Pharm Unit 1 Flashcards
Pharmacokinetics definition
how the body handles the drug
Pharmacodynamics definition
effect of the drug on the body
ADME
absorption, distribution, metabolism, excretion
What is area under the curve
the actual exposure of the body to the drug after administration
what is Cmax
Maximum plasma drug concentration
What is Tmax
time at which Cmax occurs
How does solubility affect ADME
lipophillic vs. lipophobic (the more aqueous the drug, the faster it is absorbed)
what is partition coefficient
The ratio of a drug’s concentrations in oil phase vs aqueous
how does partition coefficient affect ADME
the higher the partition coefficient the more likely the drug will accumulate in fatty tissues
how does ionization affect ADME
charged molecules (ionized) do not cross membranes by diffusion
how does drug pKa affect ADME
the higher the pKa the slower it crosses
what is pKa
pKa is the pH where unionized = ionize
non-ionized: easily diffuse
ionized: do not diffuse
what is a prodrug
inactive precursors that are metabolized into active metabolites
benefits of a prodrug
increases drug aqueous solubility
higher aqueous solubility = higher drug concentration within body
higher aqueous solubility = more likely to remain in the blood
improve ADME
bioavailabilty definition
how much of drug is available to body after first/second pass metabolism
first pass metabolism
first pass = liver metabolism
low first pass drugs
IV drugs
high first pass drugs
calcium channel blockers, beta blockers, diuretics, lidocaine
how does a low first pas mean
bypasses liver- more bioavailability
what does F=1.0 mean
F = bioavailability
F = 1.0 means 100% bioavailability
or 100% of the administered drug was able to be utilized by the body for the targeted effect
where does Phase I and Phase II metabolism occur
- mostly liver
- gut
- kidneys
- lungs
- skin
Phase I
reduction
oxidation
hydrolysis
Phase II
glucuronidation
methylation
acetylation
what happens when a drug inhibits a CYP enzyme
prevents metabolism of drugs that are metabolized by the specific enzyme
concentration of drug increases
hepatic enzyme inhibition
decrease effect of metabolic enzyme
prevents activation of drug metabolism in liver
concentration of drug increases
hepatic enzyme inhibition outcome
metabolizes slower = more effective = need less drug
decreased elim rate = increased half life
hepatic enzyme induction
increase effect of metabolic enzyme
increases activation of drug metabolism in liver
expected concentration of drug is lower
hepatic enzyme induction outcome
slow onset
long duration
metabolizes faster = less effective = need more drug
increased elim rate = decreased half life
plasma protein binding
more bound a drug is = less active drug is
capacity
availability to bind
affinity
rate of binding
albumin characteristics
high capacity for binding
low affinity for binding
alpha 1 acid glycoprotein characteristics
low capacity to bind
high affinity for binding
therapeutic range/index definition
ratio of effective dose compared to lethal dose
good therapeutic index
wide
bad therapeutic index
narrow
first order kinetics
amount of drug eliminated is proportional to amount in body
drug that follows first order kinetics
epinephrine
ibuprofen
zofran
drug that follows zero order kinetics
alcohol
phenytoin
zero order connectics
amount of drug eliminated is fixed and independent of amount present in body
how to calculate loading dose
LD = (concentration x volume of distribution) / bioavailability (F)
when is half life predictable
if a drug follows first order kinetics
how to calculate half life
0.693/slope
what does half life mean for first order drugs
50% of drug is lost each half life
agonist definition
substance that mimics endogenous effect
antagonist definition
substance that blocks endogenous effect
partial agonist/antagonist
substance that has both agonist and antagonist properties
how does ED50 determine potency
lower ED50 = more potent
how to determine efficacy
higher the maximum point on curve
tolerance definition
occurs slowly over time and does not reverse rapidly after withdrawal of drug
Tachyphylaxis
occurs rapidly and reverses rapidly after withdrawal of drug
tolerance vs tachyphylaxis
tolerance = chronic
tachyphylaxis = acute
reversible/competitive action
drugs bind to receptor but can easily be kicked off by molecule with higher affinity
irreversible action
drug binds to receptor indefinitely
sedation definition
calming and drowsiness
hypnosis definition
produces drowsiness and facilitates deep sleep
