CNS 1

Question 1

MOA of phenytoin (dilantin)

Answer 1

stabilize nerve cells to keep them from getting overexcited, works in the motor cortex of the brain where it stops the spread of seizure activity

Question 2

phenytoin uses

Answer 2

complete partial seizures, tonic-clonic seizures

Question 3

difference between phenytoin and dilantin

Answer 3

dilantin can be taken once a day..phenytoin cannot

THEY ARE NOT INTERCHANGEABLE

Question 4

drug-drug interactions of phenytoin

Answer 4

effects are reduced by:
phenobarbital
carbamazepine
rifampin
antacids
gingko
ETOH
azole drugs

may reduce effectiveness of oral contraception pills
corticosteroids
anticoagulants
levodopa
TH

Question 5

phenytoin considerations

Answer 5

enteral feedings may interfere with absorption of oral phenytoin –>stop feedings 2 hrs before or after

not compatible with D5W –> precipitates

avoid giving IV push into back of hand –> discoloration “purple glove syndrome”

discard any unused drugs after 4 hrs

Question 6

what is therapeutic range for phenytoin? at what ranges do you start seeing specific symptoms?

Answer 6

therapeutic: 10-20 mcg/ml
20-30 –> nystagmus
30-40 –> ataxia
>40 –> decreased LOC

Question 7

phenytoin adverse effects

Answer 7

nystagmus - dyplopia
sedation
ataxia
hirsutism
gingival hyperplasia

skin reactions - Stevens Johnson, toxic epidermal necrolysis - higher in Asian population

hypotension
dysrhythmias

Question 8

Carbamazapine (tegretol) MOA

Answer 8

same as phenytoin

Question 9

carbamazepine uses

Answer 9

partial and generalized tonic-clonic seizure

mixed seizure types

complex partial seizures (DOC)

relieves pain R/T trigeminal neuralgia

bipolar disorder

Question 10

therapeutic blood level of carbamazepine

Answer 10

8-12 mcg/ml

Question 11

carbamazepine drug interactions

Answer 11

reduces effects of :
oral anticoagulants
haloperidol
bupropion
TCAs
oral contraception
other anticoagulants

increases levels of:
diltiazem, 
INH, 
selective SSRIs, 
azole drugs
valproic acid
verapamil

Lithium and carbamazepine taken together leads to increase risk of toxic neurological effects

Question 12

warnings with carbamazepine

Answer 12

contraindicated if glaucoma, cardiac, renal, or hepatic disease

can cause SIADH - monitor Na+

avoid ETOH

avoid grapefruit juice

can depress bone marrow - watch for s/s of infection or bleeding

photosensitivity

watch for low sodium - HA, confusion, slurred speech, weakness, feeling unsteady

Question 13

valproic acid drugs

Answer 13

Depakote, Depakane

Question 14

MOA of valproic acid

Answer 14

unknown, thought to increase GABA, an inhibitory neurotransmitter, as well as having direct membrane stabilizing effect

Question 15

uses of valproic acid

Answer 15

absence, myoclonic, tonic-clonic, partial, neonatal seizures
prevent migraine
bipolar disorder

Question 16

therapeutic range of valproic acid

Answer 16

50-100 mcg/ml

Question 17

considerations with valproic acid

Answer 17

monitor CBC, AST

monitor for N/V, lethargy, impaired PT/PTT, hair loss, leukopenia, hepatotoxicity

increases serum phenobarbital level and alter serum phenytoin levels

monitor for drowsiness, blood dyscrasia, ataxia, nystagmus, GI distress

Question 18

valproic acid - pregnancy category

Answer 18

X

Question 19

patient teaching with anticonvulsants

Answer 19

take drug exactly as prescribed, don’t stop without HCP approval

take with food–> reduce GI upset and loss of appetite

don’t change brand/dosage forms

avoid hazardous activities that require mental alertness

space activities throughout day to allow time for rest

report persisten/bothersome effects

may cause pink, red, brown urine

ETOH may diminish drug’s benefit

perform oral hygiene

Question 20

what is levodopa used for?

Answer 20

Parkinson’s disease

we want to correct the neurotransmitter imbalance by increasing dopamine and decreasing Ach

Question 21

levodopa MOA

Answer 21

relieves motor symptoms by conversion to dopamine by decarboxylase in surviving nerve terminals in the brain

Question 22

levodopa disadvantages

Answer 22

full therapeutic effect can take months

highly effective by benefits diminish over time

orally administered, rapid absorption in the small intestine

food delays absorption - take on empty stomach

proteins compete with levodopa for intestinal absorption and for transport across BBB so don’t take with high protein meal

Question 23

what is the on-off syndrome with levodopa?

