Pharmaceutical hydrates under ambient conditions from high-pressure seeds: a case study of GABA monohydrate

The monohydrate form of the neurotransmitter gamma-amino butyric acid (GABA) has been crystallised in the 0.4-0.8 GPa pressure range, recovered to ambient pressure and then used as a seed. Theoretical calculations indicate that this hydrate is only thermodynamically favoured over the two anhydrous forms at high pressures.