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Biomedical subjects

C Feyerabend

Publications and source records attributed to C Feyerabend.

At least 73 records · Page 4Linked to original sources
PubMed1986

Determination of cotinine in biological fluids of non-smokers by packed column gas-liquid chromatography.

A method is described for the analysis of cotinine in plasma, saliva and urine using packed-column gas-liquid chromatography, which is sufficiently sensitive and reproducible for quantitative study of the low levels resulting from exposure of non-smokers to other people's smoke. The lower limit of detection of cotinine in these fluids was 100 pg ml-1. The coefficient of variation over the range 0.25 to 2.0 ng ml-1 averaged 7.7%. In a sample of 85 non-smokers the concentrations of cotinine in plasma correlated 0.82 with those in urine and saliva, while the correlation between the saliva and urine concentrations was 0.91. Saliva cotinine concentrations were quantitatively related to passive exposure to parental smoking in a population study of 569 non-smoking schoolchildren.

Chromatography, Gas↗
PubMed1986

Reduction of tar, nicotine and carbon monoxide intake in low tar smokers.

Blood nicotine, cotinine, and carboxyhaemoglobin (COHb) concentrations were measured in 392 smokers (255 women and 137 men) of "middle tar" (17-22 mg), "low to middle" (11-16 mg), and "low tar" (less than 11 mg) cigarettes. Since tar intake cannot yet be measured directly, we devised an index to estimate it based on the use of measured levels of an intake marker (eg, blood nicotine) and the ratio of the tar to marker yields of the cigarettes. This approach was validated by its ability to enhance the prediction of levels of one marker by use of another. In a practical test, using COHb and the CO/nicotine yield ratio of the cigarettes, the mean blood nicotine concentration of the low tar smokers was predicted to be 31.9 ng/ml compared with the measured mean of 31.8 ng/ml. Our main findings were that despite substantial compensatory increases in inhalation, the low tar smokers took in about 25% less tar, about 15% less nicotine, and about 10% less carbon monoxide than smokers of middle and low to middle tar cigarettes. These results indicate that low tar cigarettes of the type available in Britain since the late 1970s are likely to prove less harmful than other brands. Monitoring of smoke intakes could supplement epidemiological approaches and provide earlier evidence of whether changing cigarette designs lead to any significant dosage reduction that could affect the risk of disease.

Carbon Monoxide↗
PubMed1985

Passive exposure to tobacco smoke: saliva cotinine concentrations in a representative population sample of non-smoking schoolchildren.

Saliva cotinine concentrations in 569 non-smoking schoolchildren were strongly related to the smoking habits of their parents. When neither parent smoked the mean concentration was 0.44 ng/ml, rising to 3.38 ng/ml when both parents were cigarette smokers. Mothers' smoking had a stronger influence than did fathers' (p less than 0.01). In addition, there was a small independent effect of number of siblings who smoked (p less than 0.01). The dose of nicotine received from fathers' smoking was estimated as equivalent to the active smoking of 30 cigarettes a year, that from mothers' smoking as equivalent to smoking 50 cigarettes a year, and that from both parents smoking as equivalent to smoking 80 cigarettes a year. This unsolicited burden may be prolonged throughout childhood and poses a definite risk to health.

Adolescent↗
PubMed1985

Nicotine pharmacokinetics and its application to intake from smoking.

Five subjects were given 25 micrograms/kg nicotine intravenously over 1 min, before and after a loading period involving the smoking of six cigarettes. Plasma nicotine concentrations declined in a biphasic manner, the half-lives of the initial and terminal phases averaging 9 min and 133 min respectively. Terminal half-lives before and after the loading period were essentially the same suggesting the absence of saturation kinetics at nicotine concentrations that build up during smoking. The plasma clearance of nicotine and the volume of distribution were very high averaging 915 ml/min and 1731, respectively. Two approaches were used to calculate the nicotine intake from smoking. The average dose of nicotine absorbed from one cigarette was 1.06 mg which was 82% of the standard machine-smoked yield of 1.3 mg. To illustrate their potential use in 'nicotine titration' studies, these approaches were used to compare nicotine intake from smoking a high (2.4 mg) and low (0.6 mg) nicotine cigarette. The dose of nicotine absorbed averaged 1.14 mg and 0.86 mg per cigarette respectively, being 48% and 143% of the machine-smoked yields.

Adult↗
PubMed1984

Does switching to an ultra-low nicotine cigarette induce nicotine withdrawal effects?

