34/35: Anticonvulsant Drugs Flashcards Preview

Pharm Exam 3 > 34/35: Anticonvulsant Drugs > Flashcards

Flashcards in 34/35: Anticonvulsant Drugs Deck (66):
1

define seizure

sudden, transient episode of brain dysfunction and altered behavior due to abnormally excessive, synchronous, and rhythmic firing of certain populations of hyper-excitable neurons in the brain

2

activation of motor neurons leading to involuntary contractions of skeletal muscle =

convulsions

3

chronic neurological disorder characterized by recurrent seizures =

epilepsy

primary/idiopathic - unknown origin

secondary - identifiable cause

4

describe a simple partial seizure

-minimal spread of abnormal neuronal discharge
- no loss of consciousness
- limited motor or sensory manifestations

5

describe a complex partial seizure

- starts in a small brain area but quickly spreads to other areas
- altered consciousness with potential automatisms
- strong emotional feelings, gradual recovery of consciousness within minutes

6

what are automatisms?

lip smacking, fumbling, swallowing, etc...

7

involve the entire brain with global EEG change and bilateral manifestations

generalized epileptic seizures

8

describe absence/ petit mal seizures

- sudden onset and abrupt cessation
- brief loss of consciousness
- typically in children less than 15 yo
- inducible by hyperventilation, stress or flash light

9

describe tonic-clonic/ grand mal seizures

- tonic spasms and major convulsions of entire body bilaterally
- loss of consciousness and profound CNS depression after seizure

10

what are the four phases of a tonic-clonic seizure?

1. aura
2. tonic (tense)
3. clonic (convulsions)
4. stuporous state and sleep

11

observe: child with sudden loss of postural tone resulting in falls or dropping of head and torso if in sitting position, may be wearing a helmet

atonic generalized seizure

12

recurrent myoclonic jerks of the body with sudden flexion or extension of the body and limbs

infantile spasms

13

what is status epilepticus?

continuous or very rapid recurrin seizures, usually of tonic-clonic type
- medical emergency requiring immediate therapy

14

mechanism generating epileptic seizures: 3 stages

1. initiation (focal epileptogenesis)
2. synchronization of surrounding
3. propagation (recruitment of normal neurons)

15

goal of antiepileptic medications

restore normal patterns of electrical activity

inhibit seizures, partially effective as prophylaxis but not a cure

16

alternative treatment options for epilepsy (not meds)

- surgery (resection, particularly in temporal lobe)
- vagus nerve stimulation (for drug-resistant patients with partial seizures)

17

what medications would you use for partial seizures (complex or simple) with or without secondarily generalized seizures?

carbamazepine
phenytoin
valproate

18

what medications would you use for tonic-clonic seizures, tonic seizures, or atonic seizures?

carbamazepine
phenytoin
valporate

19

what medications would you use for absence seizures?

ethosuximide
valproate

20

what medications would you use for myoclonic seizures?

clonazepam
valproate

21

what medications would you use for status epilepticus?

diazepam
larazepam
phenytoin
fosphenytoin

22

3 major MOA for anticonvulsant medications

1. decrease excitatory effects of glutamate and repetitive firing of neurons
2. increase inhibitory effects of GABA
3. alter neuronal activation by altering movement of ions across neuronal membrane

23

anti-seizure medications can bind to Na channels in the _______ and prevent conversion ______

inactive; resting state

- this prolongs Na channel inactivation and make neuronal membrane less excitable

24

what reduces the pacemaker current that underlies the thalamic rhythm in spikes and waves seen in absence/ petit mal seizures?

reducing the calcium influx

25

general side effects of anticonvulsants

-sedation
-diplopia
- nystagmus
- ataxia
- GI upset

26

other side effects to watch for in anticonvulsants...

