Medical Drug Abuse

Although medicines have been misused for as long as they have been available, a universally accepted definition of the term "drug abuse" does not exist. Broadly, drug abuse can include any failure to comply with the prescribing physician's orders, eg, forgetting to take medication or taking less or more than directed. Commonly, however, the term "drug abuse" denotes the self-administration of psychoactive substances in a deliberate attempt to alter mood, perception, thought and behaviour. In addition to the illicit drugs, several classes of prescription medications affect brain function in this manner. If a psychoactive substance produces effects perceived as beneficial (either as a pleasurable sensation or as relief from a state of depression or anxiety) the user may take the drug repeatedly. The cycle of administration and reward may become so well established in some users that they become psychologically and possibly physically dependent on the drug, and other more constructive methods of coping with problems become less important.

Social problems, family breakdowns and unemployment may result (although it is true that such problems may have initially encouraged the use of mood-altering drugs). Medical complications are also common; individuals develop a "tolerance" for the drug, ie, as the body adapts to the presence of the substance and the desired effect decreases in intensity, users compensate by increasing the dosage, thus also increasing the risk of dangerous side effects (eg, barbiturate-induced cessation of breathing). When administration is discontinued suddenly, the body continues to compensate for the drug; with many drugs, this unmasked compensation causes withdrawal symptoms, which are usually opposite to the initial effects of the drug. For example, withdrawal from sedatives is characterized by signs of hyperexcitable nerve cells (anxiety, tremors and, in severe cases, seizures and hallucinations) while withdrawal from stimulants is characterized by lethargy and mood depression.

The psychoactive prescription drugs subject to abuse can be categorized as opioid analgesics, sedative-hypnotics and stimulants. Other drugs used in PSYCHIATRY, such as the antipsychotic tranquillizers, the antidepressants and lithium, produce effects that normal individuals find unpleasant and they are therefore seldom used for nonmedical reasons. However, they are not always taken as directed, and their misuse can cause untoward effects.

Opioid analgesics (sometimes termed narcotic analgesics) are either derived from the opium poppy or manufactured synthetically. They include heroin, morphine, methadone, meperidine and codeine. They are used medically primarily for the relief of pain, although they are also employed to suppress a cough, and occasionally in the treatment of severe diarrhea. Their dependence liability is generally high, and for this reason, their distribution and sale is strictly controlled. Over the past 10 years, nonmedical users of prescription opioids in Canada have increased so greatly in number that they outnumber street heroin users in some treatment populations and it has become difficult to make these drugs readily available to those who need them, while restricting their availability to illicit users. Users obtain drugs illegally by means of forged prescriptions, by thefts from pharmacies or by feigning the symptoms of a painful, difficult-to-diagnose disorder (eg, low back pain).

Favoured drugs include the analgesics meperidine (Demerol R), oxycodone (in the form of Percodan R) and codeine, and the cough suppressants hydromorphone and hydrocodone (in Dilaudid R and Novahistex DH R cough syrups, respectively). Unlike street heroin, prescription opioids are pure, and many are effective when taken by mouth. Oral use also eliminates the risks associated with injection. Those dependent on prescription opioids suffer the same side effects as heroin users and are treated in the same manner, ie, by methadone substitution or in drug-free therapeutic communities. Because of the high dependence liability of opioids, physicians are more reluctant to prescribe them for patients with chronic pain. Other nonpharmacological therapies are being explored. In terminally ill patients, effective and long-lasting pain relief is of primary importance and analgesics are not withheld unless the side effects become life threatening. After much public debate and discussion, the government has now allowed heroin to be legally administered to these patients. In practice, however, physicians almost always prescribe other potent analgesics instead.

The many prescription drugs that slow the activity of the central nervous system are called sedative-hypnotics. They include the barbiturates, general anesthetics, antianxiety tranquillizers (eg, benzodiazepines) and a number of nonbarbiturate sedatives. These substances are prescribed to relieve anxiety, to induce sleep, to prevent or treat epileptic seizures, or to produce surgical anesthesia. All can create dependence in some individuals.

