Proximal Tubule Diuretics
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Proximal tubule diuretics e.g. acetazolidamide
These drugs are carbonic anyhrdrase blockers. Some sodium is reabsorbed in conjunction with hydrogen. This process relies on the carbonic anhydrase to catalyse the reaction of hydrogen with bicarbonate to form water and carbon dioxide. Recall how in the process, hydrogen ions are in a cycle in and out of tubular fluid, being reacted all the time. When you bloack the action o carbonic anhydrase you limit the amount of sodium that can be absorbed by this method.
- Remember that this only account for a small proportion of sodium though!
This drug will increase the excretion of sodium, bicarbonate and potassium thus resulting in an alkaline urine.
This drug is not used clinically. This is because the drug will produce a mile acidosis as a result of H+ retention, and the body will respond by producing more carbonic anhydrase, and thus tolerance to the drug occurs very quickly.
- It is used clinically to treat glaucoma as it reduces intraocular pressure!