Anticonvulsants II

Question 1

what are the hydantoin antiseizure drugs?

Answer 1

phenytoin and fosphenytoin

Question 2

which hydantoin antiseizure drug is more soluble and used for parenteral use?

Answer 2

fosphenytoin

Question 3

where is phenytoin metabolized? by what system?

Answer 3

liver - MES system

Question 4

how is phenytoin excreted?

Answer 4

urine

Question 5

elimination of phenytoin follows what kinetics?

Answer 5

dose-dependent (zero order)

Question 6

what is the MOA of phenytoin?

Answer 6

1. blocks and prolongs inactivated state of voltage gated sodium channels
2. enhances release of GABA
3. prevents seizure progagation

Question 7

what are the clinical uses for phenytoin?

Answer 7

generalized tonic-clonic, partial, status epilepticus

Question 8

what are the dose related side effects of phenytoin?

Answer 8

sedation, ataxia, nystagmus, diplopia, cardiac dysrhythmias

Question 9

what are the idiosyncratic side effects of phenytoin?

Answer 9

gingival hyperplasia

Question 10

which drug interactions decrease phenytoin metabolism?

Answer 10

barbiturates (high), warfarin

Question 11

which drug interactions increase phenytoin metabolism?

Answer 11

barbiturates (low), carbamazepine

Question 12

which drug interactions displace the protein binding of phenytoin?

Answer 12

salicylates, valproic acid, kidney failure

Question 13

which drug class is carbamazepine?

Answer 13

tricyclic

Question 14

what is the MOA of carbamazepine?

Answer 14

inhibition of voltage gated sodium channels (same as phenytoin)

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

Question 15

what is oxacarbazepine?

Answer 15

antiseizure drug similar to carbamazepine - shorter half life but active metabolite has longer duration and fewer drug interactions

Question 16

what are the clinical uses of carbamazepine?

Answer 16

general clonic-tonic (grand mal), partial seizures, TRIGEMINAL NEURALGIA

Question 17

how is carbamazepine metabolized?

Answer 17

hepatic MES - induces p450s to upregulate its own metabolism

Question 18

what is the drug of choice for trigeminal neuralgia?

Answer 18

carbamazepine

Question 19

carbamazepine has drug interactions with which other drugs?

Answer 19

phenytoin, valproate, phenobarbital

Question 20

what is the MOA of the phenobarbital?

Answer 20

enhances phasic GABAa receptor responses - increased opening time of chloride channel

Question 21

what are the side effects of cabamazepine?

Answer 21

syndrome of inappropriate ADH secretion - fluid retention and hyponatremia

Question 22

what is the main clinical use for phenobarbital?

Answer 22

status epilepticus

Question 23

what is primidone?

Answer 23

metabolized by liver (MES) to phenobarbital and phenyl ethyl malonic acid (PEMA)

Question 24

what is the MOA of ethosuximide?

Answer 24

blocks presynaptic T type calcium channels (blocks high frequency firing of neurons)

Question 25

what are the clinical uses for ethosuximide?

Answer 25

absence seizures (petit mal)

Question 26

what are the drugs of choice for petit mal (absence) seizures?

Answer 26

ethosuximide, valproic acid

Question 27

what is the MOA of valproic acid?

Answer 27

1. inhibition of presynaptic T type calcium channels - blocks neuronal firign 2. inhibition of GABA transaminase

Question 28

what is the main clinical use of vvalproic acid?

Answer 28

absence (petit mal) seizures

Question 29

what is the main adverse event of valproic acid?

Answer 29

hepatotoxic syndrome, teratogenic risk

Question 30

what are the preferred initial agents for status epilepticus?

Answer 30

diazepam (valium) or lorazepam (longer acting)

Question 31

what is the MOA of diazepam?

Answer 31

potentiates GABAa responses by increasing frequency of channel opening

Question 32

what is the main clinical use of diazepam?

Answer 32

status epilepticus

Question 33

what are the use limitations of diazepam?

Answer 33

1. sedative | 2. tolerance

Question 34

which drugs apart from diazepam and lorazepam can be used as antiepilepsy drugs?

Answer 34

clonazepam, nitrazepam, clorazepate

Question 35

what is the MOA of gabapentin?

Answer 35

blocks presynaptic voltage gated calcium channels - decreaes excitatory transmission

Question 36

what are the clinical uses for gabapentin?

Answer 36

1. generalied tonic-clonic (grand mal) 2. partial seizures 3. ****neuropathic pain - postherpetic neuralgia and fibromyalgia****

Question 37

what is pregabalin?

Answer 37

similar to gabapentin, GABA analog

Question 38

what is the MOA of lamotrigine?

Answer 38

blocks presynaptic voltage gated sodium and calcium channels

Question 39

what are the clinical uses for lamotrigine?

Answer 39

1. partial 2. grand mal 3. petit mal

Question 40

what is the main adverse effect of lamotrigine?

Answer 40

steven johnson syndrome - severe blistering / necrosis of skin

Question 41

what are the "other" newer agents of anticonvulsants?

Answer 41

1. felbamate 2. topiramate 3. tiagabine

Question 42

definition: spasticity

Answer 42

exaggerated muscle stretch reflex syndrome that occurs following injury to CNS

Question 43

definition: spasm

Answer 43

increase in muscle tension seen after certain musculoskeletal injuries and inflammation

Question 44

what is the MOA of diazepam as a muscle relaxant?

Answer 44

increases inhibitory actions of GABA on alpha motor neurons in spinal cord

Question 45

what is the MOA of baclofen as a muscle relaxant?

Answer 45

GABAb receptor agonist - increased potassium conductance, hyperpolarization, reduction in calcium influx, reduction in excitatory transmitter release

Question 46

which drug treats spasms associated with excess exertion, MS, cerebral palsy, injury?

Answer 46

diazepam

Question 47

which drug reduces spasticity with MS, spinal, and brain injury?

Answer 47

baclofen