What is the recommended varenicline (Chantix) regimen for a 70-year-old female patient with chronic kidney disease (CKD) and impaired renal function, who smokes 1 pack per day?

Varenicline Dosing for Smoking Cessation in a Patient with CKD

For a 70-year-old female patient with chronic kidney disease (CrCl 28 ml/min) and COPD, the recommended varenicline regimen is 0.5mg PO daily for days 1-3, then 0.5mg PO BID thereafter.

Rationale for Dosing Recommendation

Renal Function Considerations

• The patient has severe renal impairment with a CrCl of 28 ml/min, which requires dose adjustment of varenicline
• The FDA label specifically states: "For patients with severe renal impairment (estimated creatinine clearance less than 30 mL per min), the recommended starting dose of varenicline tablets is 0.5 mg once daily. The dose may then be titrated as needed to a maximum dose of 0.5 mg twice daily" 1
• This dose reduction is necessary because varenicline is almost exclusively excreted unchanged in urine through glomerular filtration 2

Safety Considerations

• Varenicline has been associated with rare cases of acute renal failure, making dose adjustment particularly important in patients with pre-existing kidney disease 3
• The reduced dosing regimen helps minimize potential adverse effects while maintaining efficacy for smoking cessation
• At higher doses, the risk of adverse effects such as nausea increases, which is dose-dependent 2

Smoking Cessation Protocol

Initial Assessment

1. The patient is a good candidate for pharmacotherapy given her:
   • Heavy smoking (1 pack per day)
   • Early morning smoking (within 30 minutes of waking) indicating high nicotine dependence
   • Presence of COPD, which can significantly improve with smoking cessation 4

Treatment Plan

1. Medication Regimen:

   • Days 1-3: Varenicline 0.5mg PO daily
   • Day 4 onward: Varenicline 0.5mg PO BID (maximum dose for severe renal impairment)
   • Duration: 12 weeks of treatment 1

2. Behavioral Support:

   • Combine pharmacotherapy with behavioral counseling for optimal results 4
   • Identify smoking triggers and develop coping strategies
   • Provide resources for telephone quitlines or web-based support

3. Follow-up:

   • Schedule follow-up within 2-3 weeks to assess medication usage, side effects, and smoking status
   • Continue periodic follow-up at 12-week intervals 4

Clinical Considerations

Efficacy

• Even with the reduced dosing, varenicline remains effective for smoking cessation
• A flexible dosing study showed that lower doses (average 1.3mg/day) achieved abstinence rates of >40% at 12 weeks while reducing adverse effects 5
• Varenicline has demonstrated the highest estimated abstinence rates (33.2%) compared to other smoking cessation medications 4

Monitoring

• Monitor renal function during treatment
• Watch for neuropsychiatric symptoms, which may be more common in patients with psychiatric history 1
• Assess for common side effects including nausea, abnormal dreams, and insomnia

Important Cautions

• Avoid the standard dosing regimen (escalating to 1mg BID) as this would exceed the maximum recommended dose for patients with severe renal impairment
• Be aware that varenicline can rarely cause acute renal failure, requiring vigilant monitoring of kidney function 3
• The patient's COPD medications (fluticasone/vilanterol and tiotropium) do not have significant interactions with varenicline

Benefits of Smoking Cessation for This Patient

• Smoking cessation is particularly important for this patient as it:
  • Is the most effective intervention to slow COPD progression 4
  • Reduces cardiovascular risk, which is elevated in patients with CKD
  • Improves overall mortality, with benefits seen even in older adults 4

By following this reduced dosing regimen, the patient can safely attempt smoking cessation while minimizing risks associated with her renal impairment.