What you should be looking out for when recommending NRT products

The health benefits of giving up smoking are well documented and there is no doubt that nicotine replacement therapy has an important role. But there are some patient groups who need to be more careful than others when using NRT.

Drug interactions

Polycyclic aromatic hydrocarbons found in tobacco smoke are potent inducers of several cytochrome p450 enzyme subtypes, the most notable of which is CYP1A2. Therefore, medicines that are CYP1A2 substrates may need prescribing in higher doses than normal for smokers, and a dose reduction may be needed when they quit the habit in order to prevent side effects.

The most widely used CYP1A2 substrates are theophylline, fluvoxamine, caffeine,warfarin, chlorpromazine, haloperidol, ropinirole, clozapine and olanzapine. However, before making any dose changes, it is important to assess whether an interaction is clinically significant, and the easiest way to do this when someone has given up smoking is by monitoring for side effects.

Dose adjustment is not usually necessary when NRT is being used on a temporary basis (eg, for a flight or short hospital stay) because it takes around a week for the CP1A2 induction effect to wear off after stopping smoking.

NRT can counteract the effect of drugs that work on the sympathetic nervous system

Since nicotine activates the sympathetic nervous system, NRT can counteract the effect of drugs that work in this way (eg, beta-blockers).

However, this is likely to only become clinically significant when reducing or stopping NRT and, again, keeping an eye on side effects is a sensible approach. The only drug considered to have a direct interaction with nicotine is adenosine, the effects of which may be enhanced, thus possibly impairing myocardial conduction.

Pregnancy and breastfeeding

There is no disputing the detrimental effects that smoking during pregnancy has on both the unborn baby and the mother. The ideal situation is that a pregnant woman manages to quit without using NRT.

However, if this is proving too difficult, NRT may be used following a risk-benefit assessment that should be conducted as early in the pregnancy as possible.

Intermittent forms of NRT are preferable to minimise fetal exposure to nicotine, but patches can be used during the day if nausea or vomiting are a problem, and NRT should ideally be stopped within two to three months. Similarly, the small amount of nicotine an infant is exposed to by their breastfeeding mother using NRT is considered less hazardous than the second-hand smoke they otherwise would be subjected to.

Intermittent products are preferred to enable the mother to maximise the amount of time between using NRT and feeding in order to minimise the nicotine content of breastmilk (at least an hour is the usual guidance).

Also, patches should be avoided where possible.

Medical conditions

Patients with stable cardiovascular disease should be encouraged to quit, using NRT if needed because the risks of treatment are less than continuing to smoke. Smokers who are admitted to hospital due to uncontrolled hyperthyroidism or an acute cardiovascular disorder, such as myocardial infarction, should be encouraged to stop with no pharmacological intervention, although NRT may be used following a risk-benefit assessment and under medical supervision.

Quitters with diabetes should be advised to monitor their blood glucose levels more closely than usual when starting NRT because the nicotine releases catecholamines, which can affect carbohydrate metabolism.

Patients who suffer from anxiety or depression may find that stopping smoking exacerbates their illness due to nicotine withdrawal (see Panel).

Patients with moderate to severe hepatic impairment or severe renal impairment may experience decreased clearance of nicotine or its metabolites, so should only use NRT under medical supervision because they are at risk ofadverse effects.

Formulation

When recommending NRT, it is sensible to consider not only which formulation best suits the individual’s smoking habits, but also how the local nicotine may affect them.

Oral products

Oral products can aggravate oesophagitis, andgastric and peptic ulcers, so should be used with caution by these patients.

Quitters should also be advised that acidic drinks, such as coffee and juice, can decrease the absorption of nicotine through the buccal mucosa so should be avoided for at least 15 minutes before using oral NRT.

Gums may also adhere to and damage dentures. It is sensible to counsel users on the local side effects they are likely to experience when first using NRT, as well as the symptoms of nicotine withdrawal (see Panel), to help maintain their motivation to quit.

All oral preparations can irritate the throat and cause increased salivation in some people or a dry mouth in others, and swallowed nicotine can cause gastrointestinal symptoms, such as nausea, vomiting, indigestion, hiccups and ulcerative stomatitis.

The oral spray and lozenges can cause a number of additional side effects, including taste disturbance, flatulence, chest pain, rash and hot flushes, and the oral spray has also been associated with watery eyes, blurred vision, abdominal pain, arrhythmia, sweating, myalgia and paraesthesia.

Lozenges have additionally been linked with mouth ulcers, gingival bleeding and halitosis, diarrhoea, constipation, dysphagia, oesophagitis, gastritis and bloating.

Inhalation products

Inhalation products should be used with caution in patients with obstructive lung disease, chronic throat disease or disorders that cause bronchospasm.

Nasal sprays can aggravate bronchial asthma and cause coughing, nasal irritation, nosebleeds, sneezing and watery eyes.

Transdermal products

Patches can irritate the skin, so should be used with caution by patients with skin complaints and never applied to areas of skin that are broken, red or irritated. They can cause chest pain, sweating, myalgia, arthralgia, palpitations, cardiac arrhythmias and sleep disturbances (although removing patches at night may help).