An analgesic drug, also called simply an analgesic, antalgic, pain reliever, or painkiller, is any member of the group of drugs used for pain management. Analgesics are conceptually distinct from anesthetics, which temporarily reduce, and in some instances eliminate, sensation, although analgesia and anesthesia are neurophysiologically overlapping and thus various drugs have both analgesic and anesthetic effects.
Pain is a distressing feeling often caused by intense or damaging stimuli. The International Association for the Study of Pain defines pain as "an unpleasant sensory and emotional experience associated with, or resembling that associated with, actual or potential tissue damage."
Chronic pain or chronic pain syndrome is a type of pain that is also known by other titles such as gradual burning pain, electrical pain, throbbing pain, and nauseating pain. This type of pain is sometimes confused with acute pain and can last from three months to several years; Various diagnostic manuals such as DSM-5 and ICD-11 have proposed several definitions of chronic pain, but the accepted definition is that it is "pain that lasts longer than the expected period of recovery."
Fibromyalgia is a medical syndrome which causes chronic widespread pain, accompanied by fatigue, waking unrefreshed, and cognitive symptoms. Other symptoms can include headaches, lower abdominal pain or cramps, and depression. People with fibromyalgia can also experience insomnia and a general hypersensitivity. The cause of fibromyalgia is unknown, but is believed to involve a combination of genetic and environmental factors. Environmental factors may include psychological stress, trauma, and certain infections. Since the pain appears to result from processes in the central nervous system, the condition is referred to as a "central sensitization syndrome".
Pain management is an aspect of medicine and health care involving relief of pain in various dimensions, from acute and simple to chronic and challenging. Most physicians and other health professionals provide some pain control in the normal course of their practice, and for the more complex instances of pain, they also call on additional help from a specific medical specialty devoted to pain, which is called pain medicine.
Opioids are a class of drugs that derive from, or mimic, natural substances found in the opium poppy plant. Opioids work in the brain to produce a variety of effects, including pain relief. As a class of substances, they act on opioid receptors to produce morphine-like effects.
Low back pain or lumbago is a common disorder involving the muscles, nerves, and bones of the back, in between the lower edge of the ribs and the lower fold of the buttocks. Pain can vary from a dull constant ache to a sudden sharp feeling. Low back pain may be classified by duration as acute, sub-chronic, or chronic. The condition may be further classified by the underlying cause as either mechanical, non-mechanical, or referred pain. The symptoms of low back pain usually improve within a few weeks from the time they start, with 40–90% of people recovered by six weeks.
Neuropathic pain is pain caused by a lesion or disease of the somatosensory nervous system. Neuropathic pain may be associated with abnormal sensations called dysesthesia or pain from normally non-painful stimuli (allodynia). It may have continuous and/or episodic (paroxysmal) components. The latter resemble stabbings or electric shocks. Common qualities include burning or coldness, "pins and needles" sensations, numbness and itching.
A pain scale measures a patient's pain intensity or other features. Pain scales are a common communication tool in medical contexts, and are used in a variety of medical settings. Pain scales are a necessity to assist with better assessment of pain and patient screening. Pain measurements help determine the severity, type, and duration of the pain, and are used to make an accurate diagnosis, determine a treatment plan, and evaluate the effectiveness of treatment. Pain scales are based on trust, cartoons (behavioral), or imaginary data, and are available for neonates, infants, children, adolescents, adults, seniors, and persons whose communication is impaired. Pain assessments are often regarded as "the 5th vital sign".
Opioid-induced hyperalgesia (OIH) or opioid-induced abnormal pain sensitivity, also called paradoxical hyperalgesia, is an uncommon condition of generalized pain caused by the long-term use of high dosages of opioids such as morphine, oxycodone, and methadone. OIH is not necessarily confined to the original affected site. This means that if the person was originally taking opioids due to lower back pain, when OIH appears, the person may experience pain in the entire body, instead of just in the lower back. Over time, individuals taking opioids can also develop an increasing sensitivity to noxious stimuli, even evolving a painful response to previously non-noxious stimuli (allodynia). This means that if the person originally felt pain from twisting or from sitting too long, the person might now additionally experience pain from a light touch or from raindrops falling on the skin.
