Medications pharmacodynamics and pharmacokinetics Flashcards
What are the contra indications of Haloperidol
CNS depression, history of ventricular arrhythmia, parkinsons disease, QT interval prolongation, recent myocardial infarction,
what are the main side effects of haloperidol
depression, eye disorders, nausea, neuromuscular dysfunction, weight decreased, arrhythmias, constipation, dry mouth, movement disorders, QT interval prolongation
what is the mechanism of action for haloperidol
antipsychotic that works by blocking post synaptic dopamine receptors particularly D2 receptors in the brain
antagonising effect
reduces dopamine activity which alleviates symptoms
how is the absorption of haloperidol
haloperidol is lipophilic and therefore readily absorbed
what is haloperidols peak plasma concentration with oral administration
1-6 hours
what is haloperidols bioavailability after first pass hepatic metabolism
40-75%
what is haloperidols peak plasma concentration with intramuscular administration
20 minutes
where is haloperidol metabolised
metabolised in the liver with only 1% of the administered dose excreted unchanged in urine
what is haloperidols half life
14.5-26 hours
what is the mechanism of action for lorazepam
binds onto post synaptic GABA receptors
this will cause an increase of GABA inhibitory effects on the central nervous system
= open up more chloride ion channels
= makes the neuron less responsive
= more relaxed and promote calming and sedating effect
what is the absorption of lorazepam and bioavailability
readily absorbed with bioavailability of 90% when given orally
what is peak plasma concentration of lorazepam
2 hours
how is lorazepam metabolised and how is it eliminated
hepatically metabolised and mainly eliminated by the kidneys with around 88% recovered in urine
what is lorazepam half life
14 hours
what is clozapines mechanism of action
antagonism of D2 Dopamine receptors and serotonin receptors
= reduces positive symptoms
how well is clozapine absorbed and peak plasma concentration time
almost complete absorption and peak plasma occuring between 1 to 6 hours
what is clozapines bioavailability like and why
low oral bioavailability because it primarily undergoes first pass metabolism in the liver
- it is broken down before reaching the blood stream
what is clozapines metabolism like and excretion
almost completely metabolised and only a small amount of unchanged clozapine is detectef in the urine and faeces
what is clozapines half life
ranges from 4 to 12 hours
what is the mechanism of action of olanzapine
blocks dopamine D2 receptors antagonising effect = reduce positive symptoms
and also blocks serotonin receptors
= improve negative symptoms
absorption of olanzapine and peak plasma concentration
well absorbed after oral administration reaching peak plasma concentrations within 5-8 hours
what is olanzapines bioavailability
60%
metabolism of olanzapine and elimination
extensively metabolised in the liver and it is mainly eliminated through metabolism hence only 7% is found in its unchanged form
eliminated through 53% urine and 30% faeces
olanzapines half life
ranges between 21-54 hours
average 30 hours
venlafaxine mechanism of action and pharmacodynamics
inhibits the reuptake of both serotonin and norepinephrine at the presynaptic terminal
this results in increased levels of neurotransmitters available at the synapse for post synaptic receptors to absorb
increased serotonin= associated with alleviation of depression symptoms
venlafaxine absorption, peak plasma concentration and bioavailability
well absorbed with absolute bioavailability og 45%
peak plasma concentration 2-3 hours
how is venlafaxine metabolised and what is the half life
metabolised mainly in the liver and eliminated via the kidneys through urine which is approx 87% of it being unchanged
half life approx 5 hours
what is the mechanism of action and pharmacodynamics of sertraline
SSRI improves or relieves symptoms of depresion via the inhibition of serotonin reuptake at the pre synaptic neuron
= increased synaptic serotonin concentration
absorption of sertraline
bioavailability and peak plasma concentration
slowly absorbed with peak concentrations occuring at 4-10 hours
bioavailability = 44%
how is sertraline metabolised and excreted
heavily metabolised in the liver and because of that excretion of unchanged drug in urine is minor route
half life of sertraline
approx 26 hours
mechanism of action of salbutamol and pharmacodynamics
