Demerol is a narcotic analgesic (opiate pain medication) prescribed for short-term treatment of moderate to severe pain. Demerol acts on the central nervous system and smooth muscle tissue, slowing the central nervous system. Demerol is an effective pain reliever, narcotic analgesics have been associated with an increased risk of addiction when used improperly, or for too long. This is a very powerful class of drugs known as narcotics and Demerol is only available by prescription and its distribution is highly controlled. Often used in surgery, Demerol is used for its pain-relieving effects. Like heroin and morphine, Demerol attaches to opioid receptors found in the spinal column and brain to interfere with the transmission of pain. Demerol is available in a pill and in a syrup. It is prescribed for moderate to serious pain and reduces pain for up to 4 hours. Users of Demerol often feel euphoria as the drug triggers the brains pleasure centers as well as blocking pain. Never take Demerol in greater doses, or for a longer period of time, than recommended by your doctor. It is a drug that is available by prescription only.

Meperidine hydrochloride (Demerol) is an oral and parenteral opiate agonist. In foreign countries, it is known as pethidine. Demerol is not a natural opiate like morphine or codeine, but is a synthetic compound belonging to the phenylpiperidine class. Other members of this group include diphenoxylate and loperamide, agents commonly used to treat diarrhea, as well as the extremely potent analgesics fentanyl, alfentanil, and sufentanil. Demerol is recommended for relief of moderate to severe pain but also has the unique ability to interrupt postoperative shivering and shaking chills induced by amphotericin B. Demerol is metabolized to normeperidine, a compound capable of inducing seizures if it accumulates. Unlike morphine, which was in use long before the passage of the 1938 FD&C act, Demerol was first approved by the FDA and marketed in 1942. It is a schedule C-II controlled substance and is available in both oral and parenteral forms.

Despite being structurally distinct from morphine and related opiates, Demerol's effects on opiate receptors are similar to those of morphine; both are agonists at æ-and -receptors. Demerol alters the perception of pain in the spinal cord and CNS but has no effect on afferent nerve endings. Although the exact physiologic action of opiates is not known, stimulation of opiate receptors ultimately reduces neurotransmitter release. This effect is mediated by any or all of the following three mechanisms: changes in calcium ion mobilization; inhibition of adenylate cyclase; or changes in potassium ion conductance.

Respiration is depressed by a direct effect on the brain stem respiratory center, and the cough center is also suppressed by Demerol. Nausea and vomiting may be induced from direct stimulation of the chemoreceptor trigger zone. Opiate agonists increase smooth muscle tone, which can affect the intestinal, urinary, and biliary tracts. Digestion is delayed by a decrease in gastrointestinal secretions. Some references state that meperidine causes less biliary tract spasm than does morphine. Vasopressin output is stimulated, which can decrease urine output in conjunction with increased tone of the detrusor muscle. Miosis is another characteristic of the opioid analgesics. Compared with morphine, meperidine causes fewer of these effects.