Tuesday 12 October 2004
Renee Bittoun gave an update of current thoughts on smoking cessation before moving onto some case studies of people with other dependencies.
Ms Bittoun described genetic variations in nicotine receptors and metabolism that may predispose to dependency. She mentioned research suggesting that nicotine has antidepressant properties. This may help to explain the risk of relapse into depression among previously depressed people who try to quit smoking, and leads to the intriguing idea that nicotine patches could be used to treat depression. She told us about nicotine interactions with alcohol, caffeine and insulin.
The short plasma half life of nicotine (about 40 minutes) corresponds conveniently well to the standard cigarette packet size of about 20 a day, a fact that Ms Bittoun suggests tobacco companies have long been well aware of. Most smokers strive to keep their nicotine plasma concentrations at their particular desired levels, and will do so regardless of the nicotine content of their cigarettes. Smokers of low nicotine cigarettes may end up having higher levels of carbon-monoxide as they inhale more deeply.
Plasma nicotine concentrations form a bell-curve in the smoking population, with new smokers such as children having lower concentrations and highly dependent groups, such as people with schizophrenia, at the top end of the curve.
Average plasma concentrations may be a measure of dependence, and are lower in countries with waxing smoking epidemics (such as China) than in countries such as the US with waning epidemics. As low-dependence smokers quit more readily, there is higher dependence among people continue to smoke, which will have implications for the effectiveness of treatments in future. There are reports of falling effectiveness of such treatments as over the counter nicotine replacement.
Quit rates for spontaneous quitters are about 5% at one year, and pharmacotherapies roughly double quit rates over placebo. 50% of relapses happen in the first week, dropping to 10% in the second, so early follow-up and support is important, and 3 months abstinence is long term abstinence.
Ms Bittoun doesn't put much by the 'quit date', suggesting "why not today?". This was supported by an observation from the floor that people with mental illnesses, especially schizophrenia, may find quit dates very intimidating.
She reviewed the evidence base for treatments: bupropion and nicotine replacement treatment (NRT) of all types have a good evidence base, with evidence of better results from combinations of NRT, and NRT combined with bupropion. Interestingly she observed that about a quarter of people get a great result from bupropion but it is impossible to know in advance who will respond, and if they haven't responded within 2 weeks, it is time to stop.
Ms Bittoun wished to stress to the audience that combination NRT means two patches and/or gums and more if occasionally necessary ... 'whatever it takes to not smoke'. We need to understand that this is the very common direction we are going with NRT.
Thumbs were down for the evidence for: hypnotherapy, acupuncture, psychotherapy, weaning by cutting number of cigarettes smoked a day or their nicotine content, and shibboleths like the 4 Ds ('delay', 'distract', 'deep breaths', 'drink glass water').
The first case study that followed featured simultaneous adverse 'speed-like' reactions to bupropion in a husband and wife both on methadone maintenance, after starting bupropion on their quit day and after a strong warning from the pharmacist about risk of seizure (the wife had a history of benzodiazepine related seizures many years before, and was now on maintenance diazepam). It was suggested that the bupropion should have been started a week before the quit date to prevent confounding anxiety from nicotine withdrawal. NRT might be the better first line choice in people who have had agitated reactions to antidepressants in the past.
A second case was a 38 year old man with hazardous level after-work drinking, whose history suggested strong priming by smoking. As he chose the option of controlled drinking, the focus was on smoking cessation using NRT to help achieve the alcohol goal.
To finish off, Renee Bittoun told the audience about "chop-chop". In Sydney there is a growing market for locally-grown black market tobacco, or "chop-chop", which many people wrongly believe is more organic and less harmful. In fact there has been evidence of dangerous contamination with moulds, and analysis has shown such choice ingredients as lawn clippings and cabbage! A possible down-side to our cigarette pricing policies.