Abstract: The present invention relates to compounds of formula (I), and pharmaceutically acceptable salts, prodrugs, solvates and crystalline forms thereof, in which R1 and R2 independently represent: a C1-6alkyl group; an optionally substituted (amino)C1-4alkyl-group; an optionally substituted non-aromatic C3-15carbocyclic group; a (C3-12cycloalkyl)C1-3alkyl-group; a group —(CH2)r(phenyl)s in which r is 0, 1, 2, 3 or 4, s is 1 when r is 0 otherwise s is 1 or 2 and the phenyl groups are optionally independently substituted by Z; naphthyl; anthracenyl; an optionally substituted saturated 5 to 8 membered heterocyclic group containing one nitrogen and optionally one of the following: oxygen, sulphur or an additional nitrogen; 1-adamantylmethyl; a group —(CH2)t Het in which t is 0, 1, 2, 3 or 4, and the alkylene chain is optionally substituted and Het represents an optionally substituted aromatic heterocycle; or R1 represents H and R2 is as defined above; or R1 and R2 together with the nitrogen atom to which they are atta

Abstract: A compound of Formula I ##STR1## or pharmaceutically acceptable salts of Formula I, where R.sup.1 is H, C.sub.1 -C.sub.3 alkyl, --(CH.sub.2).sub.n CONH.sub.2 where n is 2 to 6, (CH2).sub.n -1-(4,4-dimethylpiperidine-2,6-dione-yl), or cyclopropylmethyl;R.sup.2 is hydrogen, C.sub.1 -C.sub.8 alkyl, C.sub.3 -C.sub.8 cycloalkyl or combined with R.sup.1 to form a C.sub.3 -C.sub.8 cycloalkyl, C.sub.2 -C.sub.8 alkenyl, C.sub.2 -C.sub.8 akynyl, (CH.sub.2).sub.n --X--Ar where X is O, S, or NH, 3,3,3-trifluoropropyl, --(CH.sub.2).sub.m --R.sup.9 where m is 2 or 3 and R.sup.9 is phenyl, 2-thiophenyl or 3-thiophenyl; R.sup.3 is hydrogen, C.sub.1 -C.sub.3 alkyl, 2,2,2-trifluoroethyl, 3,3,3-trifluoropropyl, formyl, CN, halogen, CH.sub.2 OR.sup.2, C(O)C(O)OR.sup.1, C(O)CO NR.sup.1 R.sup.2, --(CH.sub.2).sub.q --NR.sup.1 R.sup.2 where q is 0 to 5, C.dbd.NOR.sup.2, 2(4,5-dihydro)oxazolyl, or COR.sup.10 where R.sup.10 is H, R.sup.1, NR.sup.1 R.sup.2 or CF.sub.3 ; R.sup.4 is hydrogen, C.sub.1 -C.sub.