(pharm) pharmacology of anticonvulsants Flashcards
what are the most common drugs prescribed for epilepsy?
lamotrigine
sodium valproate
diazepam
levetiracetam
explain the primary mechanism of action of lamotrigine
blocks voltage-gated Na+ channels preventing Na+ influx = prevents depolarisation of glutamatergic neurones and reduces glutamate excitotoxicity
what is the drug target for lamotrigine?
voltage-gated Na+ channels
what are the most common side effects of lamotrigine?
rash, drowsiness
what are the less common side effects of lamotrigine?
Steven-Johnson’s syndrome, suicidal thoughts
how is lamotrigine used to prevent allergic skin reactions?
introducing lamotrigine gradually is one of the keys to reducing the frequency and severity of allergic skin reactions
explain the primary mechanism of action of sodium valproate
inhibition of GABA transaminase prevents the breakdown of GABA = increases GABA concentrations directly presynaptically + indirectly prolongs GABA in the synapse due to the fact that extraneuronal metabolism of GABA is slowed (which also slows GABA removal from the synapse) = overstimulation of inhibitory neurones due to prolonged presence of GABA in the synapse
what is the drug target for sodium valproate?
GABA transaminase
what are the common side effects of sodium valproate?
stomach pain
diarrhoea
drowsiness
weight gain
hair loss
what are the less common side effects of sodium valproate?
hepatotoxicity
teratogenicity
pancreatitis
what is the broad classification of sodium valproate?
braod CYP enzyme inhibitor
increases the serum concentration of many co-administered drugs
what is the drug target for diazepam?
benzodiazepine site on the GABA A receptor
what are the most common side effects of diazepam?
drowsiness, respiratory depression (if IV or at high dose)
what are the less common side effects of diazepam?
haemolytic anaemia, jaundice
when can respiratory depression occur when diazepam is administered?
if diazepam is given at high doses or if IV diazepam is administered