varenicline
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.