Primary care is a significant point of contact for drug users who require treatment and many patients see this route of care as being readily accessible and less stigmatising than traditional specialist addiction services. Research shows that patients prefer care from a competent general practitioner (GP) rather than from other professionals.

In the UK, government policy has promoted GPs as an important facet of modern healthcare for these patients and, indeed, the past two decades are littered with policy documents, health service circulars and government strategies laying the foundations for effective primary care involvement in a primary-care-led National Health Service (NHS). To a large degree, GPs have responded to the challenge and collectively are undoubtedly the backbone of drug misuse treatment services, including the provision of substitute medication.

Who uses drugs and why

The use of illicit drugs, such as cocaine, heroin, ecstasy and cannabis, is prevalent in every part of society and across all socio-economic groups. Use of illicit substances is, in the most part, transient and part of the adolescent stage of development. The factors that predict why an individual goes from experimental to problematic use are complex and are the result of the interplay between social, environmental and individual factors (Box 17.1).

Drug misuse or drug use is not the same as dependence. Dependence is a specific psychological state in which drug use takes an overriding importance in people's lives and when they do not have the drug, they crave it. Dependence is characterised by (World Health Organization, 1992):

1. •compulsion to use

2. •difficulty in controlling use (e.g. alcohol dependence is characterised by an inability to moderate drinking)

3. •a withdrawal state on cessation of use

4. •evidence of tolerance (i.e. requiring increasing amounts of the drug to produce the same effect)

5. •progressive neglect of other activity because of substance use

6. •persisting with use despite evidence that use is becoming or has become harmful.

Problem drug use is defined as injecting drug use or long duration/regular use of opiates, cocaine and/or amphetamines. Although small in terms of overall numbers, problem drug users are responsible for a disproportionate share of the health and social problems resulting from drug consumption. In the UK, problem drug use is characterised by the use of heroin, often in combination with other drugs.