The use of drugs such as morphine, heroin, cocaine, marihauna, LSD, and amphetamines as aphrodisiacs has become somewhat prevalent in contemporary society, and there is little doubt that these agents can, under certain circumstances, seem to enhance the enjoyment of the sexual experience for some. More commonly, however, there is a decrease in sexual behavior for those who try them. The reason for such variation in responsiveness is that these agents have no particular properties that specifically increase sexual potency but rather tend to affect the user according to the particular circumstances under which they are used. Thus the state of mind of the individual user and the amount consumed contribute considerably to the effect achieved. Like alcohol, these drugs act on the central nervous system to release inhibitions, which are often the cause of problems involving sexual behavior. Taken in excess or too often, however, these drugs, like alcohol, will have the opposite response and will inhibit sexual drive and function.

The search for substances that increase sexual potency or drive has existed almost as long as civilization itself. Inscriptions found in the ruins of ancient cultures have described the preparation of "erotic potions," and an endless number of "aphrodisiacs" have been described since then to modern times? In contemporary society, the continuous proliferation of drugs and chemicals that modify mood and behavior has enhanced the claim that many such drugs have aphrodisiac properties, and more and more agents are considered by some to fulfill this purpose.

In recent years it has been observed that sex hormones may act on parts of the central nervous system and other organs of the body to influence sexual and aggressive behavior, as well as mood and emotional outlook. Thus variations in female hormones may produce anxiety, irritability and depression, whereas male hormones are associated with aggression and increased sexual interest. Currently, there is growing evidence that the sexual drives of both men and women may be influenced by treatment with sex hormones. In one study, male hormones prescribed to women were shown to increase sexual interest and enjoyment, whereas male patients treated with the female hormone estrogen almost always experienced a decrease or cessation of libido.

Ethyl alcohol deserves to be considered for its effects on human sexual function and behavior as a drug of individual and unique notoriety. Revered for centuries as a sexual stimulant and cure of all ills, alcohol is, in fact, a depressant and is recognized today to have far greater social than therapeutic value. Its use as a social amenity has become widely accepted in contemporary society. Although a sedative, alcohol in moderate amounts may help to enhance sexual activity by relieving anxieties and loosening the inhibitions that often shroud sexual behavior. Beyond a certain limit, however, neither desire nor virility will overcome the depression of physical capability that occurs under its influence.

Histamine is a naturally occurring substance that possesses a variety of physiologic properties, including smooth muscle stimulation, mediation of the inflammatory response, and cardiovascular effects. Antihistaminic drugs act as competitive inhibitors of histamine at physiologic receptor cites and prevent its action. Well-known examples of such drugs include diphenhydramine (Benadryl), promethazine (Phenergan), and chlorpheniramine (Chlor-Trimeton). These drugs are annually consumed by millions for use as antiemetics, as mild sedatives, and for the control of allergy and cold symptoms. Most antihistamines display anticholinergic effects such as dryness of the mouth, urinary retention, and constipation. Continuous use of these drugs may result in interference with sexual activity. This effect is presumably mediated by means of the blockade of parasympathetic nerve impulses to the sex glands and organs.

Depression is considered to include emotional disorders ranging from mild despondency without somatic manifestations to severely retarded states and suicidal risks. In our increasingly complex society, characterized by increased demands on both time and ability as a way of life, depression and its manifestations are becoming more and more common. Depression is usually accompanied by decreased sexual drive, interest, and activity.

Some drugs have been successfully utilized in the treatment of high blood pressure because of the vasodilation they produce by means of blockade of the sympathetic nervous system. Such adrenergic inhibition, however, occasionally results in impotence and concomitant decrease in sexual function. Guanethidine (Ismelin) and reserpine (Serpasil), which act partially by depleting the adrenergic nerve transmitter Norepinephrine, originating from nerve endings, or by blocking release of the transmitter from the nerve terminal, may produce impotence by inactivation of the nervous mechanisms responsible for sexual function.

Drugs that have an adverse effect on sexual function and activity may do so either through an overall depressive effect on the central nervous system or through a somewhat more specific action on a portion of the autonomic nervous system that affects sexual function, or both. Male potency, in particular, seems to be susceptible to the effects of drugs that interact with the autonomic nervous system. In this section we shall investigate some of these drugs, which comprise a surprisingly large variety of clinically administered and prescribed agents in use today.

The past few decades have seen a tremendous alteration in traditional attitudes regarding many aspects of the human experience. Prevalent among these changes are new approaches to sexual behavior and drug usage. Recent advances in social technology and biomedical research have permitted and encouraged both a higher level of understanding and deeper experimentation into many heretofore unanswered questions about human sexuality. In a society characterized by an increased awareness of sexual function and the widespread availability, utilization, and even abuse of drugs that modify every facet of human behavior, it is important to consider the effects of drugs on human sexual function and activity. The purpose of this chapter is to consider recent developments from biomedical and clinical research, as well as some of the more traditional conceptions and misconceptions regarding the effects of drugs on sexual behavior in humans.

Intervention falls within the realm of sex education and counseling. Basic to understanding sexual function after traumatic paraplegia is comprehension of the normal human sexual response. It may be necessary to review the patient's understanding of healthy sexual function before beginning counseling.

Counseling is directed toward maximizing the patient's gratification as well as that of the partner. Conjoint counseling with both the man and woman is advisable if their relationship is a permanent one. It is especially important for future spouses, since adaptation in one's approach to achieving sexual gratification may have far-reaching implications for the sex partner.