What drug or substance can kill wild cats?

Wild disease carrying cats have taken over my home, they come in through a damaged board in the roof, invade my kitchen for food, frighten me and my kids, my wife is threatenning to leave with the kids if I don't do something about the wild creatures invading our home. Before you start referring me to animal control, I am in Nigeria, no pest/animal control here, a man is expected to protect/defend his family from wild animals. I want something toxic to put in left over food at night to eradicate them, also I'll like a slow acting poison so that they can go and die wherever they come from. Plz I don't need any other advice on who to call or how to help them, just give me the name of a drug or substance to use. I am hypertensive and have a lot bp lowering drugs (norvasc, lisinopril, atenolol), I don't know if grinding some and sprinkling them in left over food will be effective although I'll prefer cheaper drugs. I also have some asthma drugs like theophline and salbutamol, will they be effective? and what quantity /dose is lethal. Plz help me.