SEE BASIC SCIENCES: PHARMACOLOGY REVIEW Flashcards
Rate of change proportional to amount of drug at any given time is PROPORTIONAL to the concentration present
FIRST-ORDER KINETIC
Constant amount of drug elimination over a specific amount of time
Zero order kinetic
A drug that undergoes first order kinetic: increase drugs concentration will
lead to a larger amount of drugs elimination
What are the determinants of drug tissue uptake?
Blood flow BBB Ionization lipid solubilty Protein binding
4 methods of Drug metabolism are
Oxidation
Reduction
Hydrolysis
Conjugation
3 methods prepare for the fourth one with drug metabolism
Oxidation, reduction and hydrolysis prepare for conjugation
Effect on MAC: GENDER
No change in MAC
Effect on MAC: woman with red hair
Increased MAC
Effect on MAC: Pregnancy
Decrease MAC
Effect on MAC: Chronic ETOH abuse
Increase MAC
Effect on MAC: BP means greater than 40mmHg
No change in MAC
Effect on MAC: Alpha 2 agonists
Decrease MAC
Effect on MAC: Hyperthermia
Increase MAC
Effect on MAC: Drugs that increase CNS catecholamines
Increase MAC
Effect on MAC: Lidocaine
Decrease MAC
Effect on MAC: Hypernatremia
Increase MAC
Effect on MAC: acute alcohol intoxification
Decrease MAC
When do pharmacokinetics interactions occur
When a drug alters the ADME of another drug
Drugs with identical mechanism lead to ____Effects
Additive (2 effects leads to a greater effect of the 2 drugs combined
Inducer of hepatic drug metabolism (RPP CSC)
Rifampin Phenytoin Phenobarbital Carbamazepine Smoking St John's Wort Barbiturates Tobacco
What is the alveolar anesthetic concentration that blunts ADRENERGIC RESPONSE to noxious stimuli in 50% of patients?
MAC-BAR
MAC BAR is the
MAC required to blunt adrenergic response in 50% patients
Goals of drug combination
Decrease toxicity
Increase and maintenance of efficacy
Most important organ for metabolism
Liver
Hepatic drug clearance depends on
Hepatic blood flow
Extent of binding of the drug to blood
intrinsic ability of the liver to Metabolize the drug
Vd: is greater with lipophillic or lipophobic?
lipophillic
Dose response curve can determine pharmacodynamics?
no
What does the dose response curve tell you?
Response observed to a quantity of a drug.
Which of the following requires energy provided by the hydrolysis of ATP ?
Active transport
What is the phase II reaction?
Drug molecules who underwent reduction , hydrolysis or oxidation are assimilated- CONJUGATED into compounds more readily removed from the body.
Occurence of plasma concentration of a drug exceeding the capacity of metabolizing enzymes
Zero order kinetics.
Prolonged exposure of receptors leads to
lower drug effect at the target site
Prolonged receptor inactivity results in production of a
Relative maximal or super-maximal effect at the receptor
Chronically denervated NMJ will _____the specific receptors in an attempt to produce a signal in the face of lower concentration of agonists
Up regulate
Drugs that are incapable of producing a MAXIMAL effect even at very high concentration are called?
Partial agonist (only a limited response)
During a constant infusion , plasma steady state drug concentration reaches 90%
3 half lives.
When a steady state is achieved then
The quantity of a drug administered is equal to the quantity of drug that is eliminated via metabolism
After 1 half-live, you have reached
50% of steady state
After 2 half-lives, you will have reached
75% of steady state,
After 3 half-lives you will have reached
87.5% of steady state.
The rule of thumb is that steady state will be achieved after
5 half-lives (97% of steady state achieved)
What % of IV -administered drug remains after 5 elimination half-times have passed ?
3%
How to calculate 5 half lives
50x50x50x50x50 = 312500000 x 100 = 3.125
100- 3.125= 96.
Why is IV loading dose used ?
To achieve effective target concentration (therapeutic plasma concentration) immediately
For anaphylaxis to occur what must have happened?
