Letters to the Editor
- H Jersmann, Respiratory physician, Department of Thoracic Medicine, Royal Adelaide Hospital, Adelaide, John Litt
- Aust Prescr 2005;28:136-9
- 1 December 2005
- DOI: 10.18773/austprescr.2005.101
Editor, – It was with considerable disappointment that I read J. Litt's contribution 'What's new in smoking cessation?' (Aust Prescr 2005;28:73-5). Nothing the author reviewed was new. The only truly new development in the field of smoking cessation has been the anti-nicotine vaccine. This did not seem to get a mention in the article at all. A lot of experimental research in animals has been published since 2002 and a review of current progress has recently been published.1
Department of Thoracic Medicine
Royal Adelaide Hospital, Adelaide
Dr John Litt, the author of the article, comments:
Nicotine is the main addictive agent in cigarettes.2 A nicotine vaccine offers an additional therapeutic option to reduce the likelihood of relapse in smokers who have recently quit. Its role in assisting cessation or preventing the development of nicotine addiction remains speculative.3
Animal models have shown proof of concept.4 Specifically, vaccination with a nicotine conjugate vaccine in mice produces antibodies that prevent nicotine crossing the blood-brain barrier. The vaccine also prevents the nicotine stimulation of dopamine release in the nucleus acumbens. This pathway is the postulated pleasure/reward pathway associated with various addictions, including nicotine. Blocking significant nicotine uptake in the brain reduces the rapid gratification effect and interrupts the subsequent reward provided by smoking. The process is not compromised by concomitant nicotine administration, suggesting that the vaccine may have a role in cessation.
The first phase I study was only published in July 2005.5 After being immunised with a nicotine vaccine conjugated with bacteriophage Qb virus-like particles, 32 volunteers had significant increases in nicotine-specific IgM and IgG titres at 7 and 14 days respectively. Local reactions including erythema, local swelling and tenderness were common (88-100%) and a variable number (13-38%) experienced flu-like symptoms 2-12 hours post-injection.
A phase II trial is currently underway to assess vaccine efficacy. This and subsequent phase II studies will need to address a number of unknowns. For example, it is possible that the smoker may be able to alter their inhalation of nicotine and overcome the relative blockade of nicotine uptake into the brain.6 How many boosters are required? What is the duration of immunity? What longer-term adverse effects are there? Most investigators agree that the anti-nicotine vaccine, if shown to be efficacious, will only provide an adjunct to counselling and other strategies, for example referral to an active callback program offered by state Quitlines.36 A vaccine is unlikely to assist the patient in overcoming the habit of smoking or provide a coping strategy for dealing with negative emotions.
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Respiratory physician, Department of Thoracic Medicine, Royal Adelaide Hospital, Adelaide
Department of General Practice, Flinders University Adelaide