pharm Flashcards
which drugs can precipitate an attack of acute intermittent porphyria?
barbiturates
benzodiazepines
halothane
alcohol
oral contraceptive pill
sulphonamides
how much adrenaline is used in different situations?
anaphylaxis: 0.5ml 1:1,000 IM
cardiac arrest: 10ml 1:10,000 IV or 1ml of 1:1000 IV
how is accidental adrenaline injection managed?
local infiltration of phentolamine
which drugs act as alpha 1/beta 1/2 agonists/ antagonists?
Alpha-1 agonists
phenylephrine
Alpha-2 agonists
clonidine
Beta-1 agonists
dobutamine
Beta-2 agonists
salbutamol
Alpha antagonists alpha-1: doxazosin alpha 1a: tamsulosin - alpha-2: yohimbine non-selective: phenoxybenzamine (previously used in peripheral arterial disease)
Beta antagonists
beta-1: atenolol
non-selective: propranolol
what do the different alpha adrenoreceptors do?
Alpha-1 vasoconstriction relaxation of GI smooth muscle salivary secretion hepatic glycogenolysis
Alpha-2
mainly presynaptic: inhibition of transmitter release (inc NA, Ach from autonomic nerves)
inhibits insulin
platelet aggregation
what do the different B adrenoreceptors do?
Beta-1
mainly located in the heart
increase heart rate + force
Beta-2
vasodilation
bronchodilation
relaxation of GI smooth muscle
Beta-3
lipolysis
what drugs can be used for alcohol addiction?
disulfram: promotes abstinence - alcohol intake causes severe reaction due to inhibition of acetaldehyde dehydrogenase. Patients should be aware that even small amounts of alcohol (e.g. In perfumes, foods, mouthwashes) can produce severe symptoms. Contraindications include ischaemic heart disease and psychosis
acamprosate: reduces craving, known to be a weak antagonist of NMDA receptors, improves abstinence
how does allopurinol work?
inhibiting xanthine oxidase.
when should allopurinol be initiated?
2 weeks after an attack .. thought to precipitate an attack.
after 1st attack
colchicine should be considered when using allopurinol
what is the dose of allopurinol?
initial dose of 100 mg od, with the dose titrated every few weeks to aim for a serum uric acid of < 300 µmol/l. Lower initial doses should be given if the patient has a reduced eGFR
what are the serious adverse effects of allopurinol?
whos at risk of this?
dermatological..
advised to stop immediately if they develop a rash…
severe cutaneous adverse reaction (SCAR)
drug reaction with eosinophilia and systemic symptoms (DRESS)
Stevens-Johnson syndrome
Chinese, Korean and Thai people
HLA-B *5801 allele.
how does allopurinol interact with azothioprine?
increases effects of azothioprine
how does allopurinol interact with cyclophosphamide?
reduces renal clearance and thus increases risk of marrow toxicity of cyclophosphamide
how does allopurinol interact with theophylline?
allopurinol causes an increase in plasma concentration of theophylline by inhibiting its breakdown
why does amiodarone lead to hypothyroid?
thought to be due to the high iodine content of amiodarone causing a Wolff-Chaikoff effect
This is an autoregulatory phenomenon where thyroxine formation is inhibited due to high levels of circulating iodide
what are the different types of amiodarone induced thyrotoxicosis?
type 1
- excess iodine induced thyroid hormone synthesis.
- goitre
- treat with carbimazole
type 2
- amiodarone related destructive thyroiditis
- treat with steroids.
should amiodarone be stopped if it causes thyroid dysfunction?
hypo - can continue if needed
hyper - should be stopped
how does propofol work?
GABA receptor agonist
Rapid onset of anaesthesia
Pain on IV injection
does sodium thiopentone have a slow or rapid onset of action?
very rapid.
often used for rapid sequence induction.
how does ketamine work?