Prior exposure is needed for sensitization . UPon subsequent exposure, the IgE antibodies form during the initial exposure
Type I hypersensitivity reaction
Mediators release from mast cells and basophils after antigen binds to IgE antibodies on cell membrane
Type II hypersensitivity reaction (2 cells)
Antibody dependent, cell mediated cytotoxic hypersensitivity: IgG or IgM mediated
Type III hypersensitivity reaction
Circulating soluble antigens and antibodies bind to form iNSOLUBLE complexes that deposit in vasculature
Type IV hypersensitivity reaction I
interaction with sensitized cytotoxic ells.
DElayed hypersensitivity reaction
Anaphylaxis is what type of hypersensitivity reactions?
Type I
ABO incompatibility is what type of hypersensitivity reactions?
Type II
Serum sickness after SNAKE BITE what type of hypersensitivity reactions?
Type III
Contact dermatitis is what type of hypersensitivity reactions?
Type IV
Vasoactive mediators release during anaphylaxis are
HIstamine
Leukotrienes
Prostaglandins
Vasoactive mediator that releases endothelium derived factor Nitric oxide from vascular endothelium?
Histamine
All vasoactive mediators do what?
Increase capillary permeability
Vasoactive mediator that contracts vascular smooth muscle and airway
Histamine
Vasoactive mediator that cause intense bronchoconstriction
Leukotrienes
Vasoactive mediator that causes NEGATIVE INOTROPY
Leukotrienes
Vasoactive mediator that causes coronary artery vasoconstriction?
Leukotrienes
Vasoactive mediator that is synthesized after mast cell activation through Lipoxygenase pathway? (LL)
Leukotrienes
Vasoactive mediators that causes Pulmonary HTN and bronchospasm
Prostaglandins
Vasoactive mediator that is synthesized after mast cell activation through cyclooxygenase pathway?
Prostaglandins
What lab provides immediate proof of anaphylaxis?
Serum Tryptase level (within 60-120 mins)
Tryptase and anaphylaxis
Stored in mast cells, is an integral component, and released into the systemic circulation when anaphylaxis occurs but NOT DURING ANAPHYLACTOID
Primary treatment of anaphylaxis should include
Airway support
100% O2
stopping all drugs
IV fluids and EPINEPHRINE
Responsible for MOST INTRAOPERATIVE anaphylactic reactions?
Muscle relaxants (not ABT)
Patient with which allergies have a cross-sensitivity to LATEX (BAK)
Bananas
Avocados
Kiwis
Pharmacodynamic interaction is when the
Drug alters the sensitivity of a target receptor or tissue to the effects of a second drug. (differ from pharmacokinetics which is when one drugs alter ADME)
An example of Pharmacodynamic interaction?
Second gas effect
What is the second gas effect?
Administration of Nitrous along with VA results in an additive effect by both agents
Drug that activates or stimulates a receptor
Agonist
Absorption, distribution, metabolism and excretion of inhaled or injected drugs
pharmacokinetics
Responsiveness of receptors to drugs, and the mechanims by which drugs causes these effects to occur?
Pharmacodynamics
A drug that binds to receptors to prevent exogenous or endogenous substances from activating them
Antagonists
An effet produced by 2 drugs acting together that is greater than the effects that would occur with each drug alone
Synergistic
Calculation by which a dose of a drug is administred by IV and is divided by the plasma concentration to reflect the apparent volume of the drug into various intercellular compartments
Volume of distribution
Transmembrane protein macromolecule that acts as a mechanism for a drug to bind to and exert its effect?
Receptor
Reflect the concentration of an inhaled anesthetic measureed at 1 atm in the body to prevent skeletal muscel movement in response to a surgical incision
MAC
Difference in slope, efficacy and individual responses, depics the relationship between the dose of a drug administered or plasma concentration, and the resulting pharmacological effect
Dose-response curve
Enantiomers are
Chemical substance of exact but opposite shape, mirror images of each other
When 2 enantiomers are present in 50:50 portion, subtances are known as
Racemic mixtures
Define competitive antagonism
Competitive antagonism is based on the principle that an agonist or antagonist can bind to the same recognition site(s) on the receptor, and when both agonist and antagonist are present concomitantly, they can compete for such sites. Increasing concentration of an antagonist drugs (such as NDNMB, progressively inhibit the responses to an unchanging concentration of an agonists
Simple competitive antagonism definition?
increase in the available concentration of an agonist cannot overcome the effect produced by the antagonist.
