Organotin-Drug Interactions. Organotin Adducts of Tenoxicam: Synthesis and Characterization of the First Organotin Complex of Tenoxicam

Abstract

The synthesis and spectral characterization of the novel organotin complexes [SnBu2(ten)] (1) and [SnBu2(Hten)2] (2) of the potent and widely used anti-inflammatory drug tenoxicam (H2ten) are reported. A crystal-structure determination of 1 showed that, in this complex, the ligand is doubly deprotonated at the hydroxy O-atom and the amide N-atom and is coordinated to the SnBu2 fragment via four- and six-membered chelate rings. An extended network of Sn−O−Sn, C−H⋅⋅⋅O and C−H⋅⋅⋅π contacts lead to aggregation and a supramolecular assembly. Potentiometric titrations in nonaqueous solutions support the ionization of the drug by removal of the second H-atom, the amide H-atom, in the presence of the diorganotin(IV) fragment. The Ka values of the poorly H2O-soluble drug tenoxicam were obtained spectrophotometrically in aqueous solutions of constant ionic strength.