SIDE EFFECTS
Frequently Observed
The most frequently reported adverse reactions are drowsiness,
lightheadedness, dizziness, sedation, shortness of breath, nausea, vomiting,
abdominal pain, and intoxicated feeling.
Infrequently Observed
All adverse events tabulated below are classified as
infrequent.
Central Nervous System: headache, shaky feeling,
tingling, agitation, fainting, fatigue, heavy eyelids, high energy, hot spells,
numbness, sluggishness, seizure. Mental confusion, excitement or depression can
also occur due to intolerance, particularly in elderly or debilitated patients,
or due to overdosage of butalbital.
Autonomic Nervous System: dry mouth,
hyperhidrosis.
Gastrointestinal: difficulty swallowing,
heartburn, flatulence, constipation.
Cardiovascular: tachycardia.
Musculoskeletal: leg pain, muscle fatigue.
Genitourinary: diuresis.
Miscellaneous: pruritus, fever, earache, nasal
congestion, tinnitus, euphoria, allergic reactions. Several cases of
dermatological reactions, including toxic epidermal necrolysis and erythema multiforme,
have been reported.
The following adverse drug events may be borne in mind
as potential effects of the components of this product. Potential effects of
high dos age are listed in the OVERDOSAGE section.
Acetaminophen: allergic reactions, rash,
thrombocytopenia, agranulocytosis.
Caffeine: cardiac stimulation, irritability,
tremor, dependence, nephrotoxicity, hyperglycemia.
Drug Abuse And Dependence
Abuse and Dependee
Butalbital
Barbiturates may be habit-forming: Tolerance,
psychological dependence, and physical dependence may occur especially
following prolonged use of high doses of barbiturates. The average daily dose
for the barbiturate addict is usually about 1500 mg. As tolerance to
barbiturates develops, the amount needed to maintain the same level of
intoxication increases; tolerance to a fatal dosage, however, does not increase
more than two-fold. As this occurs, the margin between an intoxication dosage
and fatal dosage becomes smaller. The lethal dose of a barbiturate is far less
if alcohol is also ingested. Major withdrawal symptoms (convulsions and
delirium) may occur within 16 hours and last up to 5 days after abrupt
cessation of these drugs. Intensity of withdrawal symptoms gradually declines over
a period of approximately 15 days. Treatment of barbiturate dependence consists
of cautious and gradual withdrawal of the drug. Barbiturate-dependent patients
can be withdrawn by using a number of different withdrawal regimens. One method
involves initiating treatment at the patient's regular dosage level and
gradually decreasing the daily dosage as tolerated by the patient.
DRUG INTERACTIONS
The CNS effects of butalbital may be enhanced by
monoamine oxidase (MAO) inhibitors.
Butalbital, acetaminophen and caffeine may enhance the
effects of: other narcotic analgesics, alcohol, general anesthetics,
tranquilizers such as chlordiazepoxide, sedative-hypnotics, or other CNS depressants,
causing increased CNS depression.
Drug/Laboratory Test Interactions
Acetaminophen may produce false-positive test results for
urinary 5-hydroxy-indoleacetic acid.