Anesthetic not painful on Intravenous administration is

Ketamine:- * Ketamine on intravenous administration is absolutely devoid of pain at injection site. * Ketamine is a NMDA antagonist intravenous general anesthetic agent - that induces a characteristic cataleptic state called "Dissociative Anesthesia" - a state of induced dissociation from onself and surrounding. * Dissociative anesthesia is due to selective interruption of association pathways in the neocoex and thalamus --> characteristic somato-sensory blockade, a combination of Catalepsy +Catatonia+ Analgesia+ Amnesia (without complete loss of consciousness like other general anesthetics) Ref:- Goodman & Gilman Pharmacological Basis of Therapeutics 13th Ed; Pg num:- 391