NMDA receptor antagonist
May be used for induction of anaesthesia
Has moderate to strong analgesic properties
Produces little myocardial depression making it a suitable agent for anaesthesia in those who are haemodynamically unstable
which anaesthetic agents have little cardiovascular effects?
etomidate
ketamine
What is the mechanism of class 1a antiarrhythmics? give examples of drugs in this class
Procainamid, quinidine, Disopyramide
blocks Na channels and increases AP duration
what is a side effect of:
quinidine
procainamide?
quinidine - headache, tinnititus, thrombocytopenia
procainamide - drug induced lupus
What is the mechanism of class 1b antiarrhythmics? give examples of drugs in this class
blocks Na channels and decreases AP duration
Lidocaine
Mexiletine
Tocainide
What is the mechanism of class 1c antiarrhythmics? give examples of drugs in this class
blocks Na channel , no effect on AP duration
Flecainide
Encainide
Propafenone
What is the mechanism of class II antiarrhythmics?
B blockers
What is the mechanism of class III antiarrhythmics? give examples.
K+ channel blockers miodarone Sotalol Ibutilide Bretylium
What is the mechanism of class IV antiarrhythmics? give examples.
Ca CB
Verapamil
Diltiazem
which antibiotics effect cell wall synthesis?
peptidoglycan cross linking: carbopenems, penicillin, cephalosporins
peptidoglycan synthesis: glycopeptides e.g vancomycin
which antibiotics affect protein synthesis?
30S subunit: aminoglycosides, tetracyclines
50S: macrolides, chloramphenicol, clindamycin, linezolid, streptogrammins
what anitbiotics affect DNA?
DNA topoisomerase - Quinolones
damages DNA - metronidazole
which antibiotic effects RNA polymerase?
rifampicin
which antibiotics affect folate synthesis?
dihydrofolate reductase: trimethroprim
dihydroptorate synthase : sulphonamides
how does aspirin work?
blocking the action of both cyclooxygenase-1 and 2.
Cyclooxygenase is responsible for prostaglandin, prostacyclin and thromboxane synthesis.
The blocking of thromboxane A2 formation in platelets reduces the ability of platelets to aggregate
which drugs potentiate aspirin?
warfarin
steroids
oral hypoglycaemics
what age is aspirin contraindicated?
Aspirin should not be used in children under 16 due to the risk of Reye’s syndrome. An exception is Kawasaki disease, where the benefits are thought to outweigh the risks.
what are the features of a B blocker overdose?
bradycardia
hypotension
heart failure
syncope
how is B blocker overdose managed?
atropine for bradycardia
if resistant - glucagon
what are the two groups of CaCB?
mainly affects on myocardium - diltiazam and verapamil
mainly affects on peripheral blood - Nifedipine, amlodipine, felodipine
what are the indications/use of verapamil?
Angina, hypertension, arrhythmias
Highly negatively inotropic
Should not be given with beta-blockers as may cause heart block
what are the indications/use of diltiazam?
Angina, hypertension
Less negatively inotropic than verapamil but caution should still be exercised when patients have heart failure or are taking beta-blockers
what are indications/ use of Nifedipine, amlodipine, felodipine
HTN, raynauds, angina
what are the side effects of CaCB?
verapamil: Heart failure, constipation, hypotension, bradycardia, flushing
diltiazam: Hypotension, bradycardia, heart failure, ankle swelling
amlodipine etc: Flushing, headache, ankle swelling
what is the pathogenesis behind carbon monoxide poisoning?
has high affinity for Hb and myoglobin therefore left shift in dissociation curve - tissue hypoxia
what are the features of carbon monoxide toxicity?
headache: 90% of cases nausea and vomiting: vertigo: confusion: subjective weakness severe toxicity: 'pink' skin and mucosae, hyperpyrexia, arrhythmias, extrapyramidal features, coma, death
what Ix is useful / not useful for CO poisoning?
pulse oximetry - unreliable, will be high as carboxyHb gives same as oxyHb
blood gas - reliable.
how is carbon monoxide poisoning managed?
high flow O2
target sats 100%
for atleast 6 hours
until symptoms have resolved
hyperbaric chamber
what are the indications of using a hyperbaric O2 chamber?
