Drug Dependence versus Abuse

 

Drug Dependence versus Abuse

Drug dependence differs from drug abuse in three ways. First, drug dependence consists of clearly measurable periods of tolerance and withdrawal, whereas drug abuse sets the occasion for tolerance and withdrawal. Abuse means there exist early warning signs of life impairment predictive of physical and psychological dependence. Adults arrested for driving under the influence of alcohol, for instance, often face fears that their uncontrolled drinking may result in fatal vehicular accidents. Second, drug-dependent users show marked cognitive, behavioral, and psychomotor retardation in their daily activities.

 

Drug abusers, however, may or may not suffer apparent cognitive, behavioral, or psychomotor malfunctioning; they may mask intoxication symptoms by performing their jobs and vehicular operations adequately and interacting normally with their families. Third, the phenomenon of withdrawal syndrome applies only to drug dependence.

 

Drug abusers are episodic and not routine users, and their consumptive rates are variable; intermittent and lesser quantity users build resistance to adverse cognitive and visceral repercussions and only suffer mild or no side effects after abrupt cessation of desired substances.

 

Types of drug dependence

 

Dependence on a drug means that your body has become so used to having that drug regularly that you need that particular drug to function normally, and if it were stopped you would feel unwell. People who have drug dependence may have psychological dependence and/or physical dependence and/or tolerance to a particular drug.

Psychological dependence

Psychological dependence means that you have a craving or are compelled to use a particular drug to give you pleasure or to stop you from feeling bad – even though it may be dangerous to take the drug.

 

Psychiatric co-morbidity

A critical aspect of the effective treatment of substance use disorders is to identify and treat psychiatric co-morbid disorders. Some co-morbid psychiatric problems are more common in women:

 

·        Bipolar disorder

·        Panic disorder

·         PTSD

·        Cluster B personality disorders

·        Bulimia

·        Depression

 

In addition, genetic markers have been identified with a number of psychiatric disorders in which there is a higher incidence of substance use they include:

 

·        Low P3 amplitude (schizophrenia, ADHD)

·        Conduct disorder (CD)

·        personality (ASPD)

·        Decrease in dopamine receptor (D2)

·        Serotonin (5-HT) systems

 

Pharmacologic treatment of these disorders enhances recovery from substance use and also poses additional problems for the fetus including need for treatment of the neonate in special intensive care units for symptoms of withdrawal. This is especially true for benzodiazepines, which have a higher rate of teratogenicity and withdrawal, especially when combined with alcohol. Risks and benefits of pharmacologic treatment are most important when treating co-morbidity in pregnancy.

 

Physical dependence

Physical dependence means that if the drug is stopped suddenly you get withdrawal symptoms.

 

 

 

Physical Dependence

 

Physical dependence is not addiction (and the terms should not be used interchangeably). Physical dependence is a pharmacologic effect characteristic of a number of different types of medications. Physical dependence is defined as the occurrence of an abstinence syndrome (withdrawal reaction) following abrupt discontinuation of the drug, substantial dose reduction, or administration of an antagonist. Physical dependence is generally assumed to occur with regular opioid use for as brief a period as a few days.

Opioid withdrawal is manifested by significant somatomotor and autonomic outflow (reflected by agitation, hyperalgesia, hyperthermia, hypertension, diarrhea, pupillary dilation, and release of virtually all pituitary and adrenomedullary hormones) and by affective symptoms (dysphoria, anxiety, and depression).Opioid withdrawal can be minimized by slowly tapering the opioid. These phenomena are considered to be highly aversive and motivate the drug recipient to make robust efforts to avoid the withdrawal state. Initially, drug addicts are driven to repeated doses of opioids because of the euphoric effects. However, with time, the euphoric effects are lessened, and addicts are driven to continue use to avoid withdrawal.

 

Tolerance

Tolerance is usually a part of dependence. It means that you need more and more of the same drug to give you the same feeling as the smaller amount you used when you first started taking that drug.

Examples of some drugs that cause dependence include nicotine, morphine, heroin (also known as diamorphine), cocaine, amfetamine and alcohol. Some people can also become dependent on medicines that are on prescription. Examples are:

• Z drugs (called this because they begin with the letter Z: zopiclone, zolpidem and zaleplon).
• Benzodiazepines (for example, lorazepam, lormetazepam, diazepam)
• Codeine
• Opioids (such as morphine)
• Other medicines that can be bought from pharmacies – for example, over-the-counter painkillers

 

Tolerance

A person may develop tolerance to a drug when the drug is used repeatedly. For instance, when morphine or alcohol is used for a long time, larger and larger doses must be taken to produce the same effect. Usually, tolerance develops because metabolism of the drug speeds up (often because the liver enzymes involved in metabolizing drugs become more active) and because the number of sites (cell receptors) that the drug attaches to or the strength of the bond (affinity) between the receptor and drug decreases.

 

Receptors on cells

On their surface, most cells have many different types of receptors. A receptor is a molecule with a specific three-dimensional structure, which allows only substances that fit precisely to attach to it—as a key fits in its lock.

Receptors enable natural (originating in the body) substances outside the cell to influence the activity of the cell. Examples of such substances include neurotransmitters (chemicals that conduct messages between cells in the nervous system) and hormones (chemicals released into the bloodstream by one organ to affect another organ). That influence may be to stimulate or inhibit a process inside the cell. Drugs tend to mimic these natural substances and thus use receptors in the same way.

 

For example, morphine and related pain-relieving drugs act on or affect the same receptors in the brain used by endorphins, which are substances produced by the body to help control pain.

Some drugs attach to only one type of receptor. Other drugs, like a master key, can attach to several types of receptors throughout the body. A drug’s selectivity can often be explained by how selectively it attaches to receptors.

 

 

 

Resistance

Strains of microorganisms (bacteria or viruses) are said to develop resistance when they are no longer killed or inhibited by the antibiotics and antiviral drugs that are usually effective against them (or, in practice, when significantly higher than normal doses are required to have an effect). Similarly, cancer cells may develop resistance to chemotherapy drugs.

 

Resistance appears because of the mutations that take place spontaneously in any group of growing microorganisms or cells, whether exposed to drugs or not. Most such mutations change the microorganism's or cell's structure or biochemical pathways in a way that is harmful to the microorganism or cell. But some mutations change the parts of the microorganism or cell that are affected by drugs, decreasing the drug's ability to work (that is, causing resistance).

 

Because such mutations are very rare, there are normally only a few such resistant microorganisms or cells in any group. However, if all or many of the “normal” microorganisms or cells are killed by a drug, a much higher proportion of the survivors are likely to be resistant. If the resistant survivors are not killed by the body's natural defenses, which is more likely when drugs are stopped too soon or not taken in the proper manner, they may reproduce and pass on the resistant trait to their descendants.

 

 

Prevention and treatment

To prevent the development of resistance, doctors try to use antibiotics only when necessary (not for viral infections such as a cold) and have people take them for a full course of treatment. In the treatment of certain serious infections, such as HIV, doctors usually give two or more different drugs at the same time because it is very unlikely that a cell would spontaneously be resistant to two drugs at the same time. However, giving one drug for a short time followed by another can produce resistance to multiple drugs. Multi-drug resistance has become a problem with tuberculosis in particular.

Once tolerance or resistance has developed to a drug, doctors may increase the dose or use a different drug.