Drug addiction is defined as compulsive, often uncontrollable drug use in spite of negative consequences, and is the result of changes in brain function. Notes , "The Basics of Brain Imaging. Accessed at www. Department of Health and Human Services. Skip to main content. Learn more about the science of drug addiction. Long-term pharmacotherapies for opioid dependence and addiction counteract or reverse the abnormalities underlying those conditions, thereby enhancing programs of psychological rehabilitation.
Methadone and LAAM stimulate the cells much as the illicit opioids do, but they have different effects because of their different durations of action. Naltrexone and buprenorphine stimulate the cells in ways quite distinct from the addictive opioids. Each medication can play a role in comprehensive treatment for opioid addiction. Methadone is a long-acting opioid medication. Unlike morphine, heroin, oxycodone, and other addictive opioids that remain in the brain and body for only a short time, methadone has effects that last for days.
Methadone causes dependence, but—because of its steadier influence on the mu opioid receptors—it produces minimal tolerance and alleviates craving and compulsive drug use. In addition, methadone therapy tends to normalize many aspects of the hormonal disruptions found in addicted individuals Kling et al. For example, it moderates the exaggerated cortisol stress response discussed above that increases the danger of relapse in stressful situations. Methadone treatment reduces relapse rates, facilitates behavioral therapy, and enables patients to concentrate on life tasks such as maintaining relationships and holding jobs.
Patients are generally started on a daily dose of 20 mg to 30 mg, with increases of 5 mg to 10 mg until a dose of 60 mg to mg per day is achieved. The higher doses produce full suppression of opioid craving and, consequently, opioid-free urine tests Judd et al. Patients generally stay on methadone for 6 months to 3 years, some much longer.
Relapse is common among patients who discontinue methadone after only 2 years or less, and many patients have benefited from lifelong methadone maintenance.
A longer acting derivative of methadone, LAAM can be given three times per week. Food and Drug Administration, Nevertheless, long-term maintenance on moderate to high doses of LAAM can, like methadone maintenance, normalize physiological functions such as the cortisol stress response Kling et al. Dosing with LAAM is highly individualized, and three-times-weekly doses range from 40 mg to mg.
Naltrexone is used to help patients avoid relapse after they have been detoxified from opioid dependence. Naltrexone clings to the mu opioid receptors times more strongly than opioids do, but it does not promote the brain processes that produce feelings of pleasure Kosten and Kleber, An individual who is adequately dosed with naltrex-one does not obtain any pleasure from addictive opioids and is less motivated to use them.
Before naltrexone treatment is started, patients must be fully detoxified from all opioids, including methadone and other treatment medications; otherwise, they will be at risk for severe withdrawal. Naltrexone is given at 50 mg per day or up to mg twice weekly. Unfortunately, medication compliance is a critical problem with naltrexone, because unlike methadone or LAAM, naltrexone does not itself produce pleasurable feelings.
Naltrexone is also sometimes used to rapidly detoxify patients from opioid dependence. In this situation, while naltrexone keeps the addictive opioid molecules away from the mu opioid receptors, clonidine may help to suppress the excessive NA output that is a primary cause of withdrawal Kosten, At low doses buprenorphine has effects like methadone, but at high doses it behaves like naltrexone, blocking the receptors so strongly that it can precipitate withdrawal in highly dependent patients that is, those maintained on more than 40 mg methadone daily.
Buprenorphine is expected to be approved by the Food and Drug Administration for the treatment of opioid dependence in Several clinical trials have shown that when used in a comprehensive treatment program with psychotherapy, buprenorphine is as effective as methadone, except for patients with heroin addiction so severe they would require a dose of more than mg daily Kosten et al.
Buprenorphine offers a safety advantage over methadone and LAAM, since high doses precipitate withdrawal rather than the suppression of consciousness and respiration seen in overdoses of methadone, LAAM, and the addictive opioids. Buprenorphine can be given three times per week. Because of its safety and convenient dosing, it may be useful for treating opioid addiction in primary care settings, which is especially helpful since most opioid addicts have significant medical problems for example, hepatitis B or C and HIV infection.
Buprenorphine will be available in 4 mg and 8 mg tablets. A combination tablet with naloxone Suboxone has been developed to negate the reward a user would feel if he or she were to illegally divert and inject the medication.
The maintenance dose of the combination tablet can be up to 24 mg and used for every-other-day dosing. As office-based treatment of heroin addiction becomes available, the highest possible safety level that is, minimal side effects should be balanced with treatment effectiveness.
The patient taking methadone must either visit the medical office daily not feasible in most cases or be responsible for taking daily doses at home, as scheduled.
Accordingly, for an opioid-dependent patient who cannot be relied upon to take the medication as instructed and thus might overdose, buprenorphine in three doses weekly would be a safer choice than methadone.
Also, buprenorphine has less overdose potential than methadone, since it blocks other opioids and even itself as the dosage increases. Opioid dependence and addiction are most appropriately understood as chronic medical disorders, like hypertension, schizophrenia, and diabetes.
The mesolimbic reward system appears to be central to the development of the direct clinical consequences of chronic opioid abuse, including tolerance, dependence, and addiction.
Other brain areas and neurochemicals, including cortisol, also are relevant to dependence and relapse. Pharmacological interventions for opioid addiction are highly effective; however, given the complex biological, psychological, and social aspects of the disease, they must be accompanied by appropriate psychosocial treatments.
Clinician awareness of the neurobiological basis of opioid dependence, and information-sharing with patients, can provide insight into patient behaviors and problems and clarify the rationale for treatment methods and goals. National Center for Biotechnology Information , U. Journal List Sci Pract Perspect v. Sci Pract Perspect. Thomas R. Kosten , M. The human brain is the most complex organ in the body.
This three-pound mass of gray and white matter sits at the center of all human activity—you need it to drive a car, to enjoy a meal, to breathe, to create an artistic masterpiece, and to enjoy everyday activities. The brain regulates your body's basic functions, enables you to interpret and respond to everything you experience, and shapes your behavior. In short, your brain is you —everything you think and feel, and who you are.
The brain is often likened to an incredibly complex and intricate computer. Instead of electrical circuits on the silicon chips that control our electronic devices, the brain consists of billions of cells, called neurons, which are organized into circuits and networks.
Each neuron acts as a switch controlling the flow of information. If a neuron receives enough signals from other neurons that it is connected to, it fires, sending its own signal on to other neurons in the circuit. The brain is made up of many parts with interconnected circuits that all work together as a team.
Different brain circuits are responsible for coordinating and performing specific functions. Networks of neurons send signals back and forth to each other and among different parts of the brain, the spinal cord, and nerves in the rest of the body the peripheral nervous system. To send a message, a neuron releases a neurotransmitter into the gap or synapse between it and the next cell. Mice pretreated with oxycodone showed significantly greater locomotor supersensitivity to quinpirole than did morphine-pretreated mice, while hydrocodone-pretreated mice showed sensitivity in between that of mice treated with morphine and oxycodone.
This finding suggests that various opioids differentially modulate the responses of D2DRs.
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