Academic journal article Indian Journal of Psychiatry

Pharmacotherapy of Smoking Cessation

Academic journal article Indian Journal of Psychiatry

Pharmacotherapy of Smoking Cessation

Article excerpt

Byline: R. Jiloha

Nicotine in tobacco smoke causes not only pathophysiological changes in the smoker's body, but also develops tolerance to its own action with repeated use. Repeated exposure to nicotine develops neuroadaptation of the receptors, resulting in tolerance to many of the effects of nicotine. Pharmacotherapies for smoking cessation should reduce withdrawal symptoms and block the reinforcing effects of nicotine without causing excessive adverse effects. All forms of nicotine replacement therapy (NRT) - gum, patches and inhaler - and bupropion are safe and effective for increasing smoking cessation rates in the short and long-term use. Combination NRT (more than one therapy) may be indicated in patients who have failed monotherapy.

Introduction

The ubiquity of tobacco smoking and its persistence in the face of vigorous proscriptions, despite the generally agreed health risks, is a remarkable phenomenon. Tobacco smoking is highly contextual and associated with certain rituals, which start with the opening of a packet of cigarettes or a bundle of beedi, followed by the lighting process and then the sight and smell of smoke. Tobacco smoking is one of the strangest of human behaviors. [sup][1] Why should world's one-third adult population perform an act which is necessary neither for the maintenance of life nor for the satisfaction of social, cultural or spiritual needs, an act which is acknowledged by the smokers to be harmful to health and even distasteful?

Basic Neurobiology of Smoking

From the incandescent tip of a lighted cigarette, burning at a temperature of 800[degrees]C, the smoker with each puff draws into his mouth a hot potpourri of gases and many sized particles. Of the 4000 chemicals identified in tobacco smoke, nicotine is the pharmacological agent of prime importance, which is highly toxic and potentially lethal alkaloid (1-methyl-2-[3-pyrodyl] pyrrolidine), responsible for a number of pathophysiological changes in the body. Nicotine remains dissolved in the moisture of the tobacco leaf as a water soluble salt, but in a burning cigarette it volatilizes and remains suspended on minute droplets of tar as free nicotine. These droplets, less than 1000 of a millimeter across, can reach the smallest alveoli in the lungs. About 90% of nicotine present in inhaled smoke is absorbed. [sup][2] Absorption leads to a marked increase in arterial nicotine level within 15 seconds. [sup][3] Blood nicotine levels rise very rapidly and peak at the time cigarette is extinguished and steep decline occurs until the next cigarette is smoked. [sup][4] This bolus of nicotine activates the brain-reward system by increasing dopamine release as it is a potent psycho-active drug. [sup][5] This brain reward system is a common pathway for pleasurable activities in most drugs of addiction. [sup][6] The euphoria induced serves as a re-inforcer for its use. This peak in plasma nicotine level and the transient activation of the reward system is followed by a gradual fall in nicotine levels into a state of withdrawal that is, in turn, relieved by the next cigarette. Nicotine meets the criteria for a highly addictive drug and a great majority of regular smokers are dependent on tobacco smoking and not simply addicted to nicotine. [sup][7] Dependence arises from the temporal association of the rituals and sensory inputs with the repeated stimulation and relief of withdrawal symptoms. [sup][2] This required association explains why nicotine replacement therapy (NRT) products, that deliver nicotine slowly and do not produce high plasma nicotine levels, have minimal addictive potential. [sup][8]

Cues to Smoking

Some people smoke when they work alone and others when they are in company. Cues, such as an ashtray, the sight of seeing the other person smoking etc., can elicit strong craving not only in newly abstained and current smokers, but also in individuals who have achieved long term abstinence. …

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