Opioid dependency: Wikis

  

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Opioid dependency
Classification and external resources
ICD-10 F11..2
ICD-9 304.0
MeSH D009293

Opioid dependency is a medical diagnosis characterized by an individual's inability to stop using opioids even when objectively it is in his or her best interest to do so. In 1964 the WHO Expert Committee on Drug Dependence introduced "dependence" as “A cluster of physiological, behavioural and cognitive phenomena of variable intensity, in which the use of a psychoactive drug (or drugs) takes on a high priority. The necessary descriptive characteristics are preoccupation with a desire to obtain and take the drug and persistent drug-seeking behaviour. Determinants and problematic consequences of drug dependence may be biological, psychological or social, and usually interact”. The core concept of the WHO definition of “drug dependence” requires the presence of a strong desire or a sense of compulsion to take the drug; and the WHO and DSM-IV-TR clinical guidelines for a definite diagnosis of “dependence” require that three or more of the following six characteristic features be experienced or exhibited:

  • 1. A strong desire or sense of compulsion to take the drug;
  • 2. Difficulties in controlling drug-taking behaviour in terms of its onset, termination, or levels of use;
  • 3. A physiological withdrawal state when drug use is stopped or reduced, as evidenced by: the characteristic withdrawal syndrome for the substance; or use of the same (or a closely related) substance with the intention of relieving or avoiding withdrawal symptoms;
  • 4. Evidence of tolerance, such that increased doses of the drug are required in order to achieve effects originally produced by lower doses;
  • 5. Progressive neglect of alternative pleasures or interests because of drug use, increased amount of time necessary to obtain or take the drug or to recover from its effects;
  • 6. Persisting with drug use despite clear evidence of overtly harmful consequences, such as harm to the liver, depressive mood states or impairment of cognitive functioning.

The Walid-Robinson Opioid-Dependence (WROD) Questionnaire was designed based on these guidelines.

Contents

Causes

Some argue that this is a physical condition characterized by the dysregulation of the endogenous opioid receptor system, which results from chronic exposure to opiates during the period of administration. A recent study has shown that an increase in BDNF, brain-derived neurotrophic factor, in the ventral tegmental area (VTA) in rats can cause opiate-naive rats to begin displaying opiate-dependent behavior, including withdrawal and drug-seeking behavior[1]. It has been known that when an opiate-naive person begins using opiates at levels inducing euphoria, this same increase in BDNF occurs[2]. In the first cited study, it is also noted that the switch to a dopamine-dependent reward system can be characterized by a change in GABAa receptors in the VTA from inhibitory to exictatory, which switches the reward system in rats from a dopamine-indendent system to a dopamine-dependent system. How this impacts a cascading dopamine-dependent pathway to the nucleus accumbens in humans is yet unstudied. The first study does note that the dopamine-dependent reward system appears to related directly to drug-seeking behavior, a signature behavior used when diagnosing psychological opiate dependence. Drugs used to partially ameliorate symptoms of opiate withdrawal, namely benzodiazepines, clonidine, and loperamide - an opioid sold as an anti-diarrheal that does not cross the blood-brain barrier - do help to understand how various changes in the brain reward circuitry and sympathethic nervous system regulation all play a part in reversing the physical dependence. Whether or not physical dependence can be completely reversed is an open question.

In addition there may be associated physiological dysfunction in the reward circuitry of the brain which results from chronic exposure to naturally occurring opiates such as morphine or codeine or synthetically derived opiates (opioids) such as pethidine or methadone. It has been hypothesized that many users of street opiates become addicted due to an "endorphin deficiency syndrome" - analogous to the "serotonin deficiency" that is targeted by modern anti-depressants - the SSRIs. Under this theory, some opioid addicts can not feel normal or happy without using an exogenous opioid to augment the deficiency of natural opioids - endorphins and enkephalins - in their brain.

Treatment approaches include abstinence-based and harm-reduction methodologies. Both include participation in detoxification through the use of methadone or other long-acting opioids. Alternative detox protocols call for total abstention from all opiates, with the use of various benzodiazepines and other medications to reduce the uncomfortable withdrawal symptoms associated with abstinence. In an abstinence-based approach, a gradual taper of the medications follows detox, while in the harm-reduction approach, the patient remains on an ongoing dose of methadone or buprenorphine.

Symptoms of withdrawal

Symptoms of withdrawal from opiates include, but are not limited to, depression, anxiety, panic attacks, leg cramps, abdominal cramps, vomiting, diarrhea, insomnia, and cravings for the drug itself.

Additional withdrawal symptoms include, but are not limited to, rhinitis (irritation and inflammation of the nose), lacrimation (tearing), severe fatigue, lack of motivation, moderate to severe and crushing depression, feelings of panic, sensations in the legs (and occasionally arms) causing kicking movements which disrupt sleep, dangerously elevated heart rate and blood pressure (which cause most deaths by withdrawal, but are usually noted upon autopsy as "stroke," etc., not "stroke pursuant to opioid withdrawal syndrome"), chills, gooseflesh, headaches, anorexia (lack of appetite), benign fasciculation syndrome, mild or moderate tremors, and other adrenergic symptoms, severe aches and pains in muscles and perceivably bones, and weight loss in severe withdrawal.

Depending on the quantity, type, frequency, and duration of opioid use, the physical withdrawal symptoms last for as little as 5 days and as much as 14 days. When long acting opioids like methadone (Methadose) or buprenorphine (brand names: Suboxone [buprenorphine in a 4:1 ratio to naloxone] and Subutex [pure buprenorphine])are used for an extended period physical withdrawal symptoms can last up to two months and are sometimes followed by a very long period of depression, fatigue, and trouble sleeping which could last up to two years which is sometimes referred to as P.A.W.S or Post Acute Withdrawal Syndrome which is more severe and tends to occur more frequently with long acting opioids.[citation needed] The user, upon returning to the environment where they usually used opiates, can experience environmentally implied physical withdrawal symptoms well-after regaining physical homeostasis - or the termination of the physical withdrawal phase by synthesis of endogenous opioids (endorphins) and upregulation of opioid receptors to the effects of normal levels of endogenous opioids.[citation needed] These implied symptoms are often just as distressing and painful as the initial withdrawal phase.

References

  1. ^ Varga-Perez H, Ting-A Kee R, Walton C, et al. (June 2009). "Ventral Tegmental Area BDNF Induces an Opiate-Dependent-Like Reward State in Naive Rats". Science 324 (5935): 1732–34. doi:10.1126/science.1168501. 
  2. ^ Laviolette SR, van der Kooy D (2009). Eur J Neurosci 13: 1009. 

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