New pharmacotherapy for smoking cessation--论文代写范文精选

它已被证明是有效的，然而,它带来的安全与心理健康问题需要研究，当前可用的数据支持伐伦克林治疗尼古丁依赖性,但使用时也需谨慎。初级保健医生有一个新的药理选择，提供给想戒烟的吸烟者。下面的report代写范文进行论述。

Abstract 
  Background: Cigarette smoking causes significant morbidity and mortality and is a major public health concern worldwide. Primary care doctors are in a unique position that enables them to promote smoking cessation, as smokers are more aware of their health at the time of their clinic visit. It is thus important to offer effective treatment to help smokers stop smoking. 
  Methods: A search of PubMed was done up to 16 December 2009, using the keywords “varenicline” alone, “varenicline” and “family medicine”, and “varenicline” and “primary care”. The search produced 426 articles on varenicline. The articles that were chosen were case reports, meta-analyses, review articles and clinical trials published in English. 
  Results: A new drug called varenicline has recently been introduced to assist smoking cessation. It is an α4β2 nicotinic acetylcholine receptor partial agonist. Varenicline has a unique action that relieves the cravings and withdrawal symptoms that occur during smoking abstinence, while blocking the receptor and preventing any reward from additional smoking. It has been shown to be efficacious for smoking cessation in normal smokers; however, its safety in smokers with mental health problems needs to be elucidated. 
  Conclusion: The currently available data support the effectiveness of varenicline to treat nicotine dependence, but caution is needed in smokers with mental health problems. Thus, primary care doctors have a new pharmacological option to offer smokers who wish to stop smoking.

 Introduction 
  Cigarette smoking is the single most important modifiable risk factor for cardiovascular disease. It also causes respiratory diseases, cerebrovascular diseases and cancer. Globally there are 1.3 billion smokers, and the majority of these are from developing countries.1 The prevalence of smoking is 23% in the USA, 67% in China and 75% in Yemen. The present trend of smoking seen worldwide is also observed in Africa. The Medical Research Council (MRC) estimates that 8% of South African deaths are due to smoking, and the World Health Organization (WHO) has reported that smoking causes five million deaths per year. If the present trend continues, it is projected that, by the year 2025, up to 10 million smokers will die annually.2 There is, therefore, an urgent need to identify an effective treatment to help smokers stop smoking. 

  Up to 70% of smokers visit a primary care doctor each year.3 Smokers have also been reported to be more aware of their health during these clinic visits. A primary care doctor thus has an important role, as the clinic visit provides an opportunity to offer smoking cessation interventions for smokers. Primary care doctors are also in a unique position as agents for smoking cessation because of their unique, personal doctor-patient relationship and their provision of comprehensive care. Primary care clinics are also more easily accessible to patients needing close supervision and support. It has been shown that brief advice offered by primary care doctors increases the rates of smoking cessation, but the addition of pharmacotherapy further enhances cessation outcomes.3 

  In recent years, much work has been published regarding what is effective in smoking cessation.4 The combined use of pharmacotherapy and behavioural modification has consistently produced long-term smoking abstinence. A variety of pharmacological options are available to help smokers stop smoking. These options include nicotinebased medications, such as nicotine replacement therapy, and non-nicotine-based medications, such as buproprion, clonidine and nortriptyline.5 A new pharmacological agent called varenicline has recently been approved as a pharmacological agent for smoking cessation.5 Varenicline has been reported to have unique properties that help smokers refrain from smoking again.6

 Why do smokers need to stop smoking? 
  The benefits of stopping smoking are well documented. By stopping smoking, a smoker gains short-term and longterm health benefits, reduces morbidity and mortality, and reverses disease progression associated with smoking.7 The risk of dying from heart disease is 70% greater in people who smoked compared to people who did not. Compared to a non-smoker, a cigarette smoker has an increased risk of hospitalisation due to heart failure and heart attack. However, people who quit smoking have been shown to have less risk of death due to heart disease. For instance, quitting smoking at the age of 35 increases life expectancy by 6.9 to 8.5 years for men and 6.1 to 7.7 years for women.8 

