Pharmacodynamics/kinetics (Test 1) Flashcards
What are receptors?
Usually proteins
How are receptors activated?
Conformational shape changes (bound vs unbound)
Thermodynamically more/less active
How do receptors relate to the drug effect?
Drug effect depends on the number of receptors bound
greatest effect all receptors are bound
If you give a full weight based dose of a paralytic how many receptors are bound?
Should attach to many receptors and produce its full effect
What is an agonist?
Activates receptor by binding to receptor
How do agonists undergo binding to receptors?
Ion (or electrocovalent): oppositely charged ions–electron transfer
Hydrogen: binds to electronegative atom
Van der Waals interaction: weal fluctuating bonds
What bonds are not reversible?
Covalent–electrons are shared
What is an antagonist?
Binds to a receptor but does not activate the receptor
They “get in the way” of the agonist
Which bonds between receptor and antagonist and reversible?
Ion
Hydrogen
Van Der Waals
What is competitive antagonism?
Increasing amounts progressively inhibit the agonist
Shifts dose response curves to the right
What is non-competitive antagonism?
Even high concentrations of agonist cannot cause the agonist effect
Partial Agonist:
Binding to a receptor (usually at agonist site)
causes less response than the agonist even at supramaximal doses
Inverse Agonist:
Compete for the same site as the agonist but produce the opposite effect
Were categorized as antagonists
Lower constitutive activity below baseline
What are examples of inverse agonists?
Propranolol
Metoprolol
Cetirizine
Loratadine
Prazosin
Naloxone
What causes changes in receptor numbers in the body?
Numbers of receptors are not static
Can increase and decrease depending on comorbidity, drug therapy,
Can be up-regulated until tired of being used
What happens to receptors that are up-regualted?
Receptors become less responsive= tolerance/ tachyphylaxis
What are examples of common drugs/ conditions that develop receptor tolerance?
1) Albuterol–down-regulation of receptors due to repetition (less effective each time its used consecutively)
2) Ephedrine–mixed beta agonist develops tolerance very quickly
3) Pheochromocytoma–decreased B receptors in response to catecholamines
How are receptors classified?
Classified by location
What are common locations for receptors?
Lipid Bilayer
Intracellular proteins
Circulating proteins
Where are receptors located that are common for anesthesia drugs?
Lipid bilayer: membrane bound
opioids, beta blockers, BZD, catecholamines, NMBD
What are some drugs that have intracellular receptors?
insulin, steroids, milrinone
What are some drugs that have circulating protein receptors?
Anticoagulants (warfarin)
Pharmacokinetics:
What the body does teh the drug
ADME
Determines the concentration of the drug in the plasma and at effector site
How was the 1st compartment model of absorption described?
Drug is injected and concentration of drug is diluted by plasma (Small volume of distribution)
Central compartment (distribution):
Then drug goes through vessel rich groups
Then blood absorbs into muscle then fat