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Drug overdose Classification and external resources
ICD-9	960-979

The term drug overdose (or simply overdose or OD) describes the ingestion or application of a drug or other substance in quantities greater than are recommended or generally practiced. An overdose is widely considered harmful and dangerous as it can result in death.

Contents 1 Types 2 Symptoms 3 Diagnosis 4 First aid 4.1 Depressants 4.1.1 Benzodiazepines 4.2 Stimulants 5 Prevention 6 Misconceptions 7 Causes 8 Statistics 9 See also 10 References 11 External links

Types

The word "overdose" implies that there is a safe dosage; therefore, the term is commonly only applied to drugs, not poison. Drug overdoses are sometimes caused intentionally to commit suicide or as self-harm, but many drug overdoses are accidental and are usually the result of either irresponsible behavior or the misreading of product labels. Drug overdose often happens as a result of the use of multiple drugs with counter indications simultaneously (for instance, heroin/certain prescription pain medications and cocaine/amphetamines/alcohol.) Usage of illicit drugs that are of unexpected purity, in large quantities, or after a period of abstinence can also induce overdose. Cocaine users that inject intravenous can overdose accidentally as the margin between an optimal flash and an overdose is small.^[1]

A common unintentional overdose in young children involves multi-vitamins containing iron. Iron is a component of the hemoglobin molecule in blood, used to transport oxygen to living cells. When taken in small amounts, iron allows the body to replenish hemoglobin, but in large amounts it causes severe pH imbalances in the body. If this overdose is not treated with chelation therapy, it can lead to death or permanent coma.

Symptoms

Symptoms of overdose occur in various forms:

• Exaggerated form of normal action (e.g., sleepiness on antiepileptics, hypoglycemia on insulin)
• Other effects due to chemical properties of the medication (e.g., metabolic acidosis in aspirin, liver failure due to paracetamol)
• Non-specific symptoms due to central nervous system irritation (e.g., confusion, vertigo, nausea, vomiting, delirium, seizures)

Diagnosis

Diagnosis of an overdosed patient is generally straightforward if the drug is known. However, it can be very difficult if the patient cannot (or refuses to) state what drug they have overdosed on. At times, certain symptoms and signs exhibited by the patient, or blood tests, can reveal the drug in question. Even without knowing the drug, most patients can be treated with general supportive measures.

In some instances, antidotes may be administered if there is sufficient indication that the patient has overdosed on a particular type of medication.

First aid

Depressants

First aid may prevent a death from overdose of depressants. The common drugs in this category include opiates (ie. heroin, morphine and methadone), alcohol, and certain prescription drugs (such as Benzodiazepines). Signs of overdose are those of a depressed central nervous system — slow, infrequent or shallow breathing, blue lips or fingernails, cold or pale skin, slow or faint pulse, snoring or gurgling noises, and the inability to be aroused from nodding off (unresponsiveness).

• If there is no initial response, check to make sure their airway is not blocked and see if they are breathing.
• If insufficient breathing or a weak or non-existent pulse, commence cardiopulmonary resuscitation.^[2]Modern CPR methods suggest a lack of normal breathing only (i.e. no pulse check necessary), because detecting a faint pulse can be difficult for a layperson. However, if these signs are present, roll the person in question on his/her side into the recovery position.
• Call an ambulance. Ideally, someone should call an ambulance immediately while another person evaluates the patient and performs CPR if necessary.

Benzodiazepines

Benzodiazepine overdose can either be intentional, accidental, or iatrogenic in nature. Flumazenil can reverse all the effects of benzodiazepines due to its specific competitive benzodiazepine receptor antagonist properties. The initial treatment, as well as diagnosis of benzodiazepine overdose, can be achieved via incremental intravenous bolus injections of flumazenil in the range of 0.1 to 0.3 mg. These dose ranges are generally well tolerated and effective in the diagnosis and treatment of benzodiazepine overdose. Many benzodiazepines are longer-acting than flumazenil, and therefore there is a significant risk of relapse into coma or respiratory depression as the flumazenil wears off. Additional boluses of flumazenil or else an infusion (0.3 to 0.5 mg/h) therefore may need to be given, depending on the half-life of the benzodiazepine. Careful monitoring after flumazenil therapy has been discontinued is warranted in order to avoid relapse of the clinical condition. In neonates and small children, intravenous flumazenil of 10 to 20 μg/kg is an effective dose range for benzodiazepine overdose. Alternative routes of administration are intramuscular, oral (20 to 25 mg three times daily or as required), and rectal, which may be used as alternatives in long-term regimens. Flumazenil can precipitate seizures in patients that have taken mixed overdoses of carbamazepine or tricyclic antidepressants; flumazenil can also precipitate benzodiazepine withdrawal symptoms; however these complications of flumazenil administration can be avoided via a careful flumazenil dose titration. Flumazenil therefore is a relatively safe and very effective treatment of benzodiazepine overdose, provided it is carried out by an experienced and knowledgeable physician in a suitable clinical environment.^[3]

