Acetazolamide for Idiopathic intracranial hypertension

Available product: 

Acetomid/Acetazolamide 250mg Tab (short acting)

Mechanism of Action

• Carbonic anhydrase inhibitors are believed to reduce the rate of cerebrospinal fluid production. 

Indication

• usual first line treatment for IIH (appears to be the most effective agent for lowering ICP)
• Most patients experience adequate relief of symptoms (typically, headache)
• However, evidence supporting its efficacy is mostly observational

Dosing

Adults

• 500 mg twice per day and advance the dose as required and tolerated by the patient.
• Although doses of up to 2 to 4 g per day can be administered, many patients develop dose limiting side effects at higher levels
• sustained release formulation (Diamox sequels) may be better tolerated

Children

• 25mg/kg per day with a maximum dose of 100 mg/kg or 2 g per day
• 25-50mg/kg TDS-QID with Frusemide 0.25mg/kg QID (Frank Shann recommendation for TB Hydroencephalus)

Interaction

• Although a sulfa allergy is reported to be a relative contraindication to acetazolamide use, there is little clinical or pharmacologic basis for this recommendatio
• cross-reaction between sulfonamide antimicrobials and the sulfa moiety in acetazolamide and furosemide is unlikely
• For patients who have had major adverse reactions (eg, Stevens-Johnson syndrome, anaphylaxis), we usually consider that the risk precludes the use of acetazolamide. Allergy consultation or other desensitization protocols may be considered in these patients.
• However, if the previous sulfa-related reaction was minor, we usually proceed with acetazolamide treatment

Side Effects and Monitoring

• usually dose-related.
• Monitoring of electrolytes is suggested during acetazolamide treatment.
• digital and oral paresthesias, anorexia, malaise, metallic taste, fatigue, nausea, vomiting, electrolyte changes, mild metabolic acidosis, and kidney stones

References:

1. www.uptodate.com
2. http://emedicine.medscape.com/article/1214410-treatment#aw2aab6b6b2
3. Idiopathic Intracranial Hypertension. Neurol Clin. 2010 Aug; 28(3): 593–617.