| 摘要 |
Craytalline famotidine polymorphs exhibiting a specified X-ray diffraction pattern, the crystals being stable, are claimed. They may be prepd. by (a) reacting a soln. in methanol of a salt of famotidine selected from hydrochloride, hydrobromide, sulphate, nitrate or phosphate with a tertiary organic base such as triethylamine, 1,8-diazabicyclo (5.40) undec-7-ene or diazabicyclo (4.3.0) non-5-ene, (b) diluting the resulting soln. at 50-65 deg. c with a chlorinated hydrocarbon pref. selected from CH2Cl2, CHCl3, CCl4, CH2Cl-CH2Cl and CCl2=CHCl2 and (c) cooling to ppt. or crystallise the polymorph of low m.pt. and low apparent density and isolating by filtration at 0-15 deg. C. High density polymorph can be obtd. by seeding the soln. from (b) with high density crystals. |
