Viscometric and FTIR studies of chloroquine phosphate, acefylline piperazine and gentamicin sulfate in aqueous-polyethylene glycol and aqueous-polyvinyl pyrrolidone at different temperatures

Abstract This paper aimed to study the effect of aqueous, aqueous polyethylene glycol (1.0 %w/v) and aqueous polyvinyl pyrrolidone (1.0 %w/v) on the physicochemical behaviour of three pharmaceuticals substantial drugs by viscosity method. Viscosity measurements of the drugs (chloroquine phosphate, acefylline piperazine and gentamicin sulfate) solutions were performed within concentration ranges from 2.0 × 10−2 to 10.0 × 10−2 ± 0.001 mol.dm−3 at varying temperatures (293.15, 298.15, 303.15, 308.15, 313.15 and 318.15 ± 0.01 K). The viscosity data used to interpret the interactions (drug-drug and drug-solvent) existing in the solutions of drugs in terms of ‘A’ and ‘B’ coefficients of Jones–Dole equation respectively. Temperature derivatives of the B-coefficient (dB/dT) were also calculated which help to establish the relation between the nature of the solute and the structural modifications in the solution. Hence, the structure promoting ability of the AP in aqueous system and structure destroying effect of CP, AP and GS in the aqueous-polymeric system was observed. The FTIR studies of CP, AP and GS show that the chemical identity of the drug was not affected by the polymers and no binding of the new forming compound was detected.