The invention provides compounds of formula (I) wherein m, R.sup.1, n, R.sup.2, q, X, Y, Z, t, R.sup.3, R.sup.4, R.sup.5, R.sup.6, R.sup.7 and R.sup.8 are as defined in the specification, processes for their preparation, pharmaceutical compositions containing them and their use in therapy. ##STR00001##