week 1 Flashcards
drug
chemical compound that may produce psychological, behavioural and physiological effects
psychoactive effects
alterations in cognitive, behavioural and motor processes
eg. euphoria, perceptual time distortions, hallucinations, increased libido
commonly used drug groups
alcohol
caffeine
nicotine
cannabis
hallucinogens
inhalants
major stimulants
sedative-hypnotics
opiates
the same drug may fall into different categories depending on usage
ways of studying drug use on populations
surveying
- different methodologies across surveys make it hard to compare results
canadian tobacco alcohol and drugs survey
- canadians 15 of older
- approx 20% of the canadian population will develop a substance use disorder at some point
- approx 67,000 deaths every year attributable to substance use (overdose, cancer, accident etc.)
- approx 80% of canadians in the survey consumed an alcoholic beverage in the last year
- 20% exceeded the low risk alcohol drinking guidelines
(women, less than 2 standard drinks per day, max 10 per week)
(men, less than 3 standard drinks per day, max 15 per week) - 15% current smokers
- 15% tried e cigarettes
- 20% used cannabis the past year, born in canada 30%, not born 15%
- 3% stronger drugs
dicetylmorphine
heroin
- heroin is morphine with two acetyl grops added
- minor change of the morphine molecule, enters the brain more rapidly, more rewarding and addictive
chemical name
- describe the type of molecule and the location of the chemical groups of the molecule
generic name/ non proprietary name
- commonly used name, given by a company and can only be used by that company
eg, prozac, valium
street name
- sometimes derivatives of the trade name (eg, benzedrine = bennies)
- sometimes effect of the drug (the love drug)
process of administering a drug and effects
- must be administered and absorbed (into blood circulation)
- drug is then distributed throughout the body via the circulatory system
- drug reaches the site of action, exerts its effect, leaves the site of action
- drug gets metabolised into an unactive form
- the drug and its metabolites are eliminated from the body
pharmacokinetics
-administration
- absorption
- distribution
- metabolism
- elimination
pharmacodynamics
- processes involved in the interaction of the drug with receptors
routes of administration
- oral
- absorption across the mucous membranes (snorting)
- inhalation or pulmonary
- injection (intravenously, subcutaneous, intramuscular)
routes of administration
oral
- pass from the stomach/small intestine to the bloodstream
- drugs that are alkaline (most drugs) become ionized in the stomach and cannot pass into the bloodstream
- exit the stomach into the small intestine, more alkaline and can be absorbed through diffusion
- routed to the liver where a substancial part may be metabolized (first pass metabolism) before the drug can produce an effect
routes of administration
mucous membranes
- nose, eyes, vagina, rectum, across skin
- witch trials, vaginally absorbed plant hallucinogens, poles slathered with ointments
- skin usually by accident, pesticides, nicotine patch
routes of administration
inhalation
- lung damage
- nicotine, thc, solvents (glue, gasoline)
- solvents: huffing, bagging
why are drugs inhaled are faster
- enter circulation
- intravenous, go to the right side of the heart, lungs, left side of the heart and then into general circulation
- vs lungs skip going to the right side of the heart, only 5-10 second difference
routes of administration
injection
- more rapid in areas with greater volumes of blood, muscles
- intravenous, blood flow not relevant as directly in the bloodstream
- mainlining = intravenous
- skin popping = subcutaneous
time after drug administration
- inhalation
- injection
- snorting/huffing
- injestion
factors affecting the distribution of a drug
ionization
- weak acids, weak bases
- ionized molecules are noy readily absorbed
- percent of nonionized molecules determines the rate of absorption
- less and less acidic further away from the stomach
drugs that are weak acids..
- ionized in alkaline environments
- less ionized in acidic environments
drugs that are weak bases
- ionized in acidic environments
- less ionized in alkaline environments
factors affecting the distribution of a drug
lipid solubility
- diffusion, higher to lower concentration
- if high concentration of a drug in the blood it will diffuse acrsss the blood blain barrier to an area of lower concentration, depends on the drug molecules able to penetrate the cell membranes
- lipid soluble compounds penetrate cell membranes more readily than non lipid soluble compounds
- eg heroin much more lipid soluble than morphine
blood brain barrier
- permeability characteristics of brain capillaries is restricted
- reduces diffusion of water soluble and ionized molecules, does not impede lipid soluble or un-ionized materials
- similar to the placenta, drugs taken by the mother gain access to the fetal blood supply
drug concentration in fetal blood….
- reaches 75% of that of the mother within 5 minutes of administration, can be higher sometimes
receptor binding
- drugs exert their effects by interacting with the receptors at the relevant target tissue (the brain)
- bond forms between charged groups in the receptor molecule and oppositely charged groups on the drug
- proportional effect to the fraction of occupied receptors
agonist
- drug that mimics the effect of a neurotransmitter
- may occur because agonist binds to receptors, causes neurotransmitter to leak from the presynaptic element, blocks reuptake of released neurotransmitter/ inhibits metabolic breakdown of released neurotransmitter
antagonists
- compounds that reduce the effect of a receptor agonist by binding to active receptors but producing no pharmacological action
- naloxone, opiate receptor antagonist
different drugs exert different levels of…
agonistic activity
- possible to reduce the agnostic activity of one drug by using another one that will occupy the same receptors but exert a weaker agonistic action
- limited number of receptors to be occupied, even weak agonist, additional stronger one unable to access receptors
- recovery, take agonists, don’t feel the rush anymore if they take the drug
dose-response curve (DRC)
- drugs produce biological responses that are graded according to the amount of drug administered (dose)
- vertical axis: percent of subjects exhibiting the measured effect
- horizontal axis: dose
- compare potency of drugs
- more potent more left curved
- more than one DRC per drug as they can have more than one effect
ED50
- dose of the drug which is effective in producing a response in 50% of subjects
LD50
- dose which kills 50% of subjects
therapeutic index for a drug effect
- ration LD50/ED50
- higher the ration, greater the difference, less likely chance lethal/toxic effects will occur
margin of safety
-margin of safety always smaller value than therapeutic index, more conservative measure than the therapeutic index
- LD1/ED99
tolerance
- chronic use, progressive attenuation of a drug effect
- shift to the right in the dose-response curve
sensitization
- shift to the left in the dose response curve
cross tolerance
- change in responsiveness to one drug may transfer to other drugs
tolerance does not occur to a drug….
- tolerance occurs to the drug effects
- develops at different rates to different drug effects
