Mosby's 2014 Nursing Drug Reference (417 page)

BOOK: Mosby's 2014 Nursing Drug Reference
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ACTION:

Potent inhibitor of neuronal serotonin and norepinephrine uptake, weak inhibitor of dopamine; no muscarinic, histaminergic, or α-adrenergic receptors in vitro

USES:

Prevention/treatment of major depression; depression at the end of life; long-term treatment of general anxiety disorder, panic disorder, social anxiety disorder (Effexor XR only)

Unlabeled uses:
Hot flashes, premenstrual dysphoric disorder (PMDD), headache, neuropathic pain, fibromyalgia, diabetic neuropathy

CONTRAINDICATIONS:

Hypersensitivity, bipolar disorder, interstitial lung disease

Precautions:
Pregnancy (C), breastfeeding, geriatric patients, mania, hypertension, seizure disorder, recent MI, cardiac/renal/hepatic disease, eosinophilic pneumonia, desvenlafaxine hypersensitivity

 

Black Box Warning:

Children, suicidal ideation

DOSAGE AND ROUTES
Calculator
Depression

• Adult:
PO
75 mg/day in 2-3 divided doses; taken with food, may be increased to 150 mg/day; if needed, may be further increased to 225 mg/day; increments of 75 mg/day at intervals of ≥4 days; some hospitalized patients may require up to 375 mg/day in 3 divided doses;
EXT REL
37.5-75 mg PO daily, max 225 mg/day; give XR daily

Anxiety disorders

• Adult:
PO
75 mg/day or 37.5 mg/day × 4-7 days initially, max 225 mg/day

Renal dose

• Adult:
PO
CCr 10-70 ml/min, reduce dose by 25%-50%; CCr <10 ml/min, reduce dose by 50%

Hepatic dose

• Adult:
PO
Moderate impairment, 50% of dose

Hot flashes (unlabeled)

• Adult (male, prostate cancer):
PO
12.5 mg bid × 4 wk; females 37.5-75 mg/day

Neuropathic pain, diabetic neuropathy, headache, fibromyalgia (unlabeled)

• Adult:
PO
37.5-75 mg/day, max 75 mg bid (regular rel) or 150 mg/day (ext rel)

Premenstrual dysphoric disorder (PMDD) (unlabeled)

• Adult female:
PO
50-200 mg/day, start at 50 mg/day for 1st cycle, titrate upward

Available forms:
Tabs scored 25, 37.5, 50, 75, 100 mg; ext rel cap (Effexor XR) 37.5, 75, 150 mg; ext rel tab 37.5, 75, 150, 225 mg

Administer:

• 
With food, milk for GI symptoms; do not crush, chew caps; caps can be opened and contents sprinkled on applesauce, given with full glass of water

• 
Sugarless gum, hard candy, frequent sips of water for dry mouth

• 
Avoid use with CNS depressants

• 
In small amounts because of suicide potential, especially at beginning of therapy

SIDE EFFECTS

CNS:
Emotional lability,
vertigo, dizziness, weakness
, apathy, ataxia, CNS stimulation, euphoria, hallucinations, hostility, increased libido, hypertonia, hypotonia, psychosis, insomnia, anxiety,
suicidal ideation in children/adolescents, seizures, neuroleptic-malignant-syndrome–like reaction

CV:
Migraine
, angina pectoris, hypertension,
sustained hypertension, change in QTc interval,
increased pulse, increased cholesterol, extrasystoles, postural hypotension, syncope, thrombophlebitis

EENT:
Abnormal vision
, taste,
ear pain
, cataract, conjunctivitis, corneal lesions, dry eyes, otitis media, photophobia

GI:
Dysphagia, eructation
, nausea, anorexia, dry mouth, colitis, gastritis, gingivitis,
rectal hemorrhage,
stomatitis, stomach and mouth ulceration

GU:
Anorgasmia
, abnormal ejaculation,
dysuria, hematuria, metrorrhagia, vaginitis, impaired urination
, albuminuria, amenorrhea, kidney calculus, cystitis, nocturia, breast and bladder pain, polyuria,
uterine hemorrhage, vaginal hemorrhage,
moniliasis

HEMA:
Agranulocytosis, aplastic anemia, neutropenia, pancytopenia, abnormal bleeding