CO poisoning AND…. loss of consciousness at any point, neurological signs other than headache, myocardial ischaemia or arrhythmia and pregnancy as indications for hyperbaric oxygen
what is the mechanism of cyclosporin?
immunosuppressant which decreases clonal proliferation of T cells by reducing IL-2 release.
It acts by binding to cyclophilin forming a complex which inhibits calcineurin, a phosphatase that activates various transcription factors in T cells
what are the ADRs of cyclosporin?
nephrotoxicity
hepatotoxicity
fluid retention
hypertension
hyperkalaemia
hypertrichosis - hair growth
gingival hyperplasia
tremor
impaired glucose tolerance
hyperlipidaemia
increased susceptibility to severe infection
when might ciclosporin be indicated?
following organ transplantation rheumatoid arthritis psoriasis (has a direct effect on keratinocytes as well as modulating T cell function) ulcerative colitis pure red cell aplasia
how does cocaine work?
cocaine blocks the uptake of dopamine, noradrenaline and serotonin
what are the cardiovascular effects of cocaine?
coronary artery spasm → myocardial ischaemia/infarction
both tachycardia and bradycardia may occur
hypertension
QRS widening and QT prolongation
aortic dissection
what are the neuro effects of cocaine?
seizures
mydriasis
hypertonia
hyperreflexia
other than neuro/ CVS effects, what are the other S.E of cocaine?
ischaemic colitis
hyperthermia
metabolic acidosis
rhabdomyolysis
how is cocaine toxicity managed?
benzodiazepines are generally first-line for most cocaine-related problems
chest pain: benzodiazepines + glyceryl trinitrate.
hypertension: benzodiazepines + sodium nitroprusside
the use of beta-blockers in cocaine-induced cardiovascular problems is a controversial issue.
what are the contrainidication of COCPs?
relative - probably not worth the risk if…
more than 35 years old and smoking less than 15 cigarettes/day
BMI > 35 kg/m^2*
family history of thromboembolic disease in first degree relatives < 45 years
controlled hypertension
immobility e.g. wheel chair use
carrier of known gene mutations associated with breast cancer (e.g. BRCA1/BRCA2)
current gallbladder disease
diabetes
absolute:
more than 35 years old and smoking more than 15 cigarettes/day
migraine with aura
history of thromboembolic disease or thrombogenic mutation
history of stroke or ischaemic heart disease
breast feeding < 6 weeks post-partum
uncontrolled hypertension
current breast cancer
major surgery with prolonged immobilisation
what risk should women taking COCP be warned of?
only effective if taken correctly,
risk of blood clots
risk of cervical and breast ca
small risk of heart attack and stroke
may not be effective if on rifampicin or suffering from diarrhoea/vomitting.
what is the mechanism of cyanide poisoning?
Cyanide may be used in insecticides, photograph development and the production of certain metals.
Cyanide inhibits the enzyme cytochrome c oxidase, resulting in cessation of the mitochondrial electron transfer chain.
what are the symptoms of cyanide poisoning?
classical’ features: brick-red skin, smell of bitter almonds
acute: hypoxia, hypotension, headache, confusion
chronic: ataxia, peripheral neuropathy, dermatitis
how is cyanide poisoning managed?
100% O2
definitive: hydroxocobalamin (intravenously), also combination of amyl nitrite (inhaled), sodium nitrite (intravenously), and sodium thiosulfate (intravenously)
how does digoxin work?
decreases conduction through the atrioventricular node which slows the ventricular rate in atrial fibrillation and flutter
increases the force of cardiac muscle contraction due to inhibition of the Na+/K+ ATPase pump. Also stimulates vagus nerve
digoxin has a narrow therapeutic index
what are the features of digoxin toxicity?
generally unwell, lethargy, nausea & vomiting, anorexia, confusion, yellow-green vision
arrhythmias (e.g. AV block, bradycardia)
gynaecomastia
what are the precipitating factors for digoxin toxicity?
