**1. Introduction**

Today, the term "human sexual behavior" sounds familiar and is so widely used that it may be hard to imagine a time when it was unknown (Haeberle, 1981; 1983). However, the realization that people have always done certain things does not necessarily allow us to conclude that they have always thought of them the same way.

Linguists also know that seemingly simple words often have no exact equivalents in other languages and that, as the years go by, they may very well change their meaning (Haeberle, 1981; 1983).

Obviously, the distinction between physical and psychological causes of sexual inadequacy is, to a certain extent, arbitrary, since body and mind are so closely interrelated that a sharp dividing line between them cannot be drawn. Some men and women are restricted in their sexual expression by physical malformations, handicaps, diseases, or injuries.

However, there are also physically healthy individuals who cannot fully enjoy sexual intercourse because their sexual responses have become weakened, inhibited, or even completely blocked for psychological reasons. Today, such a person is usually said to suffer from "sexual inadequacy" or "sexual dysfunction" (Haeberle, 1981; 1983).

Very few people enjoy perfect health throughout their lives. Sooner or later, most of us find ourselves in need of medical attention, if only temporarily. Of course, many of the serious diseases that plague and cripple mankind also have a damaging effect on sexual abilities. Certain illnesses can affect a person's responses or weaken the body to a point where sexual intercourse becomes difficult or impossible.

Usually in such cases, the sexual difficulties are only the by-product of a general infirmity and therefore receive only minor attention (Haeberle, 1981; 1983).

There are, however, certain physical disorders and diseases that affect human sexual activity and procreation directly, such as for example addiction.

Opioid maintenance treatment is the most widespread and well-researched treatment modality for opioid dependence (Giacomuzzi, 2008; 2011; Brown & Zueldorff 2007). Methadone, slow-release oral morphine and buprenorphine are currently the most commonly used pharmacotherapeutic agents.

Maintenance Therapy and Sexual Behavior 23

The traditional distinction between addiction and habituation centers on the ability of a drug to produce tolerance and physical dependence. Tolerance is a physiological phenomenon that requires the individual to use more and more of the drug in repeated

Physical dependence manifests itself through the signs and symptoms of abstinence when the drug is withdrawn. A classic feature of physical dependence is the abstinence or withdrawal syndrome. If the addict is abruptly deprived of a drug upon which the body has physical dependence, there will ensue a set of reactions, the intensity of which will depend

Physical dependence and tolerance are normal physiological consequences of extended opioid therapy for pain and should not be considered addiction (American Academy of Pain

Addiction is currently also defined as a form of behavior through which an individual has impaired control with harmful consequences. Thus, individuals who recognize that their behavior is harming them or those they care about find themselves unable to stop engaging

The severity of the medical, psychological and social harm that can be caused by addiction, together with the fact that it violates the individual's freedom of choice, means that it is

A very commonly used reference text from the American Psychiatric Association – the Diagnostic and Statistical Manual of Mental Disorders – does not use the term addiction at all; rather, it uses substance dependence. And, to be more precise, the particular drug

Although other forms of treatment for opioid dependence continue to be explored, methadone maintenance treatment remains the most widely used form of treatment for

Methadone maintenance treatment is a key component of a comprehensive treatment and prevention strategy to address opioid dependence and its consequences (Giacomuzzi et al.,

Methadone was originally developed in Germany as a substitute analgesic for morphine. World War II brought the formula to the attention of North American researchers, who subsequently discovered that methadone could be used to treat heroin withdrawal symptoms in 1964 as a medical response to the post-World War II heroin epidemic in New

The principal effects of methadone maintenance are to relieve narcotic craving, suppress the abstinence syndrome, and block the euphoric effects associated with heroin. Methadone works by alleviating the symptoms of opioid withdrawal. A stable and sufficient blood level

Since methadone is a much longer acting drug than some other opioids, such as heroin, one oral dose daily prevents the onset of opioid withdrawal symptoms - including anxiety, restlessness, runny nose, tearing, nausea and vomiting - for 24 hours or longer. Methadone diminishes the euphoric effects of other opioids (cross tolerance), without necessarily

This means that self-administered illicit opioids will not lead to euphoria, making it less likely that clients/patients will either use illicit opioids or overdose (Giacomuzzi, 2008). Methadone maintenance treatment has been demonstrated to be an effective treatment for opioid addiction and curbs the incidence thereof. Although methadone maintenance

Medicine and the American Pain Society, 1997; Commission of Public Records, 2003).

on the amount and length of time that the drug has been used.

in the behavior when they try to do so (Giacomuzzi, 2008).

appropriate to consider it to be a disorder of motivation.

of methadone stems the chronic craving for opioids.

causing euphoria, sedation or analgesia.

people who are dependent on opioids.

York City (Giacomuzzi, 2008).

2003; 2008; 2009).

involved is specified: e.g., heroin dependence, alcohol dependence, etc.

efforts to achieve the same effect.

Maintenance treatment has become a major intervention in the care and treatment of drug dependence in Europe. But still little is known about sexual behavior and sexual dysfunction especially under maintenance treatment.

A greater understanding of sexual behaviour in different maintenance treatment contexts has important consequences for the design and evaluation of substitution programs in opioid therapy.

Sexual dysfunction has been reported as an adverse effect of opioids including methadone and buprenorphine maintenance treatment.

In recognition of this, this chapter also aims to present specific problems and facts regarding this issue. Furthermore, the chapter presents own results regarding sexual behaviour and dysfunction prevalence within maintenance treatment. This chapter therefore provides some basic information about the main physical illnesses and impairments which can interfere with human sexual functioning regarding addiction.
