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Psychopharmacology
Psychopharmacology Test 1
133
Psychology
Undergraduate 4
10/02/2012

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Term
pharmacology
Definition
=the study of the actions of drugs & their effects on a living organism
Term
drug interactions
Definition
=the specific molecular changes produced by a drug when it binds to a particular target site or receptor
--> leads to more widespread alterations: drug effects
Term
drug effects
Definition
=widespread alterations in physiological or psychological functions caused by molecular changes caused by drug action
Term
site of drug action= site of drug effect?
Definition
False, not always
Term
drugs have multiple effects because?
Definition
they act at a variety of target sites
Term
therapeutic effects
Definition
=drug-receptor interaction produces desired physical or behavioral changes
Term
side effects
Definition
=any other effect caused by drug that is not a therapeutic effect
-mildly annoying-> distressing -> dangerous
Term
specific drug effects
Definition
=effects based on physical & biochemical interactions of a drug with a target site in living tissue
Term
nonspecific drug effects
Definition
=effects not based on the chemical activity of a drug-receptor interaction but on certain unique characteristics of the individual
ie) mood, expectations, perception of drug-taking situation, attitude towards administrator of drug, etc.
ex) placebo effect
Term
bioavailability
Definition
=the amount of drug in the blood that is free to bind at specific targets to elicit drug action
-determined by pharmacokinetic component of drug action
Term
5 factors of pharmacokinetics
Definition
1. Adminstration
2. Absorption
3. Distribution
4. Biotransformation/Inactivation
5. Elimination/Excretion
Term
when a drug binds to plasma proteins in blood or is stored temporarily in bone or fat (where it is inactive)
Definition
depot binding
-causes biotransformation
Term
PO
Definition
=per os
=oral administration
-most popular route for taking drugs
--safe, self-administered, economical, avoids complication/discomfort of injections
--form: capsules, pills, tablets, liquids
--must dissolve in stomach fluids & pass through stomach wall to reach blood capillaries
--drug: must be resistant to destruction by stomach acid & enzymes
Term
can insulin be administered orally?
Definition
No, it is destroyed by digestive processes
Term
4 properties of drugs absorbed by gastrointestinal tract?
Definition
1. water soluble
2. gastric resistant
3. lipid soluble
4. first pass metabolism
Term
absorption
Definition
=movement of drug from site of administration to blood circulation
-most drugs are not fully absorbed until they reach the small intestines
Term
GI tract
Definition
-lined by tightly apposed epithelial cells
Term
factors affecting how quickly GI tract empties contents into small intestine?
Definition
1. fatty foods in stomach slow movement of drug (aka slows absorption)
2. amt of food
3. amt of physical activity of individual
etc..
Term
reduces amt of available drug molecule before reaching circulation?
Definition
first-pass effect
-by liver metabolism of some of the drug
Term
has irregular & unpredictable drug plasma levels?
Definition
Oral administration
-also has more slowly rising drug plasma
Term
IV injection
Definition
=intravenous injection
=most rapid & accurate method of drug administration
-precise quantity of agent placed directly into blood (eliminates passage through cell membranes ie stomach wall)
Term
disadvantage of IV?
Definition
quick onset of drug effect is potential hazard
-overdose or allergy to drug leaves little time for corrective measure
--drug can not be removed from body (ie stomach pumping)
-needle sharing of drug abusers
Term
IM injection
Definition
-slower, more even absorption than IV (10-30 min)
-can be further slowed by combining drug with 2nd drug that constricts blood vessels
-disadvantages: injection solution can be irritating or cause muscle discomfort
-inserted at 15 degree angle
Term
IP injection
Definition
=intraperiotoneal injection
=drug injected through abdominal wall into peritoneal cavity (space that surrounds abdominal organs)
--rarely used with humans->danger of peritoneal infection
-produce rapid effects (not as rapid as IV)
-variability depeding on where within peritoneum the drug is injected
Term
biotransformation is primarily a result of?
Definition
metabolic processes in the liver
Term
SC
Definition
=subcutaneous administration
=drug is injected 45 degrees just below skin
-absorption: depends on blood flow to site; usually slow & steady
-drug + nonaqueous solution = slows rate
-silastic capsules (produces time rls effect)
Term
Inhalation
Definition
=drugs absorbed into blood by passing through lungs
ex. smoking, inhalers
absorption: very rapid because are of pulmonary absorbing surfaces is large & rich with capillaries
-effect brain rapidly because lung capillaries go straight to brain (w/o returning to heart)
disadvantages: damage to nasal & lungs bye small particles
Term
2nd preferred method of self-administration?
Definition
inhalation
Term
effect of nicotine inhalation?
