The primary differences among many of these products are how fast they produce an effect and how long those effects last. Barbiturates are classified as ultra short, short, intermediate and long-acting. The ultra short-acting barbiturates produce anesthesia within about one minute after intravenous administration. After oral administration, the onset of action is from 15 to 40 minutes and the effects last up to 6 hours. These drugs are primarily used for sedation or to induce sleep.
Veterinarians use pentobarbital for anesthesia and euthanasia.
Effects of these drugs are realized in about one hour land last for about 12 hours and are use primarily for daytime sedation and the treatment of seizure disorders or mild anxiety. Experience showed, however, that their addiction liability and the severity of withdrawal symptoms were similar to those of barbiturates. Excessive use leads to tolerance, dependence and withdrawal symptoms similar to those of barbiturates. Overdose by glutethimide and methaqualone is more difficult to treat than barbiturate overdose, and deaths have frequently occurred. In 1991, glutethimide was transferred into Schedule II in response to an upsurge in the prevalence of diversion, abuse and overdose deaths.