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Heroin and morphine are opiates, substances that resemble the body's natural pain-fighting substances: endorphins. Endorphins are secreted into the bloodstream naturally during times of stress. They reduce physical and psychological pain and may produce a diffuse feeling that all is well.

What does heroin resemble? Is it immediately pleasurable?

The first time a person takes heroin, it may not even be pleasurable. Beecher (1959) gave non-addicted subjects injections of heroin or a harmless placebo. The subjects preferred the placebo.

Sandoz (1922) made these comments about morphine, a derivative of heroin:

The widely spread belief that morphine brings about an uncanny mental condition, accompanied by fantastic ideas, dreams, and whatnot, is wrong...

The most striking thing about morphine, taken in ordinary doses by one who is not an addict, is that it dulls general sensibility, allays or suppresses pain or discomfort, physical or mental, whatever its origin, and that disagreeable sensations of any kind, including unpleasurable states of mind are done away with. In fact, the suppression of pain is the only outstanding effect of morphine...

The more normal a person feels, the less marked...the effects will be. (p.12)

What did Sandoz call the "most striking thing" about morphine effects?

Although Sandoz did not find the effects of morphine irresistible, some people (especially those in chronic pain, physical or psych­ological) immediately want to repeat the experience. That is why heroin has one of the highest capture ratios of any drug.

As with other drugs, a user may experience, at first, a "honeymoon" phase during which the drug is highly enjoyable. The honeymoon ends when the body adjusts to the drug. Soon the addict requires larger doses to get a smaller high.

In the end, a hard-core user feels little euphoria at all from taking the drug but–as with cocaine and methamphet­amine–must have it to feel normal. Sandoz gives this description:

The same dose will become less and less effective, or must be increased in order to obtain the same effect. More than this, the original feeling of unusual well-being can no longer be obtained; under the influence of morphine the chronic user will simply feel "normal." (Sandoz, 1922, p.13)

How did the chronic user of morphine feel?

Why does the addict require progres­sively higher doses? The body adapts to constant presence of the drug and learns to combat it with natural opioid antagonists –chemicals that reduce the effects of opioids.

If opioids are constantly added to the body, the body starts producing antagonists in large amounts, neutralizing the effect of the drug. However, this also means the addict will feel great pain if he or she stops taking the drug.

In the phenomenon known as opioid-induced hyperalgesia, chronic opioid use greatly reduces a person's tolerance of pain. This was discussed on the page about transmitters in Chapter Two.

Opioid antagonists also explain why dependence is greatest just when enjoyment starts to fade. Both tolerance and dependence result from high levels of opioid antagonists produced in the body, generated by long-term exposure to opioids. At that point, if a person tries to quit, the result is great pain.

Nitrous Oxide and Inhalants

Some dentists use nitrous oxide or "laughing gas" as an anesthetic. (It is not the same as nitric oxide, the gas which functions as a transmitter, described in Chapter 2.) Mixed with oxygen, nitrous oxide induces a state of altered aware­ness in which pain is diminished or ignored.

At the transmitter level, nitrous oxide shares its drug action with opiates. Naloxone, an opioid antagonist (the drug emergency medical personnel use to save the lives of opioid overdose victims) also eliminates the anesthetic effects of nitrous oxide.

Chronic exposure to morphine, which builds up tolerance to opioids, also builds up tolerance to nitrous oxide. This effect where exposure to one drug produces tolerance for another drug is called cross-tolerance. It is evidence for an underlying chemical relationship between drugs.

What is nitrous oxide? What is cross-tolerance, and what does it demonstrate about nitrous oxide?

Overdoses of nitrous oxide can be fatal. One news report told how containers of nitrous oxide were stolen from a hosp­ital. They turned up at a party where three people died by breathing concen­trated nitrous oxide without oxygen.

A container diverted from legitimate medical use contains pure nitrous oxide, intended for mixing with oxygen. Breathing nitrous oxide directly from a tank will smother the user.

A drug of abuse with effects similar to nitrous oxide is amyl nitrate or "poppers." Once sold in small bottles masquerading as room deodorizers, these drugs were popular in the disco scene and gay culture starting in the 1970s and up to the present.

Amyl nitrate dilates blood vessels and can be prescribed to relieve angina (heart pain) in people with narrowed arteries. The psych­ological effect is similar to lightness in the head produced by standing up quickly, because vasodilation leads to a drop in blood pressure.

Like many depressants, amyl nitrate may interact strongly with alcohol and is often classified as dangerous for that reason. Overdoses are unlikely unless liquid amyl nitrate is accidentally ingested or aspirated.

Inhalants used for "huffing" (breathing fumes from a rag) or "bagging" (from a bag) include glue, nail polish remover, cleaning fluid, and gasoline. Huffing can produce harmful effects such as cardiac dysrhythmia, seizures, liver and kidney damage, and–over the long term–permanent brain damage.

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