Pharmacology And Medications Flashcards
Name a drug for hormone therapy in breast cancer and explain it s function
Tamoxifen - targets breast cancer cells with oestrogen receptors
Name a drug for treating breast cancer which has HER2 receptor
Herceptin
define hypersensitivity
reaction to an allergen which in the same dose is tolerated by normal subjects
explain the pathophysiology of type 1 hypersensitivity
Prior exposure to the antigen/drug
IgE antibodies formed after exposure to molecule
IgE becomes attached to mast cells or leucocytes, expressed as cell surface receptors
Re-exposure causes mast cell degranulation and release of pharmacologically active substances such as histamine, prostaglandins, leukotrienes, platelet activating factor etc
explain type 2 hypersensitivity reactions
Drug or metabolite combines with a protein
Body treats it as foreign protein and forms antibodies (IgG, IgM)
Antibodies combine with the antigen and complement activation damages the healthy cells e.g. rheumatoid arthritis
Type 2 hypersensitivity is like a case of mistaken identity in the body. It happens when the immune system mistakenly targets healthy cells or tissues, thinking they’re harmful. This can lead to various conditions where the body attacks its own cells or cells perceived as foreign, causing harm or damage. Examples include autoimmune disorders like rheumatoid arthritis or certain types of anemia.
explain type 3 hypersensitivity
Antigen and antibody form large complexes and activate complement
Small blood vessels are damaged or blocked because of accumulation of these complexes. Accumulation of these deposits also triggers inflammation as leucocytes are attracted to site.
Ex.: glomerulonephritis, vasculitis.
explain type 4 hypersensitivity
Antigen specific receptors develop on T-lymphocytes
Subsequent administration leads to local or tissue allergic reaction and subsequent formation of granulomas.
E.g. contact dermatitis
E.g. Stevens Johnson syndrome (TEN)
what are the symptoms of anaphylaxis
must say rash, swelling of lips face oedema, central cyanosis, wheeze, hypotension, cardiac arrest
what is the ABCDE approach and how do you examine each
airway - involves assessing the patient’s airway to ensure it’s open and unobstructed. If there’s a blockage or if the patient is having difficulty breathing, immediate interventions such as clearing the airway or placing an artificial airway
breathing - Evaluate the patient’s breathing pattern, rate, and oxygenation. Ensure adequate ventilation, and address any respiratory distress or signs of inadequate breathing. Interventions might include providing supplemental oxygen, assisting ventilation, or treating underlying causes of respiratory failure.
circulation - Assess the patient’s circulation, including their pulse, blood pressure, and signs of adequate perfusion. Treat any signs of shock or inadequate blood flow, such as administering fluids, medications to support blood pressure, or interventions to improve cardiac function if needed.
disability - evaluating the patient’s neurological status, including their level of consciousness, neurological deficits, or signs of altered mental status.
exposure - checking the patients for wounds and things and also look around to see if the environment is safe for the patient so that you can take action if required
what are common triggers of anaphylaxis
peanuts
cow’s milk
gluten
antibiotics
chemotherapy drugs
contrast media
NSAIDs
insect venom
describe the late response in anaphylaxis
happens a couple hours after the initial response –> due to the recruitment of more inflammatory mediators you get a second anaphylactic episode
what is the management of anaphylaxis
Commence basic life support. ABC
Stop the drug if infusion
Adrenaline IM –> 500micrograms(300mcg epi-pen)
High flow oxygen
IV fluids – aggressive fluid resuscitation
If anaphylactic shock may need IV adrenaline with close monitoring
Antihistamines not first line treatment but can be used for skin symptoms
Corticosteroids no longer recommended
Lie sitting or flat to breathe more easily
Lift legs to help fluid circulate prevent oedema
how does adrenaline affect all adrenergic receptors
alpha 1 receptors
Vasoconstriction - increase in peripheral vascular resistance, increased BP and coronary perfusion
Reduces oedema
Beta1-adrenoceptors
positive ionotropic and chronotropic effects on the heart
Beta 2 adrenoreceptors bronchodilates
alpha 2 adrenoreceptors
Attenuates further release of mediators from mast cells and basophils by increasing intracellular c-AMP and so reducing the release of inflammatory mediators (the negative feedback loop)
what do you do if a patient has refractory anaphylaxis
refractory anaphylaxis –> no improvement in symptoms despite 2 doses of IM adrenaline
give IM adrenaline every 5 min until IV adrenaline infusion is started
high flow o2
monitor heart for cardiac arrhythmia
what blood test is used to confirm anaphylaxis and why
mast cell tryptase because it shows rate of mast cell degradation
risk factors for hypersensitivity
Females > Males
EBV (Epstein barr virus)
HIV
Previous drug reactions
Uncontrolled asthma
Certain HLA groups
liver metabolism
what are μ receptors
one of the three main types of opioid receptors found in the body. Activation of the μ receptor plays a significant role in mediating the effects of opioid drugs.
