Compounds of formula I ##STR00001## in free or salt or solvate form, where T.sup.1, T.sup.2, X, R.sup.a, R.sup.b, R.sup.8 and R.sup.9 have the meanings as indicated in the specification, are useful for treating inflammatory or obstructive airways, pulmonary hypertension, pulmonary fibrosis, liver fibrosis, muscle diseases and systemic skeletal disorders. Pharmaceutical compositions that contain the compounds and processes for preparing the compounds are also described.