Anticonvulsant toxicity - Phenytoin Flashcards
T or F: Phenytoin tox usually leads to severe morbidity or death, regardless of care quality
F
severe morbidity and death are usually avoided w/ good supportive care
AEs of IV phenytoin
local tissue damage (alkaline), cardiotox
What can happen if we give IV phenytoin too quickly?
Increased risk of tox (tissue death, cardiotox)
T or F: po phenytoin is absorbed very predictably due to the presence of specific transporters
F
It’s erratic
What can form in the GI tract if too much phenytoin is ingested?
bezoars
Describe phenytoin’s distribution
It rapidly distributes to all tissues
T or F: Phenytoin has very poor plasma protein binding
F
It’s very extensive
What can cause variability in metabolism of CBZ within the population?
polymorphism of CYP 2C9
As [phenytoin] increases, kinetics switch from 1st to zero order.
T (this is saturation kinetics)
Therapeutic levels of phenytoin:
40-80µmol/L (this is TOTAL, not free levels)
Most common neurologic phenytoin tox sx?
drowsiness, lethargy
CV tox sx’s of phenytoin?
bradycardia, hypotn, cardiac arrest
GI/hepatic sx’s of phenytoin tox?
N/V
RUQ tenderness
hepatomegaly
hepatitis
T or F: Phenytoin tox is assoc w/ both miosis and mydriasis.
T
Mainstay of tx for phenytoin tox?
Supportive/symptomatic care (IV fluids, vasopressors for hypotn, airway protection)
