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Name /bks_53161_deglins_md_disk/venlafaxine
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Plate # 0-Composite
pg 1 # 1
Use Cautiously in: Cardiovascular disease, including hypertension; Hepatic im-
venlafaxine (ven-la-fax-een)
Effexor, Effexor XR
Classification
Therapeutic: antidepressants, antianxiety agents
Pharmacologic: selective serotonin/norepinephrine reuptake inhibitors
Pregnancy Category C
Indications
Major depressive disorder. Generalized anxiety disorder (Effexor XR only). Social
anxiety disorder (Effexor XR only). Panic disorder (Effexor XR only). Unlabeled
Use: Premenstrual dysphoric disorder.
Action
Inhibits serotonin and norepinephrine reuptake in the CNS. Therapeutic Effects:
Decrease in depressive symptomatology, with fewer relapses/recurrences. Decreased anxiety. Decrease in panic attacks.
Pharmacokinetics
Absorption: 92– 100% absorbed after oral administration.
Distribution: Extensive distribution into body tissues.
Metabolism and Excretion: Extensively metabolized on first pass through the
liver (primarily through CYP2D6 enzyme pathway). A small percentage of the population are poor metabolizers and will have higher blood levels withqeffects. One
metabolite, O-desmethylvenlafaxine (ODV), has antidepressant activity; 5% of venlafaxine is excreted unchanged in urine; 30% of the active metabolite is excreted in
urine.
Half-life: Venlafaxine— 3– 5 hr; ODV— 9– 11 hr (both areqin hepatic/renal
impairment).
TIME/ACTION PROFILE (antidepressant action)
ROUTE
PO
ONSET
within 2 wk
PEAK
2–4 wk
DURATION
unknown
Contraindications/Precautions
Contraindicated in: Hypersensitivity; Concurrent use of MAO inhibitors or MAOlike drugs (linezolid or methylene blue).
⫽ Canadian drug name.
⫽ Genetic Implication.
pairment (pdose recommended); Impaired renal function (pdose recommended);
History of seizures or neurologic impairment; History of mania; History ofqintraocular pressure or angle-closure glaucoma; History of drug abuse; OB: Use only if clearly
required, weighing benefit to mother versus potential harm to fetus (potential for discontinuation syndrome or toxicity in the neonate when venlafaxine is taken during the
3rd trimester); Lactation: Potential for serious adverse reactions in infant; discontinue drug or discontinue breast feeding; Pedi:qrisk of suicidal thinking and behavior (suicidality) in children and adolescents with major depressive disorder and
other psychiatric disorders. Observe closely for suicidality and behavior changes.
Adverse Reactions/Side Effects
CNS: NEUROLEPTIC MALIGNANT SYNDROME, SEIZURES, SUICIDAL THOUGHTS, abnormal
dreams, anxiety, dizziness, headache, insomnia, nervousness, weakness, abnormal
thinking, agitation, confusion, depersonalization, drowsiness, emotional lability,
worsening depression. EENT: rhinitis, visual disturbances, epistaxis, tinnitus. CV:
chest pain, hypertension, palpitations, tachycardia. GI: abdominal pain, altered
taste, anorexia, constipation, diarrhea, dry mouth, dyspepsia, nausea, vomiting,
weight loss. GU: sexual dysfunction, urinary frequency, urinary retention. Derm:
ecchymoses, itching, photosensitivity, skin rash. Neuro: paresthesia, twitching.
Misc: SEROTONIN SYNDROME, chills, bleeding, yawning.
Interactions
Drug-Drug: Concurrent use with MAO inhibitors may result in serious, potentially fatal reactions (wait at least 2 wk after stopping MAO inhibitor before initiating
venlafaxine; wait at least 1 wk after stopping venlafaxine before starting MAO inhibitors). Concurrent use with MAO-inhibitor like drugs, such as linezolid or
methylene blue mayqrisk of serotonin syndrome; concurrent use contraindicated;
do not start therapy in patients receiving linezolid or methylene blue; if linezolid
or methylene blue need to be started in a patient receiving venlafaxine, immediately
discontinue venlafaxine and monitor for signs/symptoms of serotonin syndrome for 2
wk or until 24 hr after last dose of linezolid or methylene blue, whichever comes first
(may resume venlafaxine therapy 24 hr after last dose of linezolid or methylene
blue). Concurrent use with alcohol or other CNS depressants, including sedatives/hypnotics, antihistamines, and opioid analgesics in depressed patients is
not recommended. Drugs that affect serotonergic neurotransmitter systems, including tricyclic antidepressants, SNRIs, fentanyl, buspirone, tramadol and trip-
CAPITALS indicate life-threatening, underlines indicate most frequent.
Strikethrough ⫽ Discontinued.
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tansqrisk of serotonin syndrome. Lithium may haveqserotonergic effects with
venlafaxine; use cautiously in patients receiving venlafaxine.qblood levels and may
qeffects of desipramine and haloperidol. Cimetidine mayqthe effects of venlafaxine (may be more pronounced in geriatric patients, those with hepatic or renal impairment, or those with pre-existing hypertension). Ketoconazole mayqthe effects
of venlafaxine.qrisk of bleeding with NSAIDS, aspirin, clopidogrel, or warfarin.
Drug-Natural Products: Concomitant use of kava-kava, valerian, chamomile, or hops canqCNS depression.qrisk of serotinergic side effects including serotonin syndrome with St. John’s wort and SAMe.
