Anesthesia Pharm Flashcards
Pharmacodynamics
The study of the intrinsic sensitivity or responsiveness of receptors to a drug and the mechanisms by which these effects occur.
Pharmacokinetics
The quantitative study of the absorption, distribution, metabolism, and excretion of injected and inhaled drugs and their metabolites.
Tachyphylaxis
Tolerance that develops acutely within only a few doses of a drug.
The most important factor in the development of tolerance to drugs is the neuronal adaptation, referred to as (1) cellular tolerance.
Other mechanisms of tolerance may include (2) enzyme induction and (3) depletion of neurotransmitters caused by sustained stimulation.
Synergistic Effect
Two drugs interact to produce an effect greater than the algebraic summation
VRG
Vessel rich group 75% of Cardiac Output; Heart = 5% Brain = 10% Lungs = 15% Kidneys = 20% Liver = 25%
Vessel Poor Group
Muscle = 19% Fat = 6% Bone/cart/lig = <1%
Synonyms for Nonionized
Non polar, lipid soluble, hydrophobic, lipophilic; ACIDS
Active drugs.
Synonyms for Ionized
Non lipid soluble, Polar, hydrophilic, lipophobic; BASES
Facilitates excretion from renal tubules.
Henderson-Hasselbalch Equation
Relationship between the pKa of the drug and pH of the solution
Acid
Proton donor
Base
Proton acceptor
What does it mean if pH=pKa?
It means 50% of drug is ionized and 50% is unionized.
What do weak acids form from?
Weak acids form from salts with positive ions. Na+, K+, Ca2+, Mg2+
Weak acids: pKa>pH
then >50% nonionized, acid (lipophilic) Propofol
Weak base: pKa>pH
then >50% ionized, base (lipophobic)
What do weak bases form from?
Name some drugs.
Weak bases form from negative ions. Cl-, SO4-, PO4-
Local anesthetics, opioids, benzos, etomidate, ketamine
Clearance
Volume of plasma cleared of drug by renal excretion and or metabolism in the liver or other organs.
Hofmann Elimination
Clearance influenced by temp and pH. Temp/pH increases, so does elimination.
Atracurium & Cisatracurium
Ester Hydrolysis
Non organ Clearance of Succs and mivacurium
Zero-order kinetics
Constant amount of drug clearance per unit time. R/t concentration of drug exceeding available enzyme.
Straight line. Phase 2 (Conjugation).
Ex: EtOH, ASA, tylenol, Dilantin
Clearance Time Constants
Half-Life