Definition
rlsd from tabacco by heat
-rapid rise in blood level & CNS effects
-peak: minutes
Term
intracoelomic administration
Definition
=i.c.
-aka intraperitoneal
Term
topical application of drugs
Definition
=application to mucous membranes (conjunctiva of eye, nasopharyns, vagina, colon, urethra)
->local drug effects
ex) snorting coke
-transdermal: drug admin through skin, can penetrate if lipid-soluble
Term
in order to penetrate skin?
Definition
-must be lipid-soluble substance (dissolve fat)
-skin is an effective barrier to the diffusion of water-soluble drugs
Term
transdermal administration
Definition
-type of topical application
=with skin patches (polymer matrix embedded with the drug in high conc)
-provides controlled & sustained delivery of drug at preprogrammed rate
-common: prevent motion sickness, reduce cigarette cravings
Term
scopolamine
Definition
transdermal medicine to prevent motion sickness
Term
administration for some drugs that act on nerve cells
Definition
special injections
-because BBB (cellular barrier)prevents/slows passage of drugs into neural tissue
ex. epidural, intracranial, intracerbroventricular
Term
epidural
Definition
-a special injection used when spinal anesthetics are administered directly into CSF surrounding SC
-bypasses BBB
ex) during childbirth
Term
intracranial
Definition
-special injection
-only in animals
-microsyringe or cannula employed
-injection into discrete area of brain tissues
-bypasses BBB
Term
intracerebroventricular
Definition
-special injection
-animals
-injection into cerbrospinal fluid-filled chambers aka ventricles
Term
how scientists study electrophysiological, biochemical, or behavioral effects of drugs on particular nerve groups?
Definition
-special injections: intracranial &/or intracerebroventricular
Term
peak level=?
Definition
=absorption rate + liver metabolism
Term
layers of Meninges
Definition
1. Dura
2. Arachnoid
3. Sub-arachnoid
4. Pia
Term
Intrathecal Administration
Definition
-lumbar puncture (spnal needle inserted between 3rd & 4th lumbar vertebrae)
-into sub-arachnoid space into CSF
Term
infected CSF
Definition
-cloudy
-trtment: anesthetics, analgestics, antibiotics
Term
analgesics for
Definition
pain reduction
Term
sensory nerves found where?
Definition
DRG- dorsal root ganglion
Term
most rapid, most accurate blood concentration administration method
Definition
IV
-OD
-need sterile needles
Term
slow & even absorption from?
Definition
IM
-but need sterile equipment
Term
slow & prolonged absorption from
Definition
SC
-but variable depending on blood flow
Term
localized action & effects
Definition
topical
-but may be absorbed into general circulation
Term
controlled & prolonged absorption?
Definition
transdermal
-but local irritation
-only useful for lipid soluble drugs
Term
longest threshold for effectiveness?
Definition
IM-oil > SC > IM > PO > IV
Term
highest drug conc?
Definition
IV > IM > IM-oil > SC >PO
Term
primary target site for psychoactive drugs?
Definition
brain
-site of admin-> blood -> circulated throughout body -> brain
Term
Absorption dependent on?
Definition
1. route of administration (bc of area, # of cell layers, amt of drug destroyed, extent of binding to inert complexes)
2. Drug concentration (determined by age, sex, size)
3. solubility & ionization of drug
Term
most important factor in determining drug plasma levels?
Definition
rate of passage of the drug through various cell layers (& membranes) between site of admin and blood
Term
cell membranes made up of?
Definition
phospholipids
=complex lipid (fat) molecules which have a negatively charged region at one end & two uncharged lip tails
-arranged into bilayer with phosphate ends forming 2 almost continuous sheets filled with fatty material
Term
phospholipid bilayer
Definition
=charged heads in contact both aqueous intracellular fluid and extracellular fluid.
=phosphate ends forms sheets filled with fatty material
-have proteins inserted into bilayer
-prevent passing unless soluble in fat
Term
what can pass through phospholipid bilayer??
Definition
molecules soluble in fat
-by passive diffusion
Term
passive diffusion
Definition
drugs leaving water in blood/stomach juice & entering lipid layers of membran
Term
cells with high lipid solubility move through cells by?
Definition
passive diffusion
Term
larger concentration difference means?
Definition
more rapid diffusion
Term
which is more lipid soluble? heroin or morphine?
Definition
heroin is more lipid soluble.
morphine is parent molecule.
Term
weak acids and weak bases may become ionized when dissolved in what?
Definition
water
Term
extent of ionization depends on?
Definition
1. relative acidity/alkalinity (pH) of the solution
2. pKa (an intrinsic property of the molecule)
Term
pKa of a drug
Definition
=represents the pH of the aqueous solution in which the drug would be 50& ionized
Term
weak acids ionize most in what type of solution?
