1. MARIA FE SALVADOR NAVARRETE MD
BIOLOGICALTHERAPIES

2. Barbiturates and Similarly Acting
Drugs
 used as sedative-hypnotic agents in 20th century
 high abuse and addiction potential,
 a narrow therapeutic range with low therapeutic index,
 and unfavorable side effects.
 The use of barbiturates and similar compounds such as
meprobamate (Miltown) has been practically eliminated by
the benzodiazepines,
 buspirone (BuSpar), and hypnotics such as zolpidem
(Ambien) and zaleplon (Sonata), which have a lower abuse
potential and a higher therapeutic index than the
barbiturates.
 the barbiturates and similarly acting drugs still have a role
in the treatment of certain mental disorders.

3. Pharmacologic Actions
 well absorbed after oral administration.
 The binding of barbiturates to plasma proteins is high, but
lipid solubility varies.
 metabolized by the liver and excreted by the kidneys.
 The half-lives of specific barbiturates range from 1 to 120
hours (Table 36.8-1).
 Barbiturates may also induce hepatic enzymes (cytochrome
P450), thereby reducing the levels of both the barbiturate
and any other concurrently administered drugs
metabolized by the liver.
 The mechanism of action of barbiturates involves the γ-
aminobutyric acid (GABA) receptor–benzodiazepine
receptor–chloride ion channel complex.

4. Therapeutic Indications:
Electroconvulsive Therapy
 Methohexital (Brevital) is commonly used as an
anesthetic agent for electroconvulsive therapy
(ECT).
 It has lower cardiac risks
 Used intravenously, methohexital produces rapid
unconsciousness and, because of rapid
redistribution, it has a brief duration of action (5
to 7 minutes)
 Typical dosing for ECT is 0.7 to 1.2 mg/kg.
Methohexital can also be used to abort
prolonged seizures in ECT or to limit postictal
agitation.

5. Seizures
 Phenobarbital (Solfoton, Luminal), the most
commonly used barbiturate for treatment of
seizures, has indications for the treatment of
generalized tonic-clonic and simple partial
seizures.
 Parenteral barbiturates are used in the
emergency management of seizures
independent of cause. Intravenous (IV)
phenobarbital should be administered slowly,
10 to 20 mg/kg for status epilepticus.

6. Narcoanalysis
 Amobarbital (Amytal) has been used
historically as a diagnostic aid in a number of
clinical conditions,
 including conversion reactions,
 catatonia,
 hysterical stupor,
 and unexplained muteness,
 and to differentiate stupor of depression,
 schizophrenia, and structural brain lesions.

7. SLEEP
 The barbiturates reduce sleep latency and the
number of awakenings during sleep, although
tolerance to these effects generally develops
within 2 weeks.
 Discontinuation of barbiturates often leads
to rebound increases on
electroencephalogram (EEG) measures of
sleep and a worsening of the insomnia.