Answer 23

works for 2-5 years –> loss of response over time

gradual wearing off at the end of dose

abrupt loss of effect can happen anytime

need to let doctor know if this is happening so adjustments can be made

Question 24

what is a drug holiday and what drug does it help with?

Answer 24

helps with the effectiveness of levodopa

with long term use of levodopa, adverse effects tend to increase and therapeutic effects tend to diminish. For some patients, taking time off (~10 days) may produce a beneficial effect with lower doses

drug holidays must take place in the hospital because drug withdrawal immobilizes the patient. The patient is at risk for all of the physical and psychological effects of this stress

Question 25

why do we use carbidopa?

Answer 25

so levodopa is broken down in the gut by decarboxylase --> need large doses to get adequate levels in the CNS --> high peripheral levels of dopamine --> increased adverse effects confusion, dyskinesia, GI distress, hypotension, dysrhythmias so levodopa is given with carbidopa, a peripheral decarboxylase inhibitor carbidopa inhibits decarboxylase --> less levodopa is broken down --> more levodopa can make it to the brain --> we can use lower doses of levodopa allows dose of levodopa to be reduced by 75%

Question 26

what drugs are levodopa/carbidopa

Answer 26

sinemet, parcopa

Question 27

adverse effects of levodopa/carbidopa

Answer 27

N/V CV: postural hypotension, arrhythmias psychosis dyskinesias

Question 28

drug interactions of levodopa/carbidopa

Answer 28

non-selective MAO inhibitors 1st gen antipsychotics anticholinergics pyridoxine (vitamin B6) - more with levodopa alone

Question 29

contraindications of levodopa

Answer 29

angle-closure glaucoma - increased intra-ocular pressure undiagnosed skin conditions - can activate malignant melanoma

Question 30

levodopa food interactions

Answer 30

high protein meals --> slows absorption --> reduce therapeutic effect vitamin B6 - fish, beef, liver

Question 31

levodopa nursing implications

Answer 31

may be taken with food to reduce N/V (avoid high protein meals - take med 30 min before/1 hr after) inform patient that benefits maybe delayed for weeks to months evaluate for improvements in ADLs and reductions in bradykinesia, postural instability, tremors, rigidity to reduce off times, combine with dopamine agonist, COMT inhibitor, or MAO-B inhibitor

Question 32

what drugs are COMT inhibitors

Answer 32

entacapone | tolcapone

Question 33

COMT inhibitor MOA

Answer 33

inhibit metabolism of levodopa in the periphery blocks enzyme COMT which breaks down levodopa --> reduces wearing off of levodopa --> prolongs time that levodopa is available to the brain

