General Principals Flashcards
Only the _____ form of a drug crosses biomembranes.
Non-ionized (uncharged)
Ionized = water soluble; Non-ionized = Lipid soluble
4 Drugs that are weak acids
Aspirin;
Penicillins
Cephalasporins;
Loop + Thiazide diuretics
4 Drugs that are weak bases
Morphine;
Local Anesthetics;
Amphetamines;
PCP
3 Ways to acidify the urine and thus increase renal clearance of weak bases
NH4Cl;
Vitamin C;
Cranberry Juice
2 ways to Alkalinize the urine and thus increase renal clearance of weak acids
NaHCO3;
Acetazolamide
Fastest Route of absorbtion?
Inhalation
Smallest drug known?
Lithium
Modification of the drug molecule via oxidation, reduction, or hydrolysis.
Phase I Biotransformation
Conjugation with Endogenous compounds via the activity of Transferases
Phase II Biotransformation
When/why do you see Grey Baby Syndrome
With Chloramphenical - due to low levels of Glucuronosyl transferase in neonates (a Phase II biotransformation reaction)
When/Why do you get Drug-induced SLE (Recall - a + anti-histone antibodies)
With slow acetyaltors (Phase II Biotransformation) with Hydralazine > Procainamide > isoniazid
Saturation. A CONSTANT amount of drug is eliminated per unit time. No fixed half-life.
Zero-order kinetics
Drugs with zero-order elimination (3)
” 0 PEAs for me” Ethanol, Phenytoin, salicylates (ASA)
A constant FRACTION of the drug is eliminated per unit time. half-life is constant
First-order kinetics
What is used to estimate GFR b/c its not reabsorbed or secreted
Inulin (120 mL/min = nml)
Time it takes to reach 95% of steady state
4-5 * Half-life
(equation): Loading dose =
LD = Cp * Vd
(equation) MD =
( [Plasma] @ SS * CL * T1/2) / f
(Equation) Half-life =
T(0.5) = Vd/Cl
How well a drug and a receptor recognize each other. inversely related to the Kd of the drug
Affinity
The quantity of drug required to achieve a desired effect
Potency
The maximal effect an agonist can achieve at the highest practical concentration
Efficacy
____ Antagonists decrease affinity but not Vmax
Competitive
_____ Antagonists decrease Vmax but do not change affinity
Noncompetitive
Steroids, thyroid hormones, gonadal steroids and vitamin D all use what type of receptors
Intracellular
MOA of NO
activates guanylyl cyclase thus increasing cGMP in smooth muscle (which dephosphorylates myosin light chains - preventing interaction with actin and thus cause vasodilation)
