Parkinson's & Epilepsy recap Flashcards
DTs
hyperadrenergic state - highly excitable
hallucinations, confusion, delusions, severe agitation, generalised tonic clonic seizures
Tx is based on a symptom score, depending on the symptoms, and if the patient scores high enough they are treated with benzodiazepines as required
management: ABC assessment treat any hypoglycaemia sedations with benzodiazepines barbiturates?ICU may be required screen for Wernicke's encephelopathy treat with oral thiamine (vit B1) eg pabrinex
wernickes encephalopathy
signs and symptoms
korsakoffs
signs and symptoms
benzodiazepines
resp depression
can precipitate hepatic encephalopathy
in patients with ALD use lower dose
phenytoin
10-20mg/l
measured using both free and protein bound phenytoin
in patients with low albumin, the free phenytoin may be normal even if the total level is low due to the low amount protein bound
important info:
inhibitor of p450 enzymes
inducder of p450
narrow therapeutic index
first order kinetics within therapeutic range
highly protein bound
causes hypotension and arrhythmias when given IVI
phenytoin kinetics
metabolism is dose dependent
first order kinetics at low concentrations - constantly increasing as dose increases
zero order kinetics at high concentrations - plateaus and metabolised at the same rate even in higher doses
sodium valproate
inhibitor of p450 enzymes
teratogenic
monitor levels
pancreatitis is a side effect
status epilepticus
> 5mins: IV lorazepam, PR diazepam, buccal midazolam
20mins: alert anaesthetist for further sedation
if benzodiazepines don’t work –> slow IV phenytoin (caution arrhythmias and hypotension)
carbamazepine and warfarin
carbamazepine is an enzyme inducer and will therefore induce the metabolism of warfarin, so the dose of warfarin must be increased accordingly, and INR monitored
it would be acceptable to continue using both, with more INR monitoring or to stop carbamazepine in favour of an alternative eg lamotrigine. patient discussion and choice
carbamazepine
p450 enzyme inducer
raised GGT due to enzyme induction
hyponatraemia due to carbamazepine causing (rarely) SIADH
can induce its own metabolism
toxicity (as with most anti-epileptics):
cerebellar signs
reduce the dose and monitor until symptoms are under control
drug induced parkinsonism
subacute, bilateral onset is unusual in normal parkinson’s, usually tremor starts in one hand
high risk drugs are dopamine antagonists, like haloperidol, stemetil (for vertigo)