Drug Facts

Type of Drug:

Diuretics (water pills); antiglaucoma agents.

How the Drug Works:

Carbonic anhydrase inhibitors block the activity of the enzyme carbonic anhydrase. This reduces the rate of fluid formation in the inner eye, resulting in reduced pressure within the eye. These drugs also cause Increased amounts of electrolytes (sodium, potassium, bicarbonate) and water to be excreted by the kidneys (diuretic effect) and slows abnormal nerve conduction in the brain (anticonvulsant effect).

Uses:

To treat chronic simple (open-angle) glaucoma and secondary glaucoma, and to lower intraocular pressure preoperatively for acute closed-angle glaucoma.

Acetazola.mide - To prevent mountain sickness in climbers who are attempting to climb rapidly and in climbers who climb gradually, but, who are prone to developing mountain sickness. Also used to treat flUid accumulation and swelling due to congestive heart failure or drugs and to treat some forms of epilepsy (eg, petit mal seizures).

Precautions:

Large doses: Taking larger than recommended doses does not increase the diuretic (water pill) activity of the drug. However, it will increase the risk of side effects.

Pregnancy: There are no adequate and well-controlled studies in pregnant women. Use only if potential benefits to the mother out weight potential risks to the fetus.

Breastfeeding: Acetazolamide may appear in breast milk. It is not known if all carbonic anhydrase inhibitors appear in breast milk. Consult your doctor before you begin breastfeeding.

Children: Safety and effectiveness in children have not been established.

Lab Tests: Lab tests may be required during treatment. Tests may include electrolyte levels (eg, potassium) and blood counts.

Drug Interactions:

Tell your doctor or pharmacist if you are taking or if you are planning to take any over-the-counter or prescription medications or doetary supplements with carbonic anhydrase inhibitors. Doses of one or both drugs may need to be modified or a different drug may need to be prescribed. The following drugs interact with carbonic anhydrase inhibitors.

• Cyclosporine (eg, Sandimmune)
• Salicylates (eg. Aspirin, Arthropan, Doan’s Tusal)
• Salsalate (eg, Disalcid)
• Steroid therapy (eg, prednisone)

Side Effects:

Every drug is capable of producing side effects. Many carbonic anhydrase inhibitor users experience no, or minor, side effects. The frequency and severity of side effects depend on many factors including dose, duration of therapy, and individual susceptibility. Possible side effects include:

Digestive Tract: Appetite loss; nausea; vomiting; diarrhea; sore throat; taste changes.

Nervous System: Drowsiness; confusion; ringing in the ears; impaired coordination; headache; tingling in the hands or feet.

Skin: Rash; itching; unusual bleeding or bruising; sensitivity to light; red or purple spots under the skin.

Urinary and Reproductive Tract: Flank or loin pain; excessive urination; crystals in urine; kidney stones.

Other: Fever; weight loss; nearsightedness when decreasing or discontinuing the drug; abnormal blood counts; hearing dysfunction; severe allergic reaction.

Guidelines for Use:

• If stomach upset occurs, take with food .
• Drink plenty of water and other fluids.
• May cause drowsiness. Use caution while driving or performing other tasks requiring alertness, coordination, or physical dexterity.
• Notify your doctor if sore throat, fever, unusual bleeding or bruising, tingling or tremors in the hands or feet, flank or loin pain, or skin rash occurs.
• May cause sensitivity to sunlight. Avoid prolonged exposure to the sun or ultraviolet (UV) light (eg, tanning beds).
• Store tablets, capsules, and injection at room temperature (59 0 to 86°F).

 

Acetazolamide:

• Tablets can be crushed and mixed with sweet foods to mask bitter taste.
• Do not crush or chew sustained release capsules. Capsules can be opened and contents sprinkled on food, if necessary.
• Acute Mountain Sickness - Dosage is 500 to 1000 mg daily, in divided doses, using tablets or sustained release capsules as appropiate. The higher dose level of 1000 mg is recommended with rapid ascent (eg, rescue or military operations). Dose should be initiated 24 to 48 hours before ascent and continued for 48 hours while at high altitude, or as long as necessary, to control symptoms. Gradual ascent is desirable to avoid acute moutain sickness. If rapid ascent is undertaken and acetazolamide used, prompt descent is still necessary if severe forms of altitude sickness (eg, lung edema or cerebral swelling) occur.
• Congestive Heart Failure - Starting dose is usually 250 to 375 mg once daily (5 mg/kg) in the morning. If the initial response fails, do not increase the dose, but allow the kidney to recover by skipping the medicine for a day.
• Acetazolamide yields the best diuretic results when given on alternate days or given for 2 days alternating with a day of rest.
• Drug-Induced Edema - Recommended dosage is 250 to 375 mg once a day for 1 to 2 days, alternating with a day of rest.
• Epilepsy - Suggested total daily dose is 8 to 30 mg/kg in divided doses. Optimum range appears to be from 375 to 1000 mg daily. When given in combination with other anticonvulsants, starting dose should be 250 mg once daily in addition to existing medicines.
• Glaucoma - Acetazolamide is used as an adjunct to the usual therapy. When using capsules, dosage is 500 mg (1 capsule) 2 times a day, usually given as 1 capsule in the morning and 1 capsule in the evening. Dosage for chronic simple (open-angle) glaucoma ranges from 250 to 1000 mg per 24 hours. Daily doses over 250 mg are usually taken in divided doses. For secondary glaucoma and in preoperative treatment of acute congestive (closed-angle) glaucoma, the preferred dosage is 250 mg every 4 hours.
• Doses larger than 1000 mg per 24 hours do not increase the effect and may increase drowsiness and other side effects.

Methazolamide:

• Effective therapeutic dose varies from 50 to 100 mg 2 to 3 times daily.
• May be used with miotic (eg, Pilocarpine) and osmotic (eg, mannitol) agents.

Dichlorphenamide:

• Usually given in conjunction with topical ocular antiglaucoma agents.
• In acute angle-closure glaucoma, it may be used together with miotic and osmotic agents in an attempt to reduce internal pressure rapidly. If this is not relieved quickly, surgery may be mandatory.
• Dose must be adjusted carefully to each individual.
• A usual initial dose is 100 to 200 mg (2 to 4 tablets), followed by 100 mg (2 tablets) every 12 hours until the desired response has been obtained.
• Recommended maintenance dosage for adults is 25 to 50 mg (V2 to 1 tablet) 1 to 3 times daily.

Tagged under:antiglaucoma agents, carbonic anhydrese, Diuretics, drug interactions enzyme