PR3153 CA Recap Flashcards
what is saltatory conduction
electrical impulse skips from node to node down the axon (can be done because of myelin sheath!)
How can we determine if a seizure might or might not be a recurrent one?
eeg (normal vs epileptiform), brain scan, prev undx seizures vs first seizure
how do migraines occur
vasodilation of intracranial extracerebral blood vessels –> activation of perivasc trigeminal nerves –> release vasoactive neuropeptides –> promotion of neurogenic inflammation
SEROTONIN helps reduce vasodilation (it promotes vasoconstriction!) by binding to 5ht1 recep
what are the MoA of the AEM (1st gen)
PHT - block na+ channel
CBZ - block na+ channel
VPA - block na+ and ca2+ channel and inhibit GABA transaminase
Benzodiazepines - bind to reg site of GABA recep to potentiate influx of Cl-
Barbiturate - bind to site distingct from benzodiazepines to potentiate influx of Cl-
what are the types of seizures each AEM is used for? (1st gen)
PHT - all except absence
CBZ - all except absence
VPA - all
benzodiazepines - diazepam for SE
barbiturate - usually only for paeds and neonates
what are things to note for pht?
- tdm needed due to narrow ther range (10-20 mg/L)
- teratogenic so use w caution in women of repro age
- non linear rs btw dose and plasma conc (dont anyhow dbl dose) [0 order kinetic]
- diff ppl have diff response to same dose
- if dose >400mg, split dose to help incr bioF
- space 2h w enteral feeds
- highly bound (watch for drugs that r also highly bound, or for low protein lvl in pt)
what are things to note for cbz?
- PGx needed HLA-B15:01
- hypersensi SJS/TEN
- autoinduction as cyp450 (3a4) inducer, will own metabolism, t1/2 might shorten with time, dose incr over time needed (max autoinduction usu 2-3wks aft initiation)
- dont start imm w desired maintainence dose, shld incr grad instead cos of induction
- high binding
what are things to note for vpa?
- highly protein bound also
- no good eqn to est free vpa so dont anyhow incr dose
what are things to note for benzodiazepines?
- respi depression can happen (too much inhib of neur)
- if OD and go to respi depression, use flumazenil (will not work for barbi tho), it is a benzo antag
- abuse potential, can develope tolerance and dependence
- gradual withdrawal needed
what are things to note for PB?
- can dev tolerence and dependence
- gradual withdrawal needed
- flumazenil cnt use if OD
- will not plateau when incr dose –> vv dangerous!
what is the MoA of 2nd gen AEM
levetiracetam - dk
lamotrigine - block na+ channel and inhib glutam8 release
topiramate - dk
what are the things to note for levetiracetam?
- adjunct tx for partial/gen epi
- monotx for newly dx partial epi
- can cause agranulocytosis
what are the things to note for lamotrigine?
- lennox gastaut
- adj/mono for partial/gen epi
- mono for absence
- t1/2 shorter in kids, cbz, pht
- t1/2 longer w vpa
- can cause agranulocytosis and mvment disorder
what are some things to note for topiramate?
- adj for lennox gastaut
- mono for partial/gen epi
- prophylaxis for migraine and headache
- can cause neutropenia
what is the MoA of headache and migraine meds?
cafergot - ergot bind to 5ht1d/b, incr tonicity of vasc sm of carotid network hence incr vasoconstriction; caffeine is adenosine antag hence allow vasoconstriction also and also incr solubility and hence abs of ergot
suma - selective (5ht1d) recep agonist hence allow vasoconstriction of carotid artery, inhib neuropeptide release, inhib nociception neurotrans
erenumab - cgrp inhibitor by binding to cgrp recep
when are these migraine/headache meds used?
cafergot - acute
sumatriptan - acute w / wo aura
erenumab - prophy if at least 4mmd
what are some things to note for cafergot?
- cyp3a4 inhib so dont use w other inhibs as will incr ergot exposure
- dont use w other vasoconstrictors (too much vasocons, space 24h)
what are some things to note for sumatriptan?
- elim by MAO so dont use w MAOi
- dont use w other vasoconstricters too like ergot (space 24h)
what is the pharm mngment of tth?
acute: nsaid, paracetamol
prophy: amtriptyline, venlafaxine, mirtazapine
how long does each phase of a migraine last and what is the pathophysio of it?
prodrome - 48h, hypothalamus messes with homeostatis giving rise to sx
aura - 5-60min, cortical spreading depression, slow spreading depolarisation which activate trigeminovasc system
ictal (headache) - 4-72h, neuropeptides lead to sensitisation of trigeminovasc system
postdrome - 48h, hypothalamus, same as prodrome
Differentiate the Dx between migraine with aura and migraine without aura.
wo aura
- =>5 fulfilling the next 3 categories
- headache last 4-72h
- 2/4 of unilateral, pulsating, aggravated by phy act, mod-sev pain
- 1 of n/v or photo/phonophob
w aura =
- =>2 fulfilling next 2 categories
- => 1 reversible aura sx (visual, sensory, speech etc.)
- =>3 of sx spread gradually over 5min, 2 or more aura sx btb, lasts 5-60min, unilateral
differentiate between chronic and episodic migraine
chronic
- =>15 mhd of which =>8 are mmd; persist for >3mth
episodic
- <15mhd/mmd OR =>5 migraine attacks lasting 4-72h in the lifetime
what are the pharm options for migraine?
acute - nsaid, ergotamine, sumatriptan (gepants, ditans)
prophy - cgrp mabs
when to start preventative tx for migraine
- =>4 mhd
- qol affected
- tx failure / se intolerable
- ci with acute tx
- pt pref
what types of cgrp blockage are there
- gepants: block cgrp recep (antagonist)
- anti cgrp recep ab
- anti crgp ab
when can cgrp mabs be used? (ie what is the criteria)
- => 18 yrs old
- 4-7mmd (8 wk trial for 2 classes, at least mod disability - midas 11 & abv)
- 8-14mmd (8 wk trial for 2 classes)
- 15mmd and abv [chronic] (8 wk trial for 2 class, 2 quarterly inj (6mth) of onabotulinumtoxin A, cnt solve)
what is the criteria for continuing mabs
- mmd reduce by at least half
- improvement in qol using scale (midas reduce =>5 pts when initial was 11-20; =>30% when initial was >20; hit6/mpfid reduce =>5)
what is the limit of acute tx one can use for headaches?
it shld be limited to avg of 2 headache days a week
what is considered medication overuse for headache and migraine?
- =>15mhd for non-specific migraine meds (nsaids, paracetamol etc.)
- =>10mhd for specific migraine meds (triptans, ergots, gepants etc.)
