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.