Pentobarbitone- Drug acting on CNS, Barbiturates and its pharmacology

                 
Introduction
A short-acting barbiturate that is effective as a sedative and hypnotic (but not as an anti-anxiety) agent and is usually given orally.

 THERAPEUTIC USES

• Sedative
• Hypnotic for short term
• Preanesthetic
• Control of convulsions in emergencies
• Also used as a veterinary anesthetic agent

SIDE EFFECT

• Confusion, agitation, hallucinations
• Weak or shallow breathing
• Drowsiness, dizziness
• Nausea, vomiting, constipation
• Sleep problems

PHARMACOKINETICS

• Bioavailability                                  70-90% oral; 90% rectal
• Protein binding                                20-45%
• Metabolism                                       Hepatic 
• Biological half-life                             15-48 hours
• Excretion                                             Renal

       
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 thr 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. The net result of barbiturate action is acute potentiation of inhibitory GABAergic tone.

DRUG-DRUG INTERACTION
Pentobarbital +Aliskiren= It may increase the hypotensive activities of Aliskiren.
Pentobarbital +Amitriptyline= The metabolism of Amitriptyline can be increased                                                                         
                                                         When combine with pentobarbital.
Pentobarbital +Acebutolol= The serum concentration of Acebutolol can be
                                                     Decreased when combine with pentobarbital.       

REFERENCE

Tripathi K.D,"Essentials of medical pharmacology",7th edition,page no.398