Smoking Cessation Matters in Primary Care

Marcus Munafro, Mark Drury, Ruth Chambers, Gill Wakley

• Publisher: CRC Press
• Year: 2018
• eBook ISBN:
  9781315348162
• Topic: Medicine
• Subtopic: Medical Theory, Practice & Reference

This work explains in clear and concise terms the business side of general practice. It provides a reference for every GP practice and is particularly relevant to the needs of the younger principal, GP trainees and other doctors who have recently entered general practice. Each of the book's chapters provides a lucid description of a key facet of general practice and tells the reader how to obtain further advice and assistance.

CHAPTER 1

Smoking initiation, nicotine addiction and the smoking life-course

It is the only product which kills people when used as intended.

More than a quarter of adults in the UK smoke 15 cigarettes a day or more, while approximately 15% of children aged between 11 and 15 years smoke once a week or more. However, the majority (around 70%) of adult smokers are keen to stop, and one-third of smokers make at least one attempt to stop in any given year. Yet only 2% of smokers successfully stop smoking every year. In the UK, 80% of those who become regular smokers do so by the age of 18 years, and 90% by the age of 19 years. There are currently approximately 10 million smokers in the UK, and somewhat more who have given up without pharmacotherapy. The possibility therefore exists that those who remain are, on average, more addicted. The history of smoking cessation is a long one, with anti-smoking campaigns being reported as far back as the seventeenth and eighteenth centuries. However, only recently has it become generally accepted that nicotine is the principal addictive component of tobacco and that, because of this, smoking initiation will in many cases result in addiction.

History of tobacco use

Introduction of nicotine

The use of tobacco as a psychoactive substance began in the Americas, possibly as early as 6000 bc, and was introduced to Europe almost immediately after Columbus’s voyages. The practice was introduced into English society in 1565, although it did not become widely popular until about 20 years later. The methods of delivery used by Native Americans included smoking, snuffing and drinking of various tobacco preparations. The use of tobacco was associated with medical and religious rituals, and a ban on the use of tobacco was included in a Papal decree of 1586, although this was motivated by a desire to prevent the contamination of Christian rituals by Native American religious rituals, rather than being a result of any health considerations. Indeed, the early growth in popularity of tobacco was a consequence of its supposed healing properties, and it was widely regarded as a medicinal plant. It was not until the beginning of the seventeenth century that the supposed benefits of smoking tobacco began to be questioned, notably by King James I in his ‘Counterblaste to Tobacco’:

a custome lothsome to the eye, hateful to the Nose, hermful to the braine, dangerous to the Lungs, and in the blacke stinking fume therof, nearest resembling the horrible Stigian smoke of the pit that is bottomlesse.

This concern continued into the eighteenth century, with an increasing number of physicians warning of the potential dangers of tobacco consumption, including its association with cancers of the nose (in the case of snuff takers) and of the lip (in the case of pipe smokers).

Patterns of tobacco consumption in Europe changed from its introduction in the sixteenth century, when the delivery device of choice was the pipe, through the eighteenth century, when snuff was commonly used, to the nineteenth century, when snuff-taking declined and cigar smoking became popular. It was not until the twentieth century that cigarette smoking became the most common form of tobacco consumption, some 50 years after the invention of this delivery device. The invention of the manufactured (as opposed to hand-prepared) cigarette led to the habit of tobacco smoking being adopted by the majority of the population, to the extent that cigarettes were included as part of the daily rations issued to soldiers in the First World War. The prevalence of tobacco smoking in the UK reached 70% in men and 50% in women between the 1940s and the 1960s, and then declined in the early 1970s as increasing evidence of the health consequences of tobacco use became available.

