<P> CNS depression is generally caused by the use of depressant drugs such as ethanol, opioids, barbiturates, benzodiazepines, general anesthetics, and anticonvulsants such as pregabalin used to treat epilepsy . Drug overdose is often caused by combining two or more depressant drugs, although overdose is certainly possible by consuming a large dose of one depressant drug . CNS depression can also be caused by the accidental or intentional inhalation or ingestion of certain volatile chemicals such as Butanone (contained in Plastic Cement) or Isopropyl Alcohol . Other causes of CNS depression are metabolic disturbances such as hypoglycaemia . </P> <P> In a study comparing the central nervous depression due to supra - therapeutic doses of Triazolam (Benzodiazepine), Pentobarbital (Barbiturate) and GHB it appeared as if GHB had the strongest dose - effect function . Since, GHB had a high correlation between its dose and its central nervous system depression it has a high risk of accidental overdose . In the case of accidental overdose of GHB, patients could become drowsy, fall asleep and may enter a coma . Although GHB had higher sedative effects at high doses as compared to Triazolam and Pentobarbital, it had less amnestic effects as compared to Triazolam and Pentobarbital . Arousal of subjects in the GHB group sometimes even required a painful stimulus; this was not seen in the Triazolam or the Pentobarbital group . Fortunately, during this heavy sedation with GHB the subjects maintained normal respiration and blood pressure . This is often not the case with opioids as they will cause respiratory depression . </P> <P> CNS depression is treated within a hospital setting by maintaining breathing and circulation . Individuals with reduced breathing may be given supplemental oxygen, while individuals who are not breathing can be ventilated with bag valve mask ventilation or by mechanical ventilation with a respirator . Sympathomimetic drugs may be used to attempt to stimulate cardiac output in order to maintain circulation . CNS Depression caused by certain drugs may respond to treatment with an antidote . </P> <P> There are two antidotes that are frequently used in the hospital setting and these are Naloxone and Flumazenil . Naloxone is an opioid antagonist and reverses the central nervous depressive effects seen in opioid overdose . In the setting of a colonoscopy, Naloxone is rarely administered but when it is administered, its half life is shorter than some common opioid agonists . Therefore, the patient may still exhibit central nervous system depression after Naloxone has been cleared . Typically, Naloxone is administered in short intervals with relatively small doses in order to prevent the occurrence of withdrawal, pain, and sympathetic nervous system activation . Flumazenil is a benzodiazepine antagonists and blocks the binding of benzodiazepines to GABAa . Similarly to Naloxone, Flumazenil has a short half life, and this needs to be taken into account because the patient may exhibit central nervous depression after the antidote has been cleared . Benzodiazepines are used in the treatment of seizures and subsequently, the administration of Flumazenil may result in seizures . Therefore, slow administration of Flumazenil is necessary to prevent the occurrence of a seizure . These agents are rarely used in the setting of a colonoscopy as 98.8% of colonoscopies use sedatives but only 0.8% of them result in the administration of one of these antidotes . Even if they are rarely used in colonoscopies they are important in preventing the patient from entering a coma or developing respiratory depression when sedatives are not properly dosed . Outside of the colonoscopy setting, these agents are used for other procedures and in the case of drug overdose . </P>

Ingestion of an opiate sedative or barbiturate can cause depression of the cns and