IV Anesthetics Flashcards
What is the triad of general anesthesia?
1) Need for unconsciousness (Hypnosis)
2) Need for analgesia
3) Need for amnesia
What is anesthesia?
The abolition of all sensation
What is analgesia?
The abolition of pain sensation
What are pharmacokinetics?
How the body processes the drugs
What are pharmacodynamics?
How a drug causes physiological and pharmacological reactions within the body
What are the key components of pharmacokinetics?
1) Administration (absorption)
2) Distribution
3) Drug metabolism
4) Drug excretion
What are the key components of pharmacodynamics?
Reponses on receptors at the cellular level
Which route of administration requires higher doses? Why?
Enteric administration; because of first pass metabolism
What is free fraction and protein binding?
Drugs bound to drugs = therapeutically inactive
Drugs not bound to drugs (free drugs) = therapeutically active
What is vd?
Total dose of drug given divided by plasma concentration
What is drug redistribution?
Some drugs will quickly distribute into certain parts of the body (brain and heart) and slowly into adipose tissue. Once more and more distribution occur into adipose tissue however, equilibrium will force them out of brain and heart, leading to less therapeutic effect.
What are high perfusion (vessel-rich) organs? Give examples.
Organs takes up disproportionately large amount of the drug; the brain
What are some examples of low perfusion organs?
1) Muscles
2) Fat
3) Vessel-poor groups
What is responsible for termination of effect of many anesthetic drugs?
The redistribution from the vessel-rich group to the vessel-poor group
Most drug excretion occurs through which organs?
1) Liver
2) Kidneys
3) Lungs
What is zero-order kinetics?
When drugs are metabolized at a fixed rate, regardless of concentration
What is first-order kinetics?
When rate of drug metabolism is proportional to concentration
What is potency?
The dose of the drug required to achieve a therapeutic effect
What is efficacy?
The maximum effect achievable with the drug
When does drug toxicity occur?
When undesirable side- effects of its administration occur
What is the therapeutic index?
The ratio of the dose producing a toxic effect to that producing a therapeutic effect
What are the most commonly used IV anesthetics?
1) Propofol
2) Etomidate
3) Ketamine
4) Thiopental (Barbiturate)
What is the mode of action of IV anesthetics?
Either
1) Stimulates inhibitory neurons
or
2) Inhibits excitatory neurons
What is the primary mechanism for most IV anesthetics?
Potentiation of GABA receptors = Increased chloride conductance across membrane and into postsynaptic neuron = hyperpolarization = inhibits neuronal signaling = a sedative and hypnotic effect
What is GABA?
The primary inhibitory neurotransmitter in the CNS
What is the primary mechanism of Ketamine?
Inhibits NMDA receptor
What is the primary mechanism of Dexmedetomidine?
Alpha-2-receptor activation
