Common Forms of Pharmacotherapy Used in Treating Chemical Dependency - Term Paper Example

?Common forms of pharmacotherapy used in treating chemical dependency Introduction Chemical dependency, defined as the physical and/or psychological addiction of the human body to a psychoactive substance, such as narcotics, alcohol, or nicotine, is one of the least understood, and frequently misunderstood, of all chronic diseases. Results from current scientific research have revealed that chemical dependency is a process that is caused by a malfunctioning cascade of neurotransmitters which is further exacerbated by drug use (Marley & Strain, 2001). Dependency on such chemicals as prescription drugs or alcohol stems from frequent use followed by the gradual adjustment in the body’s tolerance to, or ability to assimilate, that drug. Thus, much larger doses has to be consumed to reach the drug’s desired effects, which is accompanied by the temporary alleviation of depression or anxiety, or the induction of excitement. Usually withdrawal symptoms are experience without an increase in the dosage. Chemical dependency is a primary disease that has specific symptoms and it should not to be confused with stress, poor relationships, or unmanageable work demands. Thus chemical dependency can be effectively treated like other diseases. Indeed, pharmacotherapy, the use of drugs in the treatment of diseases, is used in the management of chemical dependence. Usually consists of two approaches, abstinence-based treatment and replacement-based harm reduction, pharmacotherapy aimed at getting and maintaining the patient in a drug-free state. The abstinence-based treatment is mostly recommended; however, if for whatever reason it is not possible, then the replacement-based harm reduction may be employed. Pharmacotherapy in an abstinence-based model is typically associated with drug detoxification, and involved the use of drugs designed to reduce craving and improve treatment outcomes. On the other hand, harm reduction for chemical dependency “involves the use of drugs that will occupy the addicted drug receptors much like the addict's drug of choice, at a dose that will prevent the induction of withdrawal symptoms” (Marley, Chemical Addiction, Drug Use, and Treatment, 2001). The fundamental idea in the latter treatment approach is to maintain the drug addict in an addicted state, but with a legalized chemical substance. The article will discuss the five common drugs use to treat chemical dependence. Discussion Naltrexone Marketed under the trade name Revia and Depade, Naltrexone is an opioid receptor antagonist used primarily in the management of alcohol dependence as well as opioid dependence. Naltrexone is the N-cyclopropylmethyl derivative of 14-hydroxydihydromorphinone. It is marketed in its hydrogen chloride salt. Together with its metabolite 6-?-naltrexol, naltrexone is a competitive antagonist at the ?- and к-opioid receptors and to a lesser extent at the ?-opioid receptors. It ability to block opioid receptor makes it effective in the chemical dependence management of opioid. In fact, it blocks the effects of opioids. Though the mechanism of its action in the management of alcohol dependence is yet to be fully comprehend, it is hypothesis that it is likely due to the modulation of the dopaminergic mesolimbic pathway, which is believed to be activated by all major drugs (Shader, 2003). Naltrexone is also used for the rapid detoxification of opioid dependence. The detoxification involves inducing opioid-receptor blockage while the addict is maintained in a state of partial consciousness in order to reduce the withdrawal symptoms. Currently, there is disagreement on whether detoxification should be carried out under partial consciousness as a result of the associated rapid and severe withdrawal that occurs when naltrexone displaces the opiates from the receptor sites. The main use of naltrexone is of alcohol dependence. The standard regimen involved administrating one 50 mg tablet per day. The drug reduce craving for alcohol; however, there are some side effects such as nausea and increase liver enzymes (Shader, 2003). Methadone Methadone is a synthetic opioid that is use for the treatment of opioid addicts. It is marketed under the trade names Polamidone and Heptadon. The drug has strong binding affinity to the ?