Ketamine Flashcards
Please note that the drug card information is for Educational Use ONLY, and the source is from Carrie Bowman's glossary of drug cards permitted by use of Georgetown NAP students. No permission is given to use these cards for anything other than as a study resource for our program.
What are the trade names for Ketamine?
Ketalar or Ketaject
What is the formal drug class of Ketamine?
- General anesthesia induction agent; phencyclidine derivative
- N-methyl-D-aspartate (NMDA) receptor antagonist
What are the uses of Ketamine?
Causes intense analgesia at subanesthetic doses and produces prompt induction of anesthesia when administered IV at higher doses
What is the MOA of Ketamine?
- Ketamine’s CNS effects are dose dependent and are related to its antagonistic activity at the NMDA receptor
- Glutamate and NMDA are excitatory amino acids. When glutamate binds to the NMDA subtype of the glutamate receptor, the channel opens and allows Na, K, Ca to either enter or leave the cell. Flux of these ions depolarize the POSTsynaptic neuron and initiate an action potential. ***Ketamine blocks this open channel and prevents further ion influx, thus inhibiting the excitatory response to glutamate
- dissociative anesthesia
- evidence that Ketamine depresses transmission of impulses in the medial medullary reticular formation, which is important for transmission of the affective-emotional components of nocioception from the spinal cord to higher brain centers
- it also binds with opioid, cholinergic, and monoaminergic(involves descending inhibitory pathways for antinocioception) receptors
- Ketamine inhibits neuronal sodium channels (producing a modest local anesthetic action) and calcium channels (causing cerebral vasodilation)
How does Ketamine produce “dissociative anesthesia”?
there is depression of neuronal function in association areas of the cerebral cortex and thalamus while stimulation of the hippocampus (limbic systems) producing a marked sensory loss and analgesia, as well as amnesia; basically you are getting the information to the thalamus, but you are not integrating the info appropriately! ie pt sees the light in the OR as falling bricks….
How is Ketamine metabolized?
Hepatic microsomal enzymes
- an important pathway in metabolism is demethylation of Ketamine by CYP450 enzymes to form NORKETAMINE. Norketamine is eventually hydroxylatedand then conjugated to form more water-soluble and inactive glucuronide metabolites that are excreted by the kidneys
- 1st pass effect!!
After IV administration of Ketamine, where do you see Ketamine being eliminated?
< 4% of a dose can be recovered from the urine unchanged
Fecal excretion accounts for < 5% of an injected dose
Why does Ketamine cross the BBB so rapidly (3)?
- has low-molecular weight
- a pKa near the physiologic pH, and
- relatively high lipid solubility
What is the onset of action of Ketamine?
30-60 seconds
When does the maximal effect of Ketamine occur?
within 1 minute of IV administration
What is the volume of distribution of Ketamine?
large distribution volume (3 L/kg) ; 2 compartment model-> high lipid solubility-> large Vd!
redistribution is a factor!!
What is the E 1/2 life of Ketamine?
2 - 3 hours
Is Ketamine protein bound?
approximately 12% protein bound
What is the major drawback to Ketamine administration?
Hallucination and
Emergence Delirium
What are the CNS side effects of Ketamine?
- Increased ICP and IOP
- increases CBF, CMRO2
- dose related depression of LOC
- Seizure like activity
- Nystagmus, pupil dilation
- SALIVATION, lacrimation
- Myoclonic activity
- SNS stimulation
- Emergence delirium
- Vivid dreaming
- Extracorporeal experiences
- Illusions
- Hallucinations
- Nightmares
What are the CV side effects of Ketamine?
- Direct Myocardial depressant but does cause intense SNS stimulation resulting in Tachycardia, HTN, Increased CO in those with normal catecholamine stores
- increases BP, HR, CO
- Inhibits reuptake of NE
- increases myocardial work and O2 consumption