Drugs studied Flashcards
how does activated charcoal work?
1) adsorption of toxin onto the surface of the charcoal, reducing its absorption into the blood
2) increasing the rate of elimination
which drugs are most effectively removed by activated charcoal
weakly ionic drugs like benzodiazepines and methotrexate
common side effects of activated charcoal?
black stools, vomiting, intestinal obstruction
Aspiration- pneumonitis, bronchospasm, airway obstruction
When to give single and repeat doses of activated charcoal
single dose (50mg) if poison ingested less than 1 hour ago additional doses can be given after 4 hours if they are on aspirin, opioids or TCAs as these delay gastric emptying
how does adrenaline work in anaphylaxis
acts at adrenoreceptors to bring about the fight or flight response- vasoconstriction of the blood vessels supplying the skin, increased heart rate, increased force of contraction, vasodilation of blood vessels supplying the heart, bronchodilator and suppression of inflammatory release from mast cells
adrenaline side effects
adrenaline-induced hypertension, anxiety, tremor, headache, palpitations
angina, mi and arythmia in patients with existing heart disease
adrenaline interactions
interacts with beta blockers to cause wide-spread vasoconstriction
anaphylaxis dose of adrenaline
500mg IM
list 3 aminoglycoside antibiotics
gentamicin, amikacin, neomycin
what are the indications of aminoglycosides? [4]
severe infections caused by gram negative aerobes (e.g. pseudomonas aeruginosa)
1) severe sepsis
2) complicated UTI and pyelonephritis
3) biliary and intrabdominal sepsis
4) skin, eye or ear infections
MOA if aminoglycosides
inhibit protein synthesis by binding to ribosomes - bacteriocidal
adverse effects of aminoglycosides [2]
nephrotoxicity (more likely in combo with cyclosporin, cephalosporin, vancomycin and platinum chemotherapy)
ototoxicity (more likely in combo with loop diuretics and vancomycin)
in which groups are aminoglycosides used with caution [4]
neonates, elderly, renal impairment, myasthenia gravis
aminoglycosides ROA and dosing
Intermittent IV infusion OD - dose depends on weigh and renal function
dosing interval determined by plasma level monitoring ( usually 24 hours but can be longer in renal impairment)
aminoglycosides length of course
less than 7 days
monitoring parameters for aminoglycosides
temp, crp
renal function, plasma conc 18-24 hrs after first dose
Indications of amitriptyline
1) depression
2) neuropathic pain
amitriptyline side effects
antimuscarinic block- dry mouth, constipation, urinary retention, blurred vision
sedation, hypotension
arrhythmia, ECG changes
convulsions, hallucinations, mania
dopamine block- breast changes, sexual dysfunction, EPSEs
amitriptyline overdose
severe hypotension, arrhythmia, convulsions, coma, respiratory failure- death
amitriptyline withdrawal effects
sleep disturbances, flu like symptoms, GI upset
interactions of amitriptyline
monoamine oxidase inhibitors-> serotonin syndrome
TCAs- can augment side effects
Amitriptyline starting dose in neuropathic pain
10mg ON
amitriptyline counselling points
carry on for at least 6 mo after you start feeling better
dont stop treatment suddenly- withdrawal effects - reduce slowly over 4 weeks
list 4 antihistamines
cetirizine, loratadine, fexofenadine, chlorphenamine
how do antihistamines work?
h1 receptor antagonist- prevents histamine binding
histamine causes oedema (due to increased capillary permeability) erythema (vasodilation) and itching (sensory nerve stimulation)
used as an adjunct to adrenaline in anaphylaxis
antihistamine SEs
chlorphenamine- 1st gen- sedation
others dont cross bbb so no CNS side effects
in which population should antihistamines be avoided and why
severe liver disease- may precipitate hepatic encephalopathy
chlorphenamine in anaphylaxis- dose and route
10mg IV or IM
antihistamines counselling point
hay fever- should improve sneezing, itching, runiness- not so good for nasal congestion
chlorphenamine- sedative effect- might want to take at night - driving risk, avoid taking with alcohol
list 3 anti-platelet ADP-receptor antagonist drugs
clopidogrel, ticagrelor, prasugrel
3 indications of anti platelet drugs in combo with aspirin
1) acute coronary syndrome
2) prevention of occlusion of coronary artery stent
3) secondary prevention in cardiovascular/ cerebrovascular/ peripheral artery disease
MOA of clopidogrel (ticagrelor and prasugrel)
bind to pY12 subtype of G protein coupled ADP receptors on the surface of platelets- down stream events lead to platelet aggregation
side effects of ADP-receptor antagonists
bleeding, GI upset, thrombocytopenia (platelet deficiency)
ADP-receptor antagonists are not appropriate for
should not be used in patients with active bleeds
caution in renal and hepatic impairment
should be stopped 7 days before elective surgery
interactions of clopidogrel
clopidogrel is a pro drug
interacts with cyp 450 inhibitors- omeprazole, ciprofloxacin, erythromycin, antifungals, SSRIs
ticagrelor interactions
not a pro drug- interacts with cyp inhibitors and inducers
which drugs increase bleed risk of adp receptor antagonists?
