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Part 3: The health and social consequences of drug abuse Contents INTRODUCTION The principal characteristics of the drugs covered by this report are their potential for altering mood and behaviour and for creating dependence. Although many of them have considerable therapeutic value, they are also widely misused, thereby creating a series of adverse consequences for society. The aim of this chapter is to examine the different kinds of drug which are abused and to consider their impact on the individual and the community.* Nerve cells in the brain communicate with each other by means of naturally produced chemicals known as neurotransmitters. A cell releases a neurotransmitter into the space between nerve endings known as the synapse; the molecules are then picked up by receptor proteins on the surface of the second cell. In the normal course of its activities the brain releases and absorbs neurotransmitters such as dopamine, norepinephrine and serotonin. Many drugs, including those with addictive potential, work by imitating or releasing these neurotransmitters or by blocking their actions. Blocking drugs, which occupy drug receptor sites in the brain and bind to them, are known as antagonists, while imitating drugs are known as agonists. The existence of different pathways in the brain means there are many different types of neurotransmitter and many different kinds of receptor, and the type of effect a drug produces depends on the type of neurotransmitter it reacts with. Cocaine, for example, blocks the brain’s ability to reabsorb dopamine, with the result that the neurotransmitters remain trapped in the synapse, stimulating the receptors over and over again. Prolonged stimulation causes the reward, or pleasure associated with the drug. The greater the reward, the greater is the inclination to repeat the experience. In laboratory studies the dependence potential of a drug can be measured by how long and hard an animal will work to maintain supplies. In human beings, physical dependence is characterized by drug-specific withdrawal symptoms and ‘craving’ – a slavish urge to find and consume more of the drug. This condition is both psychological and physiological, but has a biochemical explanation: the body’s ability to reproduce chemicals naturally becomes depleted by artificial chemical stimulation, causing a deficiency when the drug is no longer available. Tolerance occurs when repeated use of a drug requires the consumer to increase dosage in order to experience the same “high”. Cross tolerance exists within a specific drug type, for example the synthetic opiate methadone shows cross tolerance with morphine, while reverse tolerance implies an increased responsiveness as a result of past consumption. The shortest time that must elapse before repetition of the dose has a similar effect to the one before is called the critical interval. Cocaine is chemically processed or metabolized much faster than heroin and therefore has a much shorter critical interval. The health consequences of psychoactive drug use depend on the interaction of two sets of variables, namely the characteristics of the drug and those of the consumer. The former include • pharmacological properties; • route of administration, i.e. oral ingestion, snorting, inhalation, injection (subcutaneous, intravenous or intramuscular); • whether it is taken alone or together with other drugs or alcohol; • level of purity and presence of adulterants; • dosage level. The latter include • personality of the user; • intensity or frequency of previous use; • user’s pre-existing state of health; • social and economic circumstances of the user; • the user’s expectations of the drug’s effects (see Part 2). The existence of so many variables means that the effects of drugs can differ widely from one * The authors acknowledge a debt throughout this chapter to UNDCP, The Social Impact of Drug Abuse, a Position Paper for the World Summit for Social Development (UNDCP/TS.2, Vienna, 1996). Contents 71 individual to another. Some people may suffer no serious side effects from a single experiment with drugs while for others it may be the beginning of a illicit drug use is that the consumer – the last buyer in what may be a long chain of distribution – is rarely able to verify the dosage or the purity of the purchase. The absence of quality control and the furtive conditions in which drugs are Drugs can alter mood and behaviour dealt and consumed may result in acute poisoning – heroin may be diluted with and create dependence. Consequences strychnine or supplied in an excessively pure of their use depend on characteristics dose leading to death; gullible youngsters buying drugs at a ‘rave’ party can have no of both drug and consumer. idea of what chemical cocktail is about to bombard their brains. lifetime addiction. Even a single experience can provoke an acute toxic reaction, while chronic Drug types are described in various ways, dependeffects come from the body’s response to regular, ing on origin and effect. They can either be long-term abuse. Either pattern of use can lead to naturally occurring, semi-synthetic (chemical dependence and to an impairment of the body’s manipulations of substances extracted from natural organs or its functions, or both. Unsupervised drug materials) or synthetic (created entirely by laboruse may also have secondary effects in that it may atory manipulation). The principal categories are as conceal or delay recognition of genuine illnesses follows: requiring treatment. 1. Opiates: the generic name given to a group Estimates of morbidity and mortality are used to which includes naturally occurring drugs derived gauge the consequences of acute and chronic drug from the opium poppy (Papaver somniferum) such abuse. Morbidity indicators help us to underas opium, morphine and codeine, semi-synthetic stand the association of drugs with illness and substances such as heroin (the foregoing are opidisease by providing information on the numbers ates in the strictly correct definition); and opioids and frequency of treatment requests, drug-related – ‘opiate-like’, wholly synthetic products such as emergency room incidents at public hospitals, hosmethadone, pethidine and fentanyl. Opiates pitalizations and prevalence of communicable depress the central nervous system and are used diseases relating to drug use. Mortality data tell us therapeutically as analgesics (painkillers), as cough how many deaths are directly linked to the use of suppressants and against diarrhoea; in non-medical psychoactive drugs. Together these give us an estusage as euphoriants and as a means of reducing imate of harmfulness. anxiety, boredom, physical or emotional pain. Heroin is often the opiate preferred by consumers The term overdose is often applied in the case of because it is relatively potent, easily dissolved in drug-related mortality but in many cases death (or water for injecting and penetrates the blood-brain barrier more quickly than morphine. Effects may last from 4 – 6 hours. Heroin can also A single experience can provoke an acute be snorted, smoked or inhaled by the method known as ‘chasing the dragon’ toxic reaction, chronic effects come from whereby it is heated on foil and the fumes long-term abuse. inhaled. The effects of methadone, which is usually taken orally, may last up to 24 hours. acute illness) may not be due to an excessive quantity of the drug but to an interaction with other It can happen that opiate dependence brings few psychoactive substances or with adulterants used physical complications other than constipation, but by retailers to bulk out the dosage units. These such cases are rare; studies of British heroin addicts impurities may do as much, if not more, harm than in the 1960s showed that even when maintained the drug itself. An important factor underlying all on medically prescribed ‘clean’ heroin and supplied 72 Contents