get into brain Flashcards
what are 3 examples of drugs that result in several dose-dependent responses and how are these multiple responses possible
- Phenothiazines
- Antihistamines
- CNS depressants
multiple responses due to presence of multiple receptors being activated at different dose levels
examples of dose dependent toxicities
Excessive hypotension
arrhythmias
hypoglycemia
hemorrhage
chloramphenicol causes what toxicity
aplastic anemia
what drug causes retardation of bone growth
tetracycline
what toxicities are caused by aminoglycosides
renal + ototoxicity
type of antagonism that decreases the agonists max response
non competitive
type of antagonism where antagonist binds irreversibly to receptor so that the agonist can’t bind OR binds to secondary site so agonist can’t act
how rude!
Non competitive
type of antagonism that decreases affinity (Kd or EC50)
Competitive antagonists
type of antagonism that DOESN’T affect max response
competitive
type of antagonism that shifts the curve to the right in a parallel fashion
competitive
if the agonist concentration is high enough, the effect of this kind of antagonist can be overcome
competitive
what type of agonist is Buprenophine
partial
response caused is less than that produced by full agonist
naloxone is an…
antagonist
binds to receptor
does NOT initiate response
will block response of agonist
morphine is an…
agonist
causes max shift of receptors to the activated state
if potency of a drug decreases, which direction does the curve shift
right
efficacy of a drug is dependent on what
drug receptor interaction and intrinsic activity
what is Kd
concentration needed to produce half max binding
activation of _____ by NE and E leads to activation of Gq
α1
activated Gq leads to activated phospholipase _____which leads to the release of ____+_____
phospholipase C
IP3 and DAG
IP3 stimulates ____ release
Ca+
increased calcium can activate Ca dependent protein kinases which phosphorylate their substrates
what does DAG activate
PKC
what is the loading dose of a drug dependent on
Vd (volume of distribution)
equation for loading dose
LD = Vd x target concentration (Css)
is a loading dose dependent on half life or clearance?
naur
if a drug has a High Vd, will it require a high or low loading dose
HIGH b/c the drug plasma concentration is low
what needs to be considered in patients with decreased renal or hepatic clearance and maintenance doses
maintenance doses need to be decreased or change the dosing interval to cause a lower concentration of the drug
they cannot eliminate the drug as well
when steady state condition has been achieved, the dosing rate is equal to what
elimination rate
what is a maintenance dose
dose needed to maintain steady state concentration
equation for maintenance dose
maintenance dose = (CL * TC / F) * dosing interval
what has a large role in maintenance dose
Clearance (elimination)
what is the effect of shortening the dosing interval on steady state concentration
causes a higher steady state concentration
what is the effect of lengthening the dosing interval on steady state [ ]
gradual decrease of the plasma level of drug and a lower steady state
type of elimination in which the rate of elimination is proportional to the [drug]
first order
if drug [ ] increases so does rate of elimination
what type of elimination do aspirin, fentanyl and phenytoin undergo
zero order elim
explain enterohepatic recirculation
drugs get metbolized in liver (get conjugated) then are excreted in bile where they are metabolized back into free drug that gets reabsorbed into plasma and returned back to liver
what are the consequences of drugs that undergo enterohepatic circulation? Give a drug example
lower doses of the drugs can be therapeutically effected since elimination is reduced by the recycling of the drug
ex: opioids, benzodiazepines
Steady state concentrations and conditions can only develop for __________ order eliminations
first
what kind of tolerance is seen with morphine
Pharmacodynamic tolerance
same [drug] but effect decreases
what effect does meningitis & encephalitis have on drug metabolism
increased penetration into the CNS
what does a large Kd mean in regards to receptor - ligand affinity
what about a small Kd
large Kd: receptor binds ligand poorly
small Kd: high affinity of ligand for receptor
