A Study of 1 : 1 Plus 1 : 2 Complexes between Barbiturate and α-Cyclodextrin Using the Freezing Point Depression Method

• Published in: Chemical & pharmaceutical bulletin Vol. 41; no. 8; pp. 1444 - 1447
• Main Authors: SUZUKI, Masahiko, ITO, Kiyoko, FUSHIMI, Chigusa, KONDO, Tamotsu
• Format: Journal Article
• Language: English
• Published: Tokyo The Pharmaceutical Society of Japan 1993; Maruzen
• Subjects: 1 : 2 complex; barbiturate; Biological and medical sciences; freezing point depression; General pharmacology; inclusion complex; Medical sciences; osmotic pressure; Pharmaceutical technology. Pharmaceutical industry; Pharmacology. Drug treatments; stability constant; Complexation; Cyclodextrin; Stability; Pharmaceutical technology; Investigation method; Formulation; Interaction; Dosage form; Freezing point; Inclusion compound; Barbituric
• ISSN: 0009-2363; 1347-5223
• DOI: 10.1248/cpb.41.1444

The freezing point depression method for studying drug interaction has been extended to a system containing both 1 : 1 (AB) and 1 : 2 (AB2) complexes. The osmotic concentration of dilute aqueous solutions was measured by this method with a commercially available osmometer. On the basis of the colligative properties, a mathematical model has been proposed to calculate the apparent stability constants (K1 and K2). This method is applied to complexes of α-cyclodextrin with three barbiturate derivatives (barbital, phenobarbital, and pentobarbital). The results showed that the apparent stability constants obtained were in fair agreement with those obtained by the spectroscopic method. The advantage of this method is that the apparent stability constant could be estimated quickly using a simple procedure.