title: Spectrophotometric and spectrodensitometric methods for the determination of rivastigmine hydrogen tartrate in presence of its degradation product.
abstract: Three sensitive, selective and precise stability-indicating methods for the determination of the anti-Alzheimer's drug, rivastigmine hydrogen tartrate (RIV) in the presence of its alkaline degradation product (major metabolite, NAP 226-90) and in pharmaceutical formulation were developed and validated. The first method is a second derivative (D(2)) spectrophotometric one, which allows the determination of RIV in the presence of its degradate at 262 nm (corresponding to zero crossing of the degradate) over a concentration range of 50-500 microg/ml with mean percentage recovery 100.18 +/- 0.628. The second method is the first derivative of the ratio spectra (DD(1)) by measuring the peak amplitude at 272 nm over the same concentration range as (D(2)) spectrophotometric method, with mean percentage recovery 99.97 +/- 0.641. The third method is a TLC-densitometric one, where RIV was separated from its degradate on silica gel plates using methanol:butanol:H(2)O:ammonia (5:4:1:0.01 v:v:v) as a developing system. This method depends on the quantitative densitometric evaluation of thin layer chromatogram of RIV at 263 nm over a concentration range of 20-160 microg/spot, with mean percentage recovery 100.19 +/- 1.344. The selectivity of the proposed methods was tested using laboratory-prepared mixtures. The proposed methods have been successfully applied to the analysis of RIV in pharmaceutical dosage forms without interference from other dosage form additives and the results were statistically compared with reference method.
authors.affiliation: Analytical Chemistry Department, Faculty of Pharmacy, Cairo University, Kasr-El Aini Street, Cairo, Egypt.
authors.forename: Maissa Y
authors.initials: MY
authors.lastname: Salem
authors.forename: Amira M
authors.initials: AM
authors.lastname: El-Kosasy
authors.forename: Mohamed G
authors.initials: MG
authors.lastname: El-Bardicy
authors.forename: Mohamed K
authors.initials: MK
authors.lastname: Abd El-Rahman
mesh_terms: D001596:Benzylamines / Q000032:analysis*; D002800:Cholinesterase Inhibitors / Q000032:analysis / Q000378:metabolism; D002855:Chromatography, Thin Layer / Q000379:methods; D003720:Densitometry / Q000379:methods*; D004355:Drug Stability; D010627:Phenethylamines; D010636:Phenols / Q000032:analysis*; D048448:Phenylcarbamates / Q000032:analysis* / Q000378:metabolism; D015203:Reproducibility of Results; D000068836:Rivastigmine; D013053:Spectrophotometry / Q000379:methods*
chemical_list: C494046:3-(1-dimethylaminoethyl)phenol; D001596:Benzylamines; D002800:Cholinesterase Inhibitors; D010627:Phenethylamines; D010636:Phenols; D048448:Phenylcarbamates; D000068836:Rivastigmine