Mosby's 2014 Nursing Drug Reference (151 page)

Canada only   Side effects:
italics
= common;
bold
= life-threatening   
Nurse Alert

entacapone (Rx)

(en′ta-kah-pone)

Comtan

Func. class.:
Antiparkinson agent

Chem. class.:
COMT inhibitor

ACTION:

Inhibits COMT (catechol
O
-methyltransferase) and alters the plasma pharmacokinetics of levodopa; given with levodopa/carbidopa

USES:

Parkinson’s disease for those experiencing end of dose; decreased effect as adjunct to levodopa/carbidopa

CONTRAINDICATIONS:

Hypersensitivity

Precautions:
Pregnancy (C), breastfeeding, children, renal/hepatic disease, affective disorders, psychosis

DOSAGE AND ROUTES
Calculator

• Adult:
PO
200 mg given with carbidopa/levodopa, max 1600 mg/day; may allow for 25% dosage reduction in levodopa therapy

Available forms:
Tabs, film coated 200 mg

Administer:

• 
Only after MAOIs have been discontinued for 2 wk

• 
Give with dose of levodopa/carbidopa; product has no effect on its own

SIDE EFFECTS

CNS:
Involuntary choreiform movements, hand tremors, fatigue, headache, anxiety, twitching, numbness, dyskinesia, hypokinesia, hyperkinesia, weakness, confusion, agitation, nightmares
, psychosis, hallucination, hypo
mania, severe depression, dizziness,
neuroleptic malignant syndrome

CV:
Orthostatic hypotension

GI:
Nausea, vomiting, anorexia, abdominal distress, dry mouth, flatulence, bitter taste, diarrhea, constipation, dyspepsia
, gastritis, GI disorder

INTEG:
Rash, sweating, alopecia

MISC:
Dark urine and other body fluids, back pain, dyspnea, purpura, fatigue, asthenia, bacterial infection,
rhabdomyolysis

PHARMACOKINETICS

Duration up to 8 hr; excreted in urine, feces; well absorbed; protein binding 98%; metabolized in liver extensively; enters breast milk; half-life of levodopa extended, half-life 0.5 hr initial, 2.5 hr second

INTERACTIONS

• 
Prevents catecholamine metabolism—nonselective MAOIs; do not use together

Increase:
B/P, tachycardia, dysrhythmias, avoid use—bitolterol, DOPamine, DOBUTamine, EPINEPHrine, methyldopa, isoetharine, norepinephrine

Decrease:
excretion of entacapone—ampicillin, chloramphenicol, probenecid, erythromycin, rifampin

Drug/Herb

Increase:
B/P—ma huang

Decrease:
effect—kava

NURSING CONSIDERATIONS
Assess:

 
Neuroleptic malignant syndrome:
high temp, increased CPK, rigidity, change in LOC usually during rapid withdrawal

• 
Involuntary movements of Parkinson’s disease:
akinesia, tremors, staggering gait, muscle rigidity, drooling when given with levodopa/carbidopa

• 
B/P, respirations during initial treatment

• 
Mental status: affect, mood, behavioral changes, depression; complete suicide assessment

• 
Rhabdomyolysis:
muscle pain, tenderness, weakness; swelling of affected muscles; may lead to decreased B/P, shock

Perform/provide:

• 
Assistance with ambulation during beginning therapy

Evaluate:

• 
Therapeutic response: decrease in akathisia, increased mood when given with levodopa/carbidopa

Teach patient/family:

• 
That hallucinations, mental changes, nausea, dyskinesia can occur; may mean patient is overmedicated

• 
To change positions slowly to prevent orthostatic hypotension; not to drive, operate machinery until stabilized on medication and mental performance not affected

• 
To use product exactly as prescribed; if dose is missed, to take as soon as remembered up to 2 hr before next dose; not to discontinue abruptly; to withdraw gradually

• 
That urine, sweat may darken

• 
To notify prescriber if pregnancy is suspected; if lactating, that product excreted in breast milk

Canada only   Side effects:
italics
= common;
bold
= life-threatening   
Nurse Alert

entecavir (Rx)

(en-te′ka-veer)

Baraclude

Func. class.:
Antiretroviral nucleoside reverse transcriptase inhibitor (NRTIs)

