Cytisine Pharmacokinetics and Dose Response (C-DRAKS 3 and C-DRAKS 4)
Status:
Terminated
Trial end date:
2019-03-01
Target enrollment:
Participant gender:
Summary
A number of pharmacotherapies are available for smoking cessation in New Zealand including
nicotine replacement therapy, bupropion, an antidepressant medication and varenicline. Of
these, varenicline is the most effective, but also the most expensive. Varenicline acts like
nicotine and stimulates nicotine receptors in the brain, but to a lesser extent, and
simultaneously block nicotine binding to its receptors and thus reduces the rewarding effects
of cigarette smoking. Cytisine (Tabex® and Desmoxan®) is a plant alkaloid and also acts in a
similar way to varenicline but is significantly cheaper. It has been used for more than 50
years in some parts of eastern and central Europe as an aid to quit smoking, but is not
approved for use in many countries such as New Zealand, Australia, the UK or the US.
Randomised, placebo-controlled trials have shown that cytisine is more effective than placebo
and nicotine replacement therapy (NRT)for smoking cessation. However there is a paucity of
pre-clinical data on cytisine. In particular, there are limited data on the pharmacokinetic
and the dose response characteristics of cytisine. Furthermore, the current dosing regimen
recommended by the manufacturer is complex and has no clear basis in empirical research.
Complexity of dosing has been shown to be a key factor in determining adherence. Therefore, a
simpler regimen would likely maximise the effectiveness of treatment through improved
adherence to the treatment regimen. The investigators therefore propose to undertake two
studies to investigate the influence of dose, dosing frequency and dosing duration on the
pharmacokinetics and tolerability of cytisine and cigarette craving in smokers.