Pharm Flashcards
Effect of epinephrine at low and high dose
a-1, B1, B2
Low dose: Beta-2 vasodilation stronger (decrease DBP blood pressure)
High dose: alpha-1 constriction stronger (increase DBP blood pressure)
To prevent the low dose effects of epinephrine (lowered BP), what can you do?
Administer a beta blocker so everything goes to alpha constriction instead of Beta 1 (tachycardia) and beta 2 (vasodilation)
Succinylcholine side effects
- hyperkalemia (arrhythmia)
- malignant hyperthermia with halothane
- bradycardia
Who is predisposed to succinylcholine toxicity of hyperK
pts with burns/myopathies, anything that would cause cell lysis
–Also pts with denervating dzs (quadriplegics)
Baclofen
GABAb muscle relaxant
Dantrolene
Acts on ryanodine receptors, preventing release of calcium
–good for malignant hyperthermia
atracurium side effects
histamine release causing flushing, bronchoconstriction, hypotension.
-Seizures
If you’re worried about hyperkalemia when giving succinylcholine what is a good alt med
vecuronium/rocuronium these are non-depolarizing AchR blockers
affinity of enzyme for substrate
=1/Km
Vmax is proportional to
enzyme concentration
Michaelis-mentin kinetics means
enzyme rxn follows a hyperbolic curve
Which types of drugs are metabolized by the liver?
lipophilic drugs
–can be metabolized and excreted in bile/liver
Bioavailability of the drug is calculated through
Area under the curve, comparing oral with IV
Side effect of nitroglycerin
headaches and facial flushing from vasodilation of skin and meninges
Metformin is contraindicated in patients with
renal failure. Because lactic acid accumulates. In reality, metformin is contraindicated in anyone who might have lactic acidosis (alcoholic, septic, CHF)
which drugs require routine thyroid testing
lithium and amiodarone
Scopolamine mech
selective muscarinic ACh antagonist that reduces the effect of the cholinesterase inhibitor
Pilocarpine mech
muscarinic agonist
Efficacy:
Intrinsic ability of a drug to have a desired outcome, expressed by MAXIMUM activity Emax
Potency
Dose of a drug required to produce a given effect. Determined by AFFINITY (1/Km) and the AMOUNT of drug able to reach target.
Ed50
Lower the Ed50, high potency
–Dose of drug required to produce half of the full response
Phenylephrine
An alpha agonist. Vasopressor used for shock
Prazosin
Selective alpha-1 BLOCKER for HTN and benign prostatic hyperplasia. Thus, a vasodilator
Dobutamine
Major B1, some B2 and A1
- Increased contractility
- Small increase in HR
Side effect of dobutamine
Increased cardiac conduction velocity=arrhythmias
- -Also, increases myocardial oxygen consumption (higher heart rate and contractility)
- -Nitrates increase heart rate, but also decreases preload, reducing myo o2 consumption
Competitive inhibitor effect on Km
Increased
noncompetitive inhibitor effect on Km
none
which type of inhibitor will decrease potency?
competitive inhibitor
which type of inhibitor will affect efficacy?
noncompetitive inhibitor
Calculate volume of distribution
amount of drug/plasma drug concentration
t1/2 life
=0.7*Vd/CL
which type of drugs stay in the blood
large, charge molecules
which drugs go to ECF
small hydrophilic molecules
which drugs go to all tissues
small lipophilic molecules
clearance equation
VdxKe
Loading dose
Cp x Vd/F
Maintenance dose
Cp x CL/F
Which drugs have zero order elimination?
phenytoin
ethanol
aspirin
Pt overdoses with weak acid what do you do?
Give bicarb–charges molecule for elimination
Pt overdoses with weak base. What do you do?
Give ammonium chloride acid NH4Cl–Charges molecule for elimination
example of weak acid drugs
aspirin
phenobarbital
methotrexate
example of weak base drug
amphetamines
Phase I metabolism
reduction, oxidation, hydrolysis with cytochrome P-450. Makes drug more polar but still active
Phase II metabolism
glucuronidation, acetylation, sulfation
–makes polar and inactive metabolites
slow acetylators
slow metabolizers of drug. increase risk of side effects
First order elimination
constant fraction of drug is excreted
Therapeutic index
LD50/ED50
Partial agonist effect
decrease efficacy,
effect on potency is variable
therapeutic window is the range btw
minimum effective to minimum toxic dose
Sympathetic sweat glands innervated by
AchM
Sympathetic renal vasculature innervated by
D/D1
Adrenal medulla innervated by
Nicotinic Ach receptor. Does NOT go through the sympathetic chain!
Nicotinic ACh receptors are what type of receptors?
Ligand-gated Na/K channels
Nn vs Nm receptors?
Nn are nicotinic receptors found in autonomic ganglia Nm are found in neuromuscular junctions
What type of receptors are muscarinics?
G protein receptors with 2nd messengers
m1
CNS and enteric nervous system
m2
decrease heart rate/contractility
M3
increase exocrine secretions, peristalsis bladder contraction bronchoconstriction ciliary muscle contraction pupillary sphincter contraction
alpha 1
vascular contraction
dilation pupillary dilator
intestinal/bladder sphincter contraction
alpha2
- CNS mediated decrease in blood pressure
- Decrease aqueous humor fluid production
- inhibition of lipolysis
- inhibition of adrenergic and cholinergic release
- increased platelet aggregation
beta 1
causes renin release
beta 2
vasodilation bronchodilation increased heart rate/contractility ciliary muscle relaxation aqueous humor production decreased uterine tone
D1 receptor
relaxes renal vascular smooth muscle
D2 receptor
brain transmitter
H1
bronchial mucus
contraction of bronchioles
pruritis
H2
gastric acid secretion
Vasopressin1
vascular smooth muscle contraction
vasopressin2
Increased permeability in collecting tubules
Gprotein class of D1, D2
s
i
Gprotein class of H1, H2
q
s
Gprotein class of V1, V2
q
s
Which receptors work through Gq?
HAVe 1M&M H1 A1 V1 M1 M3
which receptors work through Gi?
M2
A2
D2
Describe the Gq pathway
Phospholipase C activated
- converts lipids to PIP2
- PIP2–>DAG and IP3
- IP3 increases [Ca]in
- DAG activates protein kinase C
Describe the Gs pathway
Activation of adenylyl cyclase
- incrase cAMP
- Activation of protein kinase A
- [Ca] increases
- myosin light chain kinase increases
what controls release of NE?
NE negative feedback to alpha-2 AII receptor (+) M2 receptor (-)
acetylcholine is made from
AcetylCoA + Choline ChAT
NE is made from
Tyrosine–>dopa-Dopamine–?NE
Hemicholinium
blocks choline entry into cholinergic neuron
vesamicol
inhibits synthesis of Ach
Botulinum
prevents release of ACh
metyrosine
inhibits tyrosine–>dopa
reserpine
inhibits dopamine–>NE
Cocaine, TCA, amphetamines
Inhibit NE reuptake