Opioid intoxication

Essential (Required) Features:

• Transient and clinically significant disturbances in consciousness, cognition, perception, affect, behaviour, or coordination that develop during or shortly after the consumption or administration of opioids.
• The symptoms must be compatible with the known pharmacological effects of opioids, and their intensity is closely related to the amount of opioids consumed.
• Presenting features of Opioid Intoxication may include somnolence, stupor, mood changes (e.g., euphoria followed by apathy and dysphoria), psychomotor retardation, impaired judgment, respiratory depression, slurred speech, and impairment of memory and attention. In severe intoxication, coma may ensue. A characteristic physical sign is pupillary constriction but this sign may be absent when intoxication is due to synthetic opioids.
• The symptoms of intoxication are time-limited and abate as opioids are cleared from the body.
• Symptoms are not better accounted for by another medical condition (See below) or another mental disorder, including another Disorder Due to Substance Use (e.g., Withdrawal from a different substance).

Examples of Medical Conditions That May Present with Symptoms Similar to Substance Intoxication

• Head injury (with or without cerebral contusion or intracranial haemorrhage or haematoma)
• Meningitis and encephalitis
• Diabetic ketoacidosis or hypoglycaemia
• Hepatic or other metabolic encephalopathy
• Wernicke’s encephalopathy
• Electrolyte disturbance
• Hypoxia or hypercapnia
• Systemic infection

Severity of Intoxication Specifier:

Depending on the specific clinical situation and the information available, Substance Intoxication may be classified according to the level of severity as mild, moderate, or severe. The level of intoxication is usually related to the dose, route of administration, half-life, and duration of action of the substance. Severity of intoxication is also affected by individual variability (e.g., differences in body weight, substance metabolism, or tolerance). Susceptibility to substance intoxication may also be greater in individuals with comorbid medical conditions affecting drug pharmacokinetics (e.g., renal or hepatic insufficiency).

For some substances, there are specific tests for detecting and determining the concentration of substances in bodily fluids (e.g., blood, urine), which can be important tools for clinical management. However, severity of intoxication should be determined on the basis of clinical assessment, as specified below, and not solely based on the presence and level of the substance in bodily fluids.

The level of medical attention that may be required in response to substance intoxication varies according to the severity of intoxication and the substance involved, and varies from precautionary observation to urgent intervention to prevent death or permanent harm (e.g., administration of antagonist treatment; intubation).

The severity of intoxication is classified using the following Extension (X) Codes in addition to the appropriate intoxication category. Extension codes are attached to the category to which they apply using an ampersand (&).

XS5W Mild

Mild substance intoxication is a state in which there are clinically recognizable disturbances in psychophysiological functions and responses (e.g., motor coordination, attention and judgement) that vary by substance, but there is little or no disturbance in the level of consciousness.

The code for Opioid Intoxication, mild is 6C43.3&XS5W.

XS0T Moderate

Moderate substance intoxication is a state in which there are marked disturbances in psychophysiological functions and responses (e.g., motor coordination, attention and judgement) that vary by substance, with substantial impairment on tasks that require these functions. There is some disturbance in level of consciousness.

The code for Opioid Intoxication, moderate is 6C43.3&XS0T.

XS25 Severe

Severe substance intoxication is a state in which there are obvious disturbances in psychophysiological functions and responses (e.g., motor coordination, attention and judgement) that vary by substance, with marked disturbance in level of consciousness. There is severe impairment to the extent that the person may not be capable of self-care or self-protection, and may be unable to communicate or cooperate with assessment and intervention.

The code for Opioid Intoxication, severe is 6C43.3&XS25.

Additional Clinical Features:

• Severe Opioid Intoxication can lead to death due to excessive respiratory depression. Overdose is more likely to occur with higher potency opioids (e.g., fentanyl), when the person has reduced tolerance (e.g., after detoxification) or when an individual who has developed tolerance uses the opioid in a novel environment.
• Opioid Intoxication shares certain features with Alcohol Intoxication and Sedative, Hypnotic or Anxiolytic Intoxication. Evidence of alcohol use (e.g., the smell of alcohol on the breath) does not rule out co-occurring Opioid Intoxication.
• Where available, laboratory testing for substances that may be contributing to the intoxication or their metabolites may be necessary to identify the intoxicating substance.
• Administration of an opioid antagonist (e.g., naloxone) may be used empirically in some settings (e.g., emergency settings) to differentiate Opioid Intoxication from intoxication with other substances.
• Psychoactive substances, whether of the same or a different pharmacological class, may interact such that they exacerbate or modify the features of intoxication. In cases of multiple psychoactive substance use in which more than one specific substance can be identified as a cause of the intoxication, it is recommended that the corresponding specific Substance Intoxication categories for each relevant substance should be assigned (e.g., 6C40.3 Alcohol Intoxication and 6C43.3 Opioid Intoxication) rather than 6C4F.3 Intoxication Due to Multiple Specified Psychoactive Substances.
• Opioid Intoxication may occur in the presence of medical conditions that cause impairment of levels of consciousness, cognition, perception, affect, behaviour, or coordination, which should be diagnosed separately. Determination of the aetiology of the disturbances in psychophysiological functions or responses may require longitudinal assessment.

Boundary with Normality (Threshold):

• Measurement of the presence or concentration of a substance in breath, blood, saliva, urine or other body fluids may be an important tool in the clinical management of Substance Intoxication. However, detection of a psychoactive substance in body fluids does not constitute a presumptive diagnosis of Substance Intoxication.