Question 34

COMT inhibitor adverse effects

Answer 34

``` liver failure GI dyskinesia diarrhea brown-orange urine discoloration (entacapone) hyper/hypokinesia syncope hypotension abd pain constipation dry mouth back pain diaphoresis ```

Question 35

anticholinergic drugs MOA

Answer 35

goal is to inhibit cholinergic effects block PNS activity --> decrease acetylcholine

Question 36

anticholinergic uses

Answer 36

tremors rigidity (cog wheeling) control sialorrhea

Question 37

anticholinergic drugs

Answer 37

benzotropine (Cogentin) biperiden (Akineton) procyclidine trijexyphenidyl

Question 38

lithium MOA

Answer 38

unknown, may regulate catecholamine release by the CNS by 1) increasing norepinephrine and serotonin uptake 2) reducing the release of norepinephrine from the synaptic vesicles (where neurotransmitters are stored) in the presynaptic neuron 3) inhibiting norepinephrine's action in the postsynaptic neuron

Question 39

lithium therapeutic uses

Answer 39

bipolar disorder: DOC for manic episodes and long term prophylaxis and preventing suicide other uses: alcoholism, migraines, bulimia, anorexia, schizophrenia, glucocorticoid-induced psychosis

Question 40

lithium facts

Answer 40

excreted by the kidneys with same mechanism as sodium - lithium excretion is low when sodium level is low effects begin in 5-7 days but full effect after 2-3 weeks narrow therapeutic range - must monitor drug levels for management of acute mania, a lithium serum level of 1-1.5 is usually required desirable long term maintenance levels range between 0.6-1.2

Question 41

lithium drug interactions

Answer 41

loss of Na+ --> kidney retain lithium to compensate --> lithium toxicity loss of Na+ can occur with: 1) thiazide or loop diuretic 2) severe salt restricted diet 3) dehydration: N/V, hot weather risk of toxicity increases when taking NSAIDS administration of lithium with haloperidol, phenothiazines, carbamazepine may produce increased risk of neurotoxicity lithium may increase hypothyroid effects of potassium iodine sodium bicarbonate may increase lithium excretion --> reduce effects

Question 42

lithium adverse effects

Answer 42

fatigue, HA, confusion, memory problems poor concentration N/V weight gain hair loss acne renal toxicity - check renal function before starting every year fine tremors polyuria/thirst (DI) - drink 8-12 glasses of fluid daily goiter and hypothyroidism - Li inhibits TH secretion

Question 43

lithium toxic effects

Answer 43

confusion, lethargy slurred speech hyperreflexia seizures pregnancy category D

Question 44

lithium patient teaching

Answer 44

take with 2-3 liters of water/day and after meals to minimize GI upset expect transient nausea, thirst, discomfort first few days of therapy avoid activities that require alertness and psychomotor coordination don't switch brands or take OTC without HCP approval wear/carry medical identification lithium has narrow therapeutic window: 1) blood level that is even slightly high can be dangerous 2) watch for s/s of toxicity including diarrhea, vomiting, tremor, drowsiness, muscle weakness, ataxia 3) withhold one dose and call HCP if toxic symptoms appear - don't stop drug abruptly

Question 45

what are the two groups of drugs for muscle spasms and spasticity

Answer 45

localized muscle spasms Diazepam (Valium) Tizanidine (Zanaflex) spasticity Baclofen (Lioresal) Diazepam (Valium) Dontrolene (Dantrium)

Question 46

therapeutic use of centrally acting muscle relaxants

Answer 46

``` relieve local muscle spasm decrease local muscle pain increase ROM neither drug is better than another - drug selection is based on prescriber preference and patient response NOT FOR SPASTICITY ```

Question 47

centrally acting muscle relaxant drugs

Answer 47

``` Carisoprodol (Soma) Chlorzoxazone (Lorzone) Cyclobenzaprine (Flexeril) Metaxalone (Skelatxin) Methocarbamol (Robaxin) Orphendrine (Norflex) Tizanidine (Zanaflex) ```

Question 48

adverse effects of muscle relaxants

Answer 48

generalized CNS depression - safety issues drowsiness, dizziness hypotension (Tizanidine) severe reactions: allergic reactions, arrhythmias, bradycardia hepatotoxicity - Tizanidine, Metaxalone hepatitis and necrosis - chlorzoxazone long term drug use can lead to physical dependence less common: abd distress, N/V, constipation/diarrhea, heartburn, ataxia NOT MEANT FOR CHRONIC USE - TAKEN FOR SHORT TIME ~2-3 WEEKS

Question 49

Baclofen MOA

Answer 49

chemically similar to GABA, probably acts on spinal cord reduces nerve impulses from the spinal cord to skeletal muscle, decreases number and severity of muscle spasms and associated pain

Question 50

Baclofen uses

Answer 50

spasticity associated with spinal cord injury multiple sclerosis trauma

Question 51

Baclofen withdrawal

Answer 51

avoid abrupt discontinuation --> baclofen withdrawal classic symptoms are sudden increase or return of spasticity or tone, profuse sweating and itching without rash, fever, high HR or RR, high/low BP, confusion severe symptoms include hallucinations, delirium, seizures, rhabdomyolysis, organ failure, death use diazepam to offset withdrawal symptoms

Question 52

Diazepam MOA

Answer 52

acts in CNS - mimics GABA

Question 53

Diazepam adverse effects

Answer 53

sedation

Question 54

Dantrolene MOA

Answer 54

act directly on skeletal muscle - suppresses release of Ca++ from sarcoplasmic reticulum

Question 55

Dantrolene uses

Answer 55

spasticity associated with MS, cerebral palsy, spinal cord injury treatment for malignant hyperthermia

Question 56

Dantrolene adverse effects

Answer 56

``` hepatotoxicity muscle weakness drowsiness diarrhea acne like rash ```

Question 57

S/S of malignant hyperthermia

Answer 57

dramatic rise in body temp --> as high as 113 F rigid/painful muscles, esp in jaw flushed skin sweating abnormally rapid/irregular heart beat rapid/uncomfortable breathing brown urine very low BP confusion muscle weakness or swelling