Exam 3 - Lec 48-49 Seizures Ott Flashcards
risk factors for seizure recurrence (9 of them; slide 8)
< 2 years seizure free
-onset of seizure after age 12
-history of atypical febrile seizures
-2-6 yrs before good seizure control in tx
> 30 episodes before control achieved
-partial seizures
-abnormal EEG throughout tx
-organic neuro disorder (brain injury, dementia)
-withdrawal of phenytoin or valproate
what medications/drug classes lower the seizure threshold at normal doses? (6 of them)
-bupropion
-clozapine
-theophylline
-varenicline
-phenothiazine antipsychotics
-CNS stimulants (amphetamines)
what medications/drug classes lower the seizure threshold at high doses and impaired renal function? (6 of them)
-carbapenems (**imipenem)
-lithium
-meperidine
-penicillin
-quinolones
-tramadol
possible reasons for tx failure for drug-resistant epilepsy (3 of them)
-failure to reach CNS target
-alteration of drug targets in CNS
-drugs missing the real target
management of drug-resistant epilepsy (3 things bolded)
-rule out pseudo-resistance (wrong drug/diagnosis)
-combination therapy
-electrical/surgical intervention
status epilepticus definition
continuous seizure activity lasting 5 min or more, or two or more discrete seizure with incomplete recovery between
possible drug therapy for status epilepticus (bolded)
benzodiazepines, most commonly lorazepam or midazolam
for status epilepticus tx, what is given if seizure continues 5-20 minutes after (initial tx phase)? (2 options)
IV lorazepam or IV midazolam
why does phenytoin have a limited infusion rate?
it can cause hypotension due to propylene glycol diluent
fosphenytoin dosing
20 mg PE (phenytoin equivs)/kg IV, may give additional dose 10 min after load
why does fosphenytoin have better IV tolerance of dosing than phenytoin?
bc fosphenytoin is a prodrug of phenytoin
phenytoin/fosphenytoin administration requires cardiac monitoring, and may also cause what local reaction?
purple glove syndrome
for oral phenytoin dosing, we must obtain what two things in the same blood draw?
-phenytoin serum conc
-serum albumin
(these are used in the equation to calculate dose)
therapeutic serum conc range for phenytoin
a. 5-10 mcg/mL
b. 10-20 mcg/mL
c. 20-40 mcg/mL
d. 50-100 mcg/mL
b. 10-20 mcg/mL
IV to PO conversion for valproate
1:1 conversion
desired serum conc range for valproate
50-125 mcg/mL (~80 mcg/mL)
carbamazepine, phenobarbital, and phenytoin are inducers of which 3 CYPS?
1A2, 2C9, 3A4
lamotrigine, oxcarbazepine, and topiramate induce which CYP?
a. 1A2
b. 2C9
c. 3A4
c. 3A4
which drug is a UGT inhibitor?
a. carbamazepine
b. phenobarbital
c. phenytoin
d. lamotrigine
e. oxcarbazepine
f. valproate
g. topiramate
f. valproate
boxed warning for lamotrigine
Stevens-Johnson Syndrome
lamotrigine dosing without concomitant UGT drug interactions (4 doses to know)
-25 mg once daily x 14 days
-50 mg once daily x 14 days
-100 mg once daily x 7 days
-200 mg once daily
(if given with UGT inhibitor, dec doses by half; if given with UGT inducer, double the doses)
what must be screened prior to starting carbamazepine or like derivatives?
screen for HLA-B*1502 allele
(it is assoc with SJ syndrome and anticonvulsant hypersensitivity syndrome; if positive, pt should not be treated with these drugs unless benefits outweigh risk)
true or false: there is strong correlation for positive HLA-B*1502 allele and AHS in Asian pts
true
which allele in pts of Northern European and Asian descent may confer similar risk for AHS to HLA-B*1502?
a. HLA-B1330
b. HLA-A3101
c. HLA-B1503
d. HLA-A3151
b. HLA-A*3101