Proglumide (Milid) is a drug that inhibits gastrointestinal motility and reduces gastric secretions. It acts as a cholecystokinin antagonist, which blocks both the CCKA and CCKB subtypes. It was used mainly in the treatment of stomach ulcers, although it has now been largely replaced by newer drugs for this application.
Ameritox was a company that provided physicians with urine drug monitoring and reporting services. Headquartered in Baltimore, Maryland, the company also had a CLIA-certified laboratory in Greensboro, North Carolina.
An opiate is an alkaloid substance derived from opium. It differs from the similar term opioid in that the latter is used to designate all substances, both natural and synthetic, that bind to opioid receptors in the brain. Opiates are alkaloid compounds naturally found in the opium poppy plant Papaver somniferum. The psychoactive compounds found in the opium plant include morphine, codeine, and thebaine. Opiates have long been used for a variety of medical conditions, with evidence of opiate trade and use for pain relief as early as the eighth century AD. Most opiates are considered drugs with moderate to high abuse potential and are listed on various "Substance-Control Schedules" under the Uniform Controlled Substances Act of the United States of America.
There is a scientific debate which questions whether crustaceans experience pain. It is a complex mental state, with a distinct perceptual quality but also associated with suffering, which is an emotional state. Because of this complexity, the presence of pain in an animal, or another human for that matter, cannot be determined unambiguously using observational methods, but the conclusion that animals experience pain is often inferred on the basis of likely presence of phenomenal consciousness which is deduced from comparative brain physiology as well as physical and behavioural reactions.
The hot plate test is a test of the pain response in animals, similar to the tail flick test. Both hot plate and tail-flick methods are used generally for centrally acting analgesic, while peripherally acting drugs are ineffective in these tests but sensitive to acetic acid-induced writhing test.
Pain is an aversive sensation and feeling associated with actual, or potential, tissue damage. It is widely accepted by a broad spectrum of scientists and philosophers that non-human animals can perceive pain, including pain in amphibians.
Pain in cephalopods is a contentious issue. Pain is a complex mental state, with a distinct perceptual quality but also associated with suffering, which is an emotional state. Because of this complexity, the presence of pain in non-human animals, or another human for that matter, cannot be determined unambiguously using observational methods, but the conclusion that animals experience pain is often inferred on the basis of likely presence of phenomenal consciousness which is deduced from comparative brain physiology as well as physical and behavioural reactions.
Undertreatment of pain is the absence of pain management therapy for a person in pain when treatment is indicated.
Opioid rotation or opioid switching is the process of changing one opioid to another to improve pain control or reduce unwanted side effects. This technique was introduced in the 1990s to help manage severe chronic pain and improve the opioid response in cancer patients. In order to obtain adequate levels of pain relief, patients requiring chronic opioid therapy may require an increase in the original prescribed dose for a number of reasons, including increased pain or a worsening disease state. Over the course of long-term treatment, an increase in dosage cannot be continued indefinitely as unwanted side effects of treatment often become intolerable once a certain dose is reached, even though the pain may still not be properly managed. One strategy used to address this is to switch the patient between different opioid drugs over time, usually every few months. Opioid rotation requires strict monitoring in patients with ongoing levels of high opioid doses for extended periods of time, since long term opioid use can lead to a patient developing tolerance to the analgesic effects of the drug. Patients may also not respond to the first opioid prescribed to them at all, therefore needing to try another opioid to help manage their pain. A patient's specific response and sensitivity to opioids include many factors that include physiology, genetics and pharmacodynamic parameters, which together determine the amount of pain control and tolerance of a particular opioid.
Beth Darnall is American scientist, pain psychologist, author, and Associate Professor of Anesthesiology, Perioperative and Pain Medicine at the Stanford University School of Medicine where she directs the Stanford Pain Relief Innovations Lab. From 2005 to 2012, Darnall was an assistant professor and associate professor at Oregon Health & Science University.
