Usual Adult Dose for Edema

Initial dose: 250 to 375 mg orally/IV once a day

• If after initial response there is a lack of response, hold therapy for a day

Maintenance dose: One dose every other day or once a day for 2 days alternating with a day of rest

Comments:

• Best diuretic results are obtained when taken on alternate days or when taken once daily for 2 days alternating with a day of rest.
• Too frequent dosage or too high a dose may result in therapeutic failure.
• For diuresis in congestive heart failure, the starting dose is approximately 5 mg/kg.

Uses: For adjunctive treatment of edema due to congestive heart failure or drug-induced edema.

Usual Adult Dose for Acute Mountain Sickness

500 to 1000 mg orally per day in divided doses

• May use immediate-release or extended-release as appropriate

Acute Mountain Sickness (AMS)/High Altitude Cerebral Edema (HACE) Prevention:
Guideline dose: 125 mg orally twice a day

AMS Treatment:
Guideline dose: 250 mg orally twice a day

Comments:

• Higher doses (1000 mg) are appropriate for rapid ascent, such as in rescue or military operations.
• Dosing should be to initiated 24 to 48 hours before ascent and continue for 48 hours while at high altitude, or longer as necessary to control symptoms.
• According to Wilderness Medical Society Consensus Guidelines, while higher doses are effective they are associated with more frequent and/or increased side effects.

Use: For the prevention or amelioration of symptoms associated with acute mountain sickness despite gradual ascent.

Usual Adult Dose for Glaucoma

Open-Angle Glaucoma:

• Immediate-release (IR) tablets: 250 to 1000 mg orally per day; amounts over 250 mg should be administered in divided doses
• Extended-release (ER) capsules: 500 mg orally 2 times a day

Maintenance: Adjust doses individually based on symptomatology and ocular tension; for patients inadequately controlled on ER capsules 1 g/day, may supplement with IR tablets

• Doses in excess of 1 g/24 hours generally do not produce increased effects

Preoperatively in Closed-Angle Glaucoma:

• Various regimens have been used including: 250 mg orally every 4 hours; 250 mg orally twice a day; OR 500 mg orally followed by 125 mg or 250 mg orally every 4 hours

Comments:

• In acute cases, IV therapy (at same oral dosage) has been used for rapid relief of ocular tension.
• A complementary effect has been observed when used in conjunction with miotics or mydriatics.

Uses: For the adjunctive treatment of chronic simple (open-angle) glaucoma, secondary glaucoma, and preoperatively in acute angle-closure glaucoma where a delay of surgery is desirable so as to decrease intraocular pressure.

Usual Adult Dose for Glaucoma (Open Angle)

Open-Angle Glaucoma:

• Immediate-release (IR) tablets: 250 to 1000 mg orally per day; amounts over 250 mg should be administered in divided doses
• Extended-release (ER) capsules: 500 mg orally 2 times a day

Maintenance: Adjust doses individually based on symptomatology and ocular tension; for patients inadequately controlled on ER capsules 1 g/day, may supplement with IR tablets

• Doses in excess of 1 g/24 hours generally do not produce increased effects

Preoperatively in Closed-Angle Glaucoma:

• Various regimens have been used including: 250 mg orally every 4 hours; 250 mg orally twice a day; OR 500 mg orally followed by 125 mg or 250 mg orally every 4 hours

Comments:

• In acute cases, IV therapy (at same oral dosage) has been used for rapid relief of ocular tension.
• A complementary effect has been observed when used in conjunction with miotics or mydriatics.

Uses: For the adjunctive treatment of chronic simple (open-angle) glaucoma, secondary glaucoma, and preoperatively in acute angle-closure glaucoma where a delay of surgery is desirable so as to decrease intraocular pressure.

