Anticonvulsants and anti-epileptic drugs Flashcards Preview

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Flashcards in Anticonvulsants and anti-epileptic drugs Deck (33)
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1

Define epilepsy

Tendency for recurrent, unprovoked seizures

2

Define seizure

sudden changes in behaviors characterised by electrical hyperchronisation of neuronal networks in the cerebral cortex

3

Types of seizures

Generalised
Partial/Focal

4

Define generlaised seizure

a seizure manifesting itself in both hemispheres

5

Define partial/focal seizure

a seizure originating from a discrete brain area in one hemisphere, has the potential to spread and develop into a global seizure

6

State the types of global seizures and what they're charcterised by

Tonic-clonic = loss of consciousness -> muscle stiffening -> rapid jerky/twitching movements -> deep sleep -> awakes (with no recollection)
Absence = brief staring episodes and behavioural arrest
Tonic/atonic = sudden muscle rigidity/relaxation
Myoclonic = sudden brief muscle contractions
Status epilepticus = state of CONTINUOUS seizure activity for >5 mins

7

State the types of partial seizures and what they're charcterised by

Simple = no impairment in awareness/consciousness
Complex = impaired awareness/consciousness

8

2 most common types of central neurotransmission

Gluatminergic = excitatory
GABA = inhibitory

9

Describe normal glutaminergic transmission

Depolarisation of presynaptic neurone
opening of VGSC, Na+ inlfux
opening of VGKC, K+ efflux
Opening of VGCC at synapse, Ca2+ influx
Stimulation of exocytosis of gluamate-containing vesicles
Docking at presynaptic membrane by SV2A docking protein
Glutamate binds to excitatiry NMDAR and Kainate-R on postsynaptic membrane
Depolarisation of postsynaptic neurone

10

Describe normal GABAergic transmission

GABA synthesised from GLU
Exocytosis and binding to inhibitory GABAAR
Cl- influx and hyperpolarisation
Reuptaken by GAT (GABA transporter) by presynaptic
Reuptaken by support cells and broken down to GLU by GABA-T (?GABA transaminase)

11

Examples of VGSC blockers

Carbamazepine, Lamotrigine

12

Carbamazepine MOA, PK

Stabilises inactive state of VGSC, reducing depol
ENZYME INDUCER
fast onset <1hr
long t1/2

13

Lamotrigine MOA, PK

Inactivates VGSC, reduced glutaminergic transmission
fast onset <1hr
long t1/2

14

Principles of anticonvulsant therapy

Inhibit excitatory central Glutaminergic transmission
Stimulate inhibitoy central GABAergic transmission

15

Types of anticonvulsant drug groups

Inhibit excitatory central Glutaminergic transmission:
VGSC blockers
VGCC blockers
docking protein inhiitors
Glutamate receptor inhibitors

Stimulate inhibitoy central GABAergic transmission
GABAAR agonists
GABA-T inhibitors

16

Example of VGCC blocker

Ethosuximide

17

Ethosuximide MOA, PK

T-type CC antagonist, reducing exocytosis of glu in relay thala mic neurones
long t1/2 50hrs

18

Example of docking protein inhibitor

Levetiracetam

19

Levetiracetam MOA, PK

binds to SV2A docking protein preventing exocytosis
fast onset <1hr, t1/2 shorter 10hrs

20

Example of glutamate receptor blockers

Topiramate

21

Topiramate MOA, PK

NMDA-R + Kainate-R antagonist (also affects VGSC + GABAAR)
fast onset <1hr, long t1/2

22

Example of GABAAR agonist

Diazepam

23

Diazepam MOA, PK

GABAAR PAM (positive allosteric mediator as binds to BDZ receptor), increases frequency of Cl- channel opening and reciprocal potentiation of GABA
PR gel, fast onset 15mins, short t1/2 2hrs

24

Example of GABA-T inhibitor

(sodium) Valproate

25

Valproate MOA, PK

Inhibits GABA-T, increases synaptic [GABA]
fast onset <1hr, long t1/2
USED IN ALL TYPES OF EPILEPSY

26

Anticonvulsants used in tonic-clonic seizures

Carbamzepine
Lamotrigine
Valproate

27

Anticonvulsants used in absence seizures

Ethosuximide
Lamotrigine
Valproate

28

Anticonvulsants used in tonic/atonic seizures

Valproate

29

Anticonvulsants used in myoclonic seizures

Levetiracetam
Topiramate
Valproate

30

Anticonvulsants used in status epilepticus

Diazepam (due to fast onset)