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14 Cards in this Set
- Front
- Back
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Define Seizure
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sudden depolarisation of a group of neurons leading to an abnormal synchronous electrical discharge from the CNS
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Name the three anticonvulsant drug mechanisms
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1.Ion channels
Inhibition of sodium or calcium channels cannot depolarise and form an action potential Potentiation of chloride channels hyperpolarising axon to inhibit action potentials 2) Potentiation of GABA increasing the effect of the main inhibitory neurons 3) Inhibition of excitatory (eg. glutamate) neurotransmission decreasing the effect of the main excitatory neurons |
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Name the mode of action of barbiturates
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The barbiturates can bind directly to the chloride
channel and open it wide open (the benzodiazepines are limited by the amount of endogenous GABA) Acts to stabilise electrical activity by raising the potential necessary for depolarisation Preferentially targets the reticular activation system (RAS) that is responsible for arousal & spreading of epileptiform activity Increases the seizure threshold Decreases the electrical activity of a seizure Mechanism of action will extend to general anaesthesia |
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Name 5 points about barbiturates. Think about the effects on the CVS and respiratory system
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Depression of the respiratory centres is depressed.
Depress myocardium but increase in heart rate (CO and BO preserved) BP falls when given rapidly IV. Low therapeutic indices Undergoes hepatic metabolism. |
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Name 3 barbiturates
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Phenobarbitone
Pentobarbitone Potassium bromide |
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Phenobarbitone. Name 4 pros and 3 cons.
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Used for controlling seizures
Dose dependent Sub- sedative effect. Oral maintenance medication Last longer than diazepam and efficacious. > Requires patience, animals will stop seizuring only once therapeutic concentrations are reached in the brain (tens of seconds-minutes) Induce HME Causes sedation. |
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Pentobarbitonne
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Profound sedation.
used for euthanasia |
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Potassium bromide.
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MOA- unknown
Dose lowering effect Oral maintenance |
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Barbiturates
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Bind directly to chloride channels to open it.
Raising the potential for depolarization therefore stabilize electrical activity. Targets RAS system: responsible for arousal & spreading of epileptiform activity. Mechanism will extend to general anaesthesia. Depression of the respiratory centres is depressed. Depress myocardium but increase in heart rate (CO and BO preserved) BP falls when given rapidly IV. Low therapeutic indices Undergoes hepatic metabolism. |
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Name 3 barbiturates
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Phenobarbitone
pentobarbitone potassium bromide |
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Phenobarbitone. Name 4 pros and 3 cons.
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Sub – sedative= anticonvulsive
Oral maintenance for owners to take home NO ceiling effect Last longer than diazepam and efficacious Induce HME Sedation |
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Pentobarbitone
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Anti-convulsants with significant sedation.
-Mainly for euthanasia |
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Potasium Bromide
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MOA- unknown
Dose lowering effect Oral maintenance |
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Barbiturates: MOA
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The barbiturates can bind directly to the chloride
channel and open it wide open (the benzodiazepines are limited by the amount of endogenous GABA) Acts to stabilise electrical activity by raising the potential necessary for depolarisation Preferentially targets the reticular activation system (RAS) that is responsible for arousal & spreading of epileptiform activity Increases the seizure threshold Decreases the electrical activity of a seizure Mechanism of action will extend to general anaesthesia |