Twenty-six smokers took part in a study which examined subjective and physiological effects of switching to an ultra-low yielding cigarette (0.1 mg nicotine) for 10 days. Subjects were randomly assigned to one of two groups. One group continued smoking their usual brand while the other group switched to the low yielding cigarette. Subjective ratings and physiological measures were taken at baseline, then after 1, 3 and 10 days in the respective conditions. Plasma nicotine concentrations dropped by some 60% after switching. Although substantial, this drop was considerably less than the drop in nominal yield of the cigarettes (around 90%), indicating marked compensation on the part of these smokers. Switching to the low yielding cigarette was accompanied by a significant increase in hunger and a drop in heart rate. These effects typically occur following cigarette withdrawal. However, other common cigarette withdrawal symptoms, such as irritability, depression, and inability to concentrate, were not detected.

Adult↗
PubMed1984

Biochemical markers of smoke absorption and self reported exposure to passive smoking.

One hundred non-smoking patients attending hospital outpatient clinics reported their degree of passive exposure to tobacco smoke over the preceding three days and provided samples of blood, expired air, saliva, and urine. Although the absolute levels were low, the concentration of cotinine in all body compartments surveyed was systematically related to self reported exposure. Salivary nicotine concentration also showed a linear increase with degree of reported exposure, although this measure was sensitive only to exposure on the day of testing. Measures of carbon monoxide, thiocyanate, and plasma nicotine concentrations were unrelated to exposure. The data indicate that cotinine provides a valid marker of the dose received from passive smoke exposure. The non-invasive samples of urine and saliva are particularly suited to epidemiological investigations. Detailed questionnaire items may also give valuable information.

Absorption↗
PubMed1983

Nasal nicotine solution: a potential aid to giving up smoking?

A nasal solution was developed containing 2 mg nicotine for use as a kind of liquid snuff. Its absorption was studied in three subjects. An average peak of plasma nicotine concentrations of 86.9 nmol/l (14.1 ng/ml) was reached seven and a half minutes after taking the solution. This compared with an average peak of 158.4 nmol/l (25.7 ng/ml) one and a half minutes after completing (but seven and a half minutes after starting) a middle tar cigarette (1.4 mg nicotine) and an average peak of 52.4 nmol/l (8.5 ng/ml) after chewing nicotine gum (2 mg nicotine) for 30 minutes. The more rapid and efficient absorption of nicotine from the nasal nicotine solution than from nicotine chewing gum suggests that it might prove a useful aid to giving up smoking. Nasal nicotine solution might be particularly useful in smokers for whom the gum is less suitable on account of dentures or peptic ulcers or who experience nausea and dyspeptic symptoms from the gum.

Administration, Intranasal↗
PubMed1983

Discriminative stimulus properties of nicotine: further evidence for mediation at a cholinergic receptor.

Rats were trained to discriminate nicotine (0.4 mg/kg SC) from saline in a standard two-bar operant conditioning procedure with food reinforcement. The response to nicotine was dose-related and at the ED50 of 0.14 mg/kg, plasma nicotine concentrations were similar to those reported previously for cigarette smokers who inhale. The nicotine analogues anabasine and cytisine increased nicotine-appropriate responding in a dose-related manner. Animals predominantly responded on the saline-associated lever when administered drugs from a range of pharmacological classes, even at doses that were sufficiently large to reduce the overall numbers of responses. The results confirm that the nicotine discriminative stimulus is highly specific. Previous work has shown anabasine and cytisine to be active at nicotinic-cholinergic binding sites in rat brain. The finding that there is some correlation between the behavioural effects of these compounds and their actions at the nicotine binding site may indicate that the nicotine cue is mediated through a cholinergic receptor.

Animals↗
PubMed1983

Absorption of nicotine and carbon monoxide from passive smoking under natural conditions of exposure.

Seven non-smokers were exposed to tobacco smoke under natural conditions for two hours in a public house. Measures of nicotine and cotinine in plasma, saliva, and urine and expired air carbon monoxide all showed reliable increases. The concentrations of carbon monoxide and nicotine after exposure averaged 15.7% and 7.5% respectively of the values found in heavy smokers. Although the increase in expired air carbon monoxide of 5.9 ppm was similar to increases in smokers after a single cigarette, the amount of nicotine absorbed was between a tenth and a third of the amount taken in from one cigarette. Since this represented a relatively extreme acute natural exposure, any health risks of passive smoking probably depend less on quantitative factors than on qualitative differences between sidestream and mainstream smoke.

