The invention provides compounds of the general formula
wherein

X represents a bond, or a C 1-6 alkylene, C 2 - 6 alkenylene or C 2 - 6 alkynylene chain, and
Y represents a bond, or a C 1-6 alkylene, C 2 - 6 alkenylene or C 2-6 alkynylene chain with the proviso that the sum total of carbon atoms in X and Y is not more than 10;
R 1 and R 2 each represent a hydrogen atom or a C 1-3 alkyl group, with the proviso that the sum total of carbon atoms in R 1 and R 2 is not more than 4; and
Py represents a pyridyl group substituted by one or two substituents selected from nitro, -(CH 2 ) t R 3 , -NR 4 R 5 , -(CH 2 ) r SO 2 NR 4 R 5 , -NR 6 COR 3 , -NR 6 S0 2 R 7 , -(CH 2 ) r COR 3 , -OCH 2 COR 3 and -O(CH 2 )qR 3 ; where
R 3 represents a hydroxy, C 1 - 3 alkoxy or NR 4 R 6 group;
R 4 and R 5 each represent a hydrogen atom or a C 1-4 alkyl group or -NR 4 R 5 forms a saturated heterocyclic amino group which has 5-7 ring members and optionally contains in the ring one or more atoms selected from -O- and -S- or a group -NH- or -N(CH 3 )-;
R 6 represents a hydrogen atom or a C 1-4 alkyl group;
R 7 represents a C 1-4 alkyl, phenyl or -NR 4 R 6 group;
q represents an integer 2 or 3;
r represents an integer from 0 to 3; and
t represents an integer 1, 2 or 3;
and physiologically acceptable salts and solvates (eg. hydrates) thereof.

The compounds have a stimulant action at β 2 -adreno receptors and may be used in the treatment of diseases associated with reversible airways obstruction such as asthma and chronic bronchitis.