EUTHA-NAZE 200MG/ML INJECTION

Indications

• Short-term insomnia
• Anxiety relief
• Preoperative sedation

Dosage

Children: Refer to the BNF for Children for specific dosing guidelines.

Adults: Refer to the BNF for specific dosing guidelines.

Mechanism of action

Pentobarbital binds at a distinct binding site associated with a Cl- ionopore at the GABAA receptor, increasing the duration for which the Cl- ionopore remains open. This prolongs the post-synaptic inhibitory effect of GABA in the thalamus and decreases GABA-sensitive neuronal calcium conductance. Additionally, pentobarbital directly inhibits excitatory AMPA-type glutamate receptors, further suppressing glutamatergic neurotransmission. The overall effect is acute potentiation of inhibitory GABAergic tone, particularly in the polysynaptic midbrain reticular formation, impacting arousal mechanisms.

Pharmacodynamics

Pentobarbital induces sedation, reduces anxiety, and promotes sleep. As a CNS depressant, it facilitates drowsiness and alleviates tension or nervousness. Its analgesic properties are minimal, and in the presence of pain, it may lead to excitation, highlighting its limited utility in pain management.

Pharmacokinetics

Pentobarbital is absorbed rapidly after administration and distributed widely throughout the body, including the CNS, due to its lipophilic nature. The metabolism occurs primarily in the liver, with various pathways leading to the formation of active and inactive metabolites. The elimination half-life varies depending on individual factors, but it is generally in the range of several hours. Excretion occurs mainly via the kidneys.

Adverse effects

• Drowsiness
• Dizziness
• Respiratory depression
• Hypotension
• Nausea
• Vomiting
• Allergic reactions

Precautions

• Use with caution in patients with respiratory impairment
• Caution in patients with a history of drug abuse
• Monitor closely in elderly patients due to increased sensitivity to CNS effects

Pregnancy

Pentobarbitone is not recommended during pregnancy due to potential risks to the fetus, including effects on fetal development.

Breast-feeding

Pentobarbitone is excreted in breast milk; caution is advised when administered to breastfeeding mothers.

Storage

Store in a cool, dry place away from light. Keep out of reach of children.

Formulations

• Injectable solution
• Oral tablets

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. The exact mechanism(s) by which barbiturates exert their effect on the CNS, has not been fully elucidated. However, it is believed that such effects are related, at least partially, to the drugs' ability to enhance the activity of gamma-aminobutyric acid (GABA), the principal inhibitory neurotransmitter in the CNS, by altering inhibitory synaptic transmissions that are mediated by GABAA receptors. /Barbiturates General Statement/ Although the drugs act throughout the CNS, a site of particular sensitivity is the polysynaptic midbrain reticular formation which is concerned with the arousal mechanism. Barbiturates induce an imbalance in central inhibitory and facilitatory mechanisms influencing the cerebral cortex and the reticular formation. The significance of the effect of barbiturates on neurotransmitters is unclear. It appears that the drugs decrease the excitability of both presynaptic and postsynaptic membranes. It has not been determined which of the various actions of barbiturates at cellular and synaptic levels are responsible for their sedative and hypnotic effects. /Barbiturates General Statement/ Relatively low doses of the barbiturates depress the sensory cortex, decrease motor activity, and produce sedation and drowsiness. In some patients, however, drowsiness may be preceded by a period of transient elation, confusion, euphoria, or excitement, especially after subhypnotic doses of aprobarbital, pentobarbital, or secobarbital. /Barbiturates General Statement/ Larger doses distort judgment, cloud perception, suppress motor activity, and produce drowsiness and sleep. Still larger doses induce anesthesia. Barbiturate-induced sleep differs from physiologic sleep. Barbiturates reduce the rapid eye movement (REM) or dreaming stage of sleep. Stages III and IV sleep are also decreased. Although tolerance develops to the REM-suppressant effects during chronic administration, REM rebound occurs when the drugs are withdrawn, and the patient may experience markedly increased dreaming, nightmares, and/or insomnia. /Barbiturates General Statement/ For more Mechanism of Action (Complete) data for Pentobarbital (22 total), please visit the HSDB record page.

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.