A method and composition for the prevention, amelioration or control of
external parasites on animals and humans utilizing a compound of formula I. or a pharmaceutically acceptable salt thereof, wherein R is
halogen, OR7, SOmR8, NO2, CN, C1-C6haloalkyl or an optionally substituted C1-C6
alkyl group; n is 0 or an integer of 1, 2 or 3; m is 0 or an integer of 1 or 2; R1 is H,
halogen, NO2, NR9R10, NR11COR12, NCHNR9R10 or NCHOR13; R2, R3, R4, R5 and R6 are each independently H,
halogen or a C1-C4
alkyl,
aryl or heteroaryl group each optionally substituted; R7 is H or a C1-C6
alkyl, C2-C6alkenyl, C2-C6alkynyl,
aryl or heteroaryl group each optionally substituted; R8 is a C1-C6alkyl, C2-C6alkenyl, C2-C6alkynyl,
aryl or heteroaryl group, each optionally substituted; R9 and R10 are each independently H, C1-C4haloalkyl or a C1-C6alkyl, C2-C6alkenyl, C2-C6alkynyl, aryl or heteroaryl group each optionally substituted or R9 and R10 may be taken together with the atom to which they are attached to form a 5 to 7-membered ring optionally containing 1 or 2 additional heteroatoms selected from O, N or S; R11 is H, COR12 or an optionally substituted C1-C4alkyl group; R12 is a C1-C6alkyl, C2-C6alkenyl, C2-C6alkynyl, aryl or heteroaryl group each optionally substituted; and R13 is H or a C1-C6alkyl, aryl or heteroaryl group each optionally substituted; or a stereoisomer or
tautomer thereof.