The effect of water-soluble polymers on drug-cyclodextrin complexation

• Published in: International journal of pharmaceutics Vol. 110; no. 2; pp. 169 - 177
• Main Authors: Loftsson, Thorsteinn, Frikdriksdóttir, Hafrún, Sigurkdardóttir, Anna M., Ueda, Haruhisa
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier B.V 19.09.1994; Elsevier
• Subjects: Biological and medical sciences; Complexation; Cyclodextrin; Drug; General pharmacology; Medical sciences; Pharmaceutical technology. Pharmaceutical industry; Pharmacology. Drug treatments; Polymer; Solubilization; Drug; Complexation; Polymer; Cyclodextrin; Solubilization; Pharmaceutical technology; Control release polymer; Oligosaccharide; Dosage form; Inclusion compound
• ISSN: 0378-5173; 1873-3476
• DOI: 10.1016/0378-5173(94)90155-4

In aqueous solutions water-soluble polymers were shown to increase the solubilising effect of cyclodextrins on drugs. For example, the solubilising effect of 2-hydroxypropyl-β-cyclodextrin (HPβCD) with molar substitution of 0.6 was improved by 6–57% (on average 27%) when 0.25% (w/v) carboxymethylcellulose was present in the solution and 12–129% (on average 49%) when 0.25% (w/v) polyvinylpyrrolidone (PVP) was present. Similar results were obtained with other cyclodextrins and other polymers. For PVP and 10% (w/v) HPβCD the PVP concentration for maximum solubilisation appeared to be between 0.05 to 0.25% (w/v). At this low concentration PVP had insignificant effect on the viscosity of the aqueous HPβCD solution. The polymers increased the stability constants of the drug-cyclodextrin complexes. Addition of PVP to the aqueous complexation medium resulted in an increased negative enthalpy change, together with an increased negative entropy change.