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pharmacology > pharmacokinetics part 2 > Flashcards

pharmacokinetics part 2 Flashcards

1
Q

phase 1 metabolism

oxidation at carbon

A

adds oh or deacylation

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2
Q

phase 1 metabolism

oxidation at Nitrogen

A

to secondary amine

to tertiary amine

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3
Q

phase 1 metabolism

oxidation at sulphur atom

A

to thioeher

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4
Q

phase 1 metabolism

drugs removed as soon as

A

it is converted into metabolite

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5
Q

phase 1 metabolism

most cases metabolite is inactive and therefore the rate of metabolism determines phase 1 metabolism

A

the duration of therapeutic effect

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6
Q

phase 1 metabolism

also metabolite can be active and therefore

A

activity remains until this is also removed from the body by further metabolism or excretion

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7
Q

pro drug

A

drug in inactive precursor

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8
Q

drug metabolism

enzymes are usually not saturated at theraputic doses therefore

A

half-life is not affected by does admin
or clearance and half life
and is not affected by other drugs which is metabolised by the same enzyme

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9
Q

microsome contains

A

cytochrome p450
p450 reductase
b5 reductase
lipid environment

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10
Q

there are —– p450 molecules per reductase

A

20

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11
Q

cytochrome p450

what is it

A

membrane bound enzyme in most tissues especially liver
part of ER
contains Fe
and binds substrate O2 and CO

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12
Q

what does cytochrome p450 do

A

catalyses oxidation of drug

generally determines deficiencies

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13
Q

what is cyto p450 induced by

A

drug: phenobarbitan

environmental : smoking

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14
Q

cyto p450 is inhibited by

A

cimetidine

grapefruit juices

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15
Q

non p450 oxidation examples

A

monoamine oxidase

alcohol dehydrogenase

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16
Q

reductions

A

p450 mediated in liver

gut flora

17
Q

hydrolysis of

A

esters

amide

18
Q

plasma pseudocholinesterase

A

breaks down mimics of Ach

19
Q

procaine is a local anaesthetic what happens to it

A

hydrolysis in plasma t1/2=10-20mins

of ester linkage

20
Q

conjugation reaction

glucurinidation what happens

A

glucuronic acid replaces the H in

  • OH
  • COOH to give water soluble inactive product
21
Q

glucurinidation activation equation

and enzyme

A

g-6-p—– g-1-p —(utp)— udp-glucose—-(nad)—- udp-glucuronic acid

UTP- glucurony transferase

22
Q

conjugation reaction

sulphation what happens

A

SO3- replaces H in -OH NH2 NHOH
very water soluble inactive
usually excretory products

23
Q

what is the sulphation activation equation

and enzyme

A

sulphate –(atp)– adenosine-5’-ps –(atp)– 3’p-adenosine -5’-ps PAPS
using enzyme sulpho-transferase

24
Q

3 main types of sulpho-tranferase

A

phenol
steroid
aryl amine

25
Q

where is sulpho-transferase found

A

cytosolic enzyme in liver
gut
most tissues

26
Q

sulphation

limited number of PAPS so what happens

A

low doses of phenol are conjugated with sulphate and high doses with glucurnic acid

27
Q

conjugation reaction

acetylation what happens

A

acetate replaces H in NH2 -SO2NH2
inactivates the functional group
no real increase in water solubility

28
Q

acetylation requires activation

A

acetate to acetylcoa

via N-acetyl transferase transfers the acetate to drug

29
Q

consequences of metabolism

A 
after metab parent drug is removed with effects
metab is now a different compound so:
no acitivity 
similar pharmacological activity
different plasma activity
toxicological action
30
Q

phase 1 metabolites what are they

A

usually inactive but show the consequences of metab

they may undergo phase 2 before excretion

31
Q

phase 2 metabolites what are they

A

nearly always inactive

usually much more water soluble and ready for excretion

32
Q

levels of p450 is determined genetically

so whats the difference with identical and non twins

A

identical : more or less same metabolism

non: different

33
Q

pharmacogenetics

mutation in plasma pseudocholinesterase what happens

A

causes no breakdown of suxamethonium

when given as a muscle relaxant it will not be removed

34
Q

isonizid can be acetylated (major) or hydrolysed

in population what happens

A

low plasma conc -fast acetylators (more effective enzyme)
poor clinical response -low incidance rate for side effects
vice versa for high plasma conc

35
Q

enzyme induction

what are the effects of phenobarbitone

A

long lasting effects
induces enzyme breakdown of dicoumarol
drugs interact with each other

36
Q

volatile route of elimination depends on

A

air borne partition coefficient
tidal vol
rate of ventilation
extent of distribution to tissues

37
Q

renal excretion

3 processes what are they

A

glomerular filtration
ph dependent reabsorption
renal tubular secretion

38
Q

biliary excretion

what happens

A

mixed in bile with bile salts
large drugs or drug conjugates are eliminated in bile
elimination depends on release in bile

pharmacology (13 decks)

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