Opioids: Pharmacokinetics and Pharmacodynamics

Opiates have been used for pain control for several thousands of years, dating back to the times of the ancient Sumerians. The Sumerians documented poppy in their pharmacopoeia and called it “HU GIL,” the plant of joy (Benedetti 1987). In the third century bc, Theophrastus has the first documented reference to poppy juice (Macht 1915). The word opium is derived from the Greek name for juice obtained from the poppy, Papaver, and the Latin name for sleep inducing, somniferum. Arab traders brought opium to the Orient, where it was used to treat the symptoms of dysentery. Opium contains approximately 20 distinct naturally occurring alkaloids, called opiates, such as morphine or codeine. In 1805, a German pharmacist Sertuner isolated a pure substance in opium and called it morphine. Morphine is named after Morpheus, the Greek god of dreams. After this initial discovery, many more opium alkaloids were discovered. Robiquet isolated codeine in 1832, and Merck isolated papaverine in 1848. In 1898, Bayer Pharmaceuticals launched an alternative to opium and morphine, diacetylmorphine or heroin, from the German word for hero. By the middle of the nineteenth century, pure opium alkaloids, rather than basic opium preparations, spread throughout the medical community. Until the early twentieth century, opioid abuse in the United States increased because of unrestricted availability of opium along with a massive influx of opium-smoking immigrants from the Orient. In fact, Thomas Jefferson grew opium poppies at Monticello. In 1942, the Opium Poppy Control Act banned opium production in the United States (Booth 1999). It is important to differentiate “opioids,” which are substances that act on the opiate receptor, and the term “narcotic,” which is a substance that produces narcosis and can be abused, such as cocaine, cannabis, and barbiturates (Reisine 1996). Narcotics are derived from the Greek word for stupor. Narcotics were initially used for sleeping aid medications rather than for opiates. Narcotic is now a legal term for drugs that are abused. In 2007, 93% of the opiates on the world market originated in Afghanistan (United Nations Office on Drugs and Crime 2007). This amounts to an annual export value of about $64 billion.