Question

Compare and contrast phenobarbital to the three other barbiturates. Discuss any significant similarities and differences related to therapeutic actions,pharmacokinetics, contraindications, most common adverse reactions and important drug to drug interactions.

Answer 1

Phenobarbital	amobarbital	pentobarbital
Phenobarbital is a long-acting barbiturate which depresses the central nervous system and causes sedation and has anticonvulsant effects.	Amobarbital sodium is an intermediate-acting barbiturate used as a sedative hypnotic. As with other barbiturates, it can depress the sensory cortex, decrease motor activity, and alter cerebellar function producing drowsiness, sedation, and hypnosis.	Pentobarbital sodium is a short-acting barbiturate that decreases motor activity, depresses sensory cortex, interrupts cerebellar functions, and promotes sedation, hypnosis and drowsiness.
Contraindications
Hypersensitivity to barbiturates History of manifest or latent porphyria Marked liver impairment Respiratory disease with evidence of dyspnea or obstruction Concomitant use with rilpivirine	History of manifest or latent porphyria Hypersensitivity to barbiturates Marked liver dysfunction Marked respiratory disease in which dyspnea or obstruction is evident	History of manifest or latent porphyria Sensitivity to barbiturates
Adverse effects
Common Neurologic:Somnolence (1% to 3%) Serious Cardiovascular:Syncope (less than 1%) Dermatologic:Erythroderma Hematologic:Megaloblastic anemia (less than 1%) Hepatic:Liver damage (less than 1%) Immunologic:Hypersensitivity reaction (less than 1%) Psychiatric:Hallucinations (less than 1%) Other:Barbiturate withdrawal	Common Neurologic:Confusion, Dizziness, Headache, Somnolence Serious Dermatologic:Stevens-Johnson syndrome (rare) Hematologic:Agranulocytosis (rare), Megaloblastic anemia, With prolonged use (rare) Hepatic:Injury of liver, With prolonged use (rare) Respiratory:Apnea, Hypoventilation	Common Neurologic:Confusion (less than 1%), Dizziness (less than 1%), Somnolence (1% to 3%) Psychiatric:Agitation (less than 1%) Serious Dermatologic:Stevens-Johnson syndrome (less than 1%) Hematologic:Megaloblastic anemia (less than 1%) Hepatic:Injury of liver (less than 1%) Respiratory:Apnea (less than 1%), Hypoventilation (less than 1%)