| Indication | For the short-term treatment of insomnia. |
| Pharmacodynamics | Pentobarbital, a barbiturate, is used for the treatment of short term insomnia. It belongs to a group of medicines called central nervous system (CNS) depressants that induce drowsiness and relieve tension or nervousness. Little analgesia is conferred by barbiturates; their use in the presence of pain may result in excitation. |
| Mechanism of action | Pentobarbital binds at a distinct binding site associated with a Cl- ionopore at the GABAA receptor, increasing the duration of time for which the Cl- ionopore is open. The post-synaptic inhibitory effect of GABA in the thalamus is, therefore, prolonged. All of these effects are associated with marked decreases in GABA-sensitive neuronal calcium conductance (gCa). The net result of barbiturate action is acute potentiation of inhibitory GABAergic tone. Barbiturates also act through potent (if less well characterized) and direct inhibition of excitatory AMPA-type glutamate receptors, resulting in a profound suppression of glutamatergic neurotransmission. |
| Absorption | Barbiturates are absorbed in varying degrees following oral, rectal, or parenteral administration. |
| Volume of distribution | Not Available |
| Protein binding | Not Available |
| Metabolism | by hepatic microsomal enzyme system |
| Route of elimination | Barbiturates are metabolized primarily by the hepatic microsomal enzyme system, and the metabolic products are excreted in the urine, and less commonly, in the feces. Approximately 25 to 50 percent of a dose of aprobarbital or phenobarbital is eliminated unchanged in the urine, whereas the amount of other barbiturates excreted unchanged in the urine is negligible. |
| Half life | 5 to 50 hours (dose dependent) |
| Clearance | Not Available |
| Toxicity | Symptoms of an overdose typically include sluggishness, incoordination, difficulty in thinking, slowness of speech, faulty judgment, drowsiness or coma, shallow breathing, staggering, and in severe cases coma and death. |