Course Features:

• The onset of Substance Intoxication varies according to the route of administration, the absorption of the substance and other pharmacokinetic factors. Generally, inhalation (smoking) and intravenous injecting routes lead to more rapid onset of intoxication, though oral ingestion may also lead to intoxication within minutes, depending on the substance.
• Substance Intoxication is a transient condition, with the duration of intoxication depending on multiple factors including: (1) the dose of the substance taken, (2) the half-life and duration of action of the particular substance, and (3) the formulation of the substance taken (e.g., for pharmaceutical preparations, whether a controlled-release drug has been taken). Intoxication may last from a few minutes up to several days following the episode of use. The intensity of intoxication lessens with time after reaching a peak of absorption, and the effects eventually disappear in the absence of further use of the substance.

Culture-Related Features:

• The degree and characteristics of intoxication displayed for a given amount of a psychoactive substance varies considerably with circumstances, with beliefs and expectations about the effects of the substance, and with the cultural acceptability of displaying these effects. These factors result in cultural differences in the extent and manifestations of intoxication.
• There are also genetic differences in susceptibility to intoxication with specific psychoactive substances associated with certain ethnic groups. Cultural and ethnically linked genetic factors have been better documented for alcohol than for other substances.

Developmental Presentations:

• Naïve users including adolescents can show features of intoxication at lower levels of use, reflecting lower physical and learned tolerance.
• Older adults may have a lower tolerance than younger people to the effects of substances.

Sex- and/or Gender-Related Features:

• The amount of substance and duration of use necessary to cause intoxication differs by sex, reflecting differences in body weight and composition.
• Behaviour while intoxicated may vary by gender, reflecting not only physiological differences, but also cultural differences and role expectations.

Boundaries with Other Disorders and Conditions (Differential Diagnosis):

• Boundary with Episode of Harmful Use of Opioids and Harmful Pattern of Use of Opioids: In Episode of Harmful Use of Opioids and Harmful Pattern of Use of Opioids, consumption or administration of opioids results in damage to the person’s physical or mental health (including a Opioid-Induced Mental Disorder) or in behaviour leading to harm to the health of others. Recovery from Opioid Intoxication is generally complete. Complications due to such effects of intoxication such as injury, the effects of hypoxia, the effects of prolonged hyperactivity or inactivity, or other tissue damage should be diagnosed as Episode of Harmful Use of Opioids or Harmful Pattern of Use of Opioids, as appropriate. If relevant at the time of the clinical encounter (e.g., in emergency settings), Opioid Intoxication can be given as an associated diagnosis, with Episode of Harmful Use of Opioids or Harmful Pattern of Use of Opioids as the primary diagnosis.
• Boundary with Opioid Dependence: Episodic or continuous intoxication with opioids is a typical feature of Opioid Dependence. If all diagnostic requirements of both conditions are met for the same episode of care, Opioid Dependence should be assigned as the primary diagnosis, with an associated diagnosis of Opioid Intoxication.
• Boundary with Opioid Withdrawal: Opioid Withdrawal occurs upon cessation or reduction of opioids in the context of physiological dependence or when opioids have been taken for a prolonged period or in large amounts. In contrast, the onset of Opioid Intoxication occurs immediately or shortly after the consumption of opioids. Moreover the intoxication and withdrawal syndromes for opioids are typically quite distinct.
• Boundary with Opioid-Induced Delirium: Delirium is characterized by disturbances in attention, orientation, and awareness that develop within a short period of time with symptoms that are transient and may fluctuate depending on the underlying aetiology. Delirium often includes disturbance of behaviour and emotion, and may include impairment in multiple cognitive domains. Disturbance of the sleep-wake cycle may also be present. Delirium can be caused by intoxication or withdrawal from substances. When symptoms of Delirium are attributable to Opioid Intoxication, an associated diagnosis of Opioid-Induced Delirium should be assigned in addition to the diagnosis of Opioid Intoxication.
• Boundary with other Opioid-Induced Mental Disorders: Mental or behavioural symptoms that arise during Opioid Intoxication should only be used as a basis for diagnosing a Opioid-Induced Mental Disorder if the intensity or duration of the symptoms is substantially in excess of those that are characteristic of Opioid Intoxication and the symptoms are sufficiently severe to warrant specific clinical attention.
• Boundary with other medical conditions: A variety of medical conditions may produce symptoms that are similar to those of Opioid Intoxication. Some of these medical conditions are life-threatening requiring immediate intervention. Evidence of opioid use (e.g., positive laboratory results) does not rule out the possibility of a comorbid medical condition. These alternative diagnoses must be considered in assessing Opioid Intoxication. Certain medical conditions may also augment or prolong the duration of intoxication. Symptoms of intoxication that persist after they can no longer be reasonably attributed to the pharmacological effects of opioids may suggest the presence of another medical condition. If it is determined that Opioid Intoxication is comorbid with a medical condition, both diagnoses should be assigned.
• Boundary with overdose: When consumption or administration of psychoactive substances results in symptoms of overdose (e.g., coma; life-threatening cardiac or respiratory suppression), it is typically more appropriate to apply a diagnosis from the grouping of Harmful Effects of Substances in the chapter on Injury, Poisoning or Certain Other Consequences of External Causes rather than Substance Intoxication.