Codeine: Usage trends

Last modified: Thursday, 25. December 2008 - 10:23 am

The United States imports about 70% of the world’s opium. About 95% of that opium is consumed in the form of schedule III preparations, of which codeine is the most common. Until the mid-1970s, opium had been the main raw material used for the production of morphine and codeine. Since 1978, however, concentrate of poppy straw has been used with increasing frequency for that purpose. “Poppy straw” is a term used for the remainder of the poppy plant — but primarily refers to the seed capsule itself — once the seeds and opium-producing fluid have been removed. The majority of morphine and codeine production now comes from concentrate of poppy straw.

The concentrations of morphine and codeine in both raw opium and poppy straw vary greatly, but morphine concentrations as a percentage of total weight are typically about 10 times greater than are those of codeine. Therefore, processing of opium and poppy straw produces much more morphine than codeine. However, greater quantities of codeine than morphine are required for medical purposes. Based on the discrepancies between production and use of the two drugs, about 80% of morphine is converted into codeine.

The global manufacture of codeine underwent a 22% increase in the 1980s, from 162 tons (147,000 kg) in 1980, to 197 tons (180,000 kg) in 1989. The rate of production increased during the 1990s, with total codeine production reaching 280 tons (255,000 kg) in 1999. Overall, a 65% increase in global codeine production occurred in the 20 years between 1980 and 1999. Most codeine goes directly into medications, but some is also used to produce other opioid medications such as dihydrocodeine and hydrocodone. Actual figures for the number of codeine prescriptions written in the United States in any particular year are difficult to obtain, since less than half of all states track these numbers. Of all prescriptions written for opioid analgesics, about 15% are for codeine.

Scope and severity

Just as the medical use of codeine has increased, its misuse and abuse have also increased, although not in proportion. The issue of drug abuse can be analyzed from many different perspectives and categorized in a number of ways. One method is to compare and contrast the abuse of illegal drugs (marijuana, cocaine, etc.) with that of legal drugs (OTC and prescription medications). The majority of national and international attention and resources go toward illegal drug abuse. However, prescription drug abuse is a large and growing proportion of the complete drug abuse picture.

Each year, the National Household Survey on Drug Abuse (NHSDA), conducted by the Substance Abuse and Mental Health Services Administration (SAMHSA) of the United States Department of Health and Human Services, collects statistical data on five drug groups, including marijuana/hashish, psychotherapeutic drugs, cocaine/crack, hallucinogens, and inhalants. The medications included in the psychotherapeutic drug group are stimulants, sedatives, tranquilizers, and pain relievers. Codeine and other opioids constitute the majority of the pain relievers in the group.

In 2000, the NHSDA found 1.7% of all people 12 years and older reported nonmedical use of a psychotherapeutic medication during the previous month. More than 9 million Americans over age 12 reported use at any time during the year. Those in the 18- to 25-year-old age group have the highest rates of drug abuse. In 2000, 3.6% of individuals in that age group reported nonmedical use of prescription drugs in the month prior to when they were surveyed, but less than half that many, 1.6%, reported the same type of drug abuse in 1994. An estimated 1.6 million Americans used prescription pain relievers nonmedically for the first time in 1998. During the 1980s, there were generally fewer than 500,000 first-time users per year.