Definition
alkaline
Term
weak acids ionize least in what type of solution?
Definition
acidic
Term
If aspirin (was) placed in stomach?
Definition
would remain primarily non-ionized -> more lipid soluble -> readily absorbed from stomach to blood
Term
aspirin in intestine?
Definition
absorption decreased compared to stomach because pH of intestine is higher and causes aspirin to ionize
Term
why would aspirin not move to stomach and back?
Definition
once aspirin is in the blood (pH 7), it becomes trapped because it becomes more ionized
-also circulation moves it away from concentrated site to maintain concentration gradient
Term
if a drug is highly charged in both acidic and basic environments?
Definition
can not be administered orally
Term
greater absorption site?
Definition
small intestine
-greater SA
-slower movement
--> rate at which stomach empties into small intestine can be rate-limiting
Term
negative part of a phospholipid molecule?
Definition
the negatively charged PO4- group head
-is attracted to water
Term
body surface area
Definition
-reflects both size & weight
--> better basis for determining drug dose
Term
why does sex affect drug dosage?
Definition
-females contain more adipose tissue (relative to water)
-->represents a laterger prportion of the total body weight
--> total fluid volume is smaller in women
Term
time it takes to carry a drug throughout the body once in the blood stream?
Definition
1-2 minutes
Term
highest blow flow will have
Definition
highest conc of the drug
Term
most drugs can move from blood and enter body tissues regardless of lipid solubility because?
Definition
blood capillaries have numerous pores
-unless the drugs are bound to proteins in depot binding
Term
CSF in?
Definition
fills subarachnoid space that surrounds entire bulk of brain & sc
-also fills ventricles & interconnecting channels (aqueducts
Term
choroid plexus of lateral ventricle
Definition
-manufactures CSF
Term
walls of typical capillaries made of?
Definition
endothelial cells that have small gaps (intercellular clefts) & larger openings (fenestrations)
-job of blood vessels: deliver nutrients to cell & remove waste
Term
pinocytotic vesicles
Definition
-contained in typical capillaries
-envelop & transport larger moleucules through capillary wall
Term
intercellular clefts of brain capillaries
Definition
-are closed because adjoining edges of enothelial cells are fused
--> forms tight junctions
Term
brain capillaries
Definition
fenestrations & intercellular clefts are absent
-pinocytotic vesicles are rare
-most material (if not lipid-soluble) is moved through walls by special transporters
Term
astrocytes
Definition
-close interface with nerve cells & brain capillaries
-glial feet surround brain capillaries
-->modify neuron function
Term
BBB
Definition
-selectively permeable
-does not diffuse water-soluble or ionized molecules
-lipid soluble molecules can diffuse
Term
areas where BBB is not complete?
Definition
1. area postrema
2. median eminence
3. subfornical origin
Term
area postrema
Definition
aka CTZ (chemical trigger zone)
-located in medulla of brain stem
-"vomiting center"
--causes vomiting when toxic substances are detected in blood
---> lifesaving response!
Term
median eminence
Definition
-in hypothalamus
-caillary fenestrations allow neurohormones (rlsing factors) manufacted by hypothalamus to move into the blood traveling to the pituitary gland
--regulate anterior pituitary hormone secretion
Term
second barrier only in women?
Definition
-placental barrier
-between blood circulation of pregnant woman and fetus
Term
teratogens
Definition
agents that induce developmental abnormalities in the fetus
-dependent on timing of exposure
-most suceptible during first trimester because organs are forming
ex. accutane
Term
drug depots
Definition
=drug binding can occur at inactive sites where no measurable biological effect is initiated
ex. plasma protein (albumin), muscles, fat
-unbinds when blood level drops
-effects magnitude and duration of drug action
Term
binding to albumin, fat, and muscles is?
Definition
nonselective
-> drugs with similar physiochemical characteristics compete with each other for these sites which can lead to higher than expected free drug blood level of displaced drug
--> can cause OD
Term
many psychoactive drugs have extensive?
Definition
90% plasma protein binding
-may contribute to drug interaction
Term
drug clearance
Definition
-usually occurs exponentially (a constant fraction of the free blood is removed in each time interval)
-first-order kinetics
Term
zero order kinetics
Definition
-not as common as first order clearance
- drug molecules are cleared at a constant rate regardless of concentration
ex) ethyl alcohol
Term
combined action of biotransformation + excretion of metabolites
Definition
=elimination process
Term
biotransformation
Definition
-chemical changes aka drug metabolism
-most common in liver
-2 types:type I & II
Term
Phase 1
Definition
-often first, not always
-involves nonsynthetic modification
ex. hydrolysis, oxidation, reduction
--oxidation is most common
Term
oxidation
Definition
-most common phase 1 reaction
-produces metabolite that is less lipid soluble & less active usually
Term
Phase 2
Definition
-biotransformation
-synthetic reactions that require conjugations of drug with small molecule
ex. glucuronide, sulfate, methyl groups
-metabolites are usually less lipid soluble & almost always biologically inactive
Term
inactivates psychoactive drugs?
