Ketamine is absolutely NOT A LOCAL anesthetic. It is a sedative-hypnotic..not a local anesthetic. Local anesthetics are drugs that work by inhibiting sodium channels therby inhibiting neurtransmission. For example lidocaine, cocaine, bupivicaine, chloroprocaine, prilocaine, mepivicaine, ropivicaine, etc. are local anesthetics. 150 mg is a large dose. Essentially that is 2mg/kg in the normal male patient. That is probably enough to cause the induction of GENERAL anesthesia..ie going to "SLEEP" for surgery. I agree 150 mg in the lay persons hands is lethal..basically without going into alot of details ED 50 is the effective dose of a drug to establish an effect in 50% of the subjects. LD 50 is the lethal dose of a drug that kills 50%. The ED/LD 50 ratio is what is important. This states that the larger the difference between the two doses, the safer the drug is. For example, if 1 mg was the ED 50 and 2 mg was the LD 50, then that drug really sucks ass.