Kenneth C Ofokansi1,
Philip F Uzor2 
For correspondence:- Philip Uzor Email: philuzor4u@yahoo.com Tel:+2348037008294
Received: 10 May 2012 Accepted: 29 January 2013 Published: 24 April 2013
Citation: Ofokansi KC, Uzor PF. Thermodynamic and Spectrophotometric Studies of Electron Donor-Acceptor Complexation Between Loratadine and Chloranilic Acid. Trop J Pharm Res 2013; 12(2):233-238 doi: 10.4314/tjpr.v12i2.16
© 2013 The authors.
This is an Open Access article that uses a funding model which does not charge readers or their institutions for access and distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/4.0) and the Budapest Open Access Initiative (http://www.budapestopenaccessinitiative.org/read), which permit unrestricted use, distribution, and reproduction in any medium, provided the original work is properly credited..
Purpose: To developing a simple, rapid and reliable analytical method for loratadine based on charge transfer complexation with chloranilic acid.
Methods: The complex between loratadine and the complexing agent, chloranilic acid, was formed by mixing appropriate volumes of their solutions in non-aqueous media. Some features of the formed complex, such as molar ratio of the reaction and effect of time, were determined spectrophotometrically. Thermodynamic parameters were determined as well, the method was utilized in the assay of the drug in both bulk and tablet dosage forms.
Results: The complex showed a wavelength of maximum absorption (λmax) at 527 nm (λmax of loratadine alone was 440 nm). Beer’s law was obeyed in the concentration range of 3.2 - 28.8 mg% (r2 = 0.9997). The stoichiometry of the complex was 2:1 (loratadine: chloranilic acid) and the complex was stable for over 60 min. Thermodynamic results show that as temperature changed from 30 to 70 °C, enthalpy change (W10;H) was steady at -0.254 kcal.mol-1 while the free energy (W10;G) changed from -3.904 to -4.450 kcal.mol-1. The complex appeared to be more stable at the slightly elevated temperature of 50 °C with a value of 757.14 mol-1. Analysis of the drug in both bulk and dosage forms showed good accuracy and precision with recovery ranging from 99.98 ± 1.00 to 100.94 ± 2.39 %.
Conclusion: Charge transfer complexation method with chloranilic acid was successfully developed for the simple, rapid and accurate determination of loratadine.
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