Rationale: Nicotine replacement therapy (NRT) in varying forms is becoming widely used. Clinicians, therapists and regulatory authorities are interested in the abuse liability and dependence potential of the different forms. Objectives: To compare the abuse liability and dependence potential of nicotine gum, transdermal patch, spray and inhaler. Methods: 504 male and female smokers seeking help with stopping smoking were randomly allocated to the four products. Measures were taken at the designated quit date, then 1 week, 4 weeks, 12 weeks and 15 weeks later. Smokers were advised to use the product for up to 12 weeks. Those still using the product at the 12-week visit were advised to cease use by week 14. Measures included: pleasantness and satisfaction ratings at weeks 1 and 4 (used as a marker of abuse liability); ratings of feeling dependent on NRT at weeks 1, 4, 12 and 15 (used as a marker of subjective dependence); mood and physical symptoms ratings at weeks 12 and 15 (the change being used to assess physical dependence on NRT), continued usage of NRT at week 15 (used as an marker of behavioural dependence). Results: Average ratings of pleasantness were low. The nicotine patch was rated as less unpleasant to use than all other products. There were no significant differences between the products in terms of satisfaction or subjective dependence except at week 15 when no patch users rated themselves as dependent. Continued use of NRT at week 15 was related to rate of delivery of nicotine from the products - 2% for patch, 7% for gum and inhaler, 10% for spray (P<0.05 for linear association). Among those abstinent for 15 weeks, the figures were: 8%, 25% and 37%, respectively. Stopping NRT use between weeks 12 and 15 was not accompanied by withdrawal discomfort or increased frequency of urges to smoke although subjects stopping inhaler use experienced a mild increase in strength of urges to smoke. We conclude that abuse liability from all four NRT products was low. Subjective dependence was moderate and did not differ across products. Behavioural dependence was modest and was positively related to rate of nicotine delivery. Physicians can reassure their patients that most are able to come off NRT as recommended without discomfort.
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