The effect of β-cyclodextrin and pH on bifonazole hydrosolubility

• Published in: Journal of the Serbian Chemical Society Vol. 69; no. 3; pp. 225 - 231
• Main Authors: Popovic, Gordana, Cakar, Mira
• Format: Journal Article
• Language: English
• Published: Serbian Chemical Society 2004
• Subjects: acidity constant; bifonazole; solubility; β-cyclodextrin
• ISSN: 0352-5139; 1820-7421
• DOI: 10.2298/JSC0403225P

The equlibria of bifonazole in saturated water solution within the pH range 4 to 10 [I = 0.1 mol/dm3 (NaCl); 25 ?C] were studied spectrophotometrically. Based on the equlibrium constants determined in a heterogeneous system, the acidity constant (pKa = 5.72) and solubility in water (S=10-5.79+10-(pH + 0.07))were calculated. The influence of ?-cyclodextrin on bifonazole solubility was examined in the presence of 10-3 and 10-4 mol/dm3 ?-cyclodextrin. At pH values over 8, bifonazole solubility was two- and 13-fold increased in the presence of 10-4 and 10-3 mol/dm3 ?-cyclodextrin respectively, compared to its solubility in water. The ratio of bifonazole solubility in the presence of ?-cyclodextrin and that in water decreased in parallel to the increase of acidity. Spektrofotometrijski su proucavane ravnoteze u zasicenom vodenom rastvoru bifonazola u pH intervalu 4?10. Na osnovu ravnoteznih konstanti odredjenih u heterogenom sistemu izracunata je kiselinska konstanta (pKa = 5,72) i rastvorljivost bifonazola u funkciji kiselosti rastvora (S=10-5.79+10-(pH + 0.07)) Uticaj ?-ciklodekstrina (?-CD) na rastvorljivost ispitivan je u prisustvu 10-3 i 10-4 mol/dm3 ?-CD. Utvrdjeno je da pri pH vrednostima vecim od 8 dolazi do povecanja rastvorljivosti 2 puta (u prisustvu 10-4 mol/dm3 ?-CD) i 13 puta (u prisustvu 10-3 mol/dm3 ?-CD) u odnosu na rastvorljivost bifonazola u vodi (u odsustvu ?-CD). Odnos rastvorljivosti bifonazola u prisustvu ?-CD i rastvorljivosti u vodi smanjuje se sa povecanjem kiselosti rastvora.