The rise of the cigarette

The cigarette, although apparently so simple in construction, is in fact a highly efficient delivery device for tobacco and nicotine, and is a highly engineered product. The Freedom of Information Act in the USA has resulted in revealing insights into the mind of tobacco manufacturers:

The cigarette should be conceived not as a product but as a package. The product is nicotine. Think of the cigarette pack as a storage container for a day’s supply of nicotine… Think of the cigarette as the dispenser for a dose unit of nicotine… Smoke is beyond question the most optimised vehicle of nicotine and the cigarette the most optimised dispenser of smoke.¹

Figure 1.1: Prevalence of smoking of manufactured cigarettes in men and women in Great Britain, 1948–1997.

Source: 1948–71 Tobacco Advisory Council data, 1972–96 General Household Survey and 1997 Omnibus Survey.

A cigarette consists primarily of a paper tube that contains chopped tobacco leaf and ‘filler’ (stems and other parts of the tobacco plant that are essentially waste, although they do contain nicotine), and a filter made of cellulose acetate. An increase in the filler content reduces the density of tobacco leaf and results in a lower tar delivery, and this varies across brands. The type of paper that is used can influence how much air is drawn into the cigarette, thereby diluting the smoke. The filter traps some of the particulate content of cigarette smoke and cools the smoke, making it easier to inhale.

In addition to the physical construction of the cigarette, the chemical engineering of the content contributes to its effectiveness. In the manufacture of cigarettes a large number of additives are permissible, including humectants to prolong shelf-life, sugars to make the smoke milder and therefore easier to inhale, and flavourings to improve the taste of the smoke. Another group of additives that are commonly used are ammonia compounds, which raise the alkalinity of cigarette smoke, thereby increasing the concentration of unbound nicotine in cigarette smoke and in turn increasing the speed with which nicotine is absorbed. In total around 600 additives are permitted, contributing to around 10% of the cigarette by weight. In practice, the actual number of additives used in the manufacture of different brands, and their exact function, are often unknown.

In the 1970s, various changes in the manufacture of cigarettes were introduced by voluntary agreement between governments and the tobacco industry in response to growing concern about the health effects of cigarette smoking, in particular in relation to lung cancer. These changes led to the introduction of ‘low-tar’ cigarettes, which resulted in lower tar yields in the particulate phase of cigarette smoke (e.g. by using filters that drew in more air, thereby diluting the smoke). In 1970, tar yields were typically 20 mg per cigarette, whereas a limit of 12 mg per cigarette was set by the European Uniontobe achieved by 1997. This will be replaced by a new directive requiring all cigarettes sold within the European Union to conform to a maximum tar yield of 10 mg per cigarette and a maximum nicotine yield of 1 mg per cigarette. However, these figures for tar yield (and corresponding nicotine yield) are generated from data on machine-smoked cigarettes, and there is increasing evidence that these data are of little relevance to nicotine and tar yields in cigarettes smoked by humans, since smoking behaviour can be modified to achieve the desired intake. For example, tar and nicotine yields can be increased by puffing on a cigarette more often, by inhaling more deeply or by blocking the filter holes with one’s fingers. Such compensatory behaviour suggests that the health benefits of changing to low-tar cigarettes may be lower than anticipated. This view is supported by recent evidence which shows that the nicotine and tar yields from machine-smoked cigarettes are poor predictors of nicotine intake (and therefore tar intake, since the two are highly correlated) in smokers.²

Cigarette smoking in the UK

The vast majority of tobacco users in the UK are cigarette smokers (approximately 10 million adults, compared with around 2 million cigar and/or pipe users). There are also a similar number of ex-smokers. The highest prevalence of cigarette smoking, when surveys were first conducted, was in 1948, when the prevalence among men was 82%. In women the figure was lower, and it gradually rose to a peak of 45% in the mid-1960s. The prevalence of cigarette smoking then declined as the health risks became more widely known, and it fell faster in men than in women, so that there is now no significant difference between men and women as a whole. However, there are signs that this decline has begun to tail off, and there is also evidence of an increase in prevalence among certain age groups.

Table 1.1 Prevalence of cigarette smoking by age in the UK (1998)

Cigarette smoking is also more common among those employed in manual occupations compared with those employed in non-manual occupations, partly due to a slower decline in cigarette smoking in the former group.

