PR3153 CA Recap Flashcards
(30 cards)
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