anesthesia definition
global (reversible) CNS depression
what triggers MH
volatile anesthetics & succinylcholine
what happens in MH
mutation in RyR causes uncontrolled release of Ca2+ [IC] resulting in intense muscle contraction
MH key symptoms
extreme muscle metabolism
tachycardia
hypercarbia
hyperthermia
MH treatment
- hyperventilate
- give NaHCO3 (met. Acidosis)
- give insulin/furosemide
- give dantrolene (2.5mg/kg)
- cool pt
- treat other symptoms
barbiturates effects
*sedative
*hypnosis
*anticonvulsant
Barbiturates mechanism of action
increase duration of GABA Cl- chloride channel
barbiturate side effects
tissue damage
decrease BP / BF / ICP
increase HR
vasodilation
respiratory depression
hyperalgesia
histamine
Barbiturate drug interactions
precipitates w/ weak bases:
*Roc
* Lido
* Labetalol
* morphine
alcohol
benzos
opioids
Barbiturates Contraindications
elderly
anemic
shock
acute intermitent porphyria
barbiturate onset and duration
O= 10-20s (fast)
D = 8-20 min (short)
Barbiturate metabolism
CYP enzymes
barbiturate examples
phenobarbital
methohexital
benzos effect
sedation
anti-anxiety
hypnosis
muscle relaxation
anterograde amnesia
anticonvulsant
thrombophlebitis
benzos MOA
increases frequency of GABA Cl- channel opening
benzos side effects
pt may develop tolerance or dependance
benzos drug interactions
opioids: hypotension/resp depres
anesthetics: enhance potency
benzos onset
fast:
Midazolam < Diazepam < Lorazepam
benzos lipid solubility
high = high Vd
M>D>L
benzos metabolism
hepatic
benzos examples
Midazolam, Diazepam, Lorazepam
Midazolam contraindications
kidney failure
active metabolite alpha-hydroxy accumulates
benzos half life
D>L>M
(fastest onset has shortest half life)
flumazenil use
reverse benzos
flumazenil side effect
shorter duration than benzos
ketamine uses
anesthesia (unconsciousness)
analgesia
amnesia
depression
anticonvulsant (no change to seizure threshold)
ketamine MOA
NMDA receptor antagonist
- Glutamate receptor
ketamine side effects
dissociative anesthesia
hallucination
cardiac stimulant (incr HR/BP/CO)
incr CBF/ICP
bronchodilator
ketamine drug interaction
blocked by alpha and beta antagonists
decrease anesthesia requirements
- additive to VA, propofol, benzos
ketamin onset and duration
O: 15-30 sec (fast)
D: 10-15 min (short)
ketamine analgesia onset
instant
ketamine analgesia duration
40 min
Ketamine contraindications
CAD
HTN
CHF
arterial aneurysms
Ketamine metabolism
CYP enzymes (hepatic)
active metabolite: Norketamine
high hepatic extraction
Ketamine excretion
renal (incl metabolites)
propofol MOA
increases affinity of GABA for GABA receptor
propofol uses
anesthesia induction/maintenance
sedataive
antiemetic
antipruritic
anxiolytic
anticonvulsant
propfol side effects
dystonic movements
decrease BP/resp
decr CBF/BV/ICP
hypertriglyceridemia
propofol infusion syndrome
pain w/injection
propofol infusion syndrome
acidosis
myocardial failyre
rhabdo
propofol drug interaction
reduce dose if used with versed or fentanyl
Propofol CI
elderly
hypovolemia
LV dysfunction
beta-blockers
propofol onset/duration
onset: 10-20 s (rapid)
duration: 2-8 min (short)
Fospropofol
water soluble pro-drug
prolonged onset/duration
etomidate use
sedation/induction
hypnotic
etomidate MOA
increases affinity of GABA for GABA receptor
etomidate side effects
seizures
muscle movements
suppressed adrenal function
PONV
decr CBF/ICP
decr SVR (CO mx’d)
etomidate onset/duration
O: 20-30 s (rapid)
D: 5 min
Etomidate metabolism
plasma esterases
CYP enzymes
precedex use
anxiolysis
sedation
analgesia
withdrawal treatment
epidural/regional
precedex MOA
alpha 2a agonist
decr NE release
decr sympathetics
precedex side effects
decr BP
decr HR
withdrawal (prolonged use)
nausea
precedex drug interactions
vasodilators
hypnotics
drugs that decr HR
precedex onset/duration
O: rapid
D: 20 min (2 hr half life)
Precedex CI
renal/hepatic insufficiency =. decr dose
doxapram use
repiratory/CNS stimulant (used for excessive resp depression)
COPD
doxapram side effects
seizure, dizzy, tachycardia, PONV
what does ED95 in NMB’s mean
dose that gives 95% twitch suppression in 50% individuals
NMB dose compared to ED95
usually 1-2x ED95
what happens when 75% of N1 receptors are bound with NMB
some weakness
what happens when 95% of N1 receptors are bound with NMB
paralysis
Upregulation
An increase in the number of receptors on the surface of target cells
cells more sensitive to a hormone or another agent
What conditions cause the Ach receptor expression to be upregulated