-opioid receptor and partial binding affinity to the N-methyl-D-aspartic acid ionotropic glutamate receptor (Xiao, Smith, Caruso, & Kellar, 2001). It thus functions as a receptor antagonist against glutamate, which is the primary excitatory neurotransmitter in the central nervous system. Its side effects include hypoventilation, constipation and miosis as well as difficulty in tolerance, dependence and withdrawal. The drug is usually found in the urine sample six to ten weeks after dose. The drug is administered orally in a racemic solution. The drug is also available as a sublingual tablet, from which two different formulations are prepared for the patient to drink. The drug can also be administrated intravenously. Indeed, due to methadone’s extraordinarily high volume of distribution, which causes it to diffuse into other tissues in the body, particularly fatty tissue; the peak concentration of the drug in the blood is attained at approximately the same time, whether the drug is administered orally or intravenously. Buprenorphine Buprenorphine is a semi-synthetic opioid, which is used in higher dosage (>2 mg) to treat opioid dependence and in lower dosages (~200 ?g) to control moderate pain in no-opioid tolerant individuals. Used as an analgesic, buprenorphine hydrochloride was first marketed as Temgesic, in a 0.2 mg sublingual tablets, and as Buprenex in a 0.3 mg/ml injectable formulation in the 1980s. The drug is currently used predominantly for detoxification and long-term replacement therapy in opioid dependence after the Food and Drug Administration (FDA) of the United States approved Suboxone and Subutex, buprenorphine's high-dose sublingual pill preparations. Buprenorphine has extremely high binding affinity at the ?- and к-opioid receptor. It also has partial agonist activity at the ?-opioid receptor, partial or full agonist activity at the ORL1/nociceptin and ?-opioid receptor, and competitive antagonist activity at the ?-opioid receptor. Buprenorphine (Subutex) itself binds more strongly to receptors in the brain than do other opioids, making it more difficult for opioids (or opiates) to react when buprenorphine is in the system. The drug can also be administered intravenously. Associated side effects include drowsiness, vomiting and respiratory depression (Budd & Raffa, 2005). Diamorphine Also known as heroin, diamorphine is a semi-synthetic opioid drug synthesized from morphine as 3,6-diacetyl ester of morphine. Under the chemical name diamorphine, heroin is a legally prescribed controlled drug used as a strong analgesic in the United Kingdom and sold in the tablet or injectable form for the same indication as morphine is. It is usually administered via subcutaneous, intramuscular, intrathecal or intravenous route. In the United Kingdom, diamorphine is prescribed for opiate addicts that do not benefit from or cannot tolerate treatment with one of the established drugs like methadone or buprenorphine (Goldacre, 2006). Usually the patients are made to appear twice at the treatment center where they are injected with their doses of diamorphine under the supervision of a medical staff. Most patients are also given an additional daily dose of methadone to avoid withdrawal symptoms in between injections. The drug can also be administered orally as it is done in Switzerland. Acamprosate Also known by the brand name Campral, acamprosate is a drug used for treating alcohol dependence. The drug is believed to function by restoring the chemical balance in the brain that is disrupted by alcoholism. Acamprosate, possibly “blocks N-methyl-D-aspartate receptors, while gamma-aminobutyric acid (GABA) type A receptors are activated” (Williams, 2005). Thus acamprosate reduces the surge in glutamate concentration. The drug also protects cultured cells from excitotoxicity induced by ethanol withdrawal and from glutamate exposure combined with ethanol withdrawal. Reports indicate that acamprosate only functions with a combination of attending support groups and abstinence from alcohol. Certain serious side effects include diarrhea, allergic reactions, irregular heartbeats, and low or high blood pressure, while less serious side effects include headaches, insomnia, and impotence. Acamprosate should not be taken by people with kidney problems or allergies to the drug. Conclusion By and large, the five drugs discussed have been reported to be effective in the treatment of chemical dependence their side effects notwithstanding. Works Cited Budd, K., & Raffa, R. B. (2005). Buprenorphine—The Unique Opioid Analgesic. Thieme Medical Publishers: Berlin. Goldacre, B. (2006, November 23). Heroin On Prescription. Retrieved May 20, 2011, from Bad Science: http://www.badscience.net/2006/11/methadone-and-heroin/ Marley, D. (2001, May 14). Chemical Addiction, Drug Use, and Treatment. Retrieved May 20, 2011, from Medscape Pharmacist Education: http://www.medscape.org/viewarticle/418525 Marley, D., & Strain, ,. E. (2001). The neuroscience and practical applications of treating chemical addiction. Platform presentation of the American Pharmaceutical Association Annual Meeting (pp. 16-20). San Francisco, California: American Pharmaceutical Association. Shader, R. I. (2003). Antagonists, Inverse Agonists, and Protagonists. Journal of Clinical Psychopharmacology , 321–322. Williams, S. H. (2005). Medications for treating alcohol dependence. American Family Physician , 1775–1780. Xiao, Y., Smith, R. D., Caruso, F. S., & Kellar, K. J. (2001). Blockade of Rat ?3?4 Nicotinic Receptor Function by Methadone, Its Metabolites, and Structural Analogs. The Journal of Pharmacology and Experimental Therapeutics , 366-371. Read More