Drug abuse and drug dependence
Drug abuse refers to the excessive administration of drugs in a societal unacceptable way. To be considered drug abuse, excessive use of the type of substance needs to be considered. Another factor to be considered is the harm that the drug in excess can cause. Drug abuse can lead to an individual developing drug dependence. This is when the drug is compulsively sought regardless of the consequences. The two types of dependence are psychological and physical. Psychological dependence involves cravings and denials. Physical dependence results in withdrawal symptoms if the drug is ceased (Bryant & Knights, 2015).
Central nervous system effects
The central nervous system consists of the brain and the spinal cord. Different classes of drugs interact with different neurochemicals and can illicit range of responses. One of these is euphoria. Euphoria is an intense feeling of pleasure, happiness, or excitement which id a desirable effect from drug usage (Gardner, 2011). This effect can result in drug reinforcement and reward. Drug users will pursue the pleasurable feeling they received from using the drug. Additionally, withdrawals can also cause reinforcement as the negative physical feelings cause users to seek more of the drug (Bryant & Knight, 2015). Dependence involves the mesolimbic dopamine pathway in the brain. Dopamine stimulates the pleasure centre and is involved in reinforcement and reward. Interruptions to this pathway have shown to decrease drug-seeking behaviour. Another important aspect to consider is drug tolerance. This involves changes on a cellular level in the brain. As drugs increase the amount of dopamine in the synapse, fewer dopamine receptors are needed on the postsynaptic neuron. This causes the neuron to down regulate the receptors, or decrease their sensitivity to dopamine. As this occurs, a drug is then needed in higher doses to exert the same pleasurable feeling. This is known as drug tolerance (Adinoff, 2004; Bryant & Knight, 2015).
Heroin is a morphine derivative with a high potential for drug abuse. For this reason, its use is not acceptable in medical settings. It is a prodrug, which is converted into morphine in the liver. The metabolism of heroin is similar to that of codeine, where it is also converted into morphine in the liver. Tolerance develops quickly with heroin so users often turn to criminal activity to pay for increased amounts needed to get the pleasurable ‘rush’. It requires more of the opioid to get the same affect due to up regulation of receptors. Many users prefer to intravenously inject opiates, inject subcutaneously, or snort them, as oral bioavailability is generally low. With the need to inject more drug to get the same affect or by the drugs being adulterated with unknown additives, acute overdose can occur. The toxic effects from an overdose can cause multi-organ failure and potentially death. An individual’s tolerance to a drug alters the amount of drug required to be a lethal dose. Those whom are regular substance users require more of the drug in order for it to be a lethal dose. When an individual has overdosed on opioids, they are treated with naloxone. This drug competes with opioid receptor binding sites in the nervous system; it is an opioid antagonist. Once administered IV or IM, it take 1-3 minutes to exert its action. The individual will then experience withdrawal from the opiate. Withdrawal is a physiological and psychological stressful process that requires specific programmes to support the individual during their journey. Pharmacological substitutes such as naltrexone, methadone of buprenorphine are often used to manage the recovery from opioid addiction (Bryant & Knight, 2015).
Treating drug abuse and drug dependence (addiction) is a multifaceted process, which first requires the individual to recognise that there is a problem with drugs. For this to occur the individual needs to be in the contemplation stage on the wheel of change. Often there may be a dual diagnosis; there may be an underlining mental illness or personality disorder that needs to addressed alongside the drug abuse. Treatment may require counselling, education, pharmacological interventions, self-help strategies, and alternative medicines. The treatment will differ depending on whether it is an acute problem, such as an overdose, treating chronic abuse or long-term maintenance (Bryant & Knight, 2015).
Adinoff, B. (2004). Neurobiological processes in drug reward and addiction. Harvard Review of Psychiatry, 12(6), 305-320. doi: 10.1080/10673220490910844
Bryant, B, & Knight, K. (2015). Pharmacology or health professionals (4th ed). Sydney, Australia: Mosby Elsevier.
Gardner, E. (2011). Introduction: Addiction and brain reward and anti-reward pathways. Advanced Psychosomatic Medicine, 30, 22-60. doi: 10.1159/000324065