Preparation, spectroscopy study of the inclusion complex of Neurontin drug with β-cyclodextrin

Neurontin is an anticonvulsant and analgesic drug that stirs more and more the interest of the researchers. Neurontin is an adjuvant anticonvulsant drug for the treatment of refractory partial seizures. Subsequently, it was shown to be effective in treating a variety of chronic pain conditions. The cyclodextrin inclusion complex was well done in enhancing drug solubility, stability and bioavailability [1,2]. The inclusion complex of Neurontin with β-cyclodextrin was prepared and characterized by ultraviolet spectroscopy (UV-Vis), fourier transform infrared spectroscopy (FTIR) and 1HNMR. The stoichiometry was established using Job s method and mole ratio method. The stoichiometry ratio was also determined to be 1:1 for the inclusion complex of β-CD with drug. The stability constant was calculated by using a modified Benesi–Hildebrand equation at 25 °C. The apparent formation constant obtained was 810 L/mol. Phase solubility equilibrium plot was obtained for β-CD complex. According to the method reported by Higuchi and Connors, the diagram was classified as a typical AL–type, where the stoichiometry of the inclusion complex was determined to be 1:1 in consistent with the result from spectroscopy study. The antioxidant activity of drug and its inclusion complex were determined by the scavenging of stable radical DPPH·. Kinetic studies of DPPH· with GBP and β-CD complex were done. The experimental results confirmed the forming of neurontin complex with β-CD also indicated that the drug/β-CD inclusion complex was the most reactive than its free form into antioxidant activity[3].