|
| U.S. Brand
Names |
|
| Mebaral® |

|
|
| Generic
Available |
|
|
No |

|
|
| Synonyms |
|
|
Methylphenobarbital |

|
|
| Pharmacological Index |
|
|
Barbiturate |

|
|
| Use |
|
|
Sedative; treatment of grand mal and petit mal epilepsy |

|
|
| Restrictions |
|
|
C-IV |

|
|
| Pregnancy Risk
Factor |
|
|
D |

|
|
| Contraindications |
|
|
Hypersensitivity to mephobarbital, other barbiturates, or any component;
pre-existing CNS depression; respiratory depression; severe uncontrolled pain;
history of porphyria |

|
|
| Adverse
Reactions |
|
|
>10%: Central nervous system: Dizziness, lightheadedness, drowsiness,
"hangover" effect
1% to 10%:
Central nervous system: Confusion, mental depression, unusual excitement,
nervousness, faint feeling, headache, insomnia, nightmares
Gastrointestinal: Constipation, nausea, vomiting |

|
|
| Drug
Interactions |
|
|
CYP2C, 2C8, and 2C19 enzyme substrate |

|
|
| Mechanism of
Action |
|
|
Increases seizure threshold in the motor cortex; depresses monosynaptic and
polysynaptic transmission in the CNS |

|
|
| Pharmacodynamics/Kinetics |
|
|
Onset of action: 20-60 minutes
Duration: 6-8 hours
Absorption: Oral: ~50%
Serum half-life: 34 hours |

|
|
| Usual Dosage |
|
|
Oral:
Children: 6-12 mg/kg/day in 2-4 divided doses
Adults: 200-600 mg/day in 2-4 divided doses
Sedation:
Children:
<5 years: 16-32 mg 3-4 times/day
>5 years: 32-64 mg 3-4 times/day
Adults: 32-100 mg 3-4 times/day
Dosing adjustment in renal or hepatic impairment: Use with caution
and reduce dosages |

|
|
| Dietary
Considerations |
|
|
High doses of pyridoxine may decrease drug effect; barbiturates may increase
the metabolism of vitamin D & K; dietary requirements of vitamin D, K, C,
B12, folate and calcium may be increased with long-term
use |

|
|
| Mental Health: Effects
on Mental Status |
|
|
Dizziness and drowsiness are common; may cause confusion, nervousness,
depression, nightmares, or insomnia; may rarely cause
hallucinations |

|
|
| Mental Health:
Effects on Psychiatric
Treatment |
|
|
May rarely cause agranulocytosis; use caution with clozapine and
carbamazepine; may induce hepatic enzymes resulting in an increase or decrease
effect of concurrent psychotropic; monitor to altered
response |

|
|
| Dental Health: Local
Anesthetic/Vasoconstrictor
Precautions |
|
|
No information available to require special precautions |

|
|
| Dental Health:
Effects on Dental Treatment |
|
|
No effects or complications reported |

|
|
| Patient
Information |
|
|
May cause drowsiness, may impair coordination and judgment; do not
discontinue abruptly; notify physician of dark urine, pale stools, jaundice,
abdominal pain, persistent nausea, and vomiting; do not skip
doses |

|
|
| Nursing
Implications |
|
|
High doses of pyridoxine may decrease drug effect |

|
|
| Dosage Forms |
|
|
Tablet: 32 mg, 50 mg, 100 mg |

|
|
| References |
|
|
Pond SM, Olson KR, Osterloh JD, et al,
"Randomized Study of the Treatment of Phenobarbital Overdose With Repeated Doses of Activated Charcoal,"
JAMA, 1984, 251(23):3104-8.
Zawada ET, Nappi J, Done G, et al,
"Advances in the Hemodialysis Management of Phenobarbital Overdose," South
Med J, 1983, 76(1):6-8. |

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