varenicline

varenicline,

a smoking cessation agent.

indication This drug is used as a smoking deterrent.

contraindications Eating disorders and known hypersensitivity to this drug prohibit its use.

adverse effects Adverse effects of this drug include headache, agitation, dizziness, insomnia, abnormal dreams, fatigue, malaise, arrhythmias, hypertension, palpitations, tachycardia, angina, hypotension, tinnitus, anorexia, increased or decreased appetite, flatulence, gastroesophageal reflux disease, erectile dysfunction, urinary frequency, menstrual irregularities, rash, pruritus, weight loss or gain, dyspnea, and rhinorrhea. A life-threatening side effect is myocardial infarction. Common side effects include blurred vision, nausea, vomiting, dry mouth, and constipation.

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varenicline

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

None

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.

Route	Onset	Peak	Duration
P.O.	Unknown	3-4 hr	Unknown

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 (rare)

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

Other: chest pain, flulike illness, edema, thirst, increased weight, nicotine withdrawal symptoms

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.
• 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

• Advise patient to set date to quit smoking and to start drug 1 week before quit date. 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.