The approved course of Chantix treatment is usually 12 weeks, an interval that can be doubled in individuals who successfully quit to increase the likelihood they will remain smoke-free, the FDA said. Other clinical trials show the drug’s effect is more pronounced for a while: 44 % of patients quit smoking following a 12-week treatment with Chantix, weighed against the thirty % of Zyban patients who quit, relating to Pfizer. However, cigarette smoking cessation experts said the longer-term data are more applicable, given the difficulty of stopping the habit once and for all.One doctor stated that denying in-vitro fertilisation to childless ladies who smoked was justified since it was only fifty % as effective for them. Another said the NHS was right to expect an obese individual or alcoholic to change their behaviour before they underwent liver transplant medical procedures. Dr Tim Ringrose, Doctors.net. Smokers and obese people are being denied operations such as IVF already, breast reconstructions and a fresh hip or knee in a few parts of England. The medical magazine Pulse last month discovered that 25 of 91 principal care trusts acquired released treatment bans for all those groupings since April 2011.