20th February 2024

Pharmacological interventions

Nicotine replacement therapy (NRT) is recommended with behavioural therapies for smoking cessation. A combination of short-acting and long-acting NRT is more successful than individual treatments. NRT aims to reduce nicotine withdrawal symptoms without exposure towards tobacco and cigarette smoke. Examples of long-acting NRT treatment include patches, while short-acting NRT comes in lozenges, gum, inhalators or nasal sprays. Treatment with NRT is usually for 8-12 weeks before a gradual reduction in the dose. 

E-cigarettes do not have long-term evidence to support their use, but patients should be informed that they carry less risk than ongoing smoking. Caution should be taken when using NRT in pregnancy, adolescent patients and patients with unstable cardiac arrhythmias or ischemia. 

Varenicline acts as a partial α4β2 nicotinic receptor, preventing nicotine binding onto the receptor. This reduces the symptoms of nicotine withdrawal and cravings. It is usually associated with altered sleep and vivid dreams. Varenicline has been associated with cardiovascular and neuropsychiatric adverse events, but current research has not substantiated this. Despite this, caution should be taken when using varenicline in patients with psychiatric or cardiovascular history.

Bupropion acts on the central adrenergic and dopaminergic reuptake inhibitor. It appears to act on the pathways associated with addiction and withdrawal, but its precise mechanism of action is unknown. Its use is contraindicated in patients with seizures, severe hepatic cirrhosis and CNS tumours. Common side effects include insomnia, agitation, dry mouth and headaches. 

It is important to note that smoking affects the metabolism of several medications, and smoking cessation may increase the plasma concentration of several medications. This is due to the impact of smoking on the CYP1A2 enzyme. Common medications that will be affected include warfarin, olanzapine, clozapine, chlorpromazine and theophylline. Monitoring for side effects following smoking cessation is advised, and dose reduction as needed should be performed.