Methods:

• Collected serum and mixed saliva samples from 12 patients on chronic procainamide therapy.
• Timed sample collection to capture peak and trough drug levels.
• Measured procainamide concentrations and saliva pH.

Main Results:

• Significant intersubject variability in saliva to serum procainamide concentration ratios (0.27-8.93).
• No correlation found between procainamide dose and minimum serum or saliva concentrations.
• Saliva to serum concentration ratio increased as saliva pH decreased, consistent with procainamide's weak base properties.

Conclusions:

• Saliva procainamide levels exhibit considerable patient-to-patient variation.
• Saliva pH is a key determinant of procainamide distribution into saliva.
• Saliva may serve as a non-invasive matrix for monitoring procainamide, but pH-dependent factors must be considered.