Flashcards in 3/15 pharm Deck (111)
Clearance can be impaired w/defects in which systems?
cardiac, renal, hepatic.
Cl = (rate of elim of drug)/(plasma drug conc.)
Cl = (Vd)*(Ke)
Cl = (Q)*(Er)
Q = flow to that organ (ie. liver)
Er = extraction ratio
Loading dose = (Cp)(Vd) / (F)
Cp = target plasma concentration at steady state
F = bioavailability
Maintenance dose (MD)
MD = (Cp)(Cl)(t) / F
t = dosage interval (time between doses), if not administered continuously.
*If continuous, leave t out. You will also know its IV so F = 1. B/c only IV is continuous.
In liver or renal disease, does maintenance dose inc. or dec.?
-less being cleared, so less dose needed.
Which drugs follow zero-order elimination?
-Phenytoin, Ethanol, and Aspirin (at high or toxic concentrations).
-PEA. (A pea is round, shaped like the “0” in
-0 or 1st order?
0 order elim.
-0 or 1st order?
1st order elim.
Phase I drug metabolism
-Reduction, oxidation, hydrolysis.
Phase II drug metabolism
Conjugation (Glucuronidation, Acetylation, Sulfation)
Which is most common P450 enzyme?
CYP3A4 = most common
Name 3 drugs that might cause trouble in a slow acetylator.
-which would also have a bimodal pop. distribution.
-hydralazine, isoniazid, procainamade
*HIP: its not hip to be a slow acetylator.
What kind of antagonist is ketamine?
-ketamine (noncompetitive antagonist) on NMDA receptors.
TI = Toxic dose/Effective dose
*high therapeutic index is good b/c that means theres a big difference btwn toxic and effective doses.
Whats good, a high or low therapeutic index?
-Safer drugs have higher TI values.
Is the therapeutic index the same as therapeutic window?
No, b/c the therapeutic window would never extend all the way until the toxic dose.
Some receptors that respond to autonomic neurotrasmitters/drugs receive NO nerve innervation (must get ligand through blood).
-can you name these uninnervated autonomic receptors?
-muscarinic receptors on endothelium of blood vessels
-adrenoreceptors on apocrine sweat glands
-alpha-2 and beta adrenoreceptors in blood vessels.
para/pre, sym/pre: all release what?
All ganglia have what type of receptor?
Nicotinic: ligand-gated ion channels.
Do all sym/post release NE?
-adrenal medulla releases NE and epi.
-sym/post release ACh that innervate sweat glands & piloerector muscles. These = sympathetic cholinergic.
sym/post that releases ACh
-innervate sweat glands & piloerector muscles.
All glands have what receptors on them?
-even sweat glands that have sym/post innervation: these sym/posts dump ACh, not NE (sympathetic cholinergic).
adrenal medulla & sweat glands = part of sym nervous system but are innervated by _______ fibers.
Nicotinic ACh receptors
-what type of receptor is it?
-ligand-gated Na/K channels.
which receptors are more sensitive to activation, alpha or beta?
Epi: acting more on alpha1 or beta2?
-low dose =
-high dose =
-low dose - acts more on beta-2
-high dose - acts more on alpha-1
*remember, beta-receptors are more sensitive.
Ciliary muscle innervation:
-its NOT dual innervated.
*if there is an effect on accomodation, its a muscarinic (agonist or antagonist) drug
Cycloplega = what is it, what can cause it?
paralysis of ciliary muscles = M-antagonist
Gs => inc. cAMP => PKA => phosphorylates MLC kinase.
-whats the result?
smooth muscle relaxation
-hence beta-2 (Gs) causing smooth muscle relaxation in lungs.