varenicline

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varenicline

Champix (UK), Chantix

Pharmacologic class: Autonomic drug, miscellaneous

Therapeutic class: Smoking cessation agent

Pregnancy risk category C

Action

In smoking cessation, action presumably results from activity at nicotinic receptor subtype, where its binding produces agonist activity while simultaneously preventing nicotine binding to alpha₄-beta₂ receptors.

Availability

Tablets (film coated): 0.5 mg, 1 mg

Indications and dosages

➣ To aid smoking-cessation treatment

Adults: Begin with 1-week titration of 0.5 mg P.O. daily on days 1 to 3; then, 0.5 mg P.O. b.i.d. on days 4 to 7. Starting on day 8, give 1 mg P.O. b.i.d. till end of treatment. If patient has successfully stopped smoking at end of 12 weeks, additional course of 12 weeks is recommended to improve likelihood of long-term abstinence.

Dosage adjustment

• Severe renal impairment

Contraindications

• History of serious hypersensitivity or skin reactions to drug

Precautions

Use cautiously in:

• renal impairment

• concurrent use of drugs affected by smoking, such as insulin, theophylline, and warfarin (whose dosages may need to be adjusted)

• elderly patients

• pregnant or breastfeeding patients

• children younger than age 18 (safety and efficacy not established).

Administration

• Give with full glass of water after a meal.

Adverse reactions

CNS: headache, migraine, somnolence, lethargy, dizziness, syncope, attention disturbance, sensory disturbance, anxiety, depression, emotional disorder, irritability, restlessness, sleep disorders, abnormal dreams, nightmares, insomnia, fatigue, malaise, asthenia, aggression, agitation, amnesia, dissociation, mood swings, parosmia, psychomotor hyperactivity, restless leg syndrome, abnormal thinking, tremor, vertigo, suicidal ideation suicide attempt, suicide

CV: hot flushes, hypertension, angina pectoris, bradycardia, hypotension, palpitations, peripheral ischemia, tachycardia, thrombosis, ventricular extrasystoles, arrhythmia, myocardial infarction

EENT: tinnitus, epistaxis, rhinorrhea

GI: nausea, vomiting, constipation, abdominal pain, flatulence, dyspepsia, gastroesophageal reflux disease, gingivitis, anorexia, increased or decreased appetite, dysgeusia, dry mouth, intestinal obstruction (rare), acute pancreatitis (rare)

GU: polyuria, menstrual disorder, decreased libido, acute renal failure (rare)

Hematologic: anemia, lymphadenopathy

Musculoskeletal: arthralgia, back pain, muscle cramp, musculoskeletal pain, myalgia

Respiratory: dyspnea, upper respiratory tract disorders, pulmonary embolism (rare)

Skin: rash, pruritus, hyperhidrosis

Stevens-Johnson syndrome, erythema multiforme (rare)

Other: chest pain, flulike illness, edema, thirst, increased weight, nicotine withdrawal symptoms, hypersensitivity reactions including angioedema

Interactions

Drug-diagnostic tests. Liver function tests: abnormal

Patient monitoring

Monitor patient for serious neuropsychiatric symptoms, including behavior changes, agitation, depressed mood, and suicidal ideation and behavior.

Closely monitor patient for hypersensitivity or serious skin reactions.

• Monitor patients taking drugs that may be affected by smoking; dosages of these drugs may need to be adjusted once patient quits smoking.

• Monitor liver function tests.

• Monitor renal function, especially in elderly patients.

Patient teaching

Instruct patient to discontinue drug and immediately report changes in behavior, including depression and suicidal thoughts or action; rash; or swelling of face, mouth, or throat.

• Advise patient to set date to quit smoking and to start drug 1 week before quit date. Or, patient can begin drug dosing and then quit smoking between days 8 and 35 of treatment.

• Teach patient how to titrate drug for first week of therapy.

• Instruct patient to take drug with full glass of water after eating.

• Give patient educational materials and counseling referral to support smoking-cessation attempt.

• Encourage patient who relapses after quit day to continue to try to quit smoking.

• Inform patient that nausea and insomnia are side effects and usually disappear. However, if these symptoms remain troubling, advise patient to notify prescriber, who may consider dosage reduction.

• Inform patient that some drugs may require dosage adjustment after smoking cessation.

• Caution patient to avoid driving and other hazardous activities until effects of drug and smoking cessation are known.

• As appropriate, review all other significant and life-threatening adverse reactions and interactions, especially those related to the tests mentioned above.

varenicline

(ver-en-i-cline) ,

Champix

(trade name),

Chantix

(trade name)

Classification

Therapeutic: smoking deterrents
Pharmacologic: nicotine agonists

Pregnancy Category: C

Indications

Treatment of smoking cessation; in conjunction with nonpharmacologic support (educational materials/counseling).

Action

Selectively binds to alpha₄, beta₂ nicotinic acetylcholine receptors, acting as a nicotine agonist; prevents the binding of nicotine to receptors.

Therapeutic effects

Decreased desire to smoke.

Pharmacokinetics

Absorption: 100% absorbed following oral administration.

Distribution: 24 hr.

Metabolism and Excretion: Minimally metabolized; 92% excreted in urine unchanged.

Half-life: 24 hr.

Time/action profile

ROUTE	ONSET	PEAK	DURATION
PO	unknown	3–4 hr	24 hr

Contraindications/Precautions

Contraindicated in: Hypersensitivity; Lactation: Lactation; Pediatric: Safety not established.