A 60 year old woman presents to her General Practice with tiredness and dry skin. She is found to have hypothyroidism and is started on oral levothyroxine 75mcg tablets, 1 tablet daily.
Levothyroxine tablets have a variable bioavailability between individuals.
Which of the following is most likely to cause a reduction in bioavailability?
A) Short bowel syndrome
B) Reduced renal function
C) Low albumin
D) Hepatic impairment
E) Low body weight
A
Bioavailability is the proportion of the substance that enters the bloodstream
A pharmaceutical company is developing a new drug (drug x) for the treatment of heart failure. The half life (t1/2) of drug x is found to be 6-10 hours (average 8 hours).
Which of the following could increase the half life (t1/2) of a drug?
A) Co-administration of a CYP450 enzyme inducer
B) Impaired absorption from GI tract
C) Increasing the administered dose
D) Changing formulation from oral to IV
E) Renal impairment
E
Which of the following types of drug interactions would result in an increased therapeutic effect and potential drug toxicity?
A) Amiodarone displacing warfarin from plasma albumin
B) Bisoprolol opposing the action of salbutamol at β2 receptors
C) Oral iron forming an insoluble drug complex with doxycycline
D) Phenytoin inducing the CYP450 enzyme which metabolises warfarin
E) Rifampicin inducing Pgp which transports rivaroxaban
A
Drug y is an antagonist at B1 receptors. Which of the following adverse drug reactions is a B1 antagonist most likely to cause?
A) Tremor
B) Bradycardia
C) Urinary retention
D) Hypertension
E) Dry mouth
B
Which type of adverse drug reaction is most likely to be identified during clinical trials?
A) Bizzare
B) Delayed
C) Chronic
D) Augmented
E) Genetic
D
Match the following pharmacodynamic mechanisms with the most likely adverse drug reaction:
Bradycardia
Tremor
Pupil constriction.
Constipation 𝜇 agonism
Urinary retention
M3 antagonism
M3 agonism
𝛽2 agonism
𝛽1 antagonism
𝜇 agonism
Bradycardia 𝛽1 antagonism
Pupil constriction M3 agonism
Urinary retention M3 antagonism
Tremor 𝛽2 agonism
what is the difference between first order and second order kinetics
first order –> constant % drug is eliminated over time –> trend is exponential for drug plasma conc/time
second order –> constant amount of drug is eliminated over time –> trend is inverse proportional for drug plasma conc over time
what is a modified release drug
medication designed to release active ingredients in a controlled or extended manner
what are the different types of modified release drugs
extended-release - slow release over time
delayed-release - release drugs at a specific location in the GI
pulsatile-release - release of drug at specific intervals
what effect does modified release doing have on the maximum plasma concentration
it decreases it because it slows down the absorption of the drug
how is the half-life of an IV drug affected if you give it at half the dose
it is not affected
what does the half-life of a drug depend on
clearance and Vd of the drug
how long does is take to clear 97% of a drug from the body in half lives in a first order kinetics drug
5 half lives
what kind of drugs are more likely to give withdrawal symptoms; short or long half life
short half life
what is the steady state in drug administration
the point at which the rate of drug input = the rate of drug elimination
you are administering a drug of first order kinetics
if you give a continuous IV infusion how long does it take in half lives till you reach steady state
5 x half life –> because you need to start eliminating the drug to reach a steady state
what effect does a 50% dose reduction in an iv infusion have on drug plasma concentration at steady state and the time required to reach steady state
drug plasma concentration –> reduction to half
time required to reach ss –> unchanged
what effect does reduced clearance have on half life, time needed to reach steady state, and plasma concentration at steady state.
they will all increase
what is a loading dose
providing an initial larger dose of a drug to ensure a quick therapeutic response –> used in emergencies
A 66 year old woman is admitted to A&E with SOB and haemoptysis.
CTPA confirms bilateral PEs. She is prescribed an IV loading dose of unfractionated heparin 5000 units followed by an IV continuous infusion. What effect will the loading does have on the heparin pharmacokinetics?
a) reduce half life
b) increase bioavailability
c) reduce time to steady state plasma conc
d) increase Vd
e) reduce drug clearance
c
what is druggability
a target in our bodies that is known to have high affinity for binding drugs and which upon binding with the drug acts with a therapeutic benefit to patient
what are potential drug targets
receptors
enzymes
transporters
ion channels
what are statins
cholesterol lowering drugs
what are the 4 types of receptors
ligand-gated ion channels
G protein coupled receptors
Kinase-linked receptors
Nuclear receptors
what is potency
the amount of drug that you need to cause a maximal response
what are all of the types of histamine receptors and their roles
H1 - allergic reactions
H2 - gastric acid secretion
H3 - associated with CNS disorders
H4 - immune system and inflammatory conditions
what is EC50
the concentration that gives half the maximal response
what are receptor affinity and efficacy
affinity - how well a ligand binds to a receptor
efficacy - how well a ligand activates a receptor
how i potency measured
via EC50
what is inverse agonism
when a drug bonds to the same receptor as an agonist but produces the opposite response to the agonsit
