The drugs we need to learn fit into two categories for treating seizures. I will outline the two mechanisms of actions, the drugs aligning with this and their individual side effects. A brush up on action potentials will increase the understanding around these drugs mechanism of action and side effects. Here’s a good video on them.

Voltage channel blockers

These drugs work by blocking sodium voltage channels in pre-synaptic neuron axons. This decreases neuronal excitability and inhibits the propagation of action potentials by inhibiting the influx of sodium and calcium. These drugs inhibit sustained repetitive firing by blocking use-dependent sodium channels. Inhibiting sodium channels decreases the release of excitatory glutamate into the synapse.

Phenytoin

Side effects include:

  • Confusion
  • Anaemia
  • Gum hyperplasia
  • Headache
  • Nausea/vomiting
  • Nervousness

Carbamazipine

Side effects include:

  • Fluid retention
  • Ataxia
  • Sedation
  • Mental disturbances
  • Involuntary eye movements

 

GABA agonists

These drugs agonise the affect of the inhibitory neurotransmitter GABA which increases the opening of chlorine channels to increase the negative charge inside of neurons (hyperpolarisation). This inhibits the propagation of action potentials, decreasing the effect of excitatory neurotransmitter glutamate.

Benzodiazapines

Lorazapam, diazapam, clonazepam

Side effects include:

  • Sedation
  • Dyspnoea
  • Decreased coordination
  • Slurred speech
  • Ataxia
  • Tolerance/dependence

Barbiturates

Phenobarbitone

Side effects include:

  • Suicidal ideation
  • Slurred speech
  • Sedation
  • Respiratory depression

Barbiturates toxicity can result in psychosis, delirium, bradypnoea and decreased LOC

 

Sodium Valporate (Epilium)

Sodium valporate is a drug that uses both mechanisms of action listed and is commonly used in the treatment of seizures.

Side effects include:

  • Weight gain
  • Nausea/vomiting
  • Sedation
  • Liver impairment

It is advisable that all woman taking sodium valporate are using birth control as it can cause fetal abnormality

 

This video explains all of these medications listed.

 

References

Bryant, B., & Knights, K. (2015). Pharmacology for health professionals (4th ed.). Sydney, Australia: Mosby Elsevier.

 

 

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