binds to beta 2 adrenergic receptors in the smooth muscle of the airways resulting in it relaxing = bronchodilation
= less airway resistance and more gas exchange
salbutamol absorption and bioavailability
absorbed in the lungs on the bronchial smooth muscle
oral bioavailability is low
how is salbutamol metabolised and eliminated and half life
metabolised in the liver and excreted in the urine with a half life of 2-5 hours
Ipratropium bromide mechanism of action and pharmacodynamic
inhibit the action of acetylcholine on muscarinic receptors in the bronchial smooth muscle (antagonist)
muscarinic receptors mediate bronchoconstriction and mucus secretion therefore by blocking these receptors- ipatropium results in bronchodilation and decreased mucus production
= better airflow
what is the absorption like for ipatropium bromide and peak plasma concentration and bioavailability
topically active but poorly absorbed
low peak concentrations after 1-2 hours
low bioavailability of 2%
how is ipatropium bromide metabolised and how is it eliminated
metabolised in the gastrointestinal tract and about 90% of the dose is excreted unchanged via urine
what is ipatropium bromides half life
1.6 hours
what is the mechanism of action and pharmacodynamics of Carbocisteine
mucolytic agent works by modifying the structure of mucus making it less viscous and easier to expel
it breaks down the bonds in mucoproteins and restores fluidity of mucous
= easier to clear mucus which reduces airway obstruction and improves air flow
what is the absorption like for Carbocisteine and peak plasma concentration
rapidly absorbed in the gastrointestinal tract with peak concentrations achieved within 1-2 hours
where is Carbocisteine metabolised and eliminated
metabolised in the liver and around 36-60% of an administered dose is detected unchanged in the urine
what is half life of carbicostine
1.3 hours
Amoxicillin mechanism of action and pharmacodynamics
competitively inhibits penicillin binding proteins
it inhibits the bacterial cell wall synthesis therefore cell walls become weaker and stops the growth of bacteria
what is the absorption like for Amoxicillin, bioavailability
well absorbed orally with a bioavailability of 60%
Amoxicillin- how is it metabolised and what is the route of elimination
minimally metabolised in the liver and excreted primarily through the kidneys in the urine around 70-78% eliminated after 6 hours
what is the half life of Amoxicillin
approx 1- 1.5 hours
Prednisolone what are the mechanism of action and pharmacodynamics
corticosteroids bind to receptors inhibiting pro inflammatory signals
it exerts anti-inflammatory signals and immunosuppressive effects - decrease inflammation and immune response
inhibits activation of T cells
decrease vasodilation and permeability of capillaries therefore minimising tissue swelling
what is the absorption like and bioavailability for Prednisolone
well absorbed orally with peak plasma concentration reached within 1-2 hours and 70% bioavailable
Prednisolone metabolism and excretion
extensively metabolised in the liver and excreted mainly in the urine
Mannitol - mechanism of action and pharmacodynamics
osmotic diuretic = increasing osmolarity therefore it reduces water reabsorption
water is drawn out of the cells which reduces fluid volume
promotes a osmotic water gradient promoting water movement = reduces intracranial pressure
Prednisolone- half life
2-3 hours
Mannitol- absorption
absorbed intravenously- high absorption
Mannitol- metabolism and elimination
minimal metabolism in the body
excreted unchanged in the urine - approx 80% of the dose is eliminated within 3 hours of administration
mannitol- half life
4.5 hours
what is the mechanism of action of paracetamol and pharmacodynamic
inhibits an enzyme in the brain which results in decreased production of prostaglandins involved in pain
so paracetamol stops chemical messengers by reducing the pain signals to the brain
overall reduces pain by decreasing prostaglandin production
paracetamol - pharmacokinetics absorption and peak plasma concentrations
rapidly absorbed in the gastrointestinal tract with peak plasma concentrations reached within 30-60 minutes and bioavailability of 88% bioavailability
paracetamol- metabolism and elimination
mainly metabolised in the liver and mainly excreted in the urine
90% of the administered dose is excreted within 24 hours
what is the half life of paracetamol
2-4 hours
