indication

For short-term treatment of insomnia and anxiety disorders

pharmacology

Butabarbital, 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

Butabarbital binds at a distinct binding site associated with a Cl^- ionopore at the GABA_A 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.

toxicity

Signs of overdose include confusion (severe), decrease in or loss of reflexes, drowsiness (severe), fever, irritability (continuing), low body temperature, poor judgment, shortness of breath or slow or troubled breathing, slow heartbeat, slurred speech, staggering, trouble in sleeping, unusual movements of the eyes, weakness (severe).

route of elimination

Barbiturates are metabolized primarily by the hepatic microsomal enzyme system, and most metabolic products are excreted in the urine.

drug interactions

Acenocoumarol: Barbiturates like butabarbital may increase the metabolism of Vitamin K Antagonists like acenocoumarol. onitor for decreased therapeutic effects of oral anticoagulants if a barbiturate is initiated/dose increased (anticoagulant dosage increases of 30% to 60% may be needed based on monitored PT), or increased effects if a barbiturate is discontinued/dose decreased. An increased frequency of PT monitoring should be considered for the period immediately following barbiturate initiation/dosage changes.

Aminophylline: The barbiturate, butabarbital, decreases the effect of aminophylline.

Amitriptyline: Barbiturates like butabarbital may increase the metabolism of tricyclic antidepressants like amitriptyline. Monitor for decreased therapeutic effects of tricyclic antidepressants if a barbiturate is initiated/dose increased, or increased effects if a barbiturate is discontinued/dose decreased. The tricyclic antidepressant dosage will likely need to be increased during concomitant barbiturate therapy, and reduced upon barbiturate discontinuation.

Amoxapine: Barbiturates like butabarbital may increase the metabolism of tricyclic antidepressants like amoxipine. Monitor for decreased therapeutic effects of tricyclic antidepressants if a barbiturate is initiated/dose increased, or increased effects if a barbiturate is discontinued/dose decreased. The tricyclic antidepressant dosage will likely need to be increased during concomitant barbiturate therapy, and reduced upon barbiturate discontinuation.

Betamethasone: The barbiturate, butabarbital, may decrease the effect of the corticosteroid, betamethasone.

Clomifene: The enzyme inducer, butabarbital, decreases the effect of the hormone agent, clomifene.

Clomipramine: Barbiturates like butabarbital may increase the metabolism of tricyclic antidepressants like clomipramine. Monitor for decreased therapeutic effects of tricyclic antidepressants if a barbiturate is initiated/dose increased, or increased effects if a barbiturate is discontinued/dose decreased. The tricyclic antidepressant dosage will likely need to be increased during concomitant barbiturate therapy, and reduced upon barbiturate discontinuation.

Conjugated Estrogens: The enzyme inducer, butabarbital, decreases the effect of the hormone agent, conjugated estrogens.

Cyclosporine: The barbiturate, butabarbital, increases the effect of cyclosporine.

Desipramine: Barbiturates like butabarbital may increase the metabolism of tricyclic antidepressants like desipramine. Monitor for decreased therapeutic effects of tricyclic antidepressants if a barbiturate is initiated/dose increased, or increased effects if a barbiturate is discontinued/dose decreased. The tricyclic antidepressant dosage will likely need to be increased during concomitant barbiturate therapy, and reduced upon barbiturate discontinuation.

Dexamethasone: The barbiturate, butabarbital, may decrease the effect of the corticosteroid, dexamethasone.

Diethylstilbestrol: The enzyme inducer, butabarbital, decreases the effect of the hormone agent, diethylstilbestrol.

Disopyramide: arbiturates may increase the metabolism of Disopyramide. Monitor for decreased therapeutic effects of disopyramide if a barbiturate is initiated/dose increased, or increased effects if a barbiturate is discontinued/dose decreased.

Doxepin: Barbiturates like butabarbital may increase the metabolism of tricyclic antidepressants like doxepin. Monitor for decreased therapeutic effects of tricyclic antidepressants if a barbiturate is initiated/dose increased, or increased effects if a barbiturate is discontinued/dose decreased. The tricyclic antidepressant dosage will likely need to be increased during concomitant barbiturate therapy, and reduced upon barbiturate discontinuation.

Doxycycline: The anticonvulsant, butabarbital, decreases the effect of doxycycline.

Droperidol: Droperidol may enhance the CNS depressant effect of CNS Depressants like butabarbital. Consider dose reductions of droperidol or of other CNS agents (e.g., opioids, barbiturates) with concomitant use.

Estradiol: The enzyme inducer, butabarbital, decreases the effect of the hormone agent, estradiol.

Ethinyl Estradiol: This product may cause a slight decrease of contraceptive effect

Felodipine: The barbiturate, butabarbital, decreases the effect of felodipine.

