NUNA1 Pharm Exam 1 Intro & IV Induction drugs

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The study of drugs; observable interaction between drug and body constituent; includes how the drug is transformed by body tissues

Pharmacology

A more precise description of the fundamental action of a drug on a physiological, biochemical, or molecular level

Pharmacodynamics

Drug concentrations in body fluids and tissues that influence how those concentrations vary with time

Pharmacokinetics

Specific macromolecule, peptide, protein, organ, cell type, enzyme, membrane component, nucleic acid, etc. where the initial molecular event occurs with the drug, leading to the therapeutic response

Drug receptor

Field of pharmacology that examines relationship of genetic factors to variations in drug response

Pharmacogenetics

Study of effects, antidotes, and detection of poisons and descriptions of effects of drug overdoses

Toxicology

A drug that binds to the same site as the endogenous ligand and produces same signal

Agonist

A drug that binds to the side used by the endogenous ligand and acts competitively to diminish or block the signal produced by the endogenous ligand

Antagonist

Which route of medication administration goes right to distribution?

Parenteral

Two types of absorption

enteral (GI tract) and parenteral

What is the major determinate of how much drug reaches the site of action?

Blood flow (part of distribution)(no blood flow to area equals no drug flow to area)

Three routes of elimination

Kidney, liver and respiratory (in that order)

A. D. M. E. ("Mantra" for how we look at drugs)

Absorption, Distribution, Metabolism and Elimination

Alpha distribution

First phase of distribution (initial crossing of blood brain barrier)

The majority of drugs are metabolized in the _______?

Liver (liver adds charges to the cell so they are more hydrophilic)

Drugs must be ______philic /______ soluble to cross blood brain barrier.

lipophilic / lipid

Once a drug has a ionic charge is can be excreted by the ______.

kidney

Once a drug has an ionic charge is becomes ______philic.

hydrophilic

What is ester hydrolysis?

So far he has said the breakdown of a medication before it goes through the liver. The medication structure is such that it is broken down before hepatic circulation. Very short acting drugs. Utilizes esters to break down meds.

What is GABA type A?

A ligand-gated ion channel that inhibits neurotransmission in inhibitory effect on neurotransmission by diminishing the chance of a successful action potential occurring. Thus is we give a GABA type A drug people go to sleep

What is the relationship between GABA A and NMDA (n-methyl-D-asparate)?

Stimulation of GABA A will put someone to sleep while stimulation of NMDA will excite and arouse the patient. Blockage of GABA A will make the patient awake and blockage of NMDA will pt the pt to sleep.

What is the ligand-gated ion channel neurotransmitter that inhibits pain response.

Glycine

True or false
NMDA play a role is pain response.

TRUE

If medication increase glycine activity you should expect a(n) (increase/decrease) in pain.

Decrease

GABA A and Glycine allow what electrolyte to enter the cell thus decreasing the action potential of the cell?

Chloride

Glycine receptors are abundant in _______ and _________.

Spinal cord and brainstem

GABA A receptors are found in ________ regions.

Higher brain regions.

Barbiturates activate the _______ receptors. (6 of them, but 1 important one)

GABA A(the important one), AMPA, kainate glutamate, adenosine, neuronal nicotinic acetylcholine receptors.

Do barbiturates have activity at glycine or NMDA receptors?

No

True or False
Barbiturates enhance and directly activate GABA A receptors.

TRUE

Etomidate is a selective ________modulator.

GABA A

Propofol is a GABA A receptor ________ (agonist/antagonist)?

Agonist (does not need GABA to work)

Propofol is an weak ________.

analgesic

Propofol also inhibits __________ which will inhibit blood pressure and heart rate.

Neuronal acetylcholine.

Ketamine provides "__________ anesthesia".

"dissociative anesthesia"

What drug provides sedation, immobility, amnesia, marked analgesia and dissociation from environment all without true unconsciousness.

Ketamine

30% of adults have _________ as an adverse reaction to ketamine.

Hallucinations.

On what receptor and how does ketamine work?

inhibition (blocks) on NMDA receptors and does not affect GABA A.

4 types of barbiturates

Oxybarbiturates, thiobarbiturates, methylbarbiturates and methlthiobarbiturates

Pale yellow powder with poor water solubility; dissolves in alkaline solution of sodium carbonate with resultant pH of 10.5

Thiopental

Which barbiturate has delayed onset and prolonged duration of action?

Oxybarbiturates

Which barbiturate has a rapid onset?

Thiopental

Another name for methylbarbiturates (methohexital)

Brevital

Thiopental characteristics of absorption

rapid onset
related to rapid uptake across BBB
highly lipid soluble

Disadvantages of thiopental

extremely caustic if infiltrated (thrombophlebitis)
not compatible with other IVFs
minimal increase in sensitivity to somatic pain

Advantages of thiopental

minimal cardiovascular depression
cerebral protection during ischemic episodes

Dosing of thiopental

induction → 3-5 mg/kg (gives you 15-20 min)
peds → 2-7 mg/kg
anticonvulsant → 1.5-3 mg/kg PRN or 3-10 mg/kg/hr (cont infusion)

Emergence and metabolism of thiopental

"Emergence
t ½ alpha → 2-7 minutes
*Metabolism
liver
decline in blood/brain concentration due to redistribution

Indications of thiopental

induction of anesthesia
maintenance of anesthesia (intermittent bolus or infusion)
anticonvulsant
sedation & control of ICP

Advantages of Methylhexital over thiopental

Better kinetic profile for both induction and maintenance of anesthesia when compared to thiopental

Disadvantages of methylhexital (brevital)

excitatory movements
depresses both BP and CO
pain on injection
lowers seizure threshold
opiate + N2O + methohexital
severe respiratory depression

What is porphyria?