antiplatelets, anticoagulants like heparin, NSAIDs
clopidogrel dose
loading dose= 300mg
maintenance dose= 75mg
oral only
clopidogrel counselling
purpose- to prolong life and prevent heart attacks and strokes
stent?- stress importance of taking every day as directed to keep stent clear
check if they are actively bleeding
if they start bleeding it may take loner for it to stop
report unusual bleeding to doctor
aspirin indications
1) ACS/ stroke
2) secondary prevention for cardiovascular/ cerebrovascular/ peripheral arterial disease
MOA of aspirin
irreversible inhibition of COX
(reduces production of thromboxane from arachidonic acid) which prevents platelet aggregation
aspirin SEs
GI irritation
peptic ulceration, haemorrhage
bronchospasm
high dose- tinnitus
aspirin overdose
hyperventilation, hearing loss, metabolic acidosis, confusion -> convulsions, cardiovascular collapse, respiratory arrest
when should aspirin be avoided
children under 16- Reyes syndrome
aspirin sensitivity (or NSAID sensitivity)
third trimester pregnancy- can cause premature closure of ductus arteriosus
caution- peptic ulcers, gout
doses of aspirin
LD= 300mg maintenance= 75mg stroke= 300mg od for 2 weeks pain= 4g
aspirin gastroprotection
should be considered if lots of risk factors for go complications / NSAIDs/ prednisolone
omeprazole 20mg
aspirin counselling
take after food
watch out for indigestion/ bleeding issues- report them to ur doctor
list 5 beta blockers
bisoprolol, atenolol, propranolol, metoprolol, carvedilol
5 indications of beta blockers
1) ischaemic heart disease- angina
2) chronic HF
3) AF
4) SVT
5) hypertension
how do beta blockers work?
act at beta 1 receptors in the heart to reduce force of contraction and rate of conductivity in heart which reduces cardiac work & oxygen consumption of heart
arrhythmia- prologue refractory period of AV node
reduce renin secretion by kidney to lower blood pressure
SEs of beta blockers
fatigue, cold extremities, headache, GI disturbances, sleep disturbances & nightmares
impotence in men
cautions and contraindications - beta blockers
contraindicated in asthmatics (bronchospasm) and heart block
can use in copd but chose bisoprolol/ metoprolol (more b1 selective)
HF- start at low dose and up titrate slowly
caution- haemodynamic instability,
dose reduction in hepatic failure
which class interact with beta blockers?
non- dihydropyridine calcium channel blockers (verapamil, diltiazem) - HF, bradycardia, asystole
beta blockers counselling
explain rationale for treatment, discuss side effects (impotence!)