neuron lesions
trauma
sepsis/infection
how is NMB dosing changed when Ach receptor expression is upregulated
more nondepolarizing (less depolarizing)
more receptors for the NMB to block
when is Ach receptor expression downregulated
myasthenia gravis, chronic AchE inhibitor use
how is NMB dosing changed when Ach receptor expression is downregulated
more depolarizing (less nondepolarizing)
less receptors for the NMB to block
succinylcholine MOA
binds Ach receptor
persistant depolarization
phase 1: depolarizing
phase 2: desensitizing
succinylcholine onset/duration
O: rapid
D:Short
Sux duration prolonged by
high dose/infusion
- decr metabolism
- hypothermia
- psuedocholinesterase def
sux metabolism
plasma psuedocholinesterase
metabolite: suxmonocholine
succinylcholine drug interaction
cholinesterase inhibitors (increase duration)
impacts NDMR
- phase 1: antagonistic
- phase 2: additive
succinylcholine contraindications
MH
decreased pseudocholinesterase activity (dibucaine 20)
hyperkalemia
sux side effects
decr HR
twitches
hyperkalemia
incr pressures
MMR
incr histamine
MH
Rocuronium/vecuronium clearance
hepatic
pancuronium/doxacuronium clearance
renal
atracurium/cisatracurium clearance
hoffman
rocuronium side effects
incr HR
decreased dose in liver failure/pregnancy
pancuronium side effects
decreased dose in kidney failure
incr BP
incr HR
pancuronium duration
long acting (60-120min)
atracurium side effects
histamine release & toxic metabolite (laudanosine)
decr BP/HR/SVR
bronchospasm (asthmatics)
roc onset/duration
onset: 1.5min
duration: 35-75 min (intd)
vecuronium o/d
onset: 2-3min
duration: 45-90 min (intd)
atracurium o/d
onset: 2.5-3 min
duration: 30-45 (intd)
neostigmine MOA
AChE inhibitor
neostigmine onset/duration
O: 5-10 min
D: 1 hr
atropine/glycopyrrolate MOA
muscarinic receptor antagonist
glycopyrrolate dosing
0.2 mg glyco/ 1 mg neostigmine
Atropine onset and duration
fast onset
short duration
glycopyrrolate onset and duration
slow onset
long duration
which antimuscarinic should be used with neostigmine or pyridostigmine
glycopyrrolate
which antimuscarinic should be used with edrophonium
atropine
Edrophonium onset and duration
onset: 1-2 min
duration: 1 hr
Pyridostigmine onset and duration
onset: 10-12 min
duration: over 2 hr
neostigmine onset and duration
onset: 5-10 min
duration: 1 hr
how many Ach receptors have to be blocked for a decrease in twitch height
75%
how many Ach receptors have to be blocked for a disappearance of a twitch
90-95%
antimuscarinic side effects
overractive sympathetics
mental status impacts (elderly)
cholinesterase inhibitor side effect
parasympathetic activation
which opiod does not accumulate over a constant infusion
remifentanil
what are the different opiod receptors
mu, kappa, delta, sigma
opioid mechanism
bind receptors in CNS
decr VGCa++
incr VG K+
hyperpolarization
decr release Ach/Ne/5Ht/sub p
where are opiod receptors located
CNS and peripheral nociceptors
opioid side effects
hyperalgesia
tolerance/dependence
respiratory depression
decr CBF/ICP/CMO2C
chest wall regidity
miosis
pruritis
PONV
histamine
opioid effects
analgesia
euphoria
sedation
what is responsible for opioid metabolite excretion
kidneys
what is the risk of using meperidine with renal dysfunction
buildup of active metabolite = seizure risk
(noremeperidine)
where are opioids metabolized
liver
Naloxone MOA
opioid receptor antagonist
naltrexone MOA
long acting opioid antagonist
what are the mixed agonist/antagonist opioids
butorphanol
nalbuphine
buprinorphine
how can buprenorphine act as a mu antagonist
high affinity for receptor but low activity
mixed opiod agonist/antagonist DOA
longer (up to 10 hr)
naloxone onset
1-3 min
naloxone dosing
0.4-2 mg every 2-3 min as needed
COX inhibitors
aspirin, colchesine
COXi MOA
irreversibly inhibit COX enzymes (inhibit prostaglandin synthesis)
COXi side effects
bleeding
NSAID benefits
reduced opiod dosing
NSAID MOA
reversibly inhibit cox enzymes
NSAID side effects
renal insufficiency & bleeding
acetaminophen class
analgesic
antipyretic
acetaminophen MOA
inhibits COX 1 & COX 2
acetaminophen side effects
liver damage in large doses
acetaminophen IV onset and duration
onset: 5-10 min, duration: 4-6 hr
acetaminophen max dose
4g/24 hrs
Does acetaminophen have anti-inflammatory effects?
nope
Acetaminophen Contraindications
liver disease
NSAID contraindications
renal disease
how long is ketorolac indicated for?
short term- no longer than 1 week
how does drug pKa affect ADME
the higher the pKa the slower it crosses