Meperidine chemical structure

Figure 7.4 The chemical structure of meperidine, its analogue MPPP, and the closely related neurotoxin MPTP, are all shown here. Meperidine, an anesthetic, was also used as an alternative to morphine. It proved advantageous because it has a shorter length of duration and fewer side effects than morphine.

The gold standard of opiate pain relievers is morphine. It was one of the first compounds extracted, isolated, and purified from the opium poppy, and it continues to be one of the most widely used pain relievers today. Morphine and other opiate drugs such as heroin, codeine, oxycodone, and hydrocodone have very similar chemical structures (Figure 3.2). However, other opiates such as fentanyl and meperidine (Demerol) have a slightly different structure (Figure 3.3). 

In the year 1939, Schaumann first identified and recognized the presence of a quatemaiy-carbon-atom in the morphine molecule, whieh eventually formed an altogether new basis and opened up a new horizon in the field of drug design ofnareotie analgesics. Intensive research further led to the evolution of pethidine (meperidine) which incidentally combines both the properties of morphine and atropine. It possesses a quaternary carbon-atom and quite astonishingly a mueh simpler chemical structure to that of morphine. 

Although morphine and meperidine are quite similar in their clinical effects, they are not that similar in chemical composition. The important chemical determinant of an opioid analgesic, however, is not its structural resemblance to morphine, but its ability to bind with and activate an opioid receptor. 

Aluminum hydroxide is constipating but is not related chemically to meperidine magnesium hydroxide is a strong laxative. The two antidiarrheal drugs that are structurally related to opioids are diphenoxylate and loperamide. Loperamide is available over-the-counter diphenoxylate is mixed with atropine alkaloids, and the product (Lomotil, others) requires a prescription. The answer is (C). 

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