Synthesis and spectroscopic characterization of albuterol double salt ionic liquids

Abstract

Many of the marketed pharmaceuticals are in solid, crystalline form. Unfortunately, most of these drugs have low bioavailability, poor transdermal delivery or dissolution. This is generally due the inherent properties of their solid state such as polymorphic interconversion and their easy conversion into solvates. Numerous research papers show that the ionic liquids strategy can be successfully applied to pharmaceuticals to overcome many of these disadvantages. Ionic liquids (ILs, low melting ionic salts with high thermal stability and low vapor pressure) are compounds comprised of two ions, a cation and an anion, in a 1:1 molar ratio. Double salt ionic liquids (DSILs) are complex ILs that contain in their structure more than two types of ions in different molar ratios (one anion and several cations; one cation and several anions; or several anions and several cations). This ratio can vary in any considerable way contributing to the variety of chemical and physical properties of DSILs. Our research focuses on applying the DSIL strategy to albuterol, an asthma drug, to form new asthma drugs with improved solubility and transdermal delivery. Several new DSILs were successfully synthesized by utilizing albuterol hydrochloride (cation precursor) and sodium salicylate and sodium docusate (anion precursors) in varying ratios. Here we present the synthetic procedures and the spectroscopic characterization of the novel compounds.