21.02.1 Nicotine Replacement Therapy

When nicotine replacement therapy is used the pharmacokinetics are different than from inhaled nicotine (Figure 21.1). With smoking a cigarette, the concentrations of nicotine become high, and this gives the high associated with smoking cigarettes. The most common form of nicotine replacement therapy is transdermal patches. Nicotine is readily absorbed from the patches, but there is no immediate or great high.

Figure 21.1 Pharmacokinetics of nicotine (Copyright Sheila Doggrell, QUT)

When using replacement therapy to wean a person off of a drug and lessen the effects of withdrawal, the principle is always the same, and that is to stabilize on a fixed dose that is close to their abuse level, and then gradually reduce the dose. With nicotine replacement therapy, smokers are usually stabilized on 30 cm²/15mg/day for 3 months, and then the dose is successively reduced. Initially, the reduction is to 20cm²/10mg for 2-3 wk, and then the transdermal nicotine replacement is reduced to 10cm²/5mg for next 2-3 weeks. Reducing the dose gradually reduces the severity of withdrawal from nicotine. Unfortunately, contrary to instructions - 3 out of 10 continue to smoke when using patches, presumably because they miss the high they get from inhaling nicotine.

The pharmaceutical companies promote nicotine replacement therapy as either increasing the quitters by 100% or doubling the number of quitters. What does this mean? Short term the quit rates are higher than long term, and it is long term quitting that we need. Clinical trials have shown that at one year, 5% of smokers given placebo patches have quit, and 10-15% of smokers given nicotine patches have quit. This means that with the use of nicotine replacement therapy, an extra 1 or 2 in 20 gives up smoking, whereas 17 in 20 continue to smoke. Thus, nicotine replacement therapy is not very effective.

The latest version of nicotine replacement therapy is pre-quit nicotine patches. This allows subjects to use nicotine replacement patches prior to quitting (i.e. while they are still smoking cigarettes). One of the ideas behind this is that it may reduce smoking reinforcement. When the subject is ready they move on to the standard nicotine replacement regimen. This approach is quite new, and there is no data for 12 months, but it has been shown that with pre-quit, the quit rates at 6 months are doubled! Thus, the quit rates are 11% with placebo, and 22% with the pre-quit approach.