The Drug Abuse Warning Network (DAWN) is an ongoing program sponsored by SAMHSA. Approximately 500 hospital emergency rooms throughout the United States gather data from admitted patients on drugs of abuse (i.e., the number of times a specific drug is mentioned by ER patients). A study published in the Journal of the American Medical Association in 2000 compared the increase in legitimate medical use of opioids with one indicator of the increase in abuse of those same drugs. Specifically, five opioid drugs — morphine, fentanyl, oxycodone, hydromorphone, and meperidine — as a group showed a cumulative increase in medical use of nearly 250% from 1990 to 1996. Data collected from DAWN for the same time period showed a 7% increase in emergency room mentions of abuse of these drugs. As a proportion of all opioid drugs mentioned, the five drugs studied decreased from 23% in 1990 to 16% in 1996. This means that mentions of other opioid analgesics, including codeine (although raw numbers for codeine were not analyzed), increased during that time period by 16%. By comparison, the reports of abuse of illicit drugs increased 110%. Admittedly, the data collected by DAWN evaluates only one facet of the drug abuse problem — drug abuse contributing to emergency room visits. However, from these data at least, it does not appear that a significant increase in medical use of opioid drugs resulted in a proportionate increase in abuse. More studies looking at a broader picture of opioid analgesic abuse are needed.

Age, ethnic, and gender trends

Between 1990 and 1998, abuse of some illegal drugs among teens and young adults leveled off or decreased slightly. However, increases in new users of prescription pain relievers were reported in young teens, age 12-17, as well as in young adults age 18-25. In 2000, the NHSDA found that the youngest teens, age 12-14, reported psychotherapeutic medications as the most frequent drugs of abuse, with that group alone making up 53% of the total of all drug abuse reports. Teens and young adults in the 18-25 age group reported prescription drug abuse at a rate of 36%, while 28% of those over age 26 reported that type of abuse. Most teenagers begin prescription drug abuse by taking someone else’s medication, usually someone from their family. Teens are also more likely than adults to be acquainted with someone who sells prescription drugs like codeine illegally.

On the other end of the age spectrum, prescription drug abuse among older adults is also a growing concern. Persons 65 and older comprise 13% of the United States population, but consume about 33% of all prescription drugs. A study of 1,500 elderly patients found that 3% were abusing prescription drugs. Unlike people in younger age groups, however, the elderly are more likely to misuse prescription drugs than abuse them. If abuse does occur, it may begin with misuse due to inappropriate prescribing or the patient not following instructions correctly. Continued misuse may then progress to dependence and abuse, especially with medications such as codeine. Other factors may influence codeine misuse and abuse in older adults. There may be age-related physical changes that influence codeine metabolism, or confusion about the effects codeine can produce. The elderly also have a higher likelihood of other undiag-nosed medical conditions, such as depression, that increase the risk for codeine abuse. Finally, a survey of elderly persons admitted to a treatment program found that 70% were female and of the various drugs of abuse in that group, 70% were opioids.

The NHSDA study showed that boys in the youngest age group (12-17) are more likely to experiment with illegal drugs, but girls of that age have a 20% higher rate of prescription drug abuse. In addition, for all teens of that age that abuse prescription drugs, girls are twice as likely to become addicted as boys are. Women are also more likely to abuse and become addicted to prescription drugs in the young- and middle- adult age groups. Part of this may be that women are prescribed potential drugs of abuse more often than men are.

At all age groups, whites are more likely than other racial or ethnic groups to abuse prescription drugs, and many people who abuse these drugs have psychiatric disorders. In 2000, the New England Journal of Medicine published a report on a survey of pharmacies in New York. The data showed that pharmacies in predominantly minority neighborhoods (greater than 60% non-white population) were three times less likely to stock enough opioid drugs to fill prescriptions on demand than were pharmacies in predominantly white neighborhoods. This may be due to financial constraints in trying to maintain inventories of drugs in those minority neighborhood pharmacies. However, it may also be from fear of crime. A number of pharmacies in the United States were burglarized for their opioid drugs, especially the drug OxyContin, in the late 1990s. The events made national headlines, and intensified the debate over the benefits and drawbacks of opioid drugs.

Health professionals (doctors, nurses, dentists, veterinarians, etc.) and their staff may be at risk for codeine abuse because of their ready access to the drug. On the other hand, one would expect health care workers to be at less risk due to their training and knowledge of the effects of drug abuse. In fact, health care workers do not appear to have rates of codeine or other opioid abuse much different from the rest of the population.

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