A drug that activates a receptor by binding to it
Agonist
Define Non-competitive antagonism?
After administration of an antagonist, even high concentrations of an agonists cannot completely overcome the antagonism
A drug that binds to the receptor without activating the receptor and at the same time prevents an agonist from stimulating the receptor
Antagonist
What does HOFFMAIN ELIMINATION rely on to degrade CISATRACURIUM?
Normal body temperature
pH
What is therapeutic Index?
relates the dose of a drug required to produce a desired effect to the dose that produces an undesired effect.
Formula for Therapeutic Index?
LD 50/ ED 50
Where are the hepatic microsomal enzymes that participates in metabolism of many drugs found? (GHAK)
GI tract
Hepatic smooth ER
Adrenal cortex
Kidneys
How many half lives to eliminate 97 % of the drugs?
5
CYP 450 3 A4 composes what % of CYP 450 activity?
40-45
Responsible for the largest portion of drug metabolism in the body?
CYP 450
Name ending “tron” associated with
Serotonin blockers
Serotonin blocking drugs act on the
5HT3 receptor
Name 3 serotonin blockers
ondansetron
dolesetron
granisetron
Name ending “pril” associated with
ACEI
Name ending “dipine” associated with
CCB exception verapamil, cardizem
Name ending “tidine” associated with
H2 receptors blockers (antagonists)
Phase I reactions are (everything except conjugation)
Methylation Oxidation Reduction Dealkylation Deamination
What is the significance of phase II reactions?
Compound can be readily eliminated from the body
Phase II reaction involves conjugation of the drug with
Glucuronide
Sulfate
Taurine
Glycine
Is phase II always required to complete drug metabolism ?
NO
Does phase II always follow phase I
NO
Physiological stimuli responsible for stimulating the release of ADH include?
Stress and anxiety
Hyperthermia
Presence of histamine-releasing stimulus
Pharmacological stimuli that stimulates the release of ADH
PPV of the lungs
Beta adrenergic stimulation
ADH secreted by
Posterior pituitary
Increased serum osmolarity indicates
Insufficient water content (dehydration)
What is the target site for ADH ?
Collecting tubules of the kidney
Primary goal of ADH is to prevent
water loss thereby decrease serum osmolarity and increasing circulating volume.
To minimize risk of Compound A production during SEVOFLURANE administration which of the following actions may be taken?
Run lower levels of sevoflurane
Use hydrated soda lime absorbent
Maintain gas flows equal to or greater than 2L/min
What are the factors that increase the risk of compound A formation ?
Low gas flow states
Increased levels of sevoflurane
Dry or warm CO2 absorbents
Which inhaled anesthetic is associated with the greatest production of heat in dessicated Co2 absorbent? how?
Sevoflurane; loss of moisture into the CO2 absorbent, facilitates an exothermic reaction between sevo and the absorbent. CAN lead to fire in the circuit
Which of the inhaled anesthetic is associated with the highest production of CO in dessicated CO2 absorbent?
Desflurane; Results in the production of the greatest amount of CO
Does higher doses of opioid decrease the MAC requirements of VA?
NO. MAC of VA is influenced to only a small degree so even higher amount of opiods analgesics won’t affect MAC
VP of desflurane is (high/low)
High
Halogenated anesthetics least metabolized?
Desflurane
The speed of an inhaled anesthetic action is determined by its solubility and expressed as which of the following?
Blood:gas solubility coefficient
The speed with which a volatile anesthetic vapor enters the pulmonary circulation is represented by the
Blood: gas solubility coefficient
Which of the following are the 2 main organs involved with volatile agent metabolism?
Lung
Liver
The main elimination of volatile anesthetics via the
lung on exhalation
Responsible for a small amount of VA metabolism
Cytochrome isoenzymes
Vapor pressure refers to
Pressure of the vapor resulting from vaporization . Pressure at which molecules of a volatile liquid escape the liquid phase.
What are the 2 most soluble volatile anesthetics
Isoflurane
Halothane
Rate of uptake is dependent on
1) alveolar ventilation rate 2) partial pressure of gas (concentration effect) 3) breathing system