Mosby's 2014 Nursing Drug Reference (30 page)

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amantadine (Rx)

(a-man′ta-deen)

Func. class.:
Antiviral, antiparkinsonian agent

Chem. class.:
Tricyclic amine

Do not confuse:
amantadine
/ranitidine/rimantidine

ACTION:

Prevents uncoating of nucleic acid in viral cell, thereby preventing penetration of virus to host; causes release of DOPamine from neurons

USES:

Prophylaxis or treatment of influenza type A, EPS, parkinsonism, Parkinson’s disease

Unlabeled uses:
Neuroleptic malignant syndrome, MS-associated fatigue

CONTRAINDICATIONS:

Hypersensitivity, breastfeeding, children <1 eczematic rash

Precautions:
Pregnancy (C), geriatric patients, epilepsy, CHF, orthostatic hypotension, psychiatric disorders, renal/hepatic disease, peripheral edema

DOSAGE AND ROUTES
Calculator
Influenza type A

• Adult and child >9 yr:
PO
200 mg/day in single dose or divided bid

• Geriatric:
PO
No more than 100 mg/day

• Child 1-8 yr:
PO
4.4-8.8 mg/kg/day divided bid-tid, max 150 mg/day

Extrapyramidal reaction/parkinsonism

• Adult: PO
100 mg bid up to 400 mg/day in EPS; give for 1 wk then 100 mg as needed up to 400 mg for parkinsonism

Renal dose

• Adult: PO
CCr 30-50 ml/min 200 mg 1st day then 100 mg/day; CCr 15-29 ml/min 100 mg 1st day then 100 mg on alternate days; CCr 15 ml/min reduce dose and interval to 200 mg q7days

MS-associated fatigue (unlabeled)

• Adult: PO
200 mg/day or 100 mg bid

Neuroleptic malignant syndrome (unlabeled)

• Adult: PO
100 mg bid × 3 wk

Available forms:
Caps 100 mg; oral sol 50 mg/5 ml; tab 100 mg

Administer:

• 
Prophylaxis:
before exposure to influenza; continue for 10 days after contact;
treatment:
initiate within 24-48 hr of onset of symptoms, continue for 24-48 hr after symptoms disappear

• 
After meals for better absorption to decrease GI symptoms; at least 4 hr before bedtime to prevent insomnia

• 
In divided doses to prevent CNS disturbances: headache, dizziness, fatigue, drowsiness

SIDE EFFECTS

CNS:
Headache, dizziness
, drowsiness, fatigue,
anxiety
, psychosis,
depression, hallucinations
, tremors,
seizures,
confusion,
insomnia

CV:
Orthostatic hypotension
,
CHF

EENT:
Blurred vision

GI:
Nausea, vomiting
, constipation, dry mouth, anorexia

GU:
Frequency, retention

HEMA:
Leukopenia, agranulocytosis

INTEG:
Photosensitivity, dermatitis, livedo reticularis

PHARMACOKINETICS

PO:
Onset 48 hr, peak 1-4 hr, half-life 24 hr, not metabolized, excreted in urine (90%) unchanged, crosses placenta, excreted in breast milk

INTERACTIONS

Increase:
anticholinergic response—atropine, other anticholinergics

Increase:
CNS stimulation—CNS stimulants

Decrease:
amantadine effect—metoclopramide, phenothiazines

Decrease:
renal excretion of amantadine—triamterene, hydrochlorothiazide

Decrease:
effect—S/B H1N1 influenza A virus vaccine; avoid use 2 wk before or 48 hr after amantadine

Drug/Lab Test

Increase:
BUN, creatinine, alk phos, CK, LDH, bilirubin, AST, ALT, GGT

NURSING CONSIDERATIONS
Assess:

• 
Mental status: may cause increased psychiatric disorders especially in the elderly

• 
CHF
(weight gain, jugular venous distention, dyspnea, crackles)

• 
Skin eruptions, photosensitivity after administration of product

• 
Reaction to each medication

• 
Signs of infection

• 
Livedo reticularis:
mottling of the skin, usually red; edema; itching in lower extremities

• 
Parkinson’s disease:
gait, tremors, akinesia, rigidity, may be effective if anticholinergics have not been effective

 
Toxicity:
confusion, behavioral changes, hypotension, seizures

Perform/provide:

• 
Storage in tight, dry container

Evaluate:

• 
Therapeutic response: absence of fever, malaise, cough, dyspnea with infection; tremors, shuffling gait with Parkinson’s disease

Teach patient/family:

• 
To change body position slowly to prevent orthostatic hypotension

• 
About aspects of product therapy: to report dyspnea, weight gain, dizziness, poor concentration, dysuria, complex sleep behaviors

• 
To avoid hazardous activities if dizziness, blurred vision occurs

• 
To take product exactly as prescribed; parkinsonian crisis may occur if product is discontinued abruptly; not to double dose; if a dose is missed, not to take within 4 hr of next dose; caps may be opened and mixed with food

