There are disclosed novel compounds of Formula (I) wherein R.sup.1, X and Y are as defined in the specification, and pharmaceutically acceptable salts thereof; together with processes for their preparation, compositions containing them and their use in therapy. The compounds are inhibitors of the enzyme MPO and are thereby particularly useful in the treatment or prophylaxis of neuroinflammatory disorders, cardio- and cerebrovascular atherosclerotic disorders and peripheral artery disease and respiratory disorders. ##STR00001##