Week 1 - Introduction of Psychopharm Flashcards
What is psychopharmacology/
The discipline that attempts to systemically study the effects of drugs on behaviour, cognitive functioning and emotions
What can studying how drugs work aid in?
- Prescribing correct dosage of medication
- Predicting Side Effects
- Predicting how 2 + drugs interact in body
- Helping to prevent and treat overdoses
- Treatment of drug addictions
- Understanding of the neural basis of normal and pathological behaviour
What are the classifications of Psychotropic drugs/
- Stimulants
- Anxiolytic
- Sedative-hypnotics
- Opiates
- Antidepressants
- Antipsychotics
What is the alternative definition of a drug
“A nonfood, non mechanical substance (usually a chemical substance) that exerts an effect upon a living system”
What is a psychoactive drug?
“Induces psychological effects by altering the normal biochemical reactions in the nervous system”
What are doses described in? (measurement) and what are they given in accordance to?
Milligrams and body weight
What is the ED50
Median effective dose - the dose that is effective in 50% of individuals tested
What is the LD50
median lethal dose; the dose that will kill 50% of individuals tested
What is the Therapeutic Index (TI)/
LD50/ED50 *e.g. 84/35 = 2.4) how safe the drug is – the dose of the drug must be 2.4 times higher than the ED50 to be lethal
What is the Potency?
differences in the ED50 between drugs. The lower the ED50 the more potent the drug
What is the difference for a graduated drug?
Look at when 50% of effectiveness for the ED50
–>Instead of effectiveness as yes/no it is the degree of effectiveness
What is needed to be balanced in drugs?
Effectiveness and safety
What is the primary/main effect
intended treatment result
What is a side effect
unintended; may be harmful
What is the therapeutic window?
Range of blood concentrations of a medicine between dose that produces undesirable side effects (toxic level) & does that has intended effect (therapeutic level)
What is the chemical name describing?
describes molecular structures 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 the generic name describing?
shorter, simpler name that is made up for a drug (e.g. diazepam)
–> Drugs falling into similar categories have similar generic names using the same stem
What is the trade name describing?
Name given to a drug manufactured by a drug company. Patented by the drug company for a number of year (e.g. Valium)
What is Pharmacokinetics/
Process involved in the movement of a drug in the body
What is absorption?
distribution; elimination/excretion
What are 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 a half life?
time taken for the body to eliminate ½ of a given blood level of a drug of a drug
What is a drug interaction?
the effect 2 (or more) drugs have on each other
What is an antagonist
A drug diminishes effect of another drug
What is the term for when a drug enhances the effect of another drug?
Addictive effect
What are super additive effects/potentiation?
A drug has a greater effect when taken with another drug than might be expected by simply combining their effects
What are the routes of administration?
- Oral
- Inhalation of gases
- Inhalation of smoke
- Intranasal Administration
- Parenteral Routes: injection (subcutaneous; intramuscular and intraperitoneal)
- Intravenous
- Intrathecal
- Intracerbrioventricular
- Transdernal administration
- Intrarectal administration
What is oral administration?
peroral (p.o.); drugs are swallowed (typically absorbed via digestive system
o Having a full stomach effects absorption rate
What is inhalation of gases?
allows fast distribution through the body and to brain o Enters into lungs and absorbs quickly into capillaries and then quickly goes to the heart brain o Also doesn’t have to go through first class metabolism
What is inhalation of smoke?
can only exhale if it is a gas – can’t exhale if it is a smoke
o Really easy to control administration – good for general anesthetics
What is intranasal administration?
inhalation of solids/powders
o Bypasses first part of metabolism
What is subcutaneous injection?
drug is injected just under the skin – fairly slow and even absorption
What is intramuscular injection?
needle is inserted into the muscle, usually the upper arm or buttock in humans
What is intraperitoneal injection?
needle inserted into peritoneal cavity (sack containing the visceral organs, e.g. intestines, liver, spleen)
What is intravenous injection?
needle inserted into the vein and drug administered directly into the bloodstream
What is intrathecal injection?
needle inserted between the base of the skull and the first vertebrae (into subarachnoid space so it reaches CSF; e.g. spinal anesthesia)
What is intracerbrioventricular injection?
Needle inserted into a cannula inserted into the ventricles of the brain (bypasses blood-brain barrier)
What is transdernal administration
drugs administered through the skin (e.g. nicotine patch)
What is intrarectal administration?
Suppositories placed in the rectum and drug is absorbed into the blood stream
What are the factors affecting drug distribution?
- Lipid solubility
- Ionization and ion tapping
- pH
How does lipid solubility affect drug distribution?
o Drugs that are lipid soluble can pass through cell membranes easily, but
o Drugs that readily dissolve in fats (high lipid solubility) tend to stay in fat and are less effective; released into the blood stream slowly
How does ionization affect drug distribution?
ions are not lipid soluble; can’t easily pass through cell membrane
How does the pH of a drug affect drug distribution
o a base is more readily ionized in an acidic solution, and an acid is more readily ionized in a basic solution
What is the pKa of a substance?
pKa of substance X is the pH at which half of its molecules are ionized
What are the barriers to drug distribution?
- Placental barrier
- Blood-brain barrier
What is the placental barrier?
substances a mother takes pass thorugh the placental barrier to the fetus (high lipid soluble drugs cross more easily)
o 75-100% of mother’s drug concentration reaches fetus < 5 mins
What is the blood-brain barrier?
prevents non-lipid soluble substances getting into the brain
What is the passive transport mechanism?
non-lipid soluble substances attach themselves to carrier molecule that can pass across membranes or uses protein channel to pass through
Diffusion from high concentration to low concentration area (no energy needed)
What is the active transport mechanism?
only takes place in living membranes; uses energy; actively concentrates a substance on one side of a membrane
How does drug concentration affect kidney function?
o Kidneys filters unwanted substances out of the blood in the form of urine
o Work best with high concentrations of drug and filter at a lower rate with low concentrations in the blood
How do liver and enzyme function help excrete drugs?
o Liver uses enzymes to break down (metabolise) toxic substances into less harmful substances (metabolites ) – i.e. presence/availability of enzymes in important
How does enzyme induction help to excrete drugs?
levels of an enzyme can be increased by prior exposure ot a drug that uses that enzyme; leads to metabolic tolerance
How does enzyme depression help to excrete drugs?
metabolism is depression when: 2 drugs that use the same enzyme are taken at the same time, or one blocks enzyme activity of other
How does age affect excretion?
enzymes are not fully functional at birth; liver function is less efficient in the elderly
How does species effect drug excretion?
levels of enzymes differ in different species
What is first-pass metabolism?
any drug absorbed from the digestive system passes thorugh the liver and undergoes some degree of metabolism before going to the heart (this is first-pass metab.)
- > 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 nasal cavities)
