WEEK 1 Flashcards
What is Psychopharmacology
Psychopharmacology is the discipline that attempts to
systematically study the effects of drugs on behavior, cognitive functioning, and emotions”
How does knowing how drugs work benefit you?
- prescribing the correct dose of a medication
- predicting side effects
- predicting how 2 or more drugs may interact in the body
- helping to prevent & treat overdoses
- treatment of substance use problems
- our understanding of the neural basis of normal & pathological behaviour
What is the history of drug use
- Drugs have been used since records began; used as part of
religious & social ceremony. - Social factors
- Nonhuman substance use –> Siegel (1989) suggested universal
“4th drive” of intoxication
What is significance of 1952
- effects of antipsychotic effects of chlorpromazine on
schizophrenia discovered (published in France). - encouraged researchers to develop new drugs & trial previouslyabandoned drugs
- development of the formal discipline of psychopharmacology
What is significance of 1952-195 for psychopharmacology
- chlorpromazine the drug of choice for all mental diseases
(European trade name of ‘Largasil’ - large range of therapeutic activity) - greater specificity of psychotropic drugs (‘a pill for every ill’)
What is The Psychopharmacological Revolution
New techniques allow researchers to look at machinery &
workings of the living brain:
- Magnetic Resonance Imaging (MRI)
- Computerized Axial Tomography (CAT)
- Positron Emission Tomography (PET)
Psychotherapeutic drugs do not cure mental disorders or
suppress symptoms in all individuals (+ potential side
effects).
Basic classification of psychotropics
Different classifications – one common approach is by desired
therapeutic action, e.g.,
* Stimulants - major (amphetamines) and minor (caffeine)
* Anxiolytic - anti-anxiety
* Sedative-hypnotics - make you sleep (alcohol)
* Opiates - pain relief
* Antidepressants
* Antipsychotics
What is a drug?
Drug: any substance that alters the physiology of the body…but is not a food or nutrient
What is Psychoactive drugs
“induce psychological effects by altering normal
biochemical reactions in the nervous system”
How do you describe doses?
- Milligrams are 1/1000 of a gram
- Doses given in accordance to body weight
What is ED50
- median effective dose
- the dose that is effective in 50% of individuals tested.
What is LD50
- median lethal dose
- the dose that will kill 50% of individuals tested.
What is Therapeutic Index (TI)
LD50/ED50 (e.g., 84/35 = 2.4)
how far the difference is between the LD and ED so that the drug is as safe as possible. Want the margin to be as far away from each other as possible.
What is Potency
differences in the ED50 between drugs. The lower
the ED50 the more potent the drug.
the lower the ED50 the less dose you need to see the intended effects
(if you need 1 pill to get pain relief versus needing 5 pills to get pain relief –> the 1 pill is more potent)
What is Effectiveness
differences in the maximum effect that drugs
will produce at any dose.
top response of the drug (max effect of the drug)
What is Primary/main effect:
intended treatment result
What is Side effect
unintended; may be harmful
What is Therapeutic window
range of blood concentrations of a medicine between dose that produces undesirable side effects (toxic level) & dose that has intended effect (therapeutic level)
window is about trying to keep blood level relatively constant in the desired range (toxic and therapeutic level) so your having the desired relief but not reaching the toxic level or getting side effects.
What are the different names of drugs
- Chemical name
- Generic name
- Trade name
- Street name
What is a Chemical name of a drug?
describes molecular structure of a drug in terms of chemical make-up (e.g. 7-chloro-1,3-dihydro-1-methyl -5-phenyl-2H-1,4-benzodiazepin-2-one)
What is Generic (or non-proprietary) name of a drug?
shorter, simpler name that is made up for a drug (e.g. diazepam).
What is a Trade* (or proprietary) name of a drug?
- name given to a drug manufactured by a drug company. Patented by the drug company for a number of years (e.g.,Valium).
- refers to company’s formulation, not just the active drug ingredient (other excipients)
What is a street name of a drug?
‘slang’ names given by community, usually in
relation to recreational drug use (e.g., pot/weed/dope/joint/cones; speed; coke/crack; smack; ICE)
What is Pharmacokinetics?
a series of processes that involve how the drug moves around in the body
* includes: Absorption; distribution; elimination/excretion
What is Enzymes?
molecules that control a certain chemical reaction;
help to break down/metabolise drugs
What is Metabolism?
the process of restructuring (breaking down)
molecules; detoxification
What is Half-life
time taken for the body to eliminate ½ of a given blood level of a drug
What is Drug interactions:
the effect 2 (or more) drugs have on each other
What is antagonists
a drug diminishes effect of another drug
What is Additive effect
drug enhances effect of another drug
What is Superadditive effects/potentiation
a drug has a greater effect when taken with another drug than might be expected by simply combining their effects
Routes of administration (oral administration )
drugs are swallowed
(typically absorbed via digestive system)
Routes of administration (inhalation of gases)
allows fast distribution of a drug through
the body & to brain
Routes of administration (inhalation of smoke)
as per gases, but drug in smoke particles cannot be exhaled
Routes of administration (Intranasal administration)
inhalation of solids/ powders (like snorting a drug)
Routes of administration (Parenteral routes)
injection
- there are different kinds of injection
Routes of administration (Subcutaneous)
(drug is injected just under the skin -
fairly slow & even absorption)
Routes of administration (Intramuscular)
needle is inserted into the muscle,
usually the upper arm or buttock in humans
Routes of administration (intraperitoneal)
needle inserted into the peritoneal cavity
(sack containing the visceral organs, e.g., intestines, liver,
spleen).
