L30 Anticonvulsant Drugs Flashcards
0
Q
What are the causes of epilepsy?
A
- Mechanisms of epilepsy: overactivity of Na channels and underactivity of GABA inhibition
- birth and perinatal injuries; congenital malformations; head trauma; infection -> these all exhibit episodic seizures (chronic)
- sometimes seizures can be produced due to acute injuries, e.g. head trauma or stroke. BUT these are not classify as epilepsy
1
Q
What are anticonvulsant drugs for?
A
- For epilepsy
2
Q
What are the triggers for seizure?
A
- change in blood glucose and pH level
- stress
- fatigue
- flashing lights and nose
- sometimes no apparent cause
3
Q
Catergorisation of seizures
A
- partial seizure vs generalise seizure: partial seizure only affects one part of the brain whereas generalise seizure can affect multiple areas to produce a generalised effect
- within partial seizure: complex vs simple. Simple seizure is where consciousness, awareness and memory are retained whereas complex seizure is not.
4
Q
Partial seizure
A
- effects dependent on the localised focus, i.e. on visual cortex
- most commonly affect temporal lobe where individual can get stereotypic movements and strong emotional responses
- Jacksonian epilepsy is referred to jerky movements on one side which spreads
5
Q
Generalised seizure
A
- tonic
- clonic
- atonic: sudden relaxation of muscles
- tonic-clonic (grand mal)
- status epilepticus: persist of tonic-clonic seizure
- absence seizure: where individual lost connection with the world and awareness (petit mal)
6
Q
How can you identify the focus of epilepsy?
A
- By using EEG or PET scan to see which area is over reacted or under reacted
- Generally can only be used for local epilepsy
7
Q
What are the causes of focal seizures?
A
- due to limited number of connected neurones firing abnormally
- generate ‘paroxysmal depolarisation shift’ (PDS)= rapid, large depolarisation
- activation of GABAergic interneurones will reduce PDS
8
Q
What are the causes of more widespread seizures?
A
- affect more numbers of neurones (than focal seizure)
- maybe due to up-regulation of excitatory (glutamatergic) transmission or down regulation of inhibitory transmission (GABAergic)
9
Q
What are the differences between grand mal and petit mal type of generalised seizure?
A
- grand mal= tonic-clonic generalised seizure where the abnormal brain activity lasts for a longer period of time
- petit mal= absence generalised seizure where the abnormal brain activity does not last as long
10
Q
What do anticonvulsant drugs do?
A
- remove symptoms of epilepsy but does not cure it
- because the drugs have to be taken for a prolonged period of time to suppress symptoms so ideally, non toxic, not sedative (as have to function normally), low incidence of interaction with other drugs
11
Q
What are the main strategies for pharmacological intervention? (4)
A
- block activity in the focus or block spread of activity by:
1) increase inhibitory (GABA)synaptic transmission
2) decrease neuronal firing rates (acts on NA channels)
3) inhibit neurotransmitter release (acts on Ca channels)
4) decrease excitatory (glutamate) synaptic transmission
12
Q
How is GABA synthesised?
A
- glutamine -> glutamate by glutaminase
- glutamate -> GABA by glutamic acid decarboxylase
13
Q
What is the GABA uptake pathway?
A
- GABA is taken up into neurones and glia via GABA transporter
14
Q
How is GABA being degraded?
A
- GABA -> succinic semialdehyde + glutamate by enzyme GABA transaminase
- succinic semialdehyde -> succinate by enzyme SSA dehydrogenase
- glutamate -> glutamine by enzyme glutamine synthase