Patients suspected of overdosing on benzodiazepines that are showing significant impairment of consciousness and respiratory depression and that are likely to need endotracheal intubation and be admitted to intensive care should be considered for flumazenil therapeutic treatment to avoid intubation and artificial ventilation. The decision to administer flumazenil to a suspected benzodiazepine-overdosed patient should be made after a comprehensive clinical evaluation including a complete clinical and biochemical evaluation of the respiratory status and the patient's ability to protect his or her own airway. Flumazenil, however, should be avoided in patients suspected of taking proconvulsant drugs, e.g., tricyclic antidepressants, and patients with a history of epilepsy. Flumazenil should also be avoided in patients that have a physical dependency on benzodiazepines, as flumazenil may precipitate an acute withdrawal syndrome due to rapidly displacing benzodiazepines from the benzodiazepine receptor, thus potentially triggering severe seizures. Flumazenil should be administrated gradually and carefully to avoid any potentially serious adverse reactions associated with flumazenil usage. The minimum effective dose should be given to patients to avoid the common unpleasant psychological effects of flumazenil administration, and also to avoid potentially serious side-effects. Patients may become agitated after awakening from flumazenil and may try to leave the treatment environment. In these cases clinicians should warn the patient that leaving the facility may result in re-sedation. Flumazenil should be used only where full resuscitation equipment is immediately available.^[4]

Stimulants

People can overdose on stimulants, such as amphetamines, and cocaine, with symptoms such as rapid heartbeat, muscle cramps, seizures, paranoia, psychosis, confusion, loss of control of movement, vomiting, lack of consciousness, and possibly cardiac arrest. It can result in an often fatal condition known as excited delirium.

First aid in these cases involves staying with the person and helping them to remain calm. Move them to a quiet area, and where possible, apply a wet cloth to their neck or forehead. If unconscious, place them in the recovery position and call an ambulance.^[2]

Prevention

• Refrain from mixing depressant drugs like alcohol, barbiturates, benzodiazepines, and opiates together. ^[5]
• Start with small amounts, in order to estimate the potency of a drug.
• Be careful when taking a drug after a period of abstinence, as your tolerance may be drastically lowered.
• If you have a pharmaceutical chemical, make sure it is not expired. Toxicity can increase drastically.

Misconceptions

Deaths caused by adulterated drugs, most commonly heroin, are often incorrectly attributed to overdose.

Negative drug-drug interactions have sometimes been misdiagnosed as an acute drug overdose, occasionally leading to the assumption of suicide. ^[6]

Additionally, recent psychological research indicates that "overdose" may be, in many cases, a misnomer. Most deaths attributed to heroin overdose, for example, are not technically due to "overdose" in the pharmacological sense: in most cases, Canadian researcher Shepard Siegel found, heroin abusers died taking the same dose of heroin they normally injected. The principles of classical conditioning may provide a framework for understanding how heroin abusers can die taking the same dose of heroin they have taken many times before. There is compelling evidence that taking heroin in a new or different environment than usual may lead to overdose. In the terms of Pavlovian conditioning, the environment where the addict usually takes the drug (for example, if he always injects in the same room with the same people) serves as the conditioned stimulus, while the drug effect of heroin serves as the unconditioned stimulus. The body tends to try to maintain homeostasis, so it creates a compensatory response to counteract the effects of the drug. In the case of heroin, which decreases pain sensitivity and slows breathing, the body's compensatory response would be to increase pain sensitivity and speed up breathing. As the environment (CS) and drug effect (US) are paired over and over, the environment alone becomes sufficient to evoke the body's compensatory response to heroin. This compensatory response, triggered by the environmental cues alone, is the conditioned response. As Pavlov's dogs learned the salivate at the ring of a bell because the bell was often paired with food, a heroin user's body creates a chemical, opposing response to heroin when the proper environmental cues are present. For this reason, the heroin abuser becomes able to take larger and larger doses of the drug, because his body creates a stronger and stronger compensatory response to its effects. "Overdose" often (more than half the time) occurs when the heroin abuser injects in a new environment. In this case, the environmental cues are not present, so the body does not produce the compensatory response required to make the usual large dose of heroin tolerable. The result is often death.^[7]

Combined Drug Intoxication or Multiple Drug Intake, is mistakenly reported by news media as Drug overdose, but it is not the same. CDI does not require drug overdose to kill a person. Death is caused by the simultaneous use of too many drugs.

