What is the primary mechanism of action of acetazolamide in treating pseudotumor cerebri?

Acetazolamide primarily acts by decreasing the production of cerebrospinal fluid (CSF). It is a carbonic anhydrase inhibitor, which reduces the conversion of carbon dioxide and water to bicarbonate and protons. This mechanism leads to a decrease in bicarbonate reabsorption in the proximal renal tubule, resulting in decreased availability of bicarbonate for CSF formation. Consequently, the overall production of CSF is reduced, which helps alleviate intracranial pressure in conditions such as pseudotumor cerebri.

By lowering CSF production, acetazolamide effectively decreases the volume of fluid in the cranial cavity, thus offering symptomatic relief from the headache and visual disturbances that accompany increased intracranial pressure. This action makes it a useful treatment option for managing pseudotumor cerebri, where elevated pressure within the skull can lead to significant clinical complications.