"A blood disorder where they produce to much heme, thus we give them heme to stop the production. (Remember that p450 is cytochrome p450 - it uses a heme molecule in the active site for electron transfer. More demand for cytochrome
more demand for heme; in someone with porphyria, that means more buildup of substrates from behind the messed-up link in the pathway...)

Contraindications of barbiturates

porphyria
proven allergy to barbiturates
airway obstruction (or potential)
hx of epilepsy (methylhexital is proconvulsive)

Precautions with barbiturates

hypovolemia
CV collapse
severe uremia
severe asthma
severe cardiac disease

Is methylhexital cardiac stable when given as an induction dose?

Yes, infusion depresses both blood pressure and cardiac output

Physical characteristics of etomidate

unstable in water
soluble in propylene glycol or as emulsion pH 8.1
pKa 4.2
99% unionized in blood
75% protein binding

Metabolism of etomidate

liver
plasma
ester hydrolysis

Excretion of etomidate

>2% unchanged in urine

Dosing of etomidate

induction→ 0.3 mg/kg
elderly→ 0.15-0.2 mg/kg
peds→ up to 0.4 mg/kg

Advantages of etomidate

cardiostability
reduction of cerebral blood flow/metabolic rate and ICP
no histamine release (low allergy prevalence)
minimal respiratory depression
ideal for decreased cardiac fxn or hypovolemia

Disadvantages of etomidate

nausea/vomiting
pain on injection/thrombophlebitis
excitatory movements/myoclonia
reversible inhibition of adrenal steroidogenesis

Contraindications of etomidate

porphyria
adrenal insufficiency (Addisons Disease)
known sensitivity

Dose of etomidate old, normal pediatric

0.2 mg/kg, 0.3 mg/kg, 0.4mg/kg

What is propofol pH, pKa and lipid solubility?

pH 7.4, pKa 11.0 and 96% lipid soluble

What makes up propofol emulsion?

soy bean oil and egg phosphatide

Where is propofol metabolized?

Liver (by the P450/P2C9 enzymes)

What has a faster time to recovery propofol or thiopental?

propofol

Propofol has a smooth induction, but a delayed in what?

eye closing (better endpoint for induction is loss of verbal contact)

Induction dose of propofol

2mg/kg (give 0.5mg to 1mg/kg and see how it goes)

How does propofol make a patient hypotensive?

Decreases SVR, blunts baroreflex in heart and blunts sympathetic response thus no compensatory mechanism is in place

What induction drug decreases hepatic blood flow thus decreasing clearance in other drugs?

propofol

What does propofol do to ventilatory effect?

decrease TV and MV, episodes of apnea and decreased accessory muscle use

What non-hypnotic effects does propofol have?

Antiemetic effects and antipruretic effects {opioids induced itching}

What effect does propofol have on central nervous system?

Decreased cerebral blood flow, ICP {cerebral protection controversial} and EEG {way to sleep for protection}

Cardiorepiratory effects of propofol

Rare cases of bradycardia, sinus arrest, heart blocks and aystole when used with other vagotonic drugs

Drawbacks of using propofol

Burns IV site, hypotension, bradycardia, apnea and epileptiform movements, ALLERGIC REACTION, emulsion bacteria breading ground

What is PRIS?

Propofol Infusion Syndrome
Cardiac failure{bradyarrhythmias}, rhabdomyolysis, metabolic acidosis and renal failure

Risk factors of PRIS?

Severe TBI, severe sepsis, prolonged infusion time and doses > 5mg/kg/hr (83mcg/kg/min)

Infusion dose of propofol

65-200mcg/kg/min {should not be used in patients <17 y/o for ICU sedation}

Absolute contraindications for propofol

Hypersensitive to propofol or related compounds {soy products, egg products and sulfite compounds} or disorders of fat metabolism

Fospropofol sucks why?

long on time and long off time, not only that but they get the paresthesias {aka burning bush syndrome}

What is the mechanism of action of ketamine?

antagonist of NMDA

Which drug is water soluble; propofol, thiopental or ketamine?

ketamine

Ketamine pH, pKa an how much is protein binding?

5.6 pH, 7.5 pKa and 12-35% protein binding

What metabolizes ketamine?

Liver (by the P450 enzyme) and has a metabolite norketamine that has a 30% potency of parent compound

What eliminates ketamine?

kidney

What are the 4 uses of ketamine?

induction of anesthesia
maintenance of anesthesia
sedation as a continuous infusion
analgesia as a continuous infusion

Ketamine dosages; induction, maintenance and analgesia

Induction 2mg/kg IV or 10 mg/kg IM
Maintenance 10-45 mcg/min infusion
Analgesia bolus of 0.1-0.25 mg IV followed by 0.2-1 mg/kg/hr

Drawbacks of using ketamine

30% emergence reactions
Elevations of HR, BP and ICP {no not give to head injury patients}
Caution in patients with poor cardiac reserve
Excessive salivation {glycopyrrolate may be given}

Absolute contraindications for ketamine

Elevated ICP or intraocular pressure
severe cardiac disease
psychotic disorders

What is the allergic reaction rate for the induction cocktail/

1/5,000 to 1/20,000 {most common with propofol and barbiturates}

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