Usual Adult Dose for Seizure Prophylaxis

Initial dose: 8 to 30 mg/kg orally/IV in divided doses
Range: 375 to 1000 mg per day

Initial dose for patients on other anticonvulsants: 250 mg orally/IV once a day

Comments:

• The above range represents an optimum range for most patients; some patients respond to a lower dose; for most patients, doses in excess of 1 g do not appear to produce better results.
• Children with petit mal have had the best results; good results have been seen in both children and adult with other seizures such as grand mal, mixed seizure pattern, myoclonic jerk patterns, etc.
• Extended-release capsules are not indicated for use in this condition.

Use: For the adjunct treatment of centrencephalic epilepsies such as petit mal, and unlocalized seizures.

Usual Pediatric Dose for Acute Mountain Sickness

12 years or older:
Extended-release capsules: 500 mg orally once or twice a day

Guideline dose (immediate-release): 2.5 mg/kg orally every 12 hours
Maximum: 125 mg per dose

Comments:

• Therapy should be initiated 24 to 48 hours before ascent and continued for 48 hours while at high altitude, or longer as necessary to control symptoms.
• Guideline dose is from the Wilderness Medical Society Consensus Guidelines; according to Wilderness Medical Society Consensus Guidelines, higher doses are effective but they are associated with more frequent and/or increased side effects.

Use: For the prevention or amelioration of symptoms associated with acute mountain sickness despite gradual ascent.

Usual Pediatric Dose for Glaucoma

12 years or older:
Extended-release (ER) capsules: 500 mg orally 2 times a day

Comments: Doses in excess of 1 g/24 hours generally do not produce increased effects.

Uses: For the adjunctive treatment of chronic simple (open-angle) glaucoma, secondary glaucoma, and preoperatively in acute angle-closure glaucoma where a delay of surgery is desirable so as to decrease intraocular pressure.

Usual Pediatric Dose for Glaucoma (Open Angle)

12 years or older:
Extended-release (ER) capsules: 500 mg orally 2 times a day

Comments: Doses in excess of 1 g/24 hours generally do not produce increased effects.

Uses: For the adjunctive treatment of chronic simple (open-angle) glaucoma, secondary glaucoma, and preoperatively in acute angle-closure glaucoma where a delay of surgery is desirable so as to decrease intraocular pressure.

Renal Dose Adjustments

Contraindicated in marked renal disease or impairment (specific CrCl level not provided, however, less than 10 mL/min has been provided by some authorities)

Liver Dose Adjustments

Contraindicated in marked liver disease of impairment

Dose Adjustments

Elderly: Dose selection should be cautious usually starting at the low end of the dosing range

Precautions

Safety and efficacy of extended-release (ER) capsules have not been established in patients younger than 12 years.
Safety and efficacy of immediate-release formulations have not been established in patients younger than 18 years.

Consult WARNINGS section for additional precautions.

Dialysis

Data not available

Other Comments

Administration advice:

• For oral or IV administration; IM administration is not recommended

Reconstitution/preparation techniques:

• Reconstitute with sterile water for injection (5 mL for 500 mg vial)
• Reconstituted solutions maintain chemical and physical properties for 3 days under refrigeration (2C to 8C [36F to 46F]) or 12 hours at room temperature (20C to 25C [68F to 77F])
• Manufacturer recommendation: Refrigerate reconstituted solutions, use within 12 hours of reconstitution

General:

• The dose used to treat congestive heart failure and drug induced edema differs considerably from that used to treat glaucoma and epilepsy as dependence on carbonic anhydrase inhibition in the kidney requires intermittent dosing to allow recovery from inhibitory effect.
• Adverse effects common to sulfonamide derivatives may occur with this drug.

Monitoring:

• CBC and platelet count: Obtain at baseline and check periodically during therapy
• Electrolytes: Periodically check, especially with long term use.

Patient advice:

• Patients should be instructed that this drug may cause drowsiness, fatigue, and myopia and that they should avoid activities such as driving or operating machinery until they know how this drug affects them.
• Patients should be instructed to report skin reactions or any symptoms of blood dyscrasias such as fatigue, shortness of breath, and bruising to their health care provider.
• Patients with diabetes or impaired glucose tolerance should be advised that this drug may affect their blood d glucose; reports of both high and low blood sugars have been received.