Flashcards
pharmacokinetics
Flashcards do conjunto (30)
- 1what are the 4 stages of pharmacokinetics?Absorption
Distribution
Metabolism
Elimination - 2what is absorption?the process by which a drug enters the blood circulation
(all have this phase, except some injections) - 3where is the majority of drugs absorbed?small intestine
- 4how does a drug get from the small intestine into the blood stream?1. traverses the mucosa to enter circulation via the hepatic vein, by the process of passive diffusion
- 5what happens when the drug enters the liver before entering the circulation?FIRST PASS EFFECT
- broken down into inactive metabolites - 6once in circulation, where can drugs go in theory?to all tissues in the body
- 7which 3 barriers prevent some drugs from distributing throughout the body?1. blood brain barrier
2. placental barrier - 8name on advantage and one disadvantage of the BBB1. stops toxic chemicals from entering the brain
2. stops potentially beneficial drugs from entering the brain - 9what can hinder drug distribution whilst drug is in the blood?1. being bound to plasma proteins
2. binding to other chemicals in the body - 10what happens when some drug is free and some is bound to albumin proteins?The bound drug is used as a storage pool, and there is a dynamic equilibrium between the free and bound drug.
- 11what type of tissue can highly lipophilic drugs accumulate in?adipose tissue
- 12accumulation in adipose tissue allows for release in circulation over long time, give an example of how this can be used clinically?give a decanoate to a non-compliant schizophrenia patient so that there is continuous release over 4-6 weeks
- 13what does metabolism do?converts a lipiphlic drug into a more hydrophilic drug to prepare for excretion
- 14are the metabolites of most drug active or inactive?majority made inactive, however, some made pharmacologically active
- 15give an example of drug which has an active metabolite?IMIPRAMINE metabolised to DESIPRAMINE, both the parent drug and the metabolites are active
- 16what is the major organ of metabolism?the liver
- 17why are the enzymes in the liver unusual? (2 reasons)1. They are non-selective, one enzyme can metabolise 100's of drugs
2. they are inducible - 18give an example of enzyme inductionPHENOBARBITONE
- increases the activity of these enzymes
- potentially lessoning the effects of other drugs
- dangerous interaction with warfarin - 19what is the name for the group of enzymes which account for the metabolism of almost 90% of drugsCYTOCHROME P-450
- 230 isoenzymes - 20what are the 2 stages of hepatic metabolism?1. oxidation - involving cytochrome p-450
2. other enzymes account for metabolism - 21why do some people tolerate drugs better than others?1. hypersensitivity
2. altered metabolism - 22what is a pharmacogenetic disorder?inborn error of drug metabolism
- 235 polymorphisms in CYP2D6 account for differences in metabolism for 25% of drugs, give an example of onethe SSRI FLUOXETINE
- inhibits numerous reactions catalysed by CYP2D6
- may give rise to significant drug interactions, including MDMA - 24what effect does a decline in liver function have on metabolism?will slow metabolic breakdown
- 25what is the primary organ for the excretion of drugs?the kidney, in urine by renal excretion
- 26what other ways are drugs excreted?- saliva
- sweat
- faeces
- expired air - 27give an example of how this knowledge is used in society?the breathalyser test which tests for ethanol in a persons breath
- 28what is the half life of a drug?The time required for a drug to reach half of its peak plasma levels
- 29what use is the information provided by drug half lives?1. guide to the duration of action of the drug
2. dosing intervals required to reach optimal levels - 30what pharmaokinetic factors are related to the half life of a drug?-binding to plasma proteins
- accumulation in adipose tissue
- metabolism
- rate of elimination
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- FlashCards sobre pharmacokinetics, criado por Johnny S em 14-01-2015.
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- Johnny S
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