pharm basics Flashcards
volume of distribution
Vd = amt drug in body (IV) / plasma drug concentration
clearance
CL = 0.7 x Vd / T1/2
loading dose
LD = Css x Vd
maintenance dose
MD = Css x CL
zero order elimination
constant amt drug eliminated
concentration decreases linearly
capacity limited
phenytoin, ethanol, ASA (high doses)
first order elimination
rate directly proportional to drug concentration
constant fraction eliminated
decreases exponentially
flow dependent
phase 1 metabolism
reduction, oxidation, hydrolysis
cyt P450
–> slightly polar, water soluble, still active
phase 2 metabolism
conjugation - glucuronidation, sulfation, acetylation
–> very polar, inactive
therapeutic index
TI = TD50/ED50
higher TI = safer
wide therapeutic window = large gap btwn ED & TD :)
a1 Rc
Gq
VSM contraction
pupillary dilator m contraction (mydriasis)
intestinal & bladder sphincter m contraction
a2 Rc
Gi
dec. SNS outflow
dec. insulin release
dec. lipolysis
inc. platelet aggregation
dec. aqueous humor production
B1 Rc
Gs
HR
contractility
renin release
lipolysis
B2 Rc
Gs
vasodilation bronchodilation lipolysis insulin release dec. uterine tone (tocolysis) ciliary m relxation inc. aqueous humor production
M1 Rc
Gq
CNS, enteric NS
M2 Rc
Gi
dec. HR
dec. contractility
M3 Rc
Gq
exocrine gland secretions gut peristalsis bladder contraction bronchoconstriction pupillary sphincter m contraction (miosis) ciliary m contraction (accommodation)
D1 Rc
Gs
relaxes renal VSM
D2 Rc
Gi
modulates transmitter release, esp in brain
H1 Rc
Gq
nasal & bronchial mucus production vascular permeability contraction of bronchioles pruritus pain
H2 Rc
Gs
gastric acid secretion
V1 Rc
Gq
VSM contraction
V2 Rc
Gs
H20 permeability & resorption in CT of kideny