classically: hypokalaemia
digoxin normally binds to the ATPase pump on the same site as potassium. Hypokalaemia → digoxin more easily bind to the ATPase pump → increased inhibitory effects
increasing age renal failure myocardial ischaemia hypomagnesaemia, hypercalcaemia, hypernatraemia, acidosis hypoalbuminaemia hypothermia hypothyroidism
drugs: amiodarone, quinidine, verapamil, diltiazem, spironolactone (competes for secretion in distal convoluted tubule therefore reduce excretion), ciclosporin. Also drugs which cause hypokalaemia e.g. thiazides and loop diuretics
how is digoxin toxicity managed?
Digibind
correct arrhythmias
monitor potassium
what is DRESS syndrome?
DRESS is an unexpected, severe reaction to medication. Several organs are affected including the skin, liver, kidneys, lungs and heart.
Patients develop a morbilliform skin rash in 80% cases which often leads to an exfoliative dermatitis, high fever, and inflammation of one or more organs.
Vesicles and bullae may be seen. Erythroderma can occur, mucosal involvement and facial swelling. The reaction usually occurs 2-8 weeks after commencing the offending drug.
May develop systematic symptoms
- haematological abnormalities (raised and low white count, eosinophilia, thrombocytopaenia, anaemia,
- enlarged lymph nodes
- kidney disease
- myocarditis, pericarditis,
- liver enlargement, hepatitis and rarely hepatic necrosis with liver failure
- lung disease (pneumonitis, pleuritis, pneumonia),
- neurological involvement which may lead to meningitis and encephalitis
- gastrointestinal symptoms, in severe cases, acute colitis and pancreatitis can occur
- endocrine abnormalities may include thyroiditis and diabetes.
what drugs can commonly cause DRESS syndrome?
allopurinol, anti-epileptics, antibiotics, immunosuppresants, HIV treatment and NSAIDS.
what is RegiSCAR diagnostic criteria for DRESS?
Patients require at least 3 of the following:
Hospitalisation
Reaction suspected to be drug related
Acute skin rash
Fever about 38ºC
Enlarged lymph nodes at two sites
Involvement of at least one internal organ
Blood count abnormalities such as low platelets, raised eosinophils or abnormal lymphocyte count.
how can DRESS syndrome be diagnosed?
Skin biopsy can help to confirm the diagnosis.
This may show inflammatory infiltrate in particularly eosinophils, extravasated erythrocytes and oedema.
Regular blood tests
Investigations looking for complications should be undertaken including ECG, CXR, echocardiogram, and urinalysis.
how is DRESS syndrome managed?
Antihistamines, topical steroids and emollients can be used to help control the rash.
Careful fluid balance
Systemic steroids may be started in severe cases where exfoliative dermatitis / pneumonitis / hepatitis is present.
Occasionally immunosuppressants, intravenous immunoglobulin and plasmapheresis may be started. Potential culprit drugs should not be restarted again.
when are dopamine receptor agonists indicated?
Parkinson’s disease
prolactinoma/galactorrhoea
cyclical breast disease
acromegaly
give examples of dopamine receptor agonists…
e.g. bromocriptine, ropinirole, cabergoline, apomorphine
what are the side effects of dopamine receptor agonists?
ergot-derived dopamine receptor agonists (bromocriptine, cabergoline) have been associated with pulmonary, retroperitoneal and cardiac fibrosis.
ESR, creatinine and chest x-ray should be obtained prior to treatment and patients should be closely monitored
nausea/vomiting
postural hypotension
hallucinations
daytime somnolence
which drugs cause agranulocytosis?
