A spectrofluorometric method for the determination of ajmaline in plasma.

1 Ajmaline was found to have maximum fluorescence at neutral pH with 300 nm excitation and 365 nm emission wavelengths (corrected). 2 The fluorescence intensity had a linear relationship to concentration up to 50 microgram ml-1 and the recovery of ajmaline after extraction from plasma was 92.5 +/- 3%. 3 Extraction of drug-free plasma and of samples containing known concentrations of ajmaline showed that drug levels in the range found clinically could be measured accurately by fluorimetry. 4 Serial plasma ajmaline concentrations were measured in a subject after intravenous injection of ajmaline (50 mg). The rates of plasma clearance of the drug were found to be similar to those obtained in previous studies.