HF- may cause worsening of symptoms at first (seek attention if this happens)
obstructive airway diseases- stop and seek attention if breathing difficulties arise
list 2 cephalosporins
cefalexin, cefotaxime
list 2 carbapenems
meropenem, ertapenem
indications of cephalosporins and carbapenems
1) urinary and respiratory tract infections
2) parenteral- very severe and complicated or caused by resistant organisms
target organism of cephalosporins
broad spectrum antibiotic- targeting gram-negative bacteria (e.g. pseudomonas aeruginosa) - first to fifth generation get more activity against them , variable activity agains gram positive organisms
why are cephalosporins and carbapenems less susceptible to resistant mutations
cephalosporins and carbapenems are naturally more resistant to beta lactamases because beta lactic ring is fused to another bulky group
mode of action of cephalosporins and carbapenems
inhibit enzymes responsible for the cross linking of peptidoglycan in bacterial cell walls - weakens cell wall preventing the bacterial cell from maintaining osmotic gradient-> cell wall swells-> lysis-> cell death
Side effects of cephalosporins and carbapenems
GI upset, antibiotic-associated colitis
C diff overgrowth (due to death of gut flora)
hypersensitivity ( can be cross reactive in penicillin allergy)
neurological toxicity including seizure
contraindications and cautions cephalospronis and carbapenems
caution- at risk of c diff, epilepsy, renal impairment
ci- allergy, penicillin allergy
interactions- cephalosporins, carbapenems
warfarin- enhance anticoagulant effect- kill gut flora which synthesise vit K
aminoglycosides- nephrotoxicity
valproate- reduce plasma conc
Roa of carbapenems
iv only
counselling carbapenems and cephalosporins
check no penicillin/ b-lactam antibiotic allergy
seek medical advice if rash or other unexpected symptom develops
if you get a reaction- tell them not to take this class of antibiotics in future
list 3 systemic glucocorticosteroids
prednisolone, hydrocortisone, dexamethasone
indications of systemic glucocorticosteroids
1) allergic inflammatory disorders e.g. asthma
2) autoimmune diseases e.g. IBS
3) cancer
4) adrenal insufficiency, hypopituitarism
Moa of glucocorticosteroids
bind to glucocorticoid receptors in cytosol -> translate to the nucleus and bind to glucocorticoid-response elements on DNA to regulate gene expression
up regulate anti-inflammatory genes and down regulate pro-inflammatory genes (like cytokines and TNF alpha)
- suppress circulating monocytes and eosinophils
- increase gluconeogenesis by increasing circulating amino acids and fatty acids
- mineralocorticoid receptor- increase sodium and water retention and increase potassium execretion
glucocorticosteroids should be used in caution in…
people with infections and children
gluco-corticosteroids interact with
NSAIDs- increase bleed risk
b2 agonists, theophylline, loop/ thiazide diuretics- enhance hypokalaemia
cyp p450 inducers (carbamazepine, phenytoin, rifampicin)
vaccines- reduce immune response
dose of prednisolone in acute asthma
40mg od
when should corticosteroids be taken?
in the morning (reduce insomnia)
what classes are commonly prescribed with corticosteroids
steroid sparing agents- azathioprine, methotrexate
bisphospates
PPIs
corticosteroid counseling points
- start to feel better in 1-2 days
- dont stop suddenly- withdrawal effects
- steroid card to carry with them
- risks and benefits- oesteoporosis, fractures, diabetes
list 4 DOACs
apixaban, dabigatran, edoxaban, rivaroxaban
indications of DOACs
VTE secondary prevention
AF primary prevention
how do DOACs work?
act on final common pathway- inhibit factor Xa- prevent conversion of prothrombin into thrombin
dabigatran inhibits thrombin directly and prevents fibrin -> fibrinogen conversion
SEs of DOACs
bleeding (epistaxis and GI) anaemia, GI upset, dizziness, elevated liver enzymes
in which people should DOACs be avoided
active bleeding, risk factors of major bleed (e.g. peptic ulcer/ cancer/ recent surgery),
preg/ BF
dose reduction needed in renal and liver disease
DOAC interactions
other antithrombotic drugs- heparin, anti platelets, NSAIDs
anticoagulant effect increased by macrolides, protease inhibitors, fluconazole
decreased by rifampicin, phenytoin
rivaroxaban dosing regimen
rivaroxaban- 15mg every 12hrs for vte
20mg OD in AF lifelong
10mg od for 14 days VTE prophylaxis after knee replacement
rivaroxaban, but not the other DOACs should be taken…
with food
counselling for DOACs
- risk of bleed
- provide alert card, show card to all health care providers especially if have an accident/ surgery/ new meds)
- contact doc if serious bleed/ weakness/ tiredness/ breathlessness (anaemia)
what are 3 indications of gabapentin and pregabalin
1) add-on for focal epilepsies
2) neuropathic pain
3) pregabalin- anxiety
how do gabapentin and pregabalin work?
bind to voltage sensitive calcium channels which inhibits the release of NTs which reduces neuronal excitability in the brain
side effects gabapentin
drowsiness, dizziness, ataxia - usually improve over first few weeks of treatment
cautions and contraindications gabapentin
dose reduction in renal impairment
gabapentin interactions
benzodiazepines and other sedating drugs- enhance sedative effect
gabapentin counselling
- diziness and drowsiness- this is why we start low and uptitrate- should improve over next few weeks
- avoid driving/ operating heavy machinery til settled
4 indications of metronidazole
1) antibiotic associated collitis
2) oral infections
3) surgical and gynaecological infection
4) protozoal infections
metronidazole is effective against
anaerobic bacteria and protozoa
Mao of metronidazole in anaerobes
reduced to nitroso free radical which binds to DNA causing damage-> cell death
metronidazole SEs
GI upset, hypersensitivity reactions
long term/ high dose= neurological effects: peripheral and optic neuropathy, seizures, encephalopathy
warnings- metronidazole
dose reduction in severe liver disease
avoid alcohol -> flushing, headache, nausea, vomitting
interactions of metronidazole
inhibits CYP- reduces warfarin metabolism & phenytoin
CYP inducers (rifampicin) - reduces antibiotic effect
increases toxicity of lithium
usual oral dose metronidazole
400mg every 8 hours
metronidazole councelling
check allergy
if allergy develops tell them not to take metronidazole in future
dont drink alcohol until 48hrs after treatment
naloxone indication
opioid overdose
how does naloxone work?
