Low-nicotine cigarettes fail to sway smokers

Smokers who successfully lowered their nicotine intake when they were switched to low-nicotine cigarettes were unable to curb their smoking habits in the long term, according to a study by researchers at UCSF and San Francisco General Hospital and Trauma Center.

The study, published online today (July 22) in the journal Addiction found that levels of cotinine, a derivative of nicotine measured in the blood, plummeted six months after smokers' regular cigarettes were replaced with low-nicotine ones. But levels started to rebound later into the study when smokers returned to regular cigarettes, suggesting that use of low-nicotine cigarettes alone may be ultimately ineffective in weaning smokers off tobacco.

Researchers led by Neal Benowitz, MD, recruited 135 smokers who had no imminent plans to quit, but were interested in trying low-nicotine cigarettes. Fifty-five of the smokers were told to continue smoking their regular brand, which was provided at no cost, while 80 were instructed to smoke "research cigarettes" with progressively lower levels of nicotine, also provided free of charge. The nicotine was eventually tapered to just 5 percent of that used in regular cigarettes.

Both groups were asked to smoke as desired, but the research cigarette smokers were told to avoid regular cigarettes and other tobacco products. Smoking cessation manuals were given to participants interested in quitting.

At 12 months, provision of both regular and research cigarettes was terminated and both groups' cotinine levels continued to be monitored for a further year. At the start of the study, the research cigarette group had an average cotinine level of 250ng/ml, which dropped to 113ng/ml at six months. But an upswing was evident at the 12-month mark, which continued to rise as smokers returned to their usual brands, and approximated that of the group that had consistently smoked regular cigarettes.

A total of 68 participants completed the two-year study. Just one participant in the research cigarette group had quit smoking, versus zero in the regular cigarette group.

"We don't know that very low nicotine cigarettes will not reduce nicotine dependence, but progressively reducing nicotine content of cigarettes in the way that we did, without other means of supporting smokers, did not produce the desired results," said Benowitz, a professor in the UCSF departments of Medicine and of Bioengineering and Therapeutic Sciences, who conducts research at the San Francisco General Hospital and Trauma Center (SFGH) Division of Clinical Pharmacology and Experimental Therapeutics, Medical Service.

The authors attributed the rebounding cotinine levels in the research cigarette group to noncompliance.

"Cotinine levels were higher than expected given that nicotine content of the very low nicotine cigarettes was only 5 percent of that of conventional cigarettes," said Benowitz, the paper's first author. "We know that at six months, 30 percent reported that they had supplemented with conventional cigarettes and this had increased to 43 percent at 12 months.