Phenobarbital 15 mg Tablet, 500-count — NDC 75826-136-50 (Billing 75826-0136-50)

WARNINGS 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.

ADVERSE REACTIONS The following adverse reactions have been reported: CNS Depression: Residual sedation or "hangover," drowsiness, lethargy, and vertigo. Emotional disturbances and phobias may be accentuated. In some persons, barbiturates such as phenobarbital repeatedly produce excitement rather than depression, and the patient may appear to be inebriated.

Like other nonanalgesic hypnotic drugs, barbiturates, such as phenobarbital, when given in the presence of pain, may cause restlessness, excitement, and even delirium. Rarely, the use of barbiturates results in localized or diffused myalgic, neuralgic, or arthritic pain, especially in psychoneurotic patients with insomnia. The pain may appear in paroxysms, is most intense in the early morning hours, and is most frequently located in the region of the neck, shoulder girdle, and upper limbs.

Symptoms may last for days after the drug is discontinued. Respiratory/Circulatory: Respiratory depression, apnea, circulatory collapse. Allergic: Acquired hypersensitivity to barbiturates consists chiefly in allergic reactions that occur especially in persons who tend to have asthma, urticaria, angioedema, and similar conditions.

Hypersensitivity reactions in this category include localized swelling, particularly of the eyelids, cheeks, or lips, and erythematous dermatitis. Rarely, exfoliative dermatitis (e.g., Stevens-Johnson syndrome and toxic epidermal necrolysis) may be caused by phenobarbital and can prove fatal. The skin eruption may be associated with fever, delirium, and marked degenerative changes in the liver and other parenchymatous organs.

In a few cases, megaloblastic anemia has been associated with the chronic use of phenobarbital. Other: Nausea and vomiting; headache. To report SUSPECTED ADVERSE REACTIONS, contact Winder Laboratories, LLC at 1-770-307-0703, or FDA at 1-800-FDA-1088 or www.fda.gov/medwatch.

Drug Interactions Phenobarbital in combination with alcohol, tranquilizers, and other central nervous system depressants has additive depressant effects, and the patient should be so advised. Patients taking this drug should be warned not to exceed the dosage recommended by their physician. Toxic effects and fatalities have occurred following overdoses of phenobarbital alone and in combination with other central nervous system depressants.

Caution should be exercised in prescribing unnecessarily large amounts of phenobarbital for patients who have a history of emotional disturbances or suicidal ideation or who have misused alcohol and other CNS drugs (see OVERDOSAGE ).

PRECAUTIONS General Precautions Barbiturates induce liver microsomal enzyme activity. This accelerates the biotransformation of various drugs and is probably part of the mechanism of the tolerance encountered with barbiturates. Phenobarbital, therefore, should be used with caution in patients with decreased liver function.

This drug should also be administered cautiously to patients with a history of drug dependence or abuse (see DRUG ABUSE AND DEPENDENCE ). Phenobarbital may decrease the potency of coumarin anticoagulants; therefore, patients receiving such concomitant therapy should have more frequent prothrombin determinations. As with other sedatives and hypnotics, elderly or debilitated patients may react to barbiturates with marked excitement, depression, or confusion.

The systemic effects of exogenous hydrocortisone and endogenous hydrocortisone (cortisol) may be diminished by phenobarbital. Thus, this product should be administered with caution to patients with borderline hypoadrenal function, regardless of whether it is of pituitary or of primary adrenal origin. Information for Patients Phenobarbital may impair the mental and/or physical abilities required for the performance of potentially hazardous tasks, such as driving a car or operating machinery.

The patient should be cautioned accordingly. Drug Interactions Phenobarbital in combination with alcohol, tranquilizers, and other central nervous system depressants has additive depressant effects, and the patient should be so advised. Patients taking this drug should be warned not to exceed the dosage recommended by their physician.

Toxic effects and fatalities have occurred following overdoses of phenobarbital alone and in combination with other central nervous system depressants. Caution should be exercised in prescribing unnecessarily large amounts of phenobarbital for patients who have a history of emotional disturbances or suicidal ideation or who have misused alcohol and other CNS drugs (see OVERDOSAGE ). Usage in Pregnancy Pregnancy Category B Reproduction studies have been performed in animals and have revealed no evidence of impaired fertility or harm to the fetus due to phenobarbital.

There are, however, no adequate and well-controlled studies in pregnant women. Because animal reproduction studies are not always predictive of human response, this drug should be used during pregnancy only if clearly needed and under the supervision of a physician . Nursing Mothers Caution should be exercised when phenobarbital is administered to a nursing woman.

DRUG ABUSE AND DEPENDENCE Controlled Substance Phenobarbital is a Schedule IV drug. Dependence Prolonged, uninterrupted use of barbiturates (particularly the short-acting drugs), even in therapeutic doses, may result in psychic and physical dependence. Withdrawal symptoms due to physical dependence following chronic use of large doses of barbiturates may include delirium, convulsions, and death.

Controlled Substance Phenobarbital is a Schedule IV drug.