misc Flashcards
how does bupropion work?
nicotine antagonist
dopamine, Na reuptake inhibitor
how does varenicline work?
aka champix
nicotine partial agonist - helps with withdrawal
side effects/ cautions/contraindications of bupropion and verenicline?
neither can be used in preg/ breast feeding
bupropion - not in patients with epilepsy
varenicline - caution in patients with depression.
other side effects of verenicline include - nausea, constipation, headache, vivid dreams
how much do blinking and laryngoscopy raise intraocular pressure by?
blinking - 10mmHg
laryngoscopy - 30 to 40 mmHg
how does rise in CVP cause increase in intraocular pressure?
via episceral vessels
what is pilocarpine and when is it relatively contraindicated?
muscarinic agonist
Can cause bronchospasm and is relatively contraindicated in asthma.
Used in glaucoma and to increase saliva in those with xerostomia
how do B blockers work in glaucoma?
decrease aqueous humour production
which anti-emetic can increase intraocular pressure?
metoclopramide - via dopamine receptors
how does latanoprost effect intraocular pressure?
Latanoprost is a prostaglandin analogue and is thought to break extracellular matrix, decreasing resistance to the outflow of aqueous humour.
how does sux increase intraocular pressure?
Suxamethonium increased IOP, probably as a result of increased choiroidal blood volume.
even when fasciculations are removed, still increases ocular pressure hence thought to be above mechanism
what is the basic chemical structure for histamine?
basic molecule
imidazole ring with amino acid side chain
produced from histadine via decarboxylation
which histamine receptor is found in CNS?
H1
what type of GPCR is H1 and H2?
H1 - Gq
H2 - Gs
when are antihistamines indicated in anaphylaxis?
indicated as second-line after adrenaline and steroids
what is the receptor mechanism for antihistamines?
inverse agonists - stabilise inactive state of H1
which generation antihistamine is chlorphenamine?
first generation
can loratidine cross BBB?
not as sedating first generation but still mild sedating effects
(second generation)
what protein binding is chlorphenamine?
70%
what is the bio oral availability of cyclizine?
high - 80%
similar dose IV and oral
how is fexofenadine excreted?
mostly in faeces unchanged.
how is epoprostenol given in resp disease? what does it do?
When nebulised, it acts as a specific pulmonary vasodilator at ventilated alveoli, reducing V/Q mismatch
how does aminophylline act?
inhibition of phosphodiesterase - intracellular enzyme
give an example of leukotriene receptor antagonist? when are they used?
Montelukast, zafirlukast, and pranlukast
chronic asthma, no effects in acute
what asthma drug is churg straus a side effect of?
montelukast - rare
what is the mechanism of terbutaline?
short acting b2 agonist
how much prednisolone is given in acute asthma?
40-50mg
what is the protein binding of acetazolamide in plasma?
70%
what chemical are thiazides related too?
sulphonamides
what is the function of triamterene?
Triamterene blocks elective Na+ channel on the collecting duct luminal membrane
how does spironolactone affect digoxin?
reduces clearance
hence increases levels
what does furosemide do to calcium?
lower it
which diuretic worsens diabetes?
thiazides.
what type of receptor is the oxytocin receptor?
GPCR
what does oxytocin do to diuresis?
anti-diuretic effects
what does ergometrine do to SVR and coronary vessels?
increases systemic vascular resistance
coronary spasm risk
what is the route of delivery of carboprost?
IM - 250ug every 15 mins up to 2mg
NOT IV
what are the symptoms of hyperMg at 4mM and 6mM plasma conc?
Muscle weakness and bradycardia are seen at a plasma concentration of 6 mmol/L.
4 mmol/L is associated with hyporeflexia, nausea and slurred speech.
what are the functions of oestrogen and progesterone on uterus towards term?
Progesterone keeps the uterus in functional quiescence
oestrogen causes the myometrium to become activated - which involves upregulation of oxytocin and prostaglandin receptors
which hormone causes uterine involution?
oxytocin
can oxytocin cross the placenta?
yes
what does oxytocin do to the CVS?
Oxytocin reduces SVR, causes transient hypotension and reflex tachycardia.
how is oxytocin metaboliseD?
Oxytocin is metabolised by the liver and by plasma oxytocinases.
which uterine agent is contraindicated in asthma?
carboprost
what type of molecule is misoprostal
Misoprostol is a synthetic prostaglandin E2⍺ analogue
what is the mechanism of ergometrine?
Ergometrine causes hypertension by the agonism of ⍺2 receptors.
at what stage in PPH is carboprost used?
Carboprost should be used third line after oxytocin and Ergometrine (unless ergometrine is contraindicated).
which inhalation agents have the most effect on uterus relaxation?
Sevoflurane and desflurane have a greater uterine relaxation effect than isoflurane.
what is atosiban?
Atosiban is an oxytocin receptor antagonist
used second line as tocolysis in pre-term labour
where is alcohol absorbed?
20% in stomach
80% in duodenum
which liver enzyme does chronic alcohol induce?
CYP 2E1
what does GORD do to alcohol breath test?
false positive
1 unit of alcohol is equivalent to how much pure ethanol?
10ml
what is the CIWA-Ar score?
measures alcohol withdrawal
what is the most common arrhythmia seen in alcoholics?
AF
which class of ilicit drug is codeine?
class B
heroin may be cut with scopolamine, what does this do?
anti-cholinergic effects
what can talc cause that is cut into ectasy ?
pulmonary granulomas
what blood result finding can be seen with cocaine?
thrombocytopenia
which opiate receptors does heroin bind?
all of them
at low doses what can cannabis do to MAC?
increase MAC
at low doses canabis can be stimulatory
in general acute canabis, reduces MAC
which component of cigarette smoke is nicotine?
the particulate phase
(not the gaseous phase)
what is the half life of nicotine and how is it metabolised?
30 mins
by CYP 450
metabolites are present for up to 20 hr
what does nicotine do at high doses?
sedative and depressive effects
how much greater is the affinity for CO to Hb than O2?
300 x
what does smoking do for PONV and why?
reduces incidence
upregulates CYP2E1 and hence quicker metabolism of anaesthetic agents
how does varenicline work?
partial nicotinic agonist
how does bupropion work?
nicotinic receptor antagonist with dopaminergic and adrenergic action
Is gentamicin bacteriostatic or cidal? What type of antibiotic
Bacteriocidal
Aminoglycoside
