Mephobarbital
editIndication
editFor the relief of anxiety, tension, and apprehension, also used as an anticonvulsant for the treatment of epilepsy.
Pharmacology
editR-mephobarbital, a barbiturate, is used in combination with acetaminophen or aspirin and caffeine for its sedative and relaxant effects in the treatment of tension headaches, migraines, and pain. Barbiturates act as nonselective depressants of the central nervous system (CNS), capable of producing all levels of CNS mood alteration from excitation to mild sedation, hypnosis, and deep coma. In sufficiently high therapeutic doses, barbiturates induce anesthesia.
Mechanism of Action
editR-mephobarbital 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.
Absorption
editApproximately 50% of an oral dose of mephobarbital is absorbed from the gastrointestinal tract.
Biotransformation
editAbout 75% of a single oral dose of mephobarbital is metabolized to phenobarbital in 24 hours.
Primidone
editIndication
editFor the treatment of epilepsy
Pharmacology
editPrimidone is a barbiturate with anticonvulsant properties. Primidone, either alone or used concomitantly with other anticonvulsants, is indicated in the control of grand mal, psychomotor, and focal epileptic seizures. It may control grand mal seizures refractory to other anticonvulsant therapy. Primidone raises electro- or chemoshock seizure thresholds or alters seizure patterns in experimental animals. Primidone per se has anticonvulsant activity as do its two metabolites, phenobarbital and phenylethylmalonamide (PEMA). In addition to its anticonvulsant activity, Primidone potentiates that of phenobarbital in experimental animals.
Mechanism of Action
editPrimidone is a GABA receptor agonist. The mechanism of Primidone's antiepileptic action is not known.
Metharbital
editIndication
editFor the treatment of epilepsy
Pharmacology
editMetharbital, 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
editMetharbital 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.
Barbiturates used as anesthetics:
- N01AF01 Methohexital
- N01AF02 Hexobarbital
- N01AF03 Thiopental
Barbiturates used as antiepileptics:
- N03AA01 Methylphenobarbital
- N03AA02 Phenobarbital
- N03AA03 Primidone
- N03AA04 Barbexaclone
- N03AA30 Metharbital
Barbiturates used as antiepileptics:
- N05CA01 Pentobarbital
- N05CA02 Amobarbital
- N05CA03 Butobarbital
- N05CA04 Barbital
- N05CA05 Aprobarbital
- N05CA06 Secobarbital
- N05CA07 Talbutal
- N05CA08 Vinylbital
- N05CA09 Vinbarbital
- N05CA10 Cyclobarbital
- N05CA11 Heptabarbital
- N05CA12 Reposal
- N05CA15 Methohexital
- N05CA16 Hexobarbital
- N05CA19 Thiopental
- N05CA20 Etallobarbital
- N05CA21 Allobarbital
- N05CA22 Proxibarbal
- N05CA24 Phenobarbital