Route/Dosage
General Anxiety Disorder
PO (Adults): Extended-release (XR) capsules— 75 mg once daily (some patients
may be started at 37.5 mg once daily) for 4– 7 days; mayqby up to 75 mg/day at intervals of not less than 4 days (not to exceed 225 mg/day).
● Assess mental status and mood changes. Inform health care professional if patient
demonstrates significant increase in anxiety, nervousness, or insomnia.
● Assess suicidal tendencies, especially in early therapy. Restrict amount
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Social Anxiety Disorder
PO (Adults): Extended-release (XR) capsules— 75 mg once daily.
Panic Disorder
PO (Adults): Extended-release (XR) capsules— 37.5 mg once daily for 7 days;
may thenqto 75 mg once daily; may thenqby 75 mg/day every 7 days (not to exceed
225 mg/day).
Hepatic Impairment
PO (Adults):pdaily dose by 50% in patients with mild-to-moderate hepatic impairment.
Renal Impairment
PO (Adults): CCr 10– 70 mL/min—pdaily dose by 25– 50%; Hemodialysis—p
daily dose by 50%.
pg 2 # 2
NURSING IMPLICATIONS
Assessment
Major Depressive Disorder
PO (Adults): Tablets— 75 mg/day in 2– 3 divided doses; mayqby up to 75 mg/day
every 4 days, up to 225 mg/day (not to exceed 375 mg/day in 3 divided doses); Extended-release (XR) capsules— 75 mg once daily (some patients may be started at
37.5 mg once daily) for 4– 7 days; mayqby up to 75 mg/day at intervals of not less
than 4 days (not to exceed 225 mg/day).
Plate # 0-Composite
●
of drug available to patient. Risk may be increased in children, adolescents, and adults ⱕ24 yr.
Monitor BP before and periodically during therapy. Sustained hypertension may
be dose-related; decrease dose or discontinue therapy if this occurs.
Monitor appetite and nutritional intake. Weigh weekly. Report continued weight
loss. Adjust diet as tolerated to support nutritional status.
Assess for serotonin syndrome (mental changes [agitation, hallucinations, coma], autonomic instability [tachycardia, labile BP, hyperthermia], neuromuscular aberrations [hyper-reflexia, incoordination],
and/or GI symptoms [nausea, vomiting, diarrhea]), especially in patients taking other serotonergic drugs (SSRIs, SNRIs, triptans).
Lab Test Considerations: Monitor CBC with differential and platelet count periodically during therapy. May cause anemia, leukocytosis, leukopenia, thrombocytopenia, basophilia, and eosinophilia.
May cause anqin serum alkaline phosphatase, bilirubin, AST, ALT, BUN, and creatinine.
May also causeqserum cholesterol.
May cause electrolyte abnormalities (hyperglycemia or hypoglycemia, hyperkalemia or hypokalemia, hyperuricemia, hyperphosphatemia or hypophosphatemia,
and hyponatremia).
May cause false-positive immunoassay screening tests for phencyclidine (PCP)
and amphetamine.
Potential Nursing Diagnoses
Ineffective coping (Indications)
Risk for injury (Side Effects)
Implementation
● Do not confuse Effexor with Effexor XR.
● PO: Administer venlafaxine with food.
● Extended-release capsules should be swallowed whole; do not crush, break, or
chew.
䉷 2015 F.A. Davis Company
CONTINUED
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Evaluation/Desired Outcomes
CONTINUED
venlafaxine
sessed. Therapy is usually continued for several months.
● Decreased anxiety.
● Increased sense of well-being.
● Renewed interest in surroundings. Need for therapy should be periodically reas-
● Extended-release capsules may be opened and contents sprinkled on a spoonful
Why was this drug prescribed for your patient?
of applesauce. Take immediately and follow with a glass of water. Do not store
mixture for later use.
Patient/Family Teaching
● Instruct patient to take venlafaxine as directed at the same time each day. Take
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missed doses as soon as possible unless almost time for next dose. Do not double
doses or discontinue abruptly. Patients taking venlafaxine for ⬎6 wk should have
dose gradually decreased before discontinuation.
Advise patient, family, and caregivers to look for suicidality, especially
during early therapy or dose changes. Notify health care professional
immediately if thoughts about suicide or dying, attempts to commit suicide; new or worse depression or anxiety; agitation or restlessness;
panic attacks; insomnia; new or worse irritability; aggressiveness; acting on dangerous impulses, mania, or other changes in mood or behavior or if symptoms of serotonin syndrome occur.
May cause drowsiness or dizziness. Caution patient to avoid driving or other activities requiring alertness until response to the drug is known.
Instruct patient to notify health care professional of all Rx or OTC medications, vitamins, or herbal products being taken and consult health care professional before taking any new medications. Caution patient to avoid taking alcohol or other
CNS-depressant drugs during therapy.
Instruct patient to notify health care professional if signs of allergy (rash, hives)
occur.
Instruct female patients to inform health care professional if pregnancy is planned
or suspected or if breast feeding.
Emphasize the importance of follow-up exams to monitor progress. Encourage
patient participation in psychotherapy.
⫽ Canadian drug name.
⫽ Genetic Implication.
CAPITALS indicate life-threatening, underlines indicate most frequent.
Strikethrough ⫽ Discontinued.
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