The barbiturates have been used since the early 1900s. Although their dangers were universally recognized (severe respiratory depression, high-dependence liability and life-threatening withdrawal reactions), safer alternatives did not exist until recently. The number of prescriptions has decreased significantly, however, since the introduction of the benzodiazepines into Canada in the 1960s. The short-acting barbiturates such as secobarbital (Seconal R) are still used illicitly, since they take effect quickly and produce the most euphoria. They are often administered to enhance the effects of other sedative-hypnotics or to terminate the unpleasant effects of a long stimulant binge.

The benzodiazepines (13 different kinds were being sold in Canada by 1986) were originally thought to be unusually safe and to have a very low dependence liability. For this reason they are heavily prescribed both for treatment of anxiety - eg, diazepam (in Canada sold under 8 trade names, including Valium R, and generically by 4 companies), chlordiazepoxide (Librium R), oxazepam (Serax R) - and for induction of sleep, eg, flurazepam (Dalmane R) and triazolam (Halcion R). Physicians agree that these drugs are safe for short-term uses (ie, less than 4 weeks), but the value of long-term drug therapy is questionable. When long-term administration of tranquillizers is stopped, the original symptoms of anxiety often reappear. This state may be temporarily enhanced by the emergence of withdrawal symptoms, which are generally less severe than those induced by barbiturates or alcohol, but can still motivate the individual to resume drug use. Some evidence suggests that the long-term use of these drugs can adversely affect memory and other aspects of brain function. Physicians are increasingly reluctant to prescribe benzodiazepines for longer than a month without supervision.

In Canada, as elsewhere, they are prescribed to women about twice as frequently as to men, and to the elderly much more often than to the young (see WOMEN AND HEALTH). Those suffering from chronic diseases are also likely to receive these medications. These imbalances have generated considerable discussion about prescribing practices, particularly among those who feel that tranquillizers are being prescribed to women for problems that could be best handled by more constructive means. Although Canadian data suggest that the great majority of benzodiazepine users (90-95%) take their medication as prescribed, given the large number of prescriptions, the remaining 5% constitute a significant number of individuals, some of whom require medical assistance to stop use. Benzodiazepines (especially diazepam) are sometimes used nonmedically, often to enhance the effects of other psychoactive drugs including alcohol.

The nonbarbiturate sedative-hypnotics offer few therapeutic advantages over the benzodiazepines. Of these, methaqualone has been the most heavily abused, although the problem does not appear to be as severe in Canada as elsewhere. This drug is no longer manufactured legally in the US, although small amounts are still made in Canada. The licit supply available for diversion of this drug to the street has decreased, but illicit consumption of other drugs of this class may increase as a consequence.

The term "stimulants" refers to a broad category of agents that includes the amphetamines and related drugs, as well as cocaine, caffeine and nicotine. The amphetamines were formerly prescribed for several disorders such as obesity, mood depression and lethargy. However, their ability to produce profound stimulation and euphoria led to epidemics of use in Japan, Sweden, the US and other countries.

Because of their high dependence liability and their ineffectiveness as long-term appetite suppressants, their use as "diet pills" was strictly curtailed in Canada in 1972. The prescribing of amphetamine and methylphenidate (Ritalin R) was limited to a few disorders that included the treatment of hyperactive children and of narcolepsy. The use of some drugs (eg, phenmetrazine) was discontinued altogether, and other less potent appetite suppressants such as diethylpropion (Tenuate R) were reclassified as controlled drugs under the Food and Drugs Act. Since the mid-1970s there has been a significant drop in the abuse of both licitly manufactured amphetamines and illegally synthesized methamphetamine. However, the consumption of illicit cocaine and of over-the-counter mild stimulants (such as ephedrine, phenylpropanolamine, caffeine and propylhexedrine), which are sold as decongestants and "wake-up" preparations, has risen. All of these drugs, when taken in sufficient quantities, can produce toxic side effects.