binds to opioid receptors- competitive antagonist (displaces morphine)
adverse effects of naloxone
opioid withdrawal effect- pain, restlessness, nausea and vomiting, dilated pupils cold dry skin, goose bumps
cautions with naloxone
opioid dependence- risk of withdrawal
lower doses in palliative care
acute opioid toxicity treatment
400-1200 micrograms naloxone
indications of nitrofurantoin
1) UTI
2) UTI prophylaxis (recurrent infections)
nitrofurantoin moa
damages bacterial DNA-> cell death
nitrofurantoin SEs
gi upset, hypersensitivity, dark yellow/ brown urine chronic pulmonary reactions hepatitis, peripheral neuropathy neonates- haemolytic anaemia
CIed groups for nitrofurantoin
pregnant women close to term, babies under 3 mo, renal impairment
acute uncomplicated UTI treatment
nitrofurantoin 50-100mg every 6 hours
how should nitrofurantoin be taken
take with food or milk
counselling nitrofurantoin
check allergies, urine colour (yellow/ dark brown)
report pins and needles and breathlessness
what are COX 1 and 2 responsible for
COX 1- GI mucosal integrity, maintains renal perfusion
COX-2- inducible in response to inflammation
which NSAID has highest gi risk and lowest cardiovascular risk?
Naproxen
which NSAID has the lowest GI risk and the highest cardiovascular risk?
Diclofenac
NSAID interactions
aspirin, corticosteroids, anticoagulants, SSRIs, venlafaxine, ACEi, diuretics
counselling NSAIDs
indigestion- stop treatment & contact doc
longterm (>10 days)- not recommended bc SEs
stop if unwell/ dehydrated (reduce kidney damage)
who needs a PPI with NSAIDs?
> 65/ previous peptic ulcer/ co-morbidity/ aspirin/ prednisolone
opioids SEs
respiratory depression nausea and vomitting- tends to settle small pupils constipation itching tolerence & dependence withdrawal effects on cessation
morphine dosing
oramorph for breakthrough -about 1/6th dose of MR MST continus maintenance
morphine counselling
addiction isn’t an issue when used for pain relief- dont worry
may need to increase dose due to tolerance effect- dont be alarmed
take slow release every 12 hours, if that’s not covering the pain take fast acting
may expiernce but this should improve- offer metoclopramide
constipation- offer Senna, stay hydrated
drowsy? dot drive
weak opioids (tramadol/ codeine/ dihydrocodeine) councelling
weaker version of morphine
take at regular intervals for best results
laxative?
drowsy? dont drive
out of reach of children
careful if contains paracetamol dont take paracetamol
paracetamol counselling
feel effect half an hour after taking
dont exceed max dose- liver poisoning
remind them that paracetamol in cold & flu pills and stuff- avoid overdose
penecillin interactions
reduces excretion of methotrexate
penicillin counselling
check allergy- if it develops they shouldn’t take it again (rash)
complete course
PPI counselling
reduce stomach acid- allowing symptoms to improve
report weight loss/ difficulty swallowing
triptan counselling
reduce severity of migraines by constricting cranial arteries
should shorten duration and make pain less intense
take as soon as you feel migraine coming on
can be taken with paracetamol and ibuprofen if needed
SEs- heaviness/ pressure on chest - should pass quickly- if it doesnt seek medical help- small risk of MI
return if you get more than 4 a month for something stronger
tetracyclines- counselling
allergy check
take treatment during a meal with a full glass of water sitting/ standing up
avoid indigestion remedies containing iron/ zinc 2 hours before antibiotic
potent skin from sunlight even on cloudy days
vancomycin counselling
report ringing in the ears- only reversible if promptly stopped
warfarin councelling
risk benefit (bleeds, preventing clots)
anticoagulant yellow book- record doses, blood test results, duration
alcohol- increases risk of bleed
food- high vit K (garlic, grapefruit, cranberry juice)
drugs- CYP inhibitors & inducers, st johns, antibiotics
