Study of the Inclusion Complexation of B - Cyclodextrin –Methyldopa and Determination of its Stability Constant (K) by U.V.-Visible Spectroscopy

Alamdar Ashnagar*, Nahid Gharib Naseri** and Bita Bigdeli*

*School of Pharmacy, Ahwaz Jundi Shapour University of Medical Sciences, Iran.

Methyldopa is a medication that belongs to the general class of medicines called antihypertensive and is used to treat high blood pressure (hypertension). Because of therapeutically importance of methyldopa, its widespread use and suitable chemical structure, its inclusion complexation with b - cyclodextrin was studied and the stability constant (K) of the complex was determined by UV-Visible spectroscopy. The stability constant (K) of the inclusion complex between b-cyclodextrin and methyldopa at lmax = 279 nm in phosphate buffer solution with pH 7.4 was determined. The absorbance at lmax = 279 nm by adding various concentrations of b - cyclodextrin to a given concentration of methyldopa solution was recorded and then plotted versus b - cyclodextrin concentration. Finally, by using the Beer-Lambert law the stability constant was calculated and found to be K = 83.9 ± 19.5 mol-1 .L

Methyldopa; b - cyclodextrin; alpha-methyldopa; aldomet®; antihypertensive; dopa decarboxylase