Definition
glucuronide (phase 2 rxn)
Term
liver enzymes responsible for metabolizing psychoactive drugs are located?
Definition
on smooth ER
-a network of tubules within liver cell cytoplasm
aka microsomal enzymes
-lack specificity & can metabolize wide bariety of compounds
-cytochrome P450
Term
cytochrome P450
Definition
-most important microsomal enzyme
-responsible for oxidizing a majority of psychoactive drugs
-contribute to cross tolerance
-Phase 1 reaction
-can be inducible (by exposure to some drugs)
Term
factors produced by enzymes of liber that influence rate of biotransformation
Definition
1. enzyme induction
2. enzyme inhibition
3. drug competition
4. differences in age, sex, genetics
Term
enzymatic induction
Definition
=when psychoactive drugs are used repeatedly, can increase amount of liver enzymes
-can cause cross tolerance (ex. smoking cigarettes means you'll need higher does because of increased P450
Term
enzyme inhibition
Definition
-drugs that directly inhibit the action of enzymes which reduces metabolism of other drugs taken at the same time
->impaired metabolism -> higher blood levels
ex. food toxicity
Term
drug competition
Definition
occurs when drugs share a metabolic system
ex. 450 metabolism of alcohol leads to higher than normal brain levels of other sedatives (eg valium)
Term
renal excretion
Definition
-most important route
-liver biotransformation of drugs into ionized (water-soluble) molecules traps the metabolites in the kidney tubules so they can be excreted with wastes in urine
Term
pharmacodynamics
Definition
=the study of the physiological and biochemical interaction of drug molecules with target tissues that is responsible for ultimate drug effeccts
Term
receptors
Definition
=large protein molecules located either on surface or within the cell
-the initial sites of action of a biologically active agent like a nts, hormone, or drug
Term
ligand
Definition
=molecule that binds to a receptor with some selectivity
Term
agonist
Definition
-lock and key
-intrinsic
-highest affinity
-can cause down regulation
Term
low efficacy
Definition
=fits in lock, but no action
-antagonists
-prevent binding of active ligand
-block
-can lead to up-regulation of receptors
Term
changes in sensitivity of receptor caused by?
Definition
second messengers
Term
receptor subtypes
Definition
=drug receptor proteins may have different characteristics in different target tissue
Term
important method to evaluate receptor activity?
Definition
dose-response curve
Term
dose-response curve
Definition
=evauluates receptor activity
-describes amt of biological or behavioral effect (response) for a given drug (dose)
-classic S shape
Term
threshold dose
Definition
=smallest dose that produces measurable effect
Term
ED50
Definition
50% effective dose
=the dose that produces half the maximal effect (ED100-when all receptors are occupied)
Term
drug potency
Definition
=the absolute amt of drug necessary to produce a specific effect
-differences in potency can be seen by comparing ED50
Term
therapeutic index
Definition
-calculates drug safety
TI=TD50/ED50
-low TI->dangerous
Term
TD50
Definition
50& toxic dose
-50% of population experiences a particular toxic dose
Term
competitive antagonist
Definition
-can be displaced from sites by an excess of agonist because an increaded conc of active drug can compete more effectively fo the fixed number of receptors
Term
addition of competetive agonist
Definition
causes decrease in potency of drug
Term
non competetive antagonst
Definition
=drugsthat reduce the effect of agonist in ways other than competing for receptor
ex. impair agonist action by bind to a portion of the receptor, disturbing cell membrane supporting receptor, interfering with intracellular processes that were initiared by the anoist
Term
k1
Definition
rate which drug associtates with receptor
Term
k2
Definition
rate which drug dissociates from receptor
Term
kd
Definition
aka dissociation constant (not same as rate of dissocation from receptor, k2)
-determines drug affinity. the conc of radioligand that labels 50% of total receptors in sample
Kd= k2/k1
Term
bmax
Definition
=maximum receptors
Term
low Kd vs high Kd
Definition
low Kd=higher affinity
so you'd need less of the drug to label receptors
Term
IC50
Definition
conc of competitor drug that inhibits 50% of radioligand binding
Term
if kD is low
Definition
high affinity, would need more competitor drug thus IC50 would be higher
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