Novel thieno[2,3-b]pyrazine-2,3(1H,3H)-diones or tautomeric forms thereof of the formula (I) ##STR1## The compounds are useful in the treatment of neurological and psychiatric diseases.
Acylamino heteroaryl compounds in which the heteroaryl nucleus is a 5-membered ring containing a single heteroatom, which may be oxygen, or sulphur, methods of making the compounds and pharmaceutical formulations containing the compounds. The compounds have anti-allergy activity.