W5 Flashcards
what is pharmacokinetics concerned with?
- route of administration - how drugs get in body
- absorption/distribution - how drugs move through the body
- metabolism - how drugs are transformed by the body
- elimination/excretion - how drugs are removed from body
what are psychoactive/psychotropic drugs?
- alter neurotransmission
- affect modd and behaviour
- effective in managing psychological problems
Study the interaction of psychoactive drugs in the body (brain/behaviour)
Routes of administration?
- oral
- rectal
- mucous membranes - sublingal/buccal/nasal
- transdermal
- inhalation
- injection - intravenous/intramuscular/subcutaneous
unless injected how does dug reach blood plasma to get around the body?
drug must cross cell membranes before it can get around body in blood plasma (acts as a barrier) - this diffusion of drugs across lipid membrame can be affected by factors:
- lipid soluble and small molecule drugs diffuse best
- un-ionized drug molecules are more lipid soluble
Metabolism processes?
- converts the drug chemically into another compound
- takes place mainly in liver as it has enzymes that help metabolism
elimination processes?
- urine - via kidneys
- breath - alcohol
- sweat/hair - often un-metabolised
what is a drug half life?
measure for duration of drug action
- time taken for amount of drug in plasma to fall by 50%
- important in determining how frequently a drug needs to be taken
definition for pharmacokinetics?
routes of administration, how drugs are processed by the body and how they bring about effects
definition for pharmacodynamics?
examples of agonists, antagonosts and allosteric modulators - what effect drug has and how they are bringing about that effect
whats quantifying drug effects?
efficacy and potency - used to make comparisons
oral administration +/-
most absorption in small intestine
pros:
- easy
- drug can be got out of system
- limited infection risk
- fast on empty stomach
cons:
- stomach acidity = drugs broken down
- food can make absorption unpredictable
- can cause vomitting
- first pass effect
what is the first pass effect?
- extent that the drug get metabolized by the liver before reaching systemic circulation
- this means only a proportion of the drug reaches the circulation and the drug is activated before they get to bloodstream/site of action
which administrative routes avoid first pass effect?
mucous membranes
injection
what is a transdermal patch?
- controlled release of drug through a membrane
- long duration
- moisture may lift patch
what is an agonist?
- direct agonist - Drugs bind to receptors on PoSN and have same effect as the endogenous NT eg morphine binds to opioid receptors
- indirect agonist - enhances action of natural NT and doesnt directly mimic effects eg cocaine prevents reuptake of dopamine
whats an antagonist?
- direct antagonist - binds to receptor but has no physiological effect at that receptor - receptor blocker and tones done effect of the NT
- indirect antagonist -dampens NT activity by preventing release of NT
what can direct agonist be classified as?
full and partial agonist depending on extent to which they mimic effects of NT
whats allosteric modulation?
a chemical (modulator) binds to different part of the receptor than the NT and so alters the receptors response to the NT
what is efficacy?
the dose size to produce the desired effect
what is potency?
amount of drug required to produce a specific effect - very potent if you need small abount for same effect
what is ED50?
the dose producing half the maximal effect
therapeutic index equation?
TD50(toxic dose) / ED50 = TI
that is a therapeutic dose
dose to produce effect wanted
