Transient LOC + Clinical Reasoning Flashcards
What is Graham’s law in relation to pharmacokinetics?
Rate of passive diffusion is inversely proportional to the square root of the molecular size
What is Fick’s law in relation to pharmacokinetics?
Rate of diffusion across a membrane is proportional to the concentration gradient across that membrane
Name a drug with an active metabolite
Morphine
Name 3 types of phase 1 reaction that occurs in the liver
- Oxidation
- Reduction
- Hydrolysis
What type of reaction is phase 2 of metabolism in the liver?
Conjugation
Name the enzyme responsible for the metabolism of catecholamines
Mitochondrial enzyme - Monoamine oxidase
What is the other name for the cytochrome p450 enzymes?
Mixed function oxidase system in the endoplasmic reticulum
Suggest 3 drugs that will induce the cytochrome p450 system in the liver
- Rifampicin
- Chronic alcohol abuse
- Anticonvulsants e.g. Phenytoin and carbamazepine
Suggest 3 drugs that will cause inhibition of the cytochrome p450 system in the liver
- Metronidazole
- Amiodarone
- Cimetidine
What is enterohepatic recycling in regards to pharmakoinetics?
Drugs excreted in the bile may be hydrolysed by bacterial enzymes. The products of hydrolysis may then be reabsorbed into the bloodstream and may have an active effect
Name a common medication that is affected by enterohepatic recycling
Oral contraceptive pill
When is phenytoin most commonly used as an anti-epileptic agent?
Emergency treatment of status epilepticus
Name the most commonly used anti-epileptic agent used throughout the world
Phenobarbital
What is the gold standard treatment for localised related seizures?
Carbamazepine
What is the gold standard treatment for a primary generalised seizure?
Sodium valproate
In which layer of the cereal cortex are pyramidal cells found?
Layer 4
What is the most common neurotransmitter in an excitatory neuron?
Glutamate
What is the most common neurotransmitter in an inhibitory neuron?
GABA
Which channel type does the drug Retigabine act upon?
Potassium channels
Describe the the action of Levetiracetam
Inhibits the release of neurotransmitter from the vesicle into the synaptic cleft
Name 5 anti-epileptic drugs that act on calcium channels
- Ethosuximide
- Pregabalin
- Gabapentin
- Lamotrigine
- Zonisamide
Name 3 anti-epileptic drugs that act on sodium channels
- Phenytoin
- Carbamazepine
- Lamotrigine
Describe the action of topiramate
Acts on the post synaptic NMDA receptors to inhibit the uptake of glutamate from the synaptic vesicle
Name 4 anti epileptic drugs that act on the postsynaptic GABA receptors
- Benzodiazepines
- Phenobarbitone
- Valproate
- Topiramate
Describe the mechanism of action of Tiagabine
GABA reuptake inhibitor
Describe the mechanism of action of Vigabatrin
GABA transaminase inhibitor
Give 3 pharmacokinetics processes involving anti-epileptic drugs that are not linear in nature
- Elimination of phenytoin
- Absorption of Gabapentin
- Protein binding of valproate
Name 3 anti-epileptics which may cause a rash
- Lamotigine
- Carbamazepine
- Phenytoin
Name 2 anti-epileptic agents which may cause bone marrow suppression
- Felbamate
2. Carbamazepine
Name 2 anti-epileptic agents which may cause hepatic toxicity
- Valproate
2. Felbamate
Outline 6 common neurotoxic side effects associated with anti-epileptic drugs
- Dizziness
- Diplopia
- Ataxia
- Incoordination
- Drowsiness
- Cognitive slowing
Name an anti-epileptic which may cause weight gain
Valproate
Name an anti-epileptic which may cause weight loss
Topiramate
Which anti-epileptics are associated with a 10% increased risk of mood disorders?
- Topiramate
2. Levetiracetam
Outline 3 potential reproductive consequences of anti-epileptic drugs
- Polycystic ovarian syndrome (valproate)
- Erectile dysfunction
- Teratogenesis
What is the medication of choice for new onset focal epilepsy?
Lamotrigine
Name an anti-epileptic that does not interact with the OCP
Sodium valproate
What is the half life of carbamazepine?
35 hours
Name an anti-epileptic that is contra-indicated for the treatment of Juvenile myoclonic epilepsy due to the risk of exacerbating seizure activity
Carbamazepine
If Phenytoin needs to be taken long term, it should be replaced with which alternative drug?
Lamotrigine