• 
To avoid alcohol

TREATMENT OF OVERDOSE:

Withdraw product, maintain airway, administer EPINEPHrine, aminophylline, O
2
, IV corticosteroids, physostigmine

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

ambrisentan (Rx)

(am-bri-sen′tan)

Letairis

Func. class.:
Antihypertensive

Chem class.:
Vasodilator/endothelin receptor antagonist

ACTION:

Endothelin-A receptor antagonist; endothelin-A is vasoconstrictor

USES:

Pulmonary arterial hypertension, alone or in combination with other antihypertensives

CONTRAINDICATIONS:

Breastfeeding, hypersensitivity, idiopathic pulmonary fibrosis (IPF)

 

Black Box Warning:

Pregnancy (X)

Precautions:
Children, females, geriatric patients, hepatitis, anemia, heart failure, jaundice, peripheral edema, hepatic disease

DOSAGE AND ROUTES
Calculator

• Adult: PO
5 mg/day; may increase to 10 mg/day if needed

Hepatic dose

• Adult: PO
Discontinue if AST/ALT >5× ULN, or if elevations are accompanied by bilirubin >2× ULN, or other signs of liver dysfunction

Available forms:
Tabs 5, 10 mg

Administer:

• 
Do not break, crush, chew tabs

• 
Daily with a full glass of water without regard to food

• 
Do not discontinue abruptly

• 
Only those facilities enrolled in the LEAP program (866-664-5327) may administer this product

SIDE EFFECTS

CNS:
Headache
, fever, flushing, fatigue

CV:
Orthostatic hypotension, hypotension,
peripheral edema
, palpitations

EENT:
Sinusitis, rhinitis

GI:
Abdominal pain, constipation, anorexia,
hepatotoxicity

GU:
Decreased sperm counts

HEMA:
Anemia

INTEG:
Rash,
angioedema

RESP:
Pharyngitis, dyspnea,
pulmonary edema, veno-occlusive disease (VOD)

PHARMACOKINETICS

Rapidly absorbed, peak 2 hr, protein binding 99%, metabolized by CYP3A4, CYP2C19, terminal half-life 15 hr, effective half-life 9 hr

INTERACTIONS

• 
Possibly increase ambrisentan: cimetidine, clopidogrel, efavirenz, felbamate, fluoxetine, modafinil, oxcarbazepine, ticlopidine

Increase:
hypotension—other antihypertensives, diuretics, MAOIs

Increase:
ambrisentan—CYP3A4 inhibitors (amprenavir, aprepitant, atazanavir, clarithromycin, conivaptan, cycloSPORINE, dalfopristin, danazol, darunavir, erythromycin, estradiol, imatinib, itraconazole, ketoconazole, nefazodone, nelfinavir, propoxyphene, quinupristin, ritonavir, RU-486, saquinavir, tamoxifen, telithromycin, troleandomycin, zafirlukast); CYP2C19/CYP3A4 (chloramphenicol, delavirdine, fluconazole, fluvoxaMINE, isoniazid, voriconazole)

Decrease:
ambrisentan—CYP3A4 inducers (carBAMazepine, PHENobarbital, phenytoin, rifampin)

Decrease:
ambrisentan absorption—mefloquine, niCARdipine, propafenone, quiNIDine, ranolazine, tacrolimus, testosterone

Drug/Herb

• 
Need for ambrisentan dosage change: St. John’s wort, ephedra (ma huang)

Drug/Food

• 
Avoid use with grapefruit products

Drug/Lab Test

Increase:
LFTs, bilirubin

Decrease:
Hct, Hgb

NURSING CONSIDERATIONS
Assess:

• 
Pulmonary status:
improvement in breathing, ability to exercise; pulmonary edema that may indicate veno-occlusive disease

• 
Blood studies: CBC with differential; Hct, Hgb may be decreased

• 
Liver function tests: AST, ALT, bilirubin

 

Black Box Warning:

Assess pregnancy status before giving this product; pregnancy category X

• 
Hepatotoxicity: nausea, vomiting, abdominal pain/cramping, jaundice, anorexia, itching

Perform/provide:

• 
Storage in tight container at room temp

Evaluate:

• 
Therapeutic response: decrease in B/P; decreased shortness of breath

Teach patient/family:

• 
The importance of complying with dosage schedule even if feeling better

 

Black Box Warning:

To notify if pregnancy is planned or suspected (if pregnant, product will need to be discontinued, pregnancy test done monthly); to use 2 contraception methods while taking this product

• 
Not to use OTC products including herbs, supplements unless approved by prescriber

• 
To report to prescriber immediately: dizziness, faintness, chest pain, palpitations, uneven or rapid heart rate, headache, edema, weight gain

• 
To report hepatic dysfunction: nausea/vomiting, anorexia, fatigue, jaundice, right upper quadrant abdominal pain, itching, fever, malaise

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