Nurses Compass
Drug Guide
Phenacemide
Classification
Therapeutic: Anticonvulsant
Pharmacological: Carboxylic acid derivative anticonvulsant
FDA Approved Indications
- Partial seizures
- Generalized seizures
Mechanism of Action
Phenacemide depresses the motor cortex, raising the threshold for neuronal excitability. Its exact mechanism is not fully understood but is believed to involve the modulation of neuronal sodium channels and inhibition of excitatory synaptic transmission.
Dosage and Administration
Adult: Initial dose: 250 mg 2-3 times daily, gradually increased based on response and tolerability. Typical maintenance dose ranges from 1 to 3 grams daily in divided doses.
Pediatric: Dosage varies; typically initiated at 10-20 mg/kg/day divided into 2-3 doses, titrated upward as needed.
Geriatric: Start with lower doses due to increased sensitivity and potential liver or kidney impairment. Monitor closely.
Renal Impairment: Adjust dose based on degree of impairment, careful monitoring recommended.
Hepatic Impairment: Use with caution; monitor liver function; dose adjustments may be necessary.
Pharmacokinetics
Absorption: Well absorbed from gastrointestinal tract.
Distribution: Widely distributed, crosses the blood-brain barrier.
Metabolism: Partially metabolized in the liver via conjugation and oxidation.
Excretion: Primarily excreted in urine, mainly as conjugates.
Half Life: Approximately 3-4 hours, but may be prolonged in hepatic or renal impairment.
Contraindications
- Hypersensitivity to phenacemide or related compounds.
- History of hepatic disease.
Precautions
- Use cautiously in patients with liver or kidney impairment, hematologic disorders, or during pregnancy. Regular monitoring of blood counts and liver function is advised.
Adverse Reactions - Common
- Drowsiness (Frequent)
- Nausea or vomiting (Frequent)
- Gastrointestinal disturbances (Common)
Adverse Reactions - Serious
- Aplastic anemia (Rare)
- Hepatotoxicity (Rare)
- Blood dyscrasias including leukopenia, thrombocytopenia (Rare)
Drug-Drug Interactions
- Other anticonvulsants (e.g., phenytoin, phenobarbital) may have additive sedative effects.
- CNS depressants may enhance sedation.
Drug-Food Interactions
N/ADrug-Herb Interactions
N/ANursing Implications
Assessment: Monitor seizure frequency, neurological status, blood counts, and liver function tests.
Diagnoses:
- Risk for ineffective tissue perfusion related to hematologic or hepatic adverse effects.
- Impaired cognitive or motor function related to CNS effects.
Implementation: Administer medication as prescribed, monitor for effectiveness and adverse effects, educate patient on side effects.
Evaluation: Assess seizure control and monitor for adverse reactions regularly.
Patient/Family Teaching
- Take medication exactly as prescribed.
- Report any signs of blood dyscrasias (e.g., unusual bleeding, unexplained sore throat) or jaundice.
- Avoid alcohol and CNS depressants unless directed.
- Regular blood tests are necessary to monitor side effects.
Special Considerations
Black Box Warnings:
- Hepatic failure, aplastic anemia, and blood dyscrasias have been reported. Use with caution and monitor blood counts and liver function.
Genetic Factors: None established.
Lab Test Interference: May interfere with liver function tests; monitor accordingly.
Overdose Management
Signs/Symptoms: Drowsiness, dizziness, nystagmus, ataxia, potentially coma in severe cases.
Treatment: Supportive care, activated charcoal if ingestion was recent, and symptomatic treatment. Dialysis may be considered in severe toxicity.
Storage and Handling
Storage: Store at room temperature away from moisture and light.
Stability: Stable under recommended storage conditions.