What are Barbiturates?

The hustle and bustle of everyday life creates stress in many people. To reduce stress, some people turn to drugs to bring back a feeling of calm. Alcohol is one drug people use to deal with stress; another class of drugs is called the "barbiturates." These drugs act to depress the central nervous system and are often called sleeping pills.

The first barbiturates were made in the 1860s by the Bayer laboratories in Germany. In 1903, the first barbiturate ("barbital") was used in medical practices. In 1912, a common barbiturate, Phenobarbital, was introduced.

There are many different types of barbiturates. The names of some common ones (and brand names) include Pentobarbital (Nembutal), Secobarbital (Seconal), Amobarbital (Amytal) and Phenobarbital (Luminal); slang names for these barbiturates include yellow jackets, reds, blues, Amy's, and rainbows.

Barbiturates have been used extensively in the past as sedatives. A new group of drugs called "benzodiazepines" has replaced many of the barbiturates. However, barbiturates are still used to treat some types of epilepsy.

Image courtesy of the
Indiana Prevention Resource Center

Image courtesy of the
Indiana Prevention Resource Center

Behavioral Effects of Barbiturates

Barbiturates have several effects on behavior depending on the dose:

In low doses: barbiturates reduce anxiety; reduce respiration, reduce blood pressure, reduce heart rate and reduce rapid eye movement (REM)sleep.

In higher doses: barbiturates can actually increase some types of behavior and act like a stimulant. These effects may be caused by depression of inhibitory brain circuits. In other words, barbiturates at these doses act to remove inhibitory behavior.

Barbiturates can lead to excessive sedation and cause anesthesia, coma and even death. Barbiturate overdoses may occur because the effective dose of the drug is not too far away from the lethal dose.

A major problem with barbiturates is that they may lead to tolerance and dependence. Tolerance occurs when a greater and greater amount of the drug is required to get the desired effect. For example, if barbiturates are used to help a person sleep, over time, a greater dose of the drug will be needed to get the person to sleep. Dependence occurs when a person feels like he or she must use the drug and withdrawal symptoms occur when the person stops using the drug.

Withdrawal symptoms that occur when people try to "kick the habit" of using barbiturates include:

  • anxiety
  • insomnia
  • seizures
  • nausea, stomach problems
  • hallucinations

Effects of Barbiturates on the Brain

Barbiturates dissolve easily in fat. Therefore, barbiturates have ready access to the brain because they can cross the blood brain barrier easily. Also, because barbiturates dissolve into body fat, they can accumulate and re-enter the blood stream later. Different barbiturates clear out of the blood stream at different rates.

Although the exact mechanisms by which barbiturates affect the brain are not understood, it is thought that these drugs bind to sodium channels on neurons and prevent the flow of sodium ions. Because sodium ions cannot flow across the neuronal membrane, action potentials cannot be produced.

Barbiturates may also increase the flow of chloride ions across the neuronal membrane. This may occur through binding to the receptor for the neurotransmitter called GABA. The increased chloride ion flow reduces the chance that an action potential will be generated.

Did you know?

  • The barbiturate called sodium pentothal is known as "truth serum." However, it really does NOT cause people to tell the truth. Rather, it may lower a person's inhibitions and make people more talkative.

  • Musician Jimi Hendrix died on September 18, 1970 of a barbiturate overdose.

For more information about barbiturates, see:
  1. Prescription Medications

GO TO: Alcohol Amphetamines Caffeine Cocaine
Heroin Inhalants LSD Marijuana
Nicotine Ecstasy Rohypnol 1,4-Butanediol
GHB Barbiturates PCP Hallucinogenic Mushrooms

BACK TO: Drug Effects on
the Nervous System
Exploring the Nervous System Table of Contents

Send E-mail

Get Newsletter

Search Pages

Donate to
Neuroscience for Kids