Abstract: According to the present invention, there is provided a compound, or a solvate or salt thereof of formula (I): ##STR1## Substituted hydroisoquinoline derivatives are potent and selective delta opioid agonists and antagonists and are of potential therapeutic utility as inter alia analgesics.

Abstract: A compound, or solvate or salt thereof, of formula (I) ##STR1## in which, R.sub.1 and R.sub.2, are, independently hydrogen, linear or branched C.sub.1-6 alkyl, C.sub.3-7 cycloalkyl, C.sub.3-7 cycloalkenyl, or C.sub.3-6 alkenyl, or together form a C.sub.3-7 alkyl;R.sub.3 and R.sub.4 are, independently, hydrogen, linear or branched C.sub.1-6 alkyl, or R.sub.4 is oxygen forming with the carbon atom to which is attached a C.dbd.O group;R.sub.5 is hydrogen, hydroxy, or C.sub.1-3 alkoxy;R.sub.6 is halogen, NH.sub.2 or a para or meta --COR-8 group, in which R.sub.8 is C.sub.1-8 -alkyl, C.sub.1-8 -alkoxy or NR.sub.9 R.sub.10, wherein R.sub.9 and R.sub.10, are, independently, hydrogen, straight or branched C.sub.1-6 alkyl, C.sub.3-7 cycloalkyl or phenyl; or R.sub.6 is a para or meta group ##STR2## in which R.sub.11 and R .sub.12 are, independently, hydrogen or straight or branched C .sub.1-6 and,R.sub.7 is hydrogen, or straight or branched C.sub.1-8 alkyl; is provided.

Abstract: Tricyclic derivatives of octahydroisoquinoline of formula (I), wherein n is zero or 1 and if n is zero, one of X or Y is NH, oxygen or sulphur, and the other is NH, CH or a R.sub.4 - or R.sub.5 -substituted carbon atom; if n is 1, then X and Y are both nitrogen, or one of them is nitrogen and the other is CH or an R.sub.4 - or R.sub.5 -substituted carbon atom, have selective receptor agonist or antagonist activity, and are of potential therapeutic utility as analgesics or immunomodulating and/or cardiovascular agents.