CARBONIC ANHYDRASE INHIBITORS (CAI)
Carbonic Anhydrase Inhibitors Nursing Considerations, Implications & Drug Study
GENERAL DESCRIPTION
Carbonic anhydrase inhibitors are prototype of modern diuretics and discovered when fond bacteriostatic sulphonamide cause an alkaline diuresis.The prototypical carbonic anhydrase is Acetazolamide. CAI are rarely used diuretics now a days but they still have several other specific applications. It inhibits bicarbonate ions in the PCT rather than Chloride ions, which are more important. Thus, CAIs have little influence on sodium reabsorption so it is considered as weak diuretic agent
EXAMPLE: Acetazolamide, Dorzolamide
ACETAZOLAMIDE
- BRAND NAME: Diamox, Diacarb, Diluran, Diuramide, , Glaumox
GENERAL DESCRIPTION
Acetazolamide is a Sulphonamide drug and use as diuretic agents. It is non-selective competitor of Carbonic Anhydrase enzyme. It inhibits the reabsorption of sodium bicarbonate from PCT, cause increase in urination and sodium loss.
MECHANISM OF ACTION
Carbonic anhydrase enzyme is present in many sites of nephron but predominantly it is present in the luminal membrane of PCT. It plays an important part in bicarbonate reabsorption from proximal convoluted tubule. Acetazolamide inhibits this reabsorption of Na2HCO3 and cause alkaline diuresis with the loss of sodium and bicarbonate. It inhibits bicarbonate ions in the PCT rather than Chloride ions, which are more important. Thus, acetazolamide has little influence on sodium reabsorption so it is considered as weak diuretic agent.
PHARMACOKINETICS
Carbonic Anhydrase are well absorbed after oral administration. Excretion of drug take place in the proximal tubule. Urine pH increases from the HCO3 diuresis within 30 mins and persists for 12 hours after single dose so, dose must be adjusted in renal insufficiency.
INDICATIONS
- Intraocular pressure
- Glaucoma (Topical use of Dorzolamide)
- Benign intracranial hypertension
- Mountain sickness
- Cyteinuria (in children)
CONTRAINDICATIONS
- Hypersensitivity
SIDE EFFECTS & ADVERSE EFFECTS
- Metabolic acidosis
- Paresthesia
- Fatigue
- Dyspepsia
- Renal stone formation (prolong use)
- GI disturbance
DRUG INTERACTION
- Acetazolamide tablets when given with timolol eye drops can cause severe mixed acidosis in a patient with chronic obstruction pulmonary disease.
- Acetazolamide when given with sodium bicarbonate can cause the development of renal calculi.
- Acetazolamide, mannitol and NSAIDs when given concurrently may cause acute renal failure.
- Acetazolamide may have interaction with antidepressants, digoxin, corticosteroids and anticonvulsant drugs.
Nursing Considerations, Implications: PRE & POST NURSING CARE
- Ask patient if he .is allergic to the sulphonamide agents.
- Obtain complete health history & inform the HP e.g. kidney &liver disease, metabolic problems, pulmonary disease, adrenal gland failure.
- Investigate blood electrolytes specially sodium, calcium and potassium levels
- Ask the patient if he is diabetic and medication used and check the current blood sugar levels.
Nursing Considerations, Implications: PATIENT EDUCATION
- Explain them the right use and dosage of drug.
- Don’t take aspirin with the Acetazolamide
- Wear dark glasses and light color clothes because acetazolamide can cause photosensitivity
- Report any visible s/s of proximal edema, SOB, potential sign of Heart Failure or Pulmonary edema
- Report immediate if feeling dizzy or change in consciousness
- Advise them to change position slowly to avoid postural hypotension
- Do not breast feed while taking the drug
- Monitor BP as specified by the HP
- Mention possible side effects that can cause by the use of diuretics such as dry mouth, increase in urination.