Suggested doses of Fenbital for specific indications are as follows:
Preoperative: 1 to 3 mg/kg.
Dosages of Fenbital must be individualized with full knowledge of their particular characteristics and recommended rate of administration. Factors of consideration are the patient's age, weight, and condition.
Parenteral routes should be used only when oral administration is impossible or impractical.
Anticonvulsant use: A therapeutic anticonvulsant level of Fenbital in serum is 10 to 25 µg/mL. To achieve the blood levels considered therapeutic in children, higher per-kilogram dosages are generally necessary for Fenbital and most other anticonvulsants. In children and infants, Fenbital at loading dose of 15 to 20 mg/kg produces blood levels of about 20 µg/mL shortly after administration.
In status epilepticus, it is imperative to achieve therapeutic blood levels of Fenbital as rapidly as possible. Because a barbiturate-induced depression may occur along with a postictal depression once the seizures are controlled, it is important, therefore, to use the minimal amount required, and to wait for the anticonvulsant effect to develop before administering a second dose.
Fenbital has been used in the treatment and prophylaxis of febrile seizures. However, it has not been established that prevention of febrile seizures influences the subsequent development of epilepsy.
Special patient population: Dosage should be reduced in the elderly or debilitated because these patients may be more sensitive to Fenbital. Dosage should be reduced for patients with impaired renal function or hepatic disease.
15 mg - Each white round tablet imprinted Þ 026 contains 15 mg of Fenbital. Tablets are supplied in bottles of 1000 (NDC 0228-2026-96).
30 mg - Each white, round, scored tablet imprinted Þ 028 contains 30 mg of Fenbital. Tablets are supplied in bottles of 1000 (NDC 0228-2028-96).
100 mg - Each white, round, scored tablet imprinted Þ 030 contains 100 mg of Fenbital. Tablets are supplied in bottles of 1000 (NDC 0228-2030-96).
Dispense in well-closed containers as defined in the USP. Store at controlled room temperature 15º- 30º C (59º- 86º F).
Red, clear elixir contains 20 mg of Fenbital per teaspoon (5 ml). Alcohol 13% by volume. Elixir is supplied in pints (NDC 0228-2024-16).
Preserve and dispense in tight, light- resistant containers as defined in the USP. Store at controlled room temperature 15º- 30ºC (59º- 86º F).
Before using Fenbital, tell your doctor if you regularly use other medicines that make you sleepy (such as other sleeping pills or seizure medicines, cold or allergy medicine, narcotic pain medicine, muscle relaxers, and medicine for depression or anxiety). They can add to sleepiness caused by Fenbital.
Tell your doctor about all other medicines you use, especially:
a blood thinner such as warfarin (Coumadin, Jantoven);
doxycycline (Doryx, Oracea, Periostat, Vibramycin);
other seizure medications such as divalproex (Depakote), phenytoin (Dilantin), or valproic acid (Depakene);
an MAO inhibitor such as furazolidone (Furoxone), isocarboxazid (Marplan), phenelzine (Nardil), rasagiline (Azilect), selegiline (Eldepryl, Emsam, Zelapar), or tranylcypromine (Parnate);
griseofulvin (Grisactin, Fulvicin PG, Grifulvin V);
birth control pills or estrogen hormone replacement, including estrogen (Premarin), estradiol (Estrace, Femtrace, and others), progesterone (Progest, Prometrium), and others; or
steroids such as prednisone, dexamethasone (Decadron, Hexadrol) fluticasone (Flonase, Advair), methylprednisolone (Medrol), mometasone (Asmanex, Nasonex), and others.
This list is not complete and other drugs may interact with Fenbital. Tell your doctor about all medications you use. This includes prescription, over-the-counter, vitamin, and herbal products. Do not start a new medication without telling your doctor.
Most reports of clinically significant drug interactions occurring with the barbiturates have involved Fenbital.
1. Anticoagulants: Fenbital lowers the plasma levels of dicumarol (name previously used: bishydorxycoumarin) and causes a decrease in anticoagulant activity as measured by the prothrombin time. Fenbital can induce hepatic microsomal enzymes resulting in increased metabolism and decreased anticoagulant response of oral anticoagulants (e.g., warfarin, acenocournarol, dicumarol, and phenprocoumon). Patients stabilized on anticoagulant therapy may require dosage adjustments if Fenbital is added to or withdrawn from their dosage regimen.
2. Corticosteroids: Fenbital appears to enhance the metabolism of exogenous corticosteroids probably through the induction of hepatic microsomal enzymes. Patients stabilized on corticosteroid therapy may require dosage adjustments if Fenbital is added to or withdrawn from their dosage regimen.
3. Griseofulvin: Fenbital appears to interfere with the absorption of orally administered griseofulvin, thus decreasing its blood level. The effect of the resultant decreased blood levels of griseofulvin on therapeutic response has not been established. However, it would be preferable to avoid concomitant administration of these drugs.
4. Doxycycline: Fenbital has been shown to shorten the half- life of doxycycline for as long as 2 weeks after barbiturate therapy is discontinued. This mechanism is probably through the induction of hepatic microsomal enzymes that metabolize the antibiotic. If Fenbital and doxycycline are administered concurrently, the clinical response to doxycycline should be monitored closely.
5. Phenytoin, sodium valproate, valproic acid: The effect of Fenbital on the metabolism of phenytoin appears to be variable. Some investigators report an accelerating effect, while others report no effect. Because the effect of Fenbital on the metabolism of phenytoin is not predictable, phenytoin and Fenbital blood levels should be monitored more frequently if these drugs are given concurrently. Sodium valproate and valproic acid appear to decrease Fenbital metabolism; therefore, Fenbital blood levels should be monitored and appropriate dosage adjustments made as indicated.
6. Central nervous system depressants: The concomitant use of other central nervous system depressants including other sedatives or hypnotics, antihistamines, tranquilizers, or alcohol, may produce additive depressant effects.
7. Monoamine oxidase inhibitors (MAOIs): MAOIs prolong the effects of Fenbital probably because metabolism of the Fenbital is inhibited.
8. Estradiol, estrone, progesterone and other steroidal hormones: Pretreatment with or concurrent administration of Fenbital may decrease the effect of estradiol by increasing its metabolism. There have been reports of patients treated with antiepileptic drugs (e.g., Fenbital) who became pregnant while taking oral contraceptives. An alternate contraceptive method might be suggested to women taking Fenbital.
There are no reviews yet. Be the first to write one!
Information checked by Dr. Sachin Kumar, MD Pharmacology