Chem. class.:
Guanosine nucleoside analog

ACTION:

Inhibits hepatitis B virus DNA polymerase by competing with natural substrates and by causing DNA termination after its incorporation into viral DNA; causes viral DNA death

USES:

Chronic hepatitis B (HBV)

CONTRAINDICATIONS:

Hypersensitivity

Precautions:
Pregnancy (C), breastfeeding, children, geriatric patients, severe renal disease

 

Black Box Warning:

Hepatic disease, hepatitis, HIV, lactic acidosis

DOSAGE AND ROUTES
Calculator
Chronic hepatitis B (nucleoside treatment naive)

• Adult and adolescent ≥16 yr:
PO
0.5 mg/day

Chronic hepatitis B with compensated liver disease and history of hepatitis B viremia while receiving lamivudine or known lamivudine/telbivudine-resistant mutations

• Adult and adolescent ≥16 yr:
PO
1 mg/day

Renal dose

• Adult:
PO
CCr ≥50 ml/min, 0.5 mg/day; CCr 30-49 ml/min, 0.25 mg/day, 0.5 mg/day or 1 mg q48hr for lamiVUDine-refractory patient; CCr 10-29 ml/min, 0.15/day, 0.3 mg or 1 mg q72hr for lamiVUDine-refractory patient; CCr <10 ml/min, 0.05 mg/day, 0.1 mg/day or 1 mg q7days for lamiVUDine-refractory patient

Available forms:
Tabs, film coated 0.5, 1 mg; oral sol 0.05 mg/ml

Administer:

• 
After hemodialysis

• 
By mouth on empty stomach 2 hr before or after food

• 
Store at room temperature

• 
Oral liquid:
use calibrated oral dosing spoon provided; may be used interchangeably with tabs

SIDE EFFECTS

CNS:
Headache
, fatigue, dizziness, insomnia

ENDO:
Hyperglycemia

GI:
Dyspepsia
, nausea, vomiting, diarrhea, elevated liver function enzymes

INTEG:
Alopecia, rash

SYST:
Lactic acidosis, severe hepatomegaly with steatosis

PHARMACOKINETICS

Peak 0.5-1.5 hr, steady state 6-10 days, 100% bioavailability, extensively distributed to tissues, protein binding 13%, terminal half-life 128-149 hr, excreted unchanged (62%-73%) via kidneys

INTERACTIONS
Drug/Food

Decrease:
absorption—high-fat meal

Drug/Lab Test

Increase:
ALT, AST, total bilirubin, amylase, lipase, creatinine, blood glucose, urine glucose

Decrease:
platelets, albumin

NURSING CONSIDERATIONS
Assess:

• 
For nephrotoxicity:
increasing CCr, BUN

 

Black Box Warning:

For HIV before beginning treatment because HIV resistance may occur in chronic hepatitis B patients; monitor HIV RNA

 

Black Box Warning:

For lactic acidosis, severe hepatomegaly with stenosis; increased serum lactate, increased hepatic enzymes, palpate line; discontinue if present

• 
Geriatric patients more carefully; may develop renal, cardiac symptoms more rapidly

 

Black Box Warning:

For exacerbations of hepatitis (jaundice, pruritus, fatigue) after discontinuing treatment, monitor LFTs

Evaluate:

• 
Therapeutic response: decreased symptoms of chronic hepatitis B, improving LFTs

Teach patient/family:

• 
Not to take with food

• 
To take exactly as prescribed

• 
Not to stop medication without approval of prescriber

• 
That optimal duration of treatment is unknown

• 
To avoid use with other medications unless approved by prescriber

• 
To notify prescriber of decreased urinary output, blood in urine

 

Black Box Warning:

Symptoms of lactic acidosis: muscle pain, severe tiredness, weakness, trouble breathing, stomach pain with nausea/vomiting, coldness in arms/legs, fast/irregular heartbeat, dizziness

 

Black Box Warning:

Symptoms of hepatotoxicity: eyes/skin turning yellow, dark urine, light bowel movements, no appetite for days, nausea, stomach pain

• 
That product does not cure but lowers amount of HBV in body

• 
That product does not stop spread of HBV to others by sex, sharing needles, or being exposed to blood

• 
Not to breastfeed

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