  Quitting smoking also reduces the risk of death for patients with left-heart failure and those who have undergone heart bypass surgery. Lung function starts to improve within three months of quitting and ex-smokers experience decreased coughing, sinus congestion, fatigue and shortness of breath.9 The risk of coronary heart disease is reduced by 50% among ex-smokers one year after quitting and, by five years, the risk of stroke returns to the level of people who have never smoked. By 10 years after quitting, the risk of lung cancer reduces to 30 to 50% of those who continue to smoke and, by 15 years, the risk of cardiovascular heart disease becomes similar to those who have never smoked.7,9,10 Thus, smoking cessation increases life expectancy regardless of age at quitting, although the effect is better when quitting at an earlier age, in those who smoked fewer cigarettes and in those who smoked for fewer years.9 For example, stopping smoking at the age of 30 was shown to avoid smokingrelated mortality, whereas stopping smoking at the age of 50 reduces the risk of death from smoking by half.11

 Source of data 
  A search of the literature up to 16 December 2009 was conducted using PubMed, with keywords “varenicline” alone, “varenicline” and “family medicine”, and “varenicline” and “primary care”. The search produced a total of 426 articles on varenicline. The articles chosen were narrowed to those published in English and limited to studies done on human subjects. Case reports, meta-analyses, review articles and clinical trials evaluating the safety, efficacy and adverse effects of varenicline were included.6,12-21 Nicotine dependence Nicotine is responsible for the highly addictive nature of cigarette smoking. 

  Stopping smoking is difficult because of nicotine dependence. Nicotine dependence is characterised by loss of control and compulsive drug-seeking behaviour. When inhaled, the nicotine in cigarette smoke is absorbed by the pulmonary alveoli, passes into the blood and enters the brain in less than 10 seconds.22 The nicotine concentration in the blood rises rapidly and this phenomenon is known as nicotine boost. The extent of nicotine boost varies between individuals, but the nicotine concentration in the arteries is about twice the concentration in the veins.23 In the brain, nicotine binds to the nicotinic acetylcholine receptors at the α4β2 subunit.22

 Varenicline 
  Varenicline is a partial agonist at the α4β2 nicotinic acetylcholine receptor developed specifically for smoking cessation. Varenicline as the tartrate salt has a molecular weight of 361.35 daltons and a molecular formula of C13H13N3 • C4 H6 O6 . 5 It stimulates dopamine release upon binding to the α4β2 receptor. However, the dopamine release from the ventral tegmental area due to varenicline is less (32 to 45%) when compared to the effect of nicotine.5 Thus, cravings and withdrawal symptoms are partially reduced. Another feature of varenicline is the high affinity for the receptor, causing it to remain bound to the receptor for a time. This impedes the ability of nicotine to activate the receptor and thus reduces the satisfaction of smoking a cigarette.4 A smoker who is motivated to stop smoking is encouraged to set a date to stop smoking, and varenicline is prescribed one week before the quit date.

  The initial dose is 0.5 mg daily for the first three days. This is gradually increased to 0.5 mg twice daily for another four days, and then further increased on day 8 to 1 mg twice daily.4,6 The recommended treatment is for 12 weeks, although an additional 12 weeks of treatment may be offered to successful patients at the end of the 12 weeks to ensure abstinence.24 Each varenicline tablet is recommended to be taken with food or drink (a glass of water) to reduce nausea. The gradual titration is also done to reduce the incidence of nausea, which is the commonest side effect. The dose may be lowered temporarily or permanently to 0.5 mg twice daily in patients who cannot tolerate the adverse effects of varenicline. Other reported adverse events are abnormal dreams, insomnia and headache.24 The rare side effects reported were changes in taste, vomiting, abdominal pain, flatulence and constipation. Drowsiness is a listed adverse reaction, thus primary care professionals who prescribe varenicline should warn patients who drive or operate machinery. Most of the side effects of varenicline are mild and can be treated with symptomatic medication.24,25

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