Which opioid medication?
Although some opioids are natural and others are synthetic, they all bind to the µ-opioid receptors in the spinal cord and periphery to produce analgesia. There are other differences as well. Some opioids have shorter action potentials (e.g., fentanyl) and others have extremely long half-lives (e.g., methadone). In addition, there are combination drugs with shorter duration and limited maximum doses related to the use of acetaminophen (e.g., oxycodone/acetaminophen and hydrocodone/acetaminophen).
An analgesic ladder endorsed by the World Health Organization (WHO) (Figure 1) can be a helpful guide.2 The three steps of the ladder list medications that are appropriate for mild, moderate, and severe pain.
When to use an extended-release medication
For a patient with chronic pain, an opioid medication with extended-release action may be the best choice. When the patient is consistently using a short-acting medication (e.g., oxycodone/acetaminophen), has consistent daily pain that needs better relief, and has reached the maximum daily dose of acetaminophen, it is time to move to an extended-release medication. There are several options, including extended-release morphine, oxycodone, or tramadol (Ultram).
One medication often prescribed by pain specialists looking for a less expensive alternative to extended-release medications is methadone. This agent, which is commonly used in maintenance programs for heroin addicts, is also a very powerful pain reliever. It can be prescribed only by clinicians holding a Drug Enforcement Agency license and requires very careful consideration prior to use.
Methadone is very difficult to titrate. With pain relief lasting only six hours and a half-life as long as 150 hours, the possibility of oversedation and respiratory depression is substantial. Dosing should start in the lower range of 2.5-5 mg and can be increased every six days. Careful monitoring for side effects is essential. Additionally, there is the potential for the cardiac arrhythmia, torsades de pointes. All patients on methadone therapy should have a baseline ECG and repeat testing every six months to monitor for cardiac complications. Methadone should be prescribed for pain control only by practitioners who are aware of the potential pitfalls and understand the mechanism and action of the drug.
All patients who use opioids to control daily pain will become dependent on the medication. Dependency is defined as a condition in which sudden stoppage of the medication causes symptoms of withdrawal. Addiction, on the other hand, is characterized by the presence of the four Cs: (1) lack of Control, (2) Craving for the drug of choice, (3) Compulsive use, and (4) Continued use despite harm.3 Dependency and addiction are not the same and should not be confused.
Although there is a risk of addiction when long-term opioids are used, it is not as high as many practitioners assume. In a study of 810 primary-care patients on long-term opioids for chronic pain, the incidence of addiction was 3.8%.4
Several techniques can be used to minimize concerns with prescribing long-term opioids. Both the Opioid Risk Tool (ORT) and the Screener and Opioid Assessment for Patient with Pain-Revised (SOAPP-R) are good screening instruments. Each screening tool is a set of questions that can help determine if the patient will demonstrate aberrant drug-taking behaviors (ORT)5 (Table 1) or if they have a high risk for addiction with opioids (SOAPP-R).
Providing the patient with an opioid agreement that lists the clinic rules for prescribing long-term opioids, defines addiction/dependency/tolerance, and outlines the drug’s dose and side effects can lessen the burden for the prescriber. By signing the agreement, the patient consents to random urine drug screens. The consequences of a positive screen for nonprescribed opioids, illicit substances, or other drugs of abuse (e.g., benzodiazepines) are also included in the agreement.
As always, these tools should be used in conjunction with each other to provide a more comprehensive picture of the patient and his treatment.