Introducing Naloxone:
Analgesics (pain-killers) are one of the most commonly prescribed drug classes across the globe. Analgesics are divided into two classes namely- opioid analgesic and NSAIDs. Naloxone is an opioid analgesic which, though belonging to the same class of analgesic (opioid), is used as an antidote for opiate-overdose.
How Naloxone works? Receptors for opioid analgesics are present in the neuronal membranes, finding in high concentration in limbic system, thalamus, hypothalamus, medulla oblongata and the spinal-cord. There are three types of opioid receptors namely μ (mu), δ (delta) and κ (kappa). These mediators perform different functions for example mu-receptors are responsible for activities such as respiratory depression, which makes the overdose of opioids extremely dangerous.
Naloxone binds to the opioid receptors and therefore is an excellent analgesic agent.The mechanism of working of naloxone is now known (blocking of the opioid receptors). Though the blocking of the opioid receptor has little effect in normal individuals, in patient with chronic pain, it produces hyperalgesia or increased sensitivity to pain. It is however an excellent antidote for opioid analgesics and the following paragraph deals with the reason-
Naloxone works as an antidote for opioid-overdose-
Opiate-overdose can cause mortality especially in injection users. This overdose can be reversed by administering naloxone. When overdose is reported, cardiopulmonary resuscitation is an effective intervention, however almost universally; naloxone is used for reversal of such an over-dose. Naloxone is a legal, non-scheduled opioid antagonist which is quickly administered by an intramuscular injection, and produces no dependence in the absence of narcotics. Naloxone is an opiate antidote, which act as a pure opioid competitive antagonist at all the receptor sites.This can be explained by the following example: Both heroine and morphine are μ (mu) -receptor agonist which causes euphoria, pain relief and suppression of respiration. Naloxone has higher affinity for this receptor compared to heroine or morphine, thus, it replaces these molecules slowly, thereby acting as an antidote. Itreverses coma as well as respiratory depression from all the opioids without any additive agonist effects. In individual who are known opioid-dependent, naloxone can induce withdrawal symptoms.
Summing up, naloxone is an opiate analgesic which acts as an antidote of opioid-overdose due to its higher affinity for the opioid receptors, which helps it to replace the opioid analgesics.In recent times, efforts are being made to make naloxone easily available so that more and more patients with opiate-overdose can use it.
References:
1. http://mdpoison.com/healthcareprofessionals/antidote%20facts/Naloxone%20Antidote%20Facts.pdf
2. http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3838403/
Primary keyword: Opiate-overdose
Secondary keyword:antidote
