please help

i used to see a late 70s ufo movie when i was a kid. thepeople would get taken, sit in a room in there underwear, were givin a vitamin pill or something. at the end there is a big battle out in space with all these ufos, one of which is shooting some zig zag lookin laser at the earth. if anyone has any idea what this movie is,please respond. ( it may have been dubbed from another country