Severe resp depression, acute intermittent porphyria. Severe renal and hepatic impairment. Intra-arterial and SC admin.
Patient w/ history or sedative/hypnotic addiction; resp disease, depression or suicidal tendencies, hypoadrenalism. Avoid abrupt withdrawal. Mild to moderate renal and hepatic impairment. Elderly or debilitated patient, childn. Pregnancy and lactation.
Monitor CBC, LFTs, mental status and seizure activity.
Symptoms: Drowsiness, dysarthria, ataxia, nystagmus, disinhibition, hypotension, hypotonia, hyporeflexia, hypothermia, absent bowel sounds, cardiac arrest, resp and CV depression, shock leading to renal failure, prolonged coma. Management: Symptomatic and supportive treatment. Admin activated charcoal w/in 1 hr prior to ingestion. Maintain adequate airway. Admin dopamine or dobutamine in severe hypotension. Perform haemodialysis or charcoal haemoperfusion in renal failure.
May reduce plasma levels of oral anticoagulants (e.g. warfarin, dicoumarol, acenocoumarol, phenprocoumon), corticosteroids, griseofulvin, doxycycline, Na valproate and valproic acid. May increase CNS depressant effect w/ phenytoin, antihistamines, sedative/hypnotics, tranquilisers. May prolong the effect w/ MAOIs. May reduce the effect of estradiol, progesterone, estrone and other steroidal hormones.
May enhance CNS depressant effect of alcohol. May reduce the effect w/ St John's wort.
May interfere w/ the results of metyrapone test, serum bilirubin estimation and phenlolamine test.
Description: Phenobarbital is a long-acting barbiturate. It depresses the sensory cortex, reduces motor activity, changes cerebellar function and produces drowsiness, sedation and hypnosis. Its anticonvulsant property is exhibited at high doses. Onset: Hypnosis: 20-60 min (oral); approx 5 min (IV). Duration: 6-10 hr (oral); 4-10 hr (IV). Pharmacokinetics: Absorption: Readily absorbed from the GI tract. Time to peak plasma concentration: Approx 2 hr (oral); w/in 4 hr (IM). Distribution: Crosses the placenta; enters breast milk. Plasma protein binding: Approx 45-60%. Metabolism: Undergoes partial hepatic metabolism via hydroxylation and glucuronide conjugation. Excretion: Via urine (approx 25% as unchanged drug). Plasma half-life: Approx 75-120 hr.
N03AA02 - phenobarbital ; Belongs to the class of barbiturates and derivatives antiepileptics.
Anon. Phenobarbital. Lexicomp Online. Hudson, Ohio. Wolters Kluwer Clinical Drug Information, Inc. https://online.lexi.com. Accessed 07/11/2014.Buckingham R (ed). Phenobarbital. Martindale: The Complete Drug Reference [online]. London. Pharmaceutical Press. https://www.medicinescomplete.com. Accessed 07/11/2014.McEvoy GK, Snow EK, Miller J et al (eds). Phenobarbital, Phenobarbital Sodium (Anticonvulsant). AHFS Drug Information (AHFS DI) [online]. American Society of Health-System Pharmacists (ASHP). https://www.medicinescomplete.com. Accessed 07/11/2014.McEvoy GK, Snow EK, Miller J et al (eds). Phenobarbital, Phenobarbital Sodium (Sedative). AHFS Drug Information (AHFS DI) [online]. American Society of Health-System Pharmacists (ASHP). https://www.medicinescomplete.com. Accessed 07/11/2014.Phenobarbital Elixir (Qualitest Pharmaceuticals). DailyMed. Source: U.S. National Library of Medicine. https://dailymed.nlm.nih.gov/dailymed/. Accessed 07/11/2014.Phenobarbital Sodium Injection (West-ward Pharmaceutical Corp.). DailyMed. Source: U.S. National Library of Medicine. https://dailymed.nlm.nih.gov/dailymed/. Accessed 07/11/2014.Phenobarbital Tablet (American Health Packaging). DailyMed. Source: U.S. National Library of Medicine. https://dailymed.nlm.nih.gov/dailymed/. Accessed 07/11/2014.