Phenobarbital Tablets, USP

Rev. 10/12 C_IV
R_x only

Phenobarbital is a barbituric acid derivative for oral administration and occurs as a white, odorless, slightly bitter powder that is soluble in chloroform, freely soluble in alcohol or ether, and slightly soluble in water. Its saturated solution has a pH of about 5.6. Chemically, it is 5-ethyl-5-phenylbarbituric acid with the molecular formula C₁₂H₁₂N₂O₃ (232.24). The structural formula is as follows:

Each Phenobarbital Tablet, USP contains 15 mg, 30 mg, 60 mg or 100 mg of phenobarbital, USP. Inactive ingredients are as follows:
15 mg, 30 and 60 mg: Calcium Stearate, Colloidal Silicon Dioxide, Corn Starch, and Microcrystalline Cellulose.
100 mg: Anhydrous Lactose, Colloidal Silicon Dioxide, Corn Starch, Docusate Sodium, Lactose Monohydrate, Magnesium Stearate, Microcrystalline Cellulose, and Sodium Starch Glycolate.

Phenobarbital, a long-acting barbiturate, is a central nervous system depressant. In ordinary doses, the drug acts as a sedative and anticonvulsant. Its onset of action occurs within 30 minutes, and the duration of action ranges from 5 to 6 hours. It is detoxified in the liver.

Phenobarbital Tablets, USP are indicated for use as a sedative or anticonvulsant.

Phenobarbital is contraindicated in patients who are hypersensitive to barbiturates. In such patients, severe hepatic damage can occur from ordinary doses and is usually associated with dermatitis and involvement of parenchymatous organs. A personal or familial history of acute intermittent porphyria represents one of the few absolute contraindications to the use of barbiturates. Phenobarbital is also contraindicated in patients with marked impairment of liver function, or respiratory disease in which dyspnea or obstruction is evident. It should not be administered to persons with known previous addiction to the sedative/hypnotic group, since ordinary doses may be ineffectual and may contribute to further addiction.

In small doses, the barbiturates may increase the reaction to painful stimuli. Taken by themselves, the barbiturates cannot be relied upon to relieve pain or even to produce sedation or sleep in the presence of severe pain.

The following adverse reactions have been reported:

Controlled Substance – Phenobarbital is a Schedule IV drug.

The signs and symptoms of barbiturate poisoning are referable especially to the central nervous system and the cardiovascular system. Moderate intoxication resembles alcoholic inebriation. In severe intoxication, the patient is comatose, the level of reflex activity conforming in a general way to the intensity of the central depression. The deep reflexes may persist for some time despite coexistent coma. The Babinski sign is often positive. The EEG may be of the “burst-suppression” type, with brief periods of electrical silence. The pupils may be constricted and react to light, but late in the courage of barbiturate poisoning they may show hypoxic paralytic dilatation. Respiration is affected early. Breathing may be either slow or rapid and shallow; Cheyne-Stokes rhythm may be present. Respiratory minute volume is diminished, and hypoxia and respiratory acidosis may develop. The blood pressure falls, owing partly to depression of medullary vasomotor centers; partly to a direct action of the drug on the myocardium, sympathetic ganglia, and vascular smooth muscle; partly to hypoxia.

The patient thus develops a typical shock syndrome, with a weak and rapid pulse, cold and clammy skin, and a rise in the hematocrit. Respiratory complications (atelectasis, pulmonary edema, and bronchopneumonia) and renal failure are much dreaded and not infrequent concomitant of severe barbiturate poisoning. There is usually hypothermia, sometimes with temperatures as low as 32°C.

Oral Sedative Dose, Adults – 30 to 120 mg daily in 2 or 3 divided doses. Children – 6 mg/kg of body weight daily in 3 divided doses.

Oral Hypnotic Dose, Adults – 100 to 320 mg.

Oral Anticonvulsant Dose, Adults – 50 to 100 mg 2 or 3 times daily.

Children – 15 to 50 mg 2 or 3 times daily.

Phenobarbital Tablets, USP 15 mg: White, Round Tablet; Debossed “West-ward 445” on one side and plain on the other side.

Bottles of 100 and 1000 tablets

Phenobarbital Tablets, USP 30 mg: White, Round, Scored Tablet; Debossed “West-ward 450” on one side and Scored on the other side.

Bottles of 100 and 1000 tablets

Phenobarbital Tablets, USP 60 mg: White, Round Tablet; Debossed “WW 455” on one side and plain on the other side.

Bottles of 100 and 1000 tablets

Phenobarbital Tablets, USP 100 mg: White, Round, Scored Tablet; Debossed “WW 458” on one side and Scored on the other side.

Bottles of 100 and 1000 tablets

Store at 20-25°C (68-77°F) [See USP Controlled Room Temperature]. Protect from light and moisture.

Dispense in a tight, light-resistant container as defined in the USP using a child-resistant closure.

Manufactured by:
West-ward Pharmaceutical Corp.

Eatontown, NJ 07724

Revised March 2012

Phenobarbital Tablets, USP 15 mg 1000s
046-6160

Phenobarbital Tablets 15 mg 1000s

Phenobarbital Tablets, USP 30mg 1000s
0463-6145

Phenobarbital Tablets 30mg 1000s

Phenobarbital Tablets, USP 60 mg 1000s
0463-6151

Phenobarbital Tablets 60mg 1000s

Phenobarbital Tablets, USP 100 mg 100s
0463-6152

Phenobarbital Tablets 100mg 100s