Use Cautiously in: Severe renal impairment (↓ dose recommended if CCr <30 mL/min);Stable cardiovascular disease (may ↑ risk of cardiovascular events);Psychiatric illness; Geriatric: Consider age-related ↓ in renal function; Obstetric: Use only if maternal benefit outweighs fetal risk.

Adverse Reactions/Side Effects

Central nervous system

stroke (life-threatening)
suicidal thoughts/behavior (life-threatening)
↓ attention span (most frequent)
anxiety (most frequent)
depression (most frequent)
insomnia (most frequent)
irritability (most frequent)
dizziness (most frequent)
restlessness (most frequent)
abnormal dreams
agitation
aggression
amnesia
disorientation
dissociation
hostility
migraine
psychomotor hyperactivity

Ear, Eye, Nose, Throat

blurred vision
visual disturbances

Cardiovascular

myocardial infarction (life-threatening)
syncope

Gastrointestinal

diarrhea (most frequent)
gingivitis (most frequent)
nausea (most frequent)
↑ appetite
constipation
dyspepsia
dysphagia
enterocolitis
eructation
flatulence
gallbladder disorder
GI bleeding
↑ liver enzymes
vomiting

Dermatologic

stevens-johnson syndrome (life-threatening)
flushing (most frequent)
hyperhydrosis (most frequent)
acne
dermatitis
dry skin

Hematologic

anemia

Musculoskeletal

arthralgia (most frequent)
back pain (most frequent)
musculoskeletal pain (most frequent)
muscle cramps
myalgia
restless legs

Miscellaneous

angioedema (life-threatening)
accidental injury
chills
fever
hypersensitivity
mild physical dependence

Interactions

Drug-Drug interaction

Smoking cessation may ↓ metabolism of theophylline, warfarin, and insulin resulting in ↑ effects; careful monitoring is recommended.Risk of adverse reactions (nausea, vomiting, dizziness, fatigue, headache) may be ↑ with nicotine replacement therapy (nicotine transdermal patches).

Route/Dosage

Oral (Adults) Treatment is started one week prior to planned smoking cessation (may also begin dosing and then quit smoking between days 8 and 35 of treatment); 0.5 mg once daily on the first three days, then 0.5 mg twice daily for the next 4 days, then 1 mg twice daily.

Renal Impairment

Oral (Adults) CCr <30 mL/min—0.5 mg daily, may ↑ to 0.5 mg twice daily.

Availability

Tablets: 0.5 mg, 1 mg Cost: All strengths $237.71 / 56

Nursing implications

Nursing assessment

Assess for desire to stop smoking.
Assess for nausea. Usually dose-dependent. May require dose reduction.
Assess mental status and mood changes, especially during initial few months of therapy and during dose changes. Risk may be increased in children, adolescents, and adults ≤24 yr. Inform health care professional if patient demonstrates significant increase in signs of depression (depressed mood, loss of interest in usual activities, significant change in weight and/or appetite, insomnia or hypersomnia, psychomotor agitation or retardation, increased fatigue, feelings of guilt or worthlessness, slowed thinking or impaired concentration, suicide attempt or suicidal ideation). Restrict amount of drug available to patient.
Assess for rash periodically during therapy. May cause Stevens-Johnson syndrome. Discontinue therapy if severe or if accompanied with fever, general malaise, fatigue, muscle or joint aches, blisters, oral lesions, conjunctivitis, hepatitis and/or eosinophilia.
Lab Test Considerations: May cause anemia.

Potential Nursing Diagnoses

Ineffective coping (Indications)

Implementation

Oral: Administer after eating with a full glass of water.

Patient/Family Teaching

Instruct patient to take varenicline as directed. Set a date to stop smoking. Start taking varenicline 1 wk before quit date. Begin with 0.5 mg/day for the first 3 days, then for the next 4 days take one 0.5 mg tablet in the morning and in the evening. After first 7 days, increase to 1 mg tablet in the morning and evening. Advise patient to read Medication Guide before starting therapy.
Encourage patient to attempt to quit, even if they had early lapses after quit day.
Advise patient to stop taking varenicline and contact health care professional promptly if agitation, depressed mood, any changes in behavior that are not typical of nicotine withdrawal, or if suicidal thoughts or behavior; rash with mucosal lesions or skin reaction, or chest pain, pressure, or dyspnea occur.
Provide patient with educational materials and counseling to support attempts to quit smoking.
Caution patient not to share varenicline with others. May be harmful.
May cause blurred vision, dizziness, and disturbance in attention. Caution patient to avoid driving and other activities requiring alertness until response to medication is known.
Inform patient that nausea, insomnia, and vivid, unusual, or strange dreams may occur and are usually transient. Advise patient to notify health care professional if these symptoms are persistent and bothersome; dose reduction may be considered.
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. Inform patient that some medications may require dose adjustments after quitting smoking.
Advise patient to notify health care professional if pregnancy is planned or suspected or if breast feeding.

Evaluation/Desired Outcomes

Smoking cessation. Patients who have successfully stopped smoking at the end of 12 wk, should take an additional 12 wk course to increase the likelihood of long-term abstinence. Patients who do not succeed in stopping smoking during 12 wk of initial therapy or who relapse after treatment, should be encouraged to make another attempt once factors contributing to the failed attempt have been identified and addressed.