Hypnotal - Amobarbital

Numerous barbiturates and oral hypoglycemic sulfonyl-ureas also have aliphatic side chains that arc su.sceptible to oxidation. Note that the sedative hypnotic amobarbital (Amytal) undergoes extensive to - I oxidation to the corresponding 3 -hydroxylated metabolite.Other barbiturates, such as pentobarbital, thiamylal,and secobarbital," reportedly are metabolized by way of a and to - I oxidation. The ri-propyl side chain attached to the oral hypoglycemic agent chlorpropamide (Diabinc.se) undergoes extensive to -I hydroxylation to yield the secondary alcohol 2 -hydroxy-chlorpropamide as a major urinary metabolite in humans. " ... 

Sedative and Hypnotic Combinations Tuinal—amobarbital, secobarbitol... 

The ultra-short-acting barbiturates include methohexital sodium (Brevi-tal) and thiopental sodium (Pentothal). These agents are used as anesthetics and are administered intravenously. Barbiturates with short-to-intermediate duration of action are used for their sedative-hypnotic effect in the treatment of anxiety. These medications include amobarbital (Amytal), butabarbital (Butisol), sodium pentobarbital (Nembutal), and secobarbital (Seconal). 

In this study, potential oscillation was measured in the presence of lOOmM sodium salts of barbital, allobarbital, phenobarbital, and amobarbital in phase wl [19]. Their chemical structures are shown in Fig. 15. Amplitude and the oscillatory and induction periods were noted to depend on the particular hypnotic used. Amplitude decreased in the order, barbital > allobarbital > phenobarbital > amobarbital. The oscillatory period increased in the order, barbital < allobarbital < phenobarbital < amobarbital. Induction period increased in the order, barbital < allobarbital < phenobarbital < amobarbital. These parameters changed depending on drug concentration. Hypnotics at less than 5 mM had virtually no effect on the oscillation mode. 

Amobarbital is a barbituric acid derivative of intermediate duration of action. It is administered orally in doses of 15 to 200 mg as a sedative hypnotic and in ampoules of 65 to 500 mg for intravenous and intramuscular injection for the seizure control.6 Following a single oral dose of 120 mg, peak serum concentrations averaged 1.8 mg/L after 2 h.7 After an oral dose of 600 mg distributed over a 3-h period, the peak blood concentration was achieved after 30 min, averaging 8.7 mg/L, with a decline to 4.1 mg/L by 18 h.6... 

Barbiturates are classified according to their duration of action (Figure 9.7). For example, thiopental [thye oh PEN tal], which acts within seconds and has a duration of action of about 30 minutes, is used in the intravenous induction of anesthesia. By contrast, phenobarbital [fee noe BAR bi tal], which has a duration of action greater than a day, is useful in the treatment of seizures (see p. 148). Pentobarbital [pen toe BAR bi tal], secobarbital [see koe BAR bi tal] and amobarbital [am oh BAR bi tal] are short-acting barbiturates, which are effective as sedative and hypnotic (but not antianxiety) agents. 

Baibiturates with an intermediate duration of action are used principally as sedative-hypnotics. They include Amobarbl-tal, USP, S-ethyl-S-isopentylbaibituric acid (Amytal), anil its water-soluble sodium salt. Amobarbital Sodium, USP, S-allyl-S-isopropylbarbituric acid (aprobarbital. Alunne) Butabarbitd Sodium, USP, the water-soluble sodium sail of S-sec-butyl-S-ethylbarbituric acid (Butisol Sodium). 

Barbiturates are lethal at about lO times the hypnotic dose that is about 6-10 g of phe-nobarbital or 2-3 g of secobarbital, pentobarbital, or amobarbital (3). 

Amobarbital, a barbiturate, is used as a sedative to treat insomnia and as a preanesthetic medication. The barbiturates were used extensively in the past as hypnotic-sedatives but have been replaced by the much safer benzodiazepine derivatives (see Table 9). They do continue to be used as anesthetics (e.g., thiopental) and anticonvulsants (e.g., phenobarbital). The primary mechanism of action of barbiturates is to increase inhibition through the gamma-aminobutyric acid (GABA) system (see Figure 50). Anesthetic barbiturates also decrease excitation via a decrease in calcium conductance. The most commonly used barbiturates are thiopental (Pentothal), methohexital (Brevital), secobarbital (Seconal), pentobarbital (Nembutal), amobarbital (Amytal), and phenobarbital (Luminal). 

Intermediate- acting Amobarbital sodium (Amytal Sodium) Sleep sustainers PB 50-60% half life 20-40 hours Sedative PO 30-50 mg bid-tid Hypnotic PO/IM 65-200 mg h.s., IV 65-200 mg... 

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