- abrupt withdrawal can cause seizures
- decreased efficacy of oral contraceptives
- teratogenic

27

what drug is considered safest for pregnancy?

phenobarbital

28

what is the elimination of phenytoin look like?

dose-dependent (zero order) elimination that is different for different patients

system can become saturated and transition ot a non-linear relationship

metabolized in liver, excreted in urine

29

MOA phenytoin

1. blocks and prolongs the inactivated state of voltage-gated Na channels
2. enhances the release of GABA
3. prevents seizure propagation

30

clinical uses for phenytoin

- grand mal
- partial seizures
- status epilepticus

31

gingival hyperplasia is a negative side effect of what drug?

phenytoin



32

what is fetal hyantoin syndrome?

teratogenic
cleft lip and palate

side effec tof phenytoin

33

MOA carbamazepine

*inhibition of voltage gated Na channels

also blocks high frequency firing of neurons and decreases synaptic release of glutamate

34

how is oxacarbazepine different than carbamazepine?

shorter half-life, but active metabolite has longer duration and fewer drug interactions

35

drug of choice for trigeminal neuralgia

carbamazepine

36

clinical uses for carbamazepine

- grand mal
- partial seizures
- trigeminal neuralgia

37

SIADH = ?

syndrome of inappropriate ADH secretion

side effect of carbamazepine that causes increased fluid retention and hyponatremia

38

what drug interactions do you need to watch for with carbaamazepine?

phenytoin
valproate
phenobarbital

39

MOA phenobarbital

enhances phasic GABAa receptor responses by increasing duration of Cl- channel opening

40

drug of choice for seizures in infants

phenobarbital

41

clinical use for phenobarbital

status epilepticus (and others)

42

metabolized by the liver to phenobarbital

primidone

43

drug of choice petit mal/ absence seizures

ethosuximide and valproic acid

44

MOA ethosuximide

blocks presynaptic t-type Ca2+ channels to stop high-freqeuncy firing of neurons

45

least sedating anticonvulsant

valproic acid

also chemically unrelated to other anticonvulsants

46

MOA valproic acid

- inhibition of presynaptic t-type Ca2+ channels to block neuronal firing
- inhibition of GABA transaminase

47

special adverse effects for valproic acid

hepatotoxic syndrome and spina bifida if preggers (teratogenic)

do not use less than 5 yo

48

preferred initial agent for status epilepticus

diazepam

49

how is lorazepam different than diazepam?

longer duration of action

50

MOA diazepam

- potentiates GABAa responses by increasing frequency of channel opening

51

use limitations for diazepam

sedative effects and tolerance

52

MOA gabapentin and pregabalin

GABA analogs that block presynaptic voltage-gated Ca2+ channels to decrease excitatory transmission

53

clinical uses gabapentin

- grand mal
- partial seizures
- neuropathic pain

54

MOA lamotrigine

blocks presynaptic voltage-gated Na and Ca channels

55

clinical uses for lamotrigine

- partial and generalized seizures
- petit and grand mal

56

adverse effect of lamotrigine

**stevens-johnson syndrome (rash)

especially if used with valproate

57

MOA felbamate

blcok Na channels and glutamate receptors

58

adverse effects felbamate

aplastic anemia, hepatic failure

59

specifically designed as an inhibitor of GABA uptake

tiagabine

60

MOA acetazolamide

carbonic anhydrase inhibitor

effect thought to be related to mild CNS acidosis

61

spasticity v. spasm

both are the result of hyperexcitabiliyt of the neurons or muscle cells

primarily an exaggerated muscle stretch reflex syndrome that occurs following injury to the CNS

v.

an increase in muscle tension seen after certain musculoskeletal injuries and inflammation (injury is local and not in the CNS)


62

goal of pharmacotherapy for muscle spasms and spasticity

normalize muscle excitability without causing a profound decrease in muscle function

63

centrally acting muscle relaxants (2)

diazepam
baclofen

64

how does diazepam act as a muscle relaxant?

works by increasing the central inhibitory actions of GABA on alpha motor neurons in the spinal cord

65

treat spasms with _____; treat spasticity with _______

diazepam; baclofen

66

MOA baclofen

GABAb receptor agonist

as effective as diazepam, but causes less sedation