Tobacco Documents Online

THE EFFECT OF INHALATION VOLUME AND BLEND ADDITIVES ON NICOTINE RETENTION AND UPTAKE. AK Armitage, M Dixon, T Higenbotham, DC Mariner and NM Sinclair It has been suggested that as 'tar' and nicotine deliveries from cigarettes have been reduced by the Tobacco Industry, in line with regulations and agreements with national governments, smokers have inhaled deeper to achieve more efficient uptake of nicotine. Furthermore, it has been suggested that the Industry has used ammonia- forming compounds to increase 'smoke pH' and thus increase the rate of uptake of nicotine because more nicotine would be in the unprotonated form and thus more readily absorbed. We have studied the effect of inhalation depth and the addition of di-ammonium phosphate (DAP) or urea to a cigarette blend on the retention of nicotine by ten smokers. Various inhalation and breath-hold manoeuvres were used to control the penetration and residence time of the cigarette smoke in the respiratory tract. The addition of 0.5% DAP increased mainstream smoke ammonia (from 16 to 28Ng/cigarette) but did not increase 'smoke pH' (from 5.6 to 5.5). The addition of 0.4% urea increased mainstream smoke ammonia further (to 38pg/cigarette) and 'smoke pH' (to 6.1). Puff number and interval were controlled. Nicotine retention was calculated from the difference between nicotine intake, assessed by duplication of smoking behaviour records, and nicotine exhaled, determined by collection of exhaled smoke. Nicotine uptake was derived from plasma nicotine levels. Results show that 90% of the nicotine intake from the control blend (without DAP or urea addition) was retained after a 75mL inhalation, increasing to >95% at 250mL and 99% at 500 or 1000mL. This does not, however, indicate whether smokers of lower'tar' are likely to inhale deeper because inhalation volumes were controlled. Since nicotine retention is almost complete at an average inhalation volume (500mL), the potential for blend additives to increase nicotine retention/uptake is limited. Nicotine retention and uptake from the DAP containing cigarette were unchanged (Cmax and AUC reduced but NS). Nicotine retention from the urea containing cigarette increased (to 99.6%, p<0.01) and uptake was unchanged (Cma, and AUC slightly lower but NS). Puff volumes did not change significantly. These data appear to refute the suggestion that the addition of ammonia-forming compounds substantially increases nicotine uptake in smokers. In addition, we believe that the almost complete retention of nicotine at typical inhalation volumes (approximately 500mL) indicates that nicotine uptake could not be the driving force for any altered inhalation claimed for smokers of low 'tar'products.