Barbiturate overdose

Barbiturate overdose
barbiturate poisoning, barbiturate toxicity
Molecular diagram of phenobarbital
Specialty	Emergency medicine
Symptoms	decrease breathing, decreased level of consciousness
Duration	6 to 12 hours
Causes	accidental, suicide
Diagnostic method	blood or urine tests
Treatment	breathing support, activated charcoal
Frequency	uncommon
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Barbiturate overdose is poisoning due to excessive doses of barbiturates. Symptoms typically include difficulty thinking, poor coordination, decreased level of consciousness, and a decreased effort to breathe (respiratory depression). Complications of overdose can include noncardiogenic pulmonary edema. If death occurs this is typically due to a lack of breathing.

Barbiturate overdose may occur by accident or purposefully in an attempt to cause death. The toxic effects are additive to those of alcohol and benzodiazepines. The lethal dose varies with a person's tolerance and how the drug is taken. The effects of barbiturates occur via the GABA neurotransmitter. Exposure may be verified by testing the urine or blood.

Treatment involves supporting a person's breathing and blood pressure. While there is no antidote, activated charcoal may be useful. Multiple doses of charcoal may be required.Hemodialysis may occasionally be considered.Urine alkalinisation has not been found to be useful. While once a common cause of overdose, barbiturates are now a rare cause.

Benzodiazepines increase the frequency of chloride channel opening while barbiturates increase the duration that the chloride pore remains open. If a normal pore opened once every 30 seconds to pass one chloride ion, a benzodiazepine may cause it to open once every ten seconds while a barbiturate may cause it to remain open until three ions have passed through. Separately, both of these increase the effect of the pore threefold, but together, the channel would allow three ions to pass every 10 seconds. This would exponentially increase the effect of the pore ninefold, greater than the sum of the two drugs effects.