Absorption↗
PubMed1982

Randomised controlled trial of nicotine chewing-gum.

The effectiveness of 2 mg nicotine chewing-gum as an aid to stopping smoking was compared with a placebo containing 1 mg nicotine, but unbuffered, in a double-blind randomised trial. Of 58 subjects given the active gum, 27 (47%) were not smoking at one-year follow-up compared with 12 (21%) of the 58 subjects treated with placebo (p less than 0.025). By the most stringent criterion of outcome, 18 (31%) subjects in the active treatment group and eight (14%) in the placebo group had not smoked at all from the start of treatment to follow-up at one year (p less than 0.05). Subjects receiving the active gum experienced less severe withdrawal symptoms and rated their gum as more helpful than did the placebo group. Minor side effects were common but only gastric symptoms were more frequent with the active gum. Subjects receiving active gum used it for longer than those receiving placebo but most stopped using it within six months and only four (7%) developed longer-term dependence. The number of gums used daily correlated significantly with pretreatment blood nicotine concentrations in the active treatment group and with pretreatment cigarette consumption in the placebo group. A lower pretreatment blood nicotine value was the best predictor of success at one year (p less than 0.001) but there was no significant relation to cigarette consumption, sex, and social class. The results clearly confirm the usefulness of nicotine chewing-gum as an aid to stopping smoking and imply a definite role for nicotine in cigarette dependence and withdrawal. Successful use of the gum requires careful attention to subjects' expectations and clear instructions on how to use it.

Adult↗
PubMed1982

Nicotine concentrations in urine and saliva of smokers and non-smokers.

Nicotine concentrations were measured in saliva and urine samples collected from 82 smokers and 56 non-smokers after a morning at work. Each subject answered a series of questions related to their recent intentional or passive exposure to tobacco smoke. All non-smokers had measurable amounts of nicotine in both saliva and urine. Those non-smokers who reported recent exposure to tobacco smoke had significantly higher nicotine concentrations (p less than 0.001) than those who had not been exposed; their concentrations overlapped those of smokers who had smoked up to three cigarettes before sampling had the greatest influence on nicotine concentrations (r=0.62 for saliva and r=0.51 for urine). Neither the nicotine for yield of cigarettes nor the self-reported degree of inhalation had any significant effect on nicotine concentrations.

Dose-Response Relationship, Drug↗
PubMed1981

Nicotine intake by snuff users.

Blood nicotine and cotinine concentrations were measured in 27 volunteers before and after taking snuff. Within 10 minutes after snuffing blood nicotine concentrations were comparable to those obtained after the 10 minutes or so that it takes to smoke a cigarette. Nicotine intake from snuffing was related to the experience of the snuffer. In daily and occasional snuffers increases in plasma nicotine concentrations averaged 77.7 and 12.3 nmol/l (12.6 and 2.0 ng/ml) respectively, while the novices showed no appreciable increase. The increase shown by thea daily snuffers was comparable to the average increase of 62.3 nmol/l (10.1 ng/ml) obtained from a single cigarette by a group of heavy smokers. The peak nicotine concentrations in the daily snuffers were also similar to the peak values in 136 heavy smokers--222.6 and 226-3 nmol/l (36.1 and 36.7 ng/ml), respectively. Unusual multiple-dose snuffing produced massive increases in plasma nicotine to concentrations that have never been recorded in smokers. The similarity of the concentrations produced by regular daily snuffing and regular daily smoking suggests that the plasma nicotine concentration has some controlling influence over the self-regulation of these two quite different forms of tobacco use. The rapid absorption of nicotine from snuff confirms its potential as an acceptable and relatively harmless substitute for smoking.

Adolescent↗
PubMed1980

Comparison of nicotine chewing-gum and psychological treatments for dependent smokers.

The results of using nicotine chewing-gum to treat dependent smokers attending a withdrawal clinic were compared with the results of psychological treatment. At one-year follow-up 26 (38%) out of 69 people who received nicotine gum were abstinent compared with seven (14%) out of 49 who received psychological treatment (p < 0.01). Abstinence was confirmed by the measurement of carboxyhaemoglobin concentrations or expired air carbon monoxide. Blood nicotine concentrations when patients used the gum averaged half the smoking values, and side effects were few. Addiction occurred in only two subjects. Thus nicotine chewing-gum is a useful aid to giving up smoking and is probably acceptable even for people with cardiovascular disease.

Adult↗