There are also regional differences in the prevalence of smoking. For example, 22% of the population of East Anglia smoke compared with 31% of the population of North-West England.

In 1999–2000, the Government received £7600 million in revenue on the sale of cigarettes, in the form of duty and VAT. Approximately 80% of the retail price of a packet of cigarettes consists of tax in one of these two forms, and increasing taxation has been the principal means by which the tobacco policy of successive governments has been implemented. There is evidence that this has a modest effect on cigarette consumption and also results in some smokers stopping the habit. The net effect over time has been an increase in the average price per pack that has outstripped the rate of inflation to a considerable degree.

Table 1.2 Prevalence of cigarette smoking by socio-economic group (1999)

Pharmacology of nicotine

Absorption

Tobacco smoke consists of both volatile and particulate phases. The volatile phase includes several hundred gaseous compounds (e.g. carbon monoxide), while the particulate phase is composed of several thousand compounds, the most significant of which is the alkaloid nicotine. Absorption of nicotine from burning tobacco is dependent on the pH of the smoke. This in turn depends on the method used for curing the tobacco. For example, smoke from cigar and pipe tobacco is alkaline and is readily absorbed in the mouth, but it is also harsher and therefore less likely to be inhaled deeply. However, smoke from cigarette tobacco is more acidic and must be inhaled into the lungs to be absorbed effectively. It is also less harsh, partly due to the presence of additives that are introduced during the curing process. Menthol cigarettes allow deeper inhalation because they are less harsh, which results in a risk of adenocarcinoma of the peripheral lung rather than squamous-cell carcinoma of the bronchus. The nicotine in cigarette smoke is therefore inhaled and deposited in the airways and alveoli. It is then rapidly absorbed into systemic arterial blood, and it reaches the brain within 10–20 seconds. Levels of nicotine in arterial blood can be up to six times those found in venous blood. This is relevant to an understanding of the addictive properties of nicotine from cigarette smoke, because while venous blood levels of nicotine after smoking a single cigarette peak after around 10 minutes and then gradually decline, the concentration of nicotine in arterial blood peaks and drops sharply after each inhalation. This strengthens the reinforcing (i.e. addictive) properties of nicotine that is absorbed in this way.

Nicotine from oral products such as chewing tobacco and nasal products such as snuff is absorbed through the mucosa, and nicotine levels rise more slowly when these products are used than in cigarette smoking. The different rates of absorption when such products are used mean that the behavioural reinforcement offered by these delivery devices is far less than that offered by cigarettes. In addition, the rapid delivery of nicotine offered by cigarette smoking allows fine titration of the plasma nicotine level in order to achieve the desired effect.

Figure 1.2: Time-course of arterial and venous nicotine concentrations.

Source: Henningfield et al. (1993).⁵

Mechanisms of action

Recent animal and cellular physiology studies have provided substantial insight into the mechanisms of action of nicotine in the brain. In particular, the areas of the brain, the types of receptor and the changes in neuronal activity that mediate the effects of nicotine use have been described in some detail. Nicotinic acetylcholine receptors are found distributed throughout the brain, being concentrated in the cortex and thalamus, but...

Table of contents

• Cover
• Title Page
• Copyright Page
• Table of Contents
• Preface
• About the authors
• 1 Smoking initiation, nicotine addiction and the smoking life-course
• 2 Smoking and health
• 3 Psychological and behavioural techniques
• 4 Pharmacological interventions and new medications
• 5 Practice policies and attitudes
• 6 Opportunities
• 7 Interventions
• 8 Clinical governance and smoking cessation
• 9 Draw up and apply your personal development plan
• 10 Draw up and apply your practice or workplace personal and professional development plan
• Appendix 1 The stages of change
• Appendix 2 Carbon monoxide monitoring
• Appendix 3 Prescribing nicotine replacement therapy
• Appendix 4 A practice protocol
• Appendix 5 Draft workplace smoking policy (ASH)
• Appendix 6 Resources
• Index