mechanism of action

Amobarbital (like all barbiturates) works by binding to the GABAA receptor at either the alpha or the beta sub unit. These are binding sites that are distinct from GABA itself and also distinct from the benzodiazepine binding site. Like benzodiazepines, barbiturates potentiate the effect of GABA at this receptor. This GABAA receptor binding decreases input resistance, depresses burst and tonic firing, especially in ventrobasal and intralaminar neurons, while at the same time increasing burst duration and mean conductance at individual chloride channels; this increases both the amplitude and decay time of inhibitory postsynaptic currents. In addition to this GABA-ergic effect, barbiturates also block the AMPA receptor, a subtype of glutamate receptor. Glutamate is the principal excitatory neurotransmitter in the mammalian CNS. Amobarbital also appears to bind neuronal nicotinic acetylcholine receptors.

drug interactions

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

Levonorgestrel: Phenobarbital decreases the effect of levonorgestrel

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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