Cytotoxic drugs - methotrexate
Antithyroid drugs - carbimazole, propylthiouracil
Antipsychotics - atypical antipsychotics (CLOZAPINE)
Antidepressant - mirtazapine
Antiepileptics - carbamazepine
Antibiotics - penicillin, chloramphenicol, co-trimoxazole
what are the most common drugs that can cause urticaria?
aspirin
penicillins
NSAIDs
opiates
For the following drugs what is the monitoring regimes..
a) statins
b) ACEi
c) amiodarone
statins LFTs - at baseline, 3 months, 12 months
ACIi - U&Es - prior to treatment, after increasing dose, atleast annually after that.
amiodarone: TFT, LFT, U&E, CXR prior to treatment
TFT, LFT every 6 months
For the following drugs what is the monitoring regimes..
a) methotrexate
b) azothioprine
methotrexate: FBC, UEs, LFTs before starting treatment and repeated weekly until therapy stabilised, thereafter patients should be monitored every 2-3 months
azothioprine:
FBC, LFT before treatment
FBC weekly for the first 4 weeks
FBC, LFT every 3 months
For the following drugs what is the monitoring regimes..
a) lithium
b) sodium valproate
c) glitazones
lithium - TFT, U&E prior to treatment
Lithium levels weekly until stabilised then every 3 months
TFT, U&E every 6 months
sodium valproate: LFT, FBC before treatment
LFT ‘periodically’ during first 6 months
glitazones: LFT before treatment
LFT ‘regularly’ during treatment
which drugs can impair glucose tolerance?
thiazides steroids tacrolimus, ciclosporin interferon-alpha nicotinic acid antipsychotics
B blockers too slightly
which drugs can induce thrombocytopenia?
quinine
abciximab
NSAIDs
diuretics: furosemide
antibiotics: penicillins, sulphonamides, rifampicin
anticonvulsants: carbamazepine, valproate
heparin
which drugs can induce urinary retention?
tricyclic antidepressants e.g. amitriptyline anticholinergics opioids NSAIDs disopyramide
which drugs cause lung fibrosis?
amiodarone
cytotoxic agents: busulphan, bleomycin
anti-rheumatoid drugs: methotrexate, sulfasalazine
nitrofurantoin
ergot-derived dopamine receptor agonists (bromocriptine, cabergoline, pergolide)
which drugs can cause optic neuritis?
ethambutol
amiodarone
metronidazole
what can steroids do to the eyes?
cataractss
which drugs can induce photosensitivity?
thiazides amiodarone tetracyclines, sulphonamides, ciprofloxacin NSAIDs e.g. piroxicam psoralens sulphonylureas
which drugs act on serotonin receptors?
sumatriptan is a 5-HT1D receptor agonist
ergotamine is a partial agonist of 5-HT1 receptors
pizotifen is a 5-HT2 receptor antagonist used in the prophylaxis of migraine attacks.
Methysergide is another antagonist of the 5-HT2 receptor but is rarely used due to the risk of retroperitoneal fibrosis
cyproheptadine is a 5-HT2 receptor antagonist which is used to control diarrhoea in patients with carcinoid syndrome
ondansetron is a 5-HT3 receptor antagonist and is used as an antiemetic
what are the features of ecstasy toxicity?
neurological: agitation, anxiety, confusion, ataxia
cardiovascular: tachycardia, hypertension
hyponatraemia
hyperthermia
rhabdomyolysis
how is ecstacy toxicity managed?
supportive
dantrolene can be used for hyperthermia
where is ethylene glycol found?
anti-freeze
what are the stages of ethylene glycol toxicity?
Stage 1: symptoms similar to alcohol intoxication: confusion, slurred speech, dizziness
Stage 2: metabolic acidosis with high anion gap and high osmolar gap. Also tachycardia, hypertension
Stage 3: acute kidney injury
how is ethylene glycol toxicity managed?
used to be ethanol which competes with ethylene glycol for the enzyme alcohol dehydrogenase
this limits the formation of toxic metabolites
fomepizole, an inhibitor of alcohol dehydrogenase, is now used first-line in preference to ethanol
haemodialysis also has a role in refractory cases
what is the action of finesteride?
inhibitor of 5 alpha-reductase, an enzyme which metabolises testosterone into dihydrotestosterone.