Routes of administration (Intravenous)
needle inserted into the vein & drug
administered directly into the bloodstream.
Routes of administration (intrathecal)
needle inserted between the base of the skull &
the first vertebra (into subarachnoid space so it reaches
cerebrospinal fluid (CSF); e.g., spinal anesthesia).
Routes of administration (Intracerebroventricular)
needle inserted into a cannula
inserted into the ventricles of the brain (bypasses blood-
brain-barrier)
Routes of administration (Transdermal administration)
drugs administered through
the skin (e.g., nicotine patch)
Routes of administration (Intrarectal administration)
suppositories placed in the
rectum & drug is absorbed into the blood stream.
What are Cell membranes
- All cells are surrounded by a membrane: double layer of fat molecules (lipid bilayer)
- Each lipid molecule has a clump of atoms (-ve charged heads) at one end & long chains at the other (uncharged tail region); in a lipid bilayer, chains (tails) point inward
- Large protein molecules are embedded in the lipid bilayer along the membrane: integral to the flow of information along neurons
- For a drug to be absorbed into the body, it must be capable of passing through several cell membranes:
1. dissolve in the lipid molecules (i.e., it must be “lipid soluble”) & pass via diffusion, or
2. be carried through by a specialised transporter molecule
What is Lipid solubility
Drugs that are lipid soluble can pass through cell membranes easily, but
* drugs that readily dissolve in fats (high lipid solubility) tend to stay in fat & are less effective; released into the blood stream slowly
What is Liver & enzyme function
- liver uses enzymes to break down (metabolise) toxic substances into less harmful substances (metabolites) - i.e., presence / availability of enzymes is important
Factors affecting distribution of a drug (lonization)
if drug molecules & ion trapping (ions are not lipid
soluble; can’t easily pass through cell membrane)
Ionisation is dependent on:
- The pH of the drug, pH of the solution in which it is dissolved, pKa of the drug
- pKa of substance X is the pH at which half of its molecules are ionized
* Fictional drugs Damital/Endital example – Fig 1-7 text
- when a drug is dissolved in fluid it becomes ionized to some extent and ions are not lipid soluble (cant pass through cell membrane) so the more ionized the molecules are the slower they will be to pass through the cell membrane
What is protein binding
some proteins are too large to pass through pores in capillaries
- substances which attach themselves to these proteins may never get to site of action
Factors affecting distribution of a drug (Placental barrier)
- substances a mother takes pass through the placental barrier to the fetus (high lipid soluble drugs
cross more easily)
—> 75-100% of mother’s drug concentration
reaches fetus <5mins
*CNS distribution: blood-brain barrier prevents non-lipid-soluble substances getting into brain
Active & passive transport (for non-lipid-soluble substances) (Passive transport mechanism)
non-lipid-soluble substancesattach themselves to carrier
molecule that can pass across membranes or uses protein channel to pass through
* Diffusion from high concentration area to low concentration area (no energy needed)
Active & passive transport (for non-lipid-soluble substances) (Active transport mechanism)
only takes place in living membranes; uses energy; actively concentrates a substance on one side of a membrane
What are the Factors & structures affecting excretion of a drug
Drug concentration & kidney function
Liver & enzyme function
What is Drug concentration & kidney function
- kidneys filter unwanted substances out of the blood in the form of urine
- work best with high concentrations of drug & filter at a lower rate with low concentrations in the blood
Factors that affect drug metabolism (Enzyme induction)
levels of an enzyme can be increased by prior exposure to a drug that uses that enzyme
–> metabolic tolerance (e.g., heavy drinkers & alcohol dehydrogenase)
Factors that affect drug metabolism (Enzyme depression:)
metabolism is depressed when 2 drugs that use the same enzyme are taken at the same time, or one blocks enzyme activity of other e.g., Antabuse & aldehyde dehydrogenase
Factors that affect drug metabolism (Age)
enzymes are not fully functional at birth; liver function is
less efficient in the elderly
Factors that affect drug metabolism (species)
levels of enzymes differ in different species
Factors that affect drug metabolism (First-pass metabolism)
any drug absorbed from the digestive system passes through the liver & undergoes some degree of metabolism before going to the heart
- Drugs taken via other modes of administration may reach
higher levels in the body because they do not undergo first-
pass metabolism (e.g., drugs absorbed through lungs)
i.e., Route of administration affects metabolism
What are the factors that affect drug metabolism
- Mode of administration produces different time courses
- The effects of a drug change over time
- Absorption & excretion functions work together to
give the “resultant” effect over time
Factors that affect drug metabolism
- enzyme induction
- enzyme depression
- Age of enzyme
- species of enzyme
What are the Drug use models
- Disease model
- Physical dependence model
- Hedonic dysregulation
- Positive reinforcement model
- Incentive sensitization theory
