Polymorphism and pseudopolymorphism of acyclovir.
Four crystal modifications of acyclovir were isolated by recrystallization and characterized by powder X-ray diffractometry, differential scanning calorimetry, and thermogravimetric analysis. It was confirmed that Form 3 is a hydrate and Form 4 is an acetic acid solvate. The dissolution patterns of three crystal forms of acyclovir were studied in water at 37 +/- 0.5 degrees C, 90 rpm for 120 minutes. The amount dissolved at 120 minutes was highest for Form 1, followed by Form 2 and Form 3. After storage of 25 hours at 0% RH (silica gel, 20 degrees C) Form 3 was transformed to Form 2.
Sohn
Young Taek
YT
College of Pharmacy, Duksung Women's University, 419 Ssangmun-Dong, Dobong-Gu, Seoul 132-714, Korea. ytsohn@duksung.ac.kr
Kim
Sang Hee
SH
D000212:Acyclovir / Q000737:chemistry*; D000998:Antiviral Agents / Q000737:chemistry*; D002152:Calorimetry, Differential Scanning; D003460:Crystallization; D007536:Isomerism; D012995:Solubility; D012997:Solvents; D013818:Thermogravimetry; D014961:X-Ray Diffraction
D000998:Antiviral Agents; D012997:Solvents; D000212:Acyclovir