Varenicline

  Issues for Surgery

Risk of smoking relapse if omitted.

Risk of withdrawal symptoms if omitted (see Further Information).

  Advice in the Perioperative period

Elective and Emergency Surgery
Continue.

If recently commenced check if any of the patient’s other medicines will be affected by smoking cessation and require dose adjustments (see Further Information).

Post-operative Advice
Restart post-operatively as soon as next dose is due.

Monitor renal function – dose reduction may be necessary if renal function is impaired (consult current product literature)^{1, 2}.

  Interaction(s) with Common Anaesthetic Agents

 
None specifically listed^1,2,3.

Seizure Threshold
Clinical trials and post-marketing experience note some reports of seizures in patients with or without a history of seizures given varenicline; manufacturers advise use with caution in conditions that potentially lower seizure threshold².  Concurrent use with medicines that also lower the seizure threshold (e.g. anaesthetic agents, tramadol) may have an additive effect on the risk of seizure.

  Interaction(s) with other Common Medicines used in the Perioperative Period

 
None^{1, 2, 3}.

  Further Information

Withdrawal
Risk of relapse, irritability, depression and insomnia have been noted on discontinuation at the end of the 12-week treatment course; manufacturer advises dose tapering may be necessary^{1, 2}.  Sudden pre-operative cessation could be anticipated to have similar effects. 

Smoking Cessation
Quitting smoking pre-operatively improves surgical outcomes through reducing risk of post-operative complications⁴. Pre-operative initiation of varenicline was found to increase abstinence from smoking at three, six and twelve months after elective non-cardiac surgery with no increase in serious adverse events⁵.

However, if a patient decides to quit smoking during the perioperative period it must be remembered that smoking cessation can reduce clearance of some medicines due to tobacco’s effect on CYP1A2 (potential for increased plasma levels)² – dosage adjustments and / or close monitoring are likely to be necessary with CYP1A2 substrates including agomelatine, clozapine, duloxetine, olanzapine, ropinirole and theophylline (consult current product literature)³.

  References

1. Joint Formulary Committee. British National Formulary (online) London: BMJ Group and Pharmaceutical Press. http://www.medicinescomplete.com [Accessed on 5^th November 2020]
2. Summary of Product Characteristics – Champix^® (varenicline) 1mg film-coated tablets. Pfizer Limited. Accessed via www.medicines.org.uk 5/11/2020 [date of revision of the text July 2019]
3. Baxter K, Preston CL (eds), Stockley’s Drug Interactions (online) London: Pharmaceutical Press. http://www.medicinescomplete.com [Accessed on 5^th November 2020]
4. Faculty of Public Health, The Royal College of Surgeons of Edinburgh, The Royal College of Anaesthetists, ash (action on smoking and health). Joint Briefing: Smoking and surgery. April 2016. Available at www.rcoa.ac.uk [Accessed on 5^th November 2020]
5.  Wong J. Abrishami A. Yang Y et al.  A Perioperative Smoking Cessation Intervention with Varenicline: A Double-blind, Randomized, Placebo-controlled Trial. Anesthesiology 2012; 117:755-764