The inclusion of the recently developed antihistamines in cold tablets has led to the interesting problem of quantitatively estimating constituents which have very similar chemical and physical properties. Formulations have appeared containing aspirin, caffeine, phenacetin, and quinine hydrobromide in combination with the well established antihistaminic, Pyrilamine Maleate. The pyrilamine maleate (pyranisamine maleate) and quinine in such combinations pose a difficult problem in separation and estimation. Pyrilamine maleate has the empirical formula C<sub>17</sub>H<sub>23</sub>N<sub>3</sub>OC<sub>4</sub>H<sub>4</sub>O<sub>4</sub>, is very soluble in chloroform and water, freely soluble in alcohol and slightly soluble in benzene and ether. In alkaline solution the free base is liberated. Most of the chemical reactions for its determination or separation from other constituents make use of the one tertiary amine type nitrogen contained in the molecule. Quinine hydrobromide is, of course, one of the well known alkaloid by addition of ammonia followed by the extraction of the free alkaloid with chloroform. Under such conditions, pyrilamine base will be extracted along with the alkaloid. Thus, it is quite impractical to attempt a chemical separation of these constituents from a mixture containing both. The actual deter mination of one in the presence of the other is not possible by the chemical analytical procedures usually used. However, their resolution by ultraviolet spectrophotometric means is a relatively simple matter.
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