Nurses Compass
Drug Guide
Dichlorphenamide
Classification
Therapeutic: Anticonvulsant, Carbonic Anhydrase Inhibitor
Pharmacological: Carbonic Anhydrase Inhibitor
FDA Approved Indications
- Primary hyperkalemic periodic paralysis
- Primary hypokalemic periodic paralysis
- Andersen-Tawil syndrome
Mechanism of Action
Dichlorphenamide inhibits carbonic anhydrase enzymes, leading to decreased hydrogen ion secretion in renal tubules, which in turn alters ion transport and stabilizes muscle cell membranes, reducing episodes of paralysis.
Dosage and Administration
Adult: Typically 50-100 mg orally once or twice daily, adjusted based on response and tolerability.
Pediatric: Not generally recommended due to limited data; consult specialist.
Geriatric: Start at lower doses with careful monitoring due to increased risk of side effects.
Renal Impairment: Use with caution; adjust dose as necessary, considering renal function.
Hepatic Impairment: Use with caution; no specific dosage adjustment established.
Pharmacokinetics
Absorption: Well absorbed orally.
Distribution: Widely distributed, crosses blood-brain barrier.
Metabolism: Minimal hepatic metabolism.
Excretion: Primarily renal excretion of unchanged drug.
Half Life: Approximately 2-4 hours.
Contraindications
- Known hypersensitivity to dichlorphenamide or sulfonamides.
Precautions
- Monitor for sulfa allergies.
- Use with caution in patients with renal or hepatic impairment.
- Monitor serum electrolytes regularly.
- May cause metabolic acidosis; monitor acid-base status.
Adverse Reactions - Common
- Paresthesia (Common)
- Dizziness (Common)
- Gastrointestinal upset (Common)
Adverse Reactions - Serious
- Metabolic acidosis (Rare)
- Electrolyte disturbances (hypokalemia, hyponatremia) (Rare)
- Acute myopia and secondary glaucoma (Rare)
Drug-Drug Interactions
- Other carbonic anhydrase inhibitors, digoxin (risk of toxicity), corticosteroids (altered electrolyte balance)
Drug-Food Interactions
N/ADrug-Herb Interactions
N/ANursing Implications
Assessment: Monitor serum electrolytes, renal function, and acid-base status regularly. Evaluate muscle strength and frequency of paralysis episodes.
Diagnoses:
- Risk for electrolyte imbalance
- Risk for impaired renal function
Implementation: Administer with food if GI upset occurs. Encourage hydration. Educate patient on adherence and monitoring requirements.
Evaluation: Assess frequency of paralysis episodes, electrolyte levels, and side effects periodically.
Patient/Family Teaching
- Take medication exactly as prescribed.
- Report signs of electrolyte imbalance, visual changes, or new neurological symptoms.
- Maintain hydration.
- Avoid abrupt discontinuation.
Special Considerations
Black Box Warnings:
- None currently.
Genetic Factors: No specific genetic markers influence response or risk.
Lab Test Interference: May affect serum electrolyte and acid-base measurements.
Overdose Management
Signs/Symptoms: Severe metabolic acidosis, electrolyte disturbances, CNS depression.
Treatment: Supportive care, correction of electrolyte imbalances, alkalinization if necessary. Hemodialysis in severe cases.
Storage and Handling
Storage: Store at room temperature, away from moisture and light.
Stability: Stable when stored properly, check expiration date.