Aim:The aim of the study was to develop and validate a new simple, accurate, sensitive and specifi c bioanalytical spectrofluorimetric method for quantitative determination of donepezil hydrochloride (DH) in human plasma. Method: Estimation of DH in human plasma was done by spiked human plasma studies. Forestimation of DH in human plasma extraction was carried out using 5% TCA forprotein precipitation followed by liquid-liquid extraction with 5% IPA in n-Hexane.Under spectrofl uorimetric conditions delta value 65 applied in synchronous mode(medium sensitivity mode) and wavelength used in analysis was 389 nm. Result: Developed method found linear, in the concentration range of 50-105 ng/mL with correlation coeffi cient (R 2 ) 0.9965. Percentage recovery was found to be 75 %-85 %for DH. High recovery show that the method is free from the interference from plasma constituents. Conclusion: Proposed method can be used for estimation of DH in routine quality control laboratories for quantitative determination of DH in bulk as well as in human plasma. Further it can also be used to determine plasma DH concentration in drug monitoring or in pharmacokinetic investigations.

A new, simple, accurate, sensitive and specific bioanalytical spectrofluorimetric method was developed and validated for estimation of memantine hydrochloride (MEM) in human plasma. Estimation of MEM in human plasma was done by spiked human plasma studies. Extraction of MEM from human plasma was carried out using 5% trichloroacetic acid for protein precipitation followed by liquid-liquid extraction with 5% IPA in n-hexane. For spectrofluorimetric estimation delta value 65 applied in synchronous mode (medium sensitivity mode) and fluorescence intensity was measured at 420 nm. Developed method was found linear to be in the concentration range of 50-300 ng/mL with correlation coefficient (R2) 0.9951. Percentage recovery was found to be 77.85-83.68% for MEM. High recovery shows that the method is free from the interference from plasma constituents. Hence, proposed method can be used for estimation of MEM in routine quality control laboratories for quantitative determination of MEM in bulk as well as in human plasma. Further it can also be used to determine plasma MEM concentration in drug monitoring or in pharmacokinetic investigations.