利福定晶型转化研究

CRYSTAL MODIFICATION OF RIFANDIN

根据不同温度、湿度及水-乙醇气氛中晶体转化试验,并结合晶体中乙醇含量的测定结果,认为利福定Ⅰ型晶与Ⅳ型晶在一定条件下可相互转化,其转化的物质基础是水与乙醇的相互交换。另外,两晶型在较高温度下,可产生另一较稳定的非溶剂化晶型,定为Ⅴ型晶。利福定Ⅱ、Ⅲ型晶在实验研究中未见到任何转晶现象。

The transformation of four types of crystalline rifandin under controlled condition was investigated by means of ethanol content measurement, X-ray powder diffraction analysis. When exposed to an atmosphere of 83~85% relative humidity for 7 days at 37℃ or 24~48 hrs at 50℃ , crystal type Ⅳ, a rifandin solvate containing ethanol, was transformed into type Ⅰ, a rifandin hydrate. However, type Ⅰ cryta) when stored at 37℃ for 7 days in a desiccator containing water-ethanol(1:1) or ethanol, this crystal was converted to type Ⅳ. Type Ⅰ contains≤0.1% of ethanol and type Ⅳ contains about 2~9% of ethanol, as determined by gas chromatography. When type Ⅰ and Ⅳ is heated at 100℃ for 0.5 hr, both were transformed into a new anhydrous crystalline form (type Ⅴ),which was different from type Ⅰ(an anhyd. form reported previously) .There is no evidence that crystal type Ⅱ or Ⅲ was converted to the type Ⅰ, Ⅳ or Ⅴ under similar conditions.