One of the most common drugs to be implicated in Combined Drug Intoxication deaths, or in non-lethal overdoses causing harm to the body is acetaminophen (or paracetamol as it is known in some countries), an analgesic that is available over the counter. While considered harmless and beneficial when taken at recommended dosages, acetaminophen can be acutely toxic to the liver when taken in amounts exceeding its recommended dosage; this toxicity is compounded when the drug is taken in combination with alcoholic beverages, especially by chronic drinkers and people with preexisting liver disease such as hepatitis. In addition, long-term use of acetaminophen at high dosage (and especially concurrent with alcohol) is a common cause of chronic damage to the liver. See the main article on Paracetamol for more information.

Since Paracetamol is not considered, by itself, an addictive medication, complications arising from its overuse are often referred to in medical literature as Paracetamol Poisoning. However, since paracetamol is often contained in formulations which contain other drugs with a high potential for abuse, it is often ingested in amounts far exceeding its therapeutic dose in order to get a "high" from the coexisting drug. Examples include over-the-counter cough syrup and cold remedies which include, along with paracetamol, dextromethorphan, a cough suppressant that, when taken in high amounts, can cause hallucinations and euphoria (the name dextromethorphan is often abbreviated as "DXM", particularly among those who abuse it.) Because of its availability as an over-the-counter preparation in most jurisdictions (in brands such as Robitussin), DXM abuse is particularly popular among teenagers because it is easy to obtain. Many preparations contain DXM by itself, without paracetamol, or with other medications which are less dangerous like Guaifenesin, making them seemingly 'safer' to take; however, other common ingredients in cough/cold remedies can be dangerous as well, particularly pseudoephedrine. It is common for a user to ingest an entire bottle of DXM-containing syrup to obtain the amount needed to get the wanted effects, which can deliver a dose of paracetamol (when present in the formulation) that is well above levels that can cause acute toxicity. Refer to the main article on DXM abuse for more information.

Paracetamol is also combined with many narcotic analgesics that are, in most countries, strictly regulated as controlled substances because of their highly abusive potential. When patients or recreational users of these medications (examples include the brand names Vicodin, Darvocet, and Percocet) ingest these drug combinations in large amounts, they risk acute paracetamol poisoning (and sometimes overdose of the desired narcotic) or, over time, chronic hepatic damage. The abuse of these medications is on the increase, despite the fact that most physicians who prescribe them supply the patient with only a limited quantity in order to prevent their potential for chronic use and abuse. However, it is relatively simple for a user to find supplies of these medications, either on the street or by "jumping" from one physician to the other; dentists are often approached for prescriptions, since narcotic medications are given quite frequently to patients with dental pain, due to their efficacy in pain management for many dental problems. However, most dentists give prescriptions for a very limited supply of a narcotic analgesic, because, with treatment, most cases of tooth pain are relatively short-lived. NSDEA

Causes

Common types of drugs that are overdosed on:

• Barbiturates
  • Seconal
  • Nembutal
• Benzodiazepines
  • Temazepam
  • Triazolam
• Narcotics
  • Morphine
  • Heroin
• Stimulants
  • Methamphetamine
  • Cocaine
• Ethyl Alcohol
  • Alcoholic beverages
• Prescription drugs
  • Drug "cocktails", or a combination of numerous drugs

Statistics

While they do not give separate figures for drug overdoses and other kinds of accidental poisoning, the National Center for Health Statistics report that 19,250 out of 30,000 people died of accidental poisoning in the U.S. in the year 2004.^[8]

See also

• List of deaths by accidental drug overdose
• Combined Drug Intoxication
• Suicide

References

External links

• Fact sheets on illicit drugs, overdose prevention, detox and harm reduction strategies.

Wikipedia content modification information:

• This page was last modified on 20 August 2008, at 18:25.

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