Take this medicine only as directed. Do not take more of it and do not take it more often than your doctor ordered. To do so may increase the chance of side effects without increasing the effectiveness of this medicine.

This medicine may be taken with meals to lessen the chance of stomach upset. However, if stomach upset (nausea or vomiting) continues, check with your doctor.

This medicine may cause an increase in the amount of urine or in your frequency of urination. If you continue to take the medicine every day, these effects should lessen or stop. To keep the increase in urine from affecting your nighttime sleep:

• If you are to take a single dose a day, take it in the morning after breakfast.
• If you are to take more than one dose a day, take the last dose no later than 6 p.m., unless otherwise directed by your doctor.

However, it is best to plan your dose or doses according to a schedule that will least affect your personal activities and sleep. Ask your health care professional to help you plan the best time to take this medicine.

Dosing

The doses of carbonic anhydrase inhibitors will be different for different patients. Follow your doctor's orders or the directions on the label. The following information includes only the average doses of these medicines. If your dose is different, do not change it unless your doctor tells you to do so.

The number of capsules or tablets that you take depends on the strength of the medicine. Also, the number of doses you take each day, the time allowed between doses, and the length of time you take the medicine depend on the medical problem for which you are taking the carbonic anhydrase inhibitor.

For acetazolamide
• For oral dosage form (extended-release capsules):
  • For glaucoma:
    • Adults 500 milligrams (mg) two times a day, in the morning and evening.
    • Children Use and dose must be determined by your doctor.
  • For altitude sickness:
    • Adults 500 mg one or two times a day.
    • Children Use and dose must be determined by your doctor.
• For oral dosage form (tablets):
  • For glaucoma:
    • Adults 250 mg one to four times a day.
    • Children Dose is based on body weight and must be determined by your doctor. The usual dose is 10 to 15 mg per kilogram (kg) (4.5 to 6.8 mg per pound) of body weight a day in divided doses.
  • For epilepsy:
    • Adults and children Dose is based on body weight and must be determined by your doctor. The usual dose is 10 mg per kg (4.5 mg per pound) of body weight a day in divided doses.
  • For altitude sickness:
    • Adults 250 mg two to four times a day.
    • Children Use and dose must be determined by your doctor.
• For injection dosage form:
  • For glaucoma:
    • Adults 500 mg, injected into a muscle or vein, for one dose.
    • Children Dose is based on body weight and must be determined by your doctor. The usual dose is 5 to 10 mg per kg (2.3 to 4.5 mg per pound) of body weight every six hours, injected into a muscle or vein.

For dichlorphenamide
• For oral dosage form (tablets):
  • For glaucoma:
    • Adults 25 to 50 milligrams (mg) one to three times a day.
    • Children Use and dose must be determined by your doctor.

For methazolamide
• For oral dosage form (tablets):
  • For glaucoma:
    • Adults 50 to 100 milligrams (mg) two or three times a day.
    • Children Use and dose must be determined by your doctor.

Missed dose

If you miss a dose of this medicine, take it as soon as possible. However, if it is almost time for your next dose, skip the missed dose and go back to your regular dosing schedule. Do not double doses.

Storage

To store this medicine:

• Keep out of the reach of children.
• Store away from heat and direct light.
• Do not store the capsule or tablet form of this medicine in the bathroom, near the kitchen sink, or in other damp places. Heat or moisture may cause the medicine to break down.
• Do not keep outdated medicine or medicine no longer needed. Be sure that any discarded medicine is out of the reach of children.

In deciding to use a medicine, the risks of taking the medicine must be weighed against the good it will do. This is a decision you and your doctor will make. For carbonic anhydrase inhibitors, the following should be considered:

Allergies Tell your doctor if you have ever had any unusual or allergic reaction to carbonic anhydrase inhibitors, sulfonamides (sulfa drugs), or thiazide diuretics (a type of water pill). Also tell your health care professional if you are allergic to any other substances, such as foods, preservatives, or dyes.

Pregnancy Carbonic anhydrase inhibitors have not been studied in pregnant women. However, studies in animals have shown that carbonic anhydrase inhibitors cause birth defects. Before taking this medicine, make sure your doctor knows if you are pregnant or if you may become pregnant.

Breast-feeding Carbonic anhydrase inhibitors may pass into the breast milk. These medicines are not recommended during breast-feeding, because they may cause unwanted effects in nursing babies. It may be necessary for you to use another medicine or to stop breast-feeding during treatment. Be sure you have discussed this with your doctor.

Children Although there is no specific information comparing use of carbonic anhydrase inhibitors in children with use in other age groups, these medicines are not expected to cause different side effects or problems in children than they do in adults.

Older adults Many medicines have not been studied specifically in older people. Therefore, it may not be known whether they work exactly the same way they do in younger adults. Although there is no specific information comparing use of carbonic anhydrase inhibitors in the elderly with use in other age groups, these medicines are not expected to cause different side effects or problems in older people than they do in younger adults.

Other medicines Although certain medicines should not be used together at all, in other cases two different medicines may be used together even if an interaction might occur. In these cases, your doctor may want to change the dose, or other precautions may be necessary. When you are using carbonic anhydrase inhibitors, it is especially important that your health care professional know if you are using any of the following:

• Amphetamines or
• Mecamylamine (e.g., Inversine) or
• Quinidine (e.g., Quinidex) Use of carbonic anhydrase inhibitors may increase the chance of side effects

• Methenamine (e.g., Mandelamine) Use of carbonic anhydrase inhibitors may decrease the effectiveness of methenamine

• Diabetes mellitus (sugar diabetes) Use of carbonic anhydrase inhibitors may increase the patient's blood and urine sugar concentrations

• Emphysema or other chronic lung disease Use of carbonic anhydrase inhibitors may increase the risk of acidosis (shortness of breath, troubled breathing)

• Gout or
• Low blood levels of potassium or sodium Use of carbonic anhydrase inhibitors may make the condition worse

• Kidney disease or stones Higher blood levels of carbonic anhydrase inhibitors may result, which may increase the chance of side effects; also, these medicines may make the condition worse

• Liver disease Use of carbonic anhydrase inhibitors may increase the risk of electrolyte imbalance and may make the condition worse

• Underactive adrenal gland (Addison's disease) Use of carbonic anhydrase inhibitors may increase the risk of electrolyte imbalance