Polymorphic forms of a GABA
Two new crystalline monohydrates and two new crystalline anhydrates of gaboxadol are disclosed together with methods for preparing them.
1. A process for preparing crystalline gaboxadol monohydrate of form I which is characterized by an X-ray powder diffraction spectrum in 2θ values using CuKα radiation having a peak at 11.5°; comprising the steps of:
(a) dissolving an acid addition salt of gaboxadol in water;
(b) adding sufficient base to provide a pH of about 6.5; and
(c) collecting the resulting precipitate immediately.
2. A process for preparing crystalline gaboxadol monohydrate of form II which is characterised by an X-ray powder diffraction spectrum in 2θ values using CuKα radiation having a peak at 25.2° comprising the steps of:
(a) dissolving an acid addition salt of gaboxadol in water;
(b) adding sufficient base to provide a pH of about 6.5;
(c) aging the resulting mixture for at least 12 hours; and
(d) collecting the resulting solid.
3. A process for preparing crystalline gaboxadol anhydrate of form I which is characterised by an X-ray powder diffraction spectrum in 2θ values using CuKα radiation having a peak at 12.8°; by heating crystalline gaboxadol monohydrate of form I at a temperature above 100° C. at atmospheric pressure.
4. A process for preparing crystalline gaboxadol anhydrate of form II which is characterised by an X-ray powder diffraction spectrum in 2θ values using CuKα radiation having a peak at one or more of 16.0°, 24.7° and 28.4°:
by heating crystalline gaboxadol monohydrate of form II at a temperature above 100° C. at atmospheric pressure; or
by stirring a suspension of gaboxadol anhydrate of form I in an alcohol containing up to 6 carbon atoms at ambient temperature or with warming.