INTEG:
Ecchymosis, acne, alopecia, brittle nails, dry skin, photosensitivity, sweating,
angioedema (ext rel)

META:
Peripheral edema, weight loss or gain
, diabetes mellitus, edema, glycosuria, hyperlipemia, hypokalemia

MS:
Arthritis, bone pain, bursitis, myasthenia, tenosynovitis, arthralgia

RESP:
Bronchitis, dyspnea
, asthma, chest congestion, epistaxis, hyperventilation, laryngitis

SYST:
Malaise, neck pain
, enlarged abdomen, cyst, facial edema, hangover, hernia

PHARMACOKINETICS

Well absorbed; extensively metabolized in liver by CYP2D6 to active metabolite; 87% of product recovered in urine; 27% protein binding; half-life 5, 11 hr (active metabolite), respectively

INTERACTIONS

 
Hyperthermia, rigidity, rapid fluctuations of vital signs, mental status changes, neuroleptic malignant syndrome: MAOIs

Increase:
bleeding risk—salicylates, NSAIDs, platelet inhibitors, anticoagulants

Increase:
venlafaxine effect—cimetidine

Increase:
CNS depression—alcohol, opioids, antihistamines, sedative/hypnotics

Increase:
levels of cloZAPine, desipramine, haloperidol, warfarin

Increase:
serotonin syndrome—sibutramine, SUMAtriptan, traZODone, traMADol, SSRIs, serotonin receptor agonist, linezolid, methylene blue, tryptophan

Decrease:
effect of indinavir

Decrease:
venlafaxine effect—cyproheptadine

Drug/Herb

• 
Serotonin syndrome: St. John’s wort, tryptophan

Increase:
CNS depression—kava, valerian

Drug/Lab Test

Increase:
alk phos, bilirubin, AST, ALT, BUN, creatinine, serum cholesterol, CPK, LDH

False positive:
amphetamines, phencyclidine

NURSING CONSIDERATIONS
Assess:

 

Black Box Warning:

Mental status: mood, sensorium, affect, increase in psychiatric symptoms; depression, panic; assess for suicidal ideation in children/adolescents

• 
B/P lying, standing; pulse q4hr; if systolic B/P drops 20 mm Hg, hold product, notify prescriber; take VS q4hr in patients with CV disease

 
Bleeding:
GI, ecchymosis, epistaxis, hematomas, petechiae, hemorrhage

• 
Blood studies: CBC, differential, leukocytes, cardiac enzymes if patient is receiving long-term therapy

• 
Hepatic studies: AST, ALT, bilirubin

• 
Weight weekly; weight loss or gain; appetite may increase; peripheral edema may occur; monitor cholesterol

• 
Withdrawal symptoms:
flulike symptoms, headache, nervousness, agitation, nausea, vomiting, muscle pain, weakness; not usual unless product is discontinued abruptly

 
Serotonin syndrome, neuroleptic malignant syndrome:
increased heart rate, shivering, sweating, dilated pupils, tremors, high B/P, hyperthermia, head
ache, confusion; if these occur, stop product, administer serotonin antagonist if needed, usually worse if given with linezolid, methylene blue, tryptophan

Perform/provide:

• 
Storage in tight container at room temp; do not freeze

• 
Assistance with ambulation during beginning therapy because drowsiness, dizziness occur

Evaluate:

• 
Therapeutic response: decreased depression, anxiety; increased well-being

Teach patient/family:

• 
To notify prescriber of rash, hives, allergic reactions, bleeding

• 
To use with caution when driving, performing other activities requiring alertness because of drowsiness, dizziness, blurred vision

 

Black Box Warning:

That worsening of symptoms, suicidal thoughts/behaviors may occur in children/young adults

• 
To avoid alcohol ingestion

• 
Not to discontinue medication abruptly after long-term use; may cause nausea, headache, malaise

• 
To wear sunscreen or large hat because photosensitivity occurs

• 
To avoid pregnancy or breastfeeding while taking this product, birth defects have occurred when used in the 3rd trimester

• 
To monitor B/P with hypertension

TREATMENT OF OVERDOSE:

ECG monitoring; lavage, activated charcoal; administer anticonvulsant; may require whole-bowel irrigation for ext rel product

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

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