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Butamyrate citrate, 2-(2-diethylaminoethoxy)ethyl 2-phenylbutamyrate dihydrogen citrate, is widely used as a central cough suppressant.1,2 The drug is mainly prescribed in the form of a syrup. Although the drug is freely available on the European market, it is not described officially in any pharmacopoeia. A literature survey reveals that only two previous methods are described in the literature referring to both the relative bioavailability of different butamyrate citrate preparations after single dose oral administration 3 and to the determination of the compound using an optical compensation method. 4 As there is no method reported in the literature for the determination of butamyrate in cough preparations, it was deemed useful to develop a derivative spectrophotometric method together with an HPLC procedure for quantification of the drug in the presence of various excipients, sugar bases and other combinations encountered in such preparations. Derivative transformation of spectral data has been proven to be a valuable and sensitive procedure for the quantification of different drugs in several pharmaceutical products, whereas chromatographic separation of a drug from its excipients in a formulation has other advantages over alternative extraction techniques. One of these advantages is that quantifications of rather complex formulations can be handled promptly. Formulations that tend to form emulsions during simple extraction can often be separated easily by column chromatography. Therefore column separations are sometimes used as an alternative for elixirs, ointments, creams, gels, oral suspensions and syrups. Experimental Chemicals and solutionsButamyrate citrate was kindly donated by Medichrom S. A. Pharmaceuticals, Athens, Hellas. Also HPLC-grade methanol, acetonitrile and water were bought from Riedel-de Haën, Germany. All other chemicals (Sigma Chemicals Co.) were analytical reagents and were used as received.Stock solutions were prepared by accurately weighing the appropriate amounts of butamyrate citrate and then dissolving them in methanol in 50-mL volumetric flasks to yield standard stock solutions. Working standard solutions of butamyrate citrate were prepared from the stock solutions by sequential dilution, using the mobile phase to give concentrations in the ranges indicated in Table 1. Samples from the syrups were also dissolved appropriately in mobile phase and portions of the sample solutions were analyzed properly.Also, for degradation of the compound by acid, base or oxidation, 2.0 mL of the stock solution (200 mg/100 mL) was ) in cough syrups have been developed. In the spectrophotometric method, direct measurement of the drug at its absorption maxima is impossible because of interference from different absorbing excipients. Extraction of butamyrate citrate was performed with n-pentane/isopropyl alcohol. Quantification was carried out through the use of 1 D derivative at a trough depth of 253.6 nm where interferences from other coextracted compounds are negligible. The extraction efficiency...

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