Fludrocortisone: The barbiturate, butabarbital, may decrease the effect of the corticosteroid, fludrocortisone.

Folic Acid: Folic acid decreases the effect of anticonvulsant, butabarbital.

Gefitinib: The CYP3A4 inducer, butabarbital, may decrease the serum concentration and therapeutic effects of gefitinib.

Griseofulvin: The barbiturate, butabarbital, decreases the effect of griseofulvin.

Hydrocortisone: The barbiturate, butabarbital, may decrease the effect of the corticosteroid, hydrocortisone.

Hydroxyzine: Hydroxyzine may enhance the CNS depressant effect of barbiturates like butabarbital. Consider a decrease in the barbiturate dose, as appropriate, when used together with hydroxyzine. With concurrent use, monitor patients closely for excessive response to the combination.

Imipramine: Barbiturates like butabarbital may increase the metabolism of tricyclic antidepressants like imipramine. Monitor for decreased therapeutic effects of tricyclic antidepressants if a barbiturate is initiated/dose increased, or increased effects if a barbiturate is discontinued/dose decreased. The tricyclic antidepressant dosage will likely need to be increased during concomitant barbiturate therapy, and reduced upon barbiturate discontinuation.

Lamotrigine: Barbiturates like butabarbital may decrease the serum concentration of lamotrigine. There are separate patient management guidelines for patients age 12 and under and for patients older than 12 years of age. Monitor for decreased serum concentrations/therapeutic effects of lamotrigine if a barbiturate is initiated/dose increased, or increased effects if a barbiturate is discontinued/dose decreased.

Levonorgestrel: Phenobarbital decreases the effect of levonorgestrel

Medroxyprogesterone: The enzyme inducer, butabarbital, decreases the effect of the hormone agent, medroxyprogesterone.

Megestrol: The enzyme inducer, butabarbital, decreases the effect of the hormone agent, megestrol.

Methadone: The barbiturate, butabarbital, decreases the effect of methadone.

Metronidazole: The barbiturate, butabarbital, decreases the effect of metronidazole.

Nifedipine: The barbiturate, butabarbital, decreases the effect of the calcium channel blocker, nifedipine.

Norethindrone: This product may cause a slight decrease of contraceptive effect

Nortriptyline: Barbiturates like butabarbital may increase the metabolism of tricyclic antidepressants like nortriptyline. Monitor for decreased therapeutic effects of tricyclic antidepressants if a barbiturate is initiated/dose increased, or increased effects if a barbiturate is discontinued/dose decreased. The tricyclic antidepressant dosage will likely need to be increased during concomitant barbiturate therapy, and reduced upon barbiturate discontinuation.

Oxtriphylline: The barbiturate, butabarbital, decreases the effect of oxtriphylline.

Prednisolone: The barbiturate, butabarbital, may decrease the effect of the corticosteroid, prednisolone.

Prednisone: The barbiturate, butabarbital, may decrease the effect of the corticosteroid, prednisone.

Protriptyline: Barbiturates like butabarbital may increase the metabolism of tricyclic antidepressants like protriptyline. Monitor for decreased therapeutic effects of tricyclic antidepressants if a barbiturate is initiated/dose increased, or increased effects if a barbiturate is discontinued/dose decreased. The tricyclic antidepressant dosage will likely need to be increased during concomitant barbiturate therapy, and reduced upon barbiturate discontinuation.

Quinidine: The anticonvulsant, butabarbital, decreases the effect of quinidine.

Teniposide: Barbiturates like butabarbital may decrease the serum concentration of Teniposide. arbiturates may decrease the serum concentration of Teniposide.

Theophylline: The barbiturate, butabarbital, decreases the effect of theophylline.

Triamcinolone: The barbiturate, butabarbital, may decrease the effect of the corticosteroid, triamcinolone.

Trimipramine: The barbiturate, Butabarbital, may increase the metabolism and clearance of Trimipramine. Monitor for changes in the therapeutics and adverse effects of Trimipramine if Butabarbital is initiated, discontinued or dose changed. Dose adjustments of Trimipramine may be required.

Triprolidine: The CNS depressants, Triprolidine and Butabarbital, may increase adverse/toxic effects due to additivity. Monitor for increased CNS depressant effects during concomitant therapy.

Verapamil: Butabarbital, a CYP3A4 inducer, may increase the serum concentration of Verapamil, a CYP3A4 substrate. Monitor for changes in the therapeutic/adverse effects of Verapamil if Butabarbital is initiated, discontinued or dose changed.

Voriconazole: Butabarbital may reduce serum concentrations and efficacy of voriconazole. Concomitant voriconazole and long-acting barbiturates therapy is contraindicated.

Warfarin: Butabarbital may decrease the serum concentration of warfarin by increasing its metabolism. Monitor for changes in the therapeutic and adverse effects of warfarin if butabarbital is initiated, discontinued or dose changed.