REPRO REVISION PART 2 Flashcards
what are the two types of adverse drug reactions
Type A- or pharmalogical
- Most common type of ADR a consequence of the drug action.
- It is predictable from knowledge of drug pharmacodynamics & pharmakinetics
- Often dose dependent and not usually life- threatening.
- Can be resolved by lowering the dose or withdrawal of the treatment
- Generally picked up and understood during drug testing
- Type B- idiosyncratic or dizaree
- Rare
- Unrelated to known pharmacology of drug so difficult to predict
- Not dose related
- Often involves immune system and/or genetic abnormality, Can be fatal
- Need to withdraw drug – do not use again
- Need longer term and widespread use in the population to identify
- Hence important of pharmacovigilance
what are some examples of Type A Adverse drug reactions vs type B Adverse drug reactions.
type A Examples:
NSAIDS: GI bleeds, peptic ulcer, renal impairment, bronchospasm
Due to COX inhibition, reduction of PGs
Diuretics: hypotension, dehydration, electrolyte changes
Due to vasodilatation effects, excess fluid/electrolyte excretion
Opioids: vomiting, confusion, constipation, urinary retention, respiratory depression (overdose)
Due to stimulation of opiate receptors
Insulin/Oral hypoglycaemic drugs: hypoglycaemia
Due to poor control of blood glucose, excess glucose uptake, storage
All these ADRs are predictable
Consequence of drug action
Type B examples:
Hypersensitivity reactions
Can lead to anaphylaxis shock – life-threatening
Amoxicillin (broad-spectrum penicillin), Anti-convulsants
Various drugs have been linked to: Steven Johnson Syndrome Very severe, Very rare, Very difficult to predict Linked to genetics, infections, poor liver metabolism of drug metabolites Flu like symptoms/high fever Blistering of skin, mucous membranes Skin falls off <10% body affected – mortality of 5% organ damage, blindness
Why does penicillin cause an ADR is some people?
For most people penicillin is non-immunogenic, like most drugs it has a small molecular weight as it is too big the body will pick it up as a foreign object.
In some people a chemical reaction will happen where penicillin binds with a plasma protein.
The larger compound is not recognised by the body as a foreign object This leads to: Immunogenic penicilloyl hapten Trigger immune response Mast cells – release histamine Anaphylaxis
What is the reporting system to monitor suspected ADR’s -pharmacovigilance?
yellow cards- anyone can make a report but only reports people with ADR but not how many people took the drug
Black triangle- present on med packaging-highlights possible ADRs
Green form- Green form reporting is limited to a small number of (usually new) drugs. Numerator and denominator data are available, as all patients prescribed drug are monitored (Good)
Return of forms can be variable (bad)
unitary incontinence. The patient returns to their GP within two weeks complaining that the drug causes diarrhoea.
What best describes why this adverse drug reaction is defined as Type A?
a) Common
b) Identified by patient
c) Predictable
d) Severe
e) Unrelated to drug action
c
what is allergic rhinitis
Allergic rhinitis is inflammation of the inside of the nose caused by an allergen, such as pollen, dust, mould or flakes of skin from certain animals
Why do you not give a beta-blocker to an asthmatic treated with salbutamol?
Asthma and chronic obstructive pulmonary disease (COPD) have been classic contraindications to the use of beta blockers because of their potential for causing bronchospasm/ broncoconstriction.
Why should you not drink alcohol with diazepam?
Alcohol can increase the effects of diazepam. It can make you go into a very deep sleep. There’s a risk you will not be able to breathe properly, and may have difficulty waking up.
Why caution taking warfarin with grapefruit juice?
Drugs can be liver enzyme induces or inhibitors, e.g P450 (remember this is the enzyme in the first phase of metabolism breakdown)
e.g. Grapefruit juice - inhibit P450 (prevents breakdown of drugs) and inhibit P-glycoprotein transporters (prevent excretion of drugs into intestine)
Increased bioavailability of drug, potentially greater drug plasma concentrations, increased likelihood of ADRs
how do diuretics work and what could they be use to treat?
Diuretics, sometimes called water pills, help rid your body of salt (sodium) and water. Most of them help your kidneys release more sodium into your urine.
Elderly woman presents to ED with broken hip
following a collapse at home.
She is currently being treated for heart failure with a diuretic
hypotension form the diuretics making her dizzy and faint
Middle-aged man presents to ED with haematemesis. (vommiting blood)
He suffers with arthritis and regularly takes NSAIDs
blood thinnner
A young women presents to her GP suspecting she is pregnant, despite being on the contraceptive pill.
She is currently after taking St Johns Wort for depression
St John’s wort interacts with hormonal contraceptives reducing the effectiveness and increasing the risk of unplanned pregnancy.
what is the difference between nociceptive pain and neuropathic pain?
nociceptive pain- tissue damage
neuropathic pain- brain/nerve damage
what is the difference between opiated and opioids?
opiates- substance from poppy somniferum e.g. morphine, codeine
opioids- endrogenous (endorphin) and synthetic compounds (fentanyl) that produce morphine-like effects
what are some examples opioid drugs and endogenous opioids
Drugs – morphine, diamorphine (heroin), codeine, methadone Endogenous opioids – endorphin, enkephalin
what is the main receptor for opioids
MOP
Outline the definition of tolerance, dependence.
tolerance- when a person’s reaction to a drug decreases that larger doses are required to achieve the same effects
drug dependence- an adaptive state that develops from repeated drug administration, and which results in the emergence of physical and emotional withdrawal symptoms upon cessation of drug use.