what are the indications for fenasteride?
male pattern baldness
BPH
what does finesteride do to PSA?
decreases levels
what are the indications of finasteride?
impotence
decrease libido
ejaculation disorders
gynaecomastia and breast tenderness
what class drug does flecainide belong to?
class 1c antiarrhythmics
when is flecanide contraindicated?
post myocardial infarction
structural heart disease: e.g. heart failure
sinus node dysfunction; second-degree or greater AV block
atrial flutter
when is flecanide indicated?
atrial fibrillation
SVT associated with accessory pathway e.g. Wolf-Parkinson-White syndrome
what are the adverse effects of flecainide?
negatively inotropic bradycardia proarrhythmic oral paraesthesia visual disturbances
what are the adverse effects of gentamicin?
ototoxic - vestibular nerve damage, irreversible.
nephrotoxic - acute tubular necrosis. use with furosemide increases risk.
dosing required due to this
what are the contraindications of gentamicin use?
myasthenia gravis
which drugs can be cleared by haemodialysis?
BLAST: barbiturates. lithium alcohol salicyclates theophyllines
which drugs cant be cleared by haemodialysis?
tricyclics benzodiazepines dextropropoxyphene (Co-proxamol) digoxin beta-blockers
how does heparin work?
by activating antithrombin III
e.g. lmwh increases action of ATIII on factor Xa.
what are the adverse effects of heparin?
bleeding
thromocytopenia (lower risk in LMWH)
osteoporosis (lower risk in LMWH)
hyperK
how is heparin given compared to LMWH?
LMWH sub cut
heparain - IV
what is the mechanism behind heparin induced thrombocytopenia?
immune mediated - antibodies form against complexes of platelet factor 4 (PF4) and heparin
these antibodies bind to the PF4-heparin complexes on the platelet surface and induce platelet activation by cross-linking receptors
usually does not develop until after 5-10 days of treatment
how does heparin induced thrombocytopenia present?
despite being associated with low platelets HIT is actually a prothrombotic condition
features include reduction in platelets, thrombosis and skin allergy
how is heparin overdose reversed?
protamine sulphate, although this only partially reverses the effect of LMWH.
what is the mechanism of action of
a) statin
b) ezetimibe
c) nicotinic acid
d) fibrates
e) cholestyramine
a) HMG coA reductase inhibitor
b) decreases cholesterol absorption in the small intestine
c) decreases hepatic VLDL
d) agonist of PPAR-a and so increases lipoprotein lipase expression
e) Decreases bile acid reabsorption in the small intestine, upregulating the amount of cholesterol that is converted to bile acid
what are the side effects of
a) statin
b) ezetimibe
c) nicotinic acid
d) fibrates
e) cholestyramine
a) myositis, deranged LFTs
b) headache
c) flushing, myositis
d) myositis, pruritis, cholestasis
e) GI side effects
what are the causes of low Mg
PPI, diuretics, TPN diarrhoea hypoK hyperCa alcohol gitleman/bartters
what are the features of hypocalcaemia?
paraesthesia
tetany
seizures
arrhythmias
ECG features similar to those of hypokalaemia
exacerbates digoxin toxicity
how is low Mg managed?
if <0.4 or arrhyhmias, seizures, tetany - IV MG SO4
otherwise oral
what can lithium toxicity be precipitated by?
dehydration
renal failure
drugs: diuretics (especially thiazides), ACE inhibitors/angiotensin II receptor blockers, NSAIDs and metronidazole
what are the features of lithium toxicity?
coarse tremor (a fine tremor is seen in therapeutic levels) hyperreflexia acute confusion polyuria seizure coma
how is lithium toxicity managed?
mild-moderate toxicity may respond to volume resuscitation with normal saline
haemodialysis may be needed in severe toxicity
sodium bicarbonate is sometimes used
what effect does adrenaline have on anaesthetic drugs?
drenaline may be added to local anaesthetic drugs. It prolongs the duration of action at the site of injection and permits usage of higher doses