random Flashcards
what is the only drug that has a predictable difference of 10 fold in genetic variations, explain
marker drug = 6 mercaptopurine
is used to treat acute lymphatic leukemia in children
treatment limited due to the severe toxicity of thio-purine-methyl-transferase
those with the mutation need 1/10th of the usual dose
severe toxicity = diarrhoea & neutropenia
what are the physiological determinants of the bioavailability of a drug in terms of pharmacokinetics
extend of absorption
- fraction absorbed
- first pass extraction
rate of absorption
- bolus
- zero - order
- first order
name 5 sites of drug actions on a synapse, the effect on neurotransmission and a drug that acts in this way
- Ligand-gated ion channel (GABA receptor)
- block AP firing
- decrease neurotransmission
- e.g. benzodiazepine - blockage of post-synaptic GPCR
- B2-agonist
- decreased neurotransmission
- e.g. sulbutamol - Enzyme
- reversible AChE inhibitors
- increases neurotransmission
- pyridostigmine e.g. mestinon - Pre-synaptic voltage-gated ion channel
- calcium channel blocker
- decreases neurotransmission
- e.g. varapamil
- Pre-synaptic carrier protein
- block reuptake of transporters (SSRIs)
- increases neurotransmission
- e.g. fluoxitine
angiotensin receptor blockers
e.g. losarton
competitive antagonists at AT-1 receptor
blocks activity of RAAS
Angiotensin-converting enzyme inhibitor
e.g. cilazipril
decreased levels of angiotensin 2
increased bradykinin
adverse effects = dry cough + angioedema
calcium channel blockers
e.g. varapamil
blocks smooth muscle contraction
- decreased vasoconstriction
- decreased BP
beta blocker
e.g. metoprolol
decreased contractility
decreased renin
why is there a delay in warfarin response
- Due to circulating clotting factors
- ‘Rate limiting’ step in warfarin effect is the T1/2 of clotting factors in blood
(physiological intermediate)
what does accumulation depend on
half-life
dosing interval
what drug properties are used to predict target concentration
Emax
EC50
what are the physiological determinants of the rate of drug absorption
dependent of stomach emptying which is a zero-order process. Independent on the concentration of the drug, dependent on the rate that the stomach empty as to how much of the drug gets absorbed from gut wall into portal system.
Is the gut that determines the rate not the drug itself
name the organ of clearance for:
- digoxin
- warfarin
- morphine
- theophylline
- gentamicin
- glyceryl trinitrate
digoxin = kidneys and liver
warfarin = liver
morphine = liver
theophylline = liver
gentamicin = kidney
glyceryl trinitrate = breaks down in many tissues, CL not limited to BF of a single organ
What are the physiological factors that determine the concentration observed for any given amount of drug in the body?
Apparent volume of distribution
- physiological compartments e.g. vascular, body water, extracellular.
- tissue binding
- partition - binding to fat causes a large volume of distribution. Therefore, individuals with a greater proportion of fat mass will have a low concentration due to it being bound to fat.
- plasma protein binding - leads to a smaller apparent volume as drugs bind to plasma proteins e.g. albumin and present as a high concentration. An example of a drug that carries out this mechanism is warfarin.
2 sources that tell if a medicine is subsidized or not
NZ formulary
Pharmac schedule
Name 5 classes of chemotherapy drugs, briefly describing their mode of action and
giving examples
anti-microtubules
- bind microtubules
- paclitaxel
Hormonal agents
- block action of production of sex steroids
- tamoxifen
anti-metabolites
- inhibit DNA synthesis
- methotrexate
platinum-based drugs
- binds DNA
- cisplatin
target therapies
- block oncogenic proteins
- imatinib
