There are fears amongst patients and healthcare professionals that the use of medication to manage long-term pain will result in tolerance of, dependence upon, or addiction to that medication. Definitions of, and differences between, these conditions are often confused.
Many people legitimately rely on their medication to function, and most patients taking long-term opioids will become physically dependent on them. It is a misconception that physical dependence is always a negative outcome of opioid therapy. Concerns about this are often culturally rather than medically driven. Patients become physically dependant upon drugs such as clonidine, but this does not produce the same negative responses from health carers and society. With one in five Europeans, suffering from persistent pain,1 this misconception can have detrimental effects. It may mean that people do not receive the most suitable medical care to manage pain, and that the more powerful therapies, such as opioids, are withheld.
‘Addiction’ is most often perceived as an outcome of drug therapy. However, it is often confused with ‘tolerance’ and ‘physical dependence’. This perpetuates misinformation regarding addictive behaviours, and may result in fewer people receiving optimal pain management.
In understanding the benefits of long-term pain management, it is therefore important that the differences between tolerance, dependence and addiction, and the effects of these conditions, are accurately understood and communicated to the patient.
Studies have shown that, while withdrawal syndrome and tolerance commonly occur in patients who take opioids over a long period, addiction is rare.2 Consequently, the risk of addiction should not be a factor in deciding whether to use opioids to treat patients with persistent pain.
“Addiction is a primary, persistent, neurobiologic disease, with genetic, psychosocial, and environmental factors influencing its development and manifestations. It is characterised by behaviors that include one or more of the following: impaired control over drug use, compulsive use, continued use despite harm, and craving”2
Drug addiction is the compulsive use of drugs despite the social, emotional, or physical harm they may cause the individual. Addiction is a neurobiological disease, which occurs when a person is controlled by getting and using medication for what they ‘believe’ they feel, rather than for ‘actual’ pain relief.
Key points to note:
Tolerance occurs when a person becomes used to a drug and it no longer provides the same relief as when they started using it. Tolerance may happen with a variety of pain medications and results in a patient needing more medicine to control their pain.
Key points to note:
“Tolerance is a state of adaptation in which exposure to a drug induces changes that result in a diminution of one or more of the drug's effects over time.”3
“Physical dependence is a state of adaptation that is manifested by a drug class specific withdrawal syndrome that can be produced by abrupt cessation, rapid dose reduction, decreasing blood levels of the drug, and/or administration of an antagonist.”2
Physical dependence occurs as a physiological response once drug therapy is stopped or the dose is rapidly reduced. In these cases, the individual has become so accustomed to a particular substance that they can only function ‘normally’ if the drug is present. As the body maintains a carefully balanced homeostatic environment, any adjustment can result in withdrawal symptoms that can manifest in various ways. It is important to note that the presence of withdrawal symptoms does not mean a patient is addicted to the drug.
Key points to note:
1) Breivik H, Collett B, Ventafridda V, et al. Survey of chronic pain in Europe: prevalence, impact on daily life, and treatment. Eur J Pain 2006; 10:287-333.
2) OPENMinds online; Available from: URL: www.openmindsonline.org.
3) Definitions related to the Use of Opioids for the Management of Pain. A consensus document from the American Academy of Pain Medicine, the American Pain Society and the American Society of Addiction Medicine. February 2001.
4) World Health Organization. Achieving balance in National opioids control policy. Guidelines for assessment. Available from: URL: http://whqlibdoc.who.int/hq/2000/who_edm_qsm_2000.4.pdf.