Nicotine replacement

Nicotine replacement 

General information

Nicotine withdrawal symptoms are worst in the first two weeks. It has been recommended that the dose of nicotine replacement should then be tapered off before being withdrawn completely at about three months. This is logical, but there is some evidence that this has no beneficial effect on outcome. Very few people become addicted to nicotine replacement therapy. Some ex-smokers continue to use it for a year or more; however, this usually relates to anxiety about returning to smoking.

Patches

Even the strongest nicotine replacement therapy (NRT) patches produce trough blood concentrations of nicotine only about half those achieved by the average smoker. Blood concentrations rise over several hours with transdermal administration.

The patches should be applied to clean, dry, nonhairy skin on the upper part of the body, and left in place for 24 hours. The siting of the patch should be rotated to avoid skin irritation.

Skin irritation can be due to a reaction to the patch adhesive, or to the effect of nicotine; it can be treated with hydrocortisone cream. Sleep disturbances, particularly vivid dreaming, are the most common adverse effect of NRT patches, but this does not seem to affect success rates. The use of the 16-hour patch may be useful in this setting.

Patients should be advised that used patches still contain nicotine, and they can be dangerous if swallowed by small children or pets. Used patches should be disposed of carefully.

Subjects should stop smoking completely at the time that they commence treatment with nicotine patches.

Gum

Nicotine is readily and rapidly absorbed through the oral mucosa, and nicotine gum increases blood concentrations of nicotine fairly rapidly. Gum is available in Australia in 2 mg and 4 mg strengths; both strengths produce plasma concentrations much lower than those found in smokers. The oral gratification of the gum can help some smokers.

Chewing technique is important. The gum should be chewed slowly with frequent pauses, during which the gum is pushed to the side of the mouth or under the tongue. If the gum is chewed quickly or strongly, more saliva is created, which can cause dyspepsia and nausea. The gum has a bitter taste, which people usually get accustomed to if they persist.

It takes about 30 minutes for most of the nicotine to be chewed out of the gum.

A piece of gum should be used at regular intervals and at least six times during the day, plus extra ones when the urge to smoke does not disappear quickly. Most people use 10 or more pieces a day to give them sufficient nicotine replacement, and in most cases this results in lower serum nicotine concentrations than smoking. The rate should not be more than one piece per hour.

If the taste is too strong or the gum too bulky, it can be cut in half; however, the halves will need to be taken more frequently.

Subjects should stop smoking completely at the time that they commence treatment with nicotine gum.

Inhaler

A nicotine inhaler consists of a mouthpiece resembling a cigarette holder, into which is inserted a capsule that releases about 4 mg of gaseous nicotine. Absorption is slower than from cigarettes, but the action mimics smoking and this may help some smokers. Each capsule lasts about 20 minutes.

Sublingual tablets

Nicotine sublingual tablets are available as 2 mg tablets, and these can be used every 1 to 2 hours. Gradually taper dose after 2 to 3 months. The microtab is placed under the tongue and allowed to slowly dissolve over 30 minutes. Tablets are not to be swallowed. Sore mouth or throat, dry mouth, a burning sensation in the mouth, coughing, headache, hiccups, and nausea have been reported.

Lozenges

The lozenge should be placed in the mouth and allowed to dissolve. This can take 20 to 30 minutes, and allows the nicotine released to be absorbed through the buccal and gastric mucosa. No food or drink should be consumed while the lozenge is dissolving. Lozenges should not be chewed or swallowed whole, as this decreases nicotine absorption.

Adverse reactions and contraindications

The risk of using nicotine replacement must be balanced against the risks of smoking. This is particularly important for patients with coronary heart disease or cerebrovascular or peripheral vascular disease. For patients with recent myocardial infarction, severe arrhythmias or recent cerebrovascular event, nicotine replacement therapy (NRT) is listed as contraindicated; however, NRT patches have been used in patients with less severe cardiovascular disease. In hospitalised patients, there are risks associated with continued smoking; in patients with severe nicotine dependence, there are risks of adverse effects of nicotine withdrawal.

There are concerns about the safety of NRT in pregnancy. Nicotine is teratogenic in animals, but NRT is associated with lower blood levels than smoking. The effects of sustained low-level nicotine exposure on the fetus remain unclear, and studies are continuing. In one trial in pregnant smokers, those on NRT showed an increase in birth weight. Women should be encouraged to quit smoking before contemplating pregnancy. In pregnant women who are heavy smokers, NRT should only be considered if other methods have failed. Intermittent therapy (gum, inhaler) may be preferred. Monitoring urinary cotinine may be helpful for monitoring compliance or exposure to nicotine during pregnancy.