Low doses ketamine: antihyperalgesic drug, non-analgesic
Richebe P, Rivat C, Rivalan B, Maurette P, Simonnet G.
Departement d'anesthesie et de reanimation 3,
hopital Pellegrin, place Amelie-Raba-Leon,
33076 Bordeaux cedex, France;
Laboratoire homeostasie-allostasie-pathologie,
EA3666, universite Bordeaux-II,
146, rue Leo-Saignat, 33076 Bordeaux cedex, France.
Ann Fr Anesth Reanim. 2005 Aug 19


Recent data in animal experiments as in clinical trials have clearly reported that pain modulation is related to an equilibrium between antinociceptive and pronociceptive systems. Therefore, the apparent pain level could not only be a consequence of a nociceptive input increase but could also result from a pain sensitization process. Glutamate, via NMDA receptors, plays a major role in the development of such a neuronal plasticity in the central nervous system, leading to a pain hypersensitivity that could facilitate chronic pain development. By an action on NMDA receptors opioids also induce, in a dose dependent manner, an enhancement of this postoperative hypersensitivity. "Antihyperalgesic" doses of ketamine, an NMDA receptor antagonist, were able to decrease this central sensitization not only in painful animal but also in human volunteers exposed to different pain models, or in the postoperative period. Many studies have reported that ketamine effects are elicited when this drug is administered the following manner: peroperative bolus (0.1 to 0.5 mg/kg), followed by a constant infusion rate (1 to 2 mug/kg per min) during the peroperative period and for 48 to 72 hours after anaesthesia. Those ketamine doses improved postoperative pain management by reducing hyperalgesia due to both surgical trauma and high peroperative opioid doses. This antihyperalgesic action of ketamine also limited the postoperative morphine tolerance leading to a decrease in analgesic consumption and an increase in the analgesia quality.
Ketamine in Nepal
Obstetric anaesthesia
Molecular mechanisms
'My beloved chloroform'
'The secularisation of pain'
Ketamine - dreams and realities
Ketamine as an intravenous anaesthetic
Volatile anesthetics and NMDA glutamate receptors
Ketamine attenuates acute tolerance to analgesic effect of opioids
Schizophrenia, dissociative anaesthesia and near-death experience

and further reading

Future Opioids
BLTC Research
Utopian Surgery?
The Good Drug Guide
The Abolitionist Project
The Hedonistic Imperative
The Reproductive Revolution
Critique of Huxley's Brave New World