Ketamine is an NMDA receptor antagonist.
The NMDA receptor is an excitatory amino acid receptor. Combining an excitatory amino acid antagonist with
an inhibitory amino acid agoinst such as midazolam provides sedation during or following precipatated opiate
withdrawal. This combination has been used in conjunction with elective precipitated withdrawal, the
controversial Rapid Opiate Detoxification (ROD); also known as Ultra Rapid Opiate Detoxification
(UROD) or just rapid detox.
The ketamine / midazolam combination has been shown to be useful and less controversial in emergency
situations such as the precipitated opiate withdrawal associated with the emergency administration of
naloxone (Narcan) in the unconscious patient who has overdosed and has respiratory depression.
The medications may be administered in a 10:1 ketamine to midazolam ratio resulting in sedation of
approximately one minute for each milligram of ketamine in the mixture. The misxture of the two medications
is usually administered as ketamine 25 mg and midazolam 2.5 mg or ketamine 50 mg and midazolam 5.0 mg for
one half hourr one hour of sedation respectively. The dose may be administered intravenously,
subcutaneously or intramuscularly and repeated as needed.
The utility is readily apparent in the patient with a history of IV drug abuse who has limited venous access
and may be in an uncooperative state due to the discomfort associated with the antagonist induced emergency
precipitated withdrawal
.
