Aminoglycosides are given orally primarily for which two conditions?

Aminoglycosides, such as neomycin, are typically not absorbed well through the gastrointestinal tract when taken orally, which is why they are mainly used in specific situations. The two conditions most commonly treated with oral aminoglycosides are hepatic encephalopathy and preoperative bowel surgery.

In hepatic encephalopathy, the aminoglycosides help to reduce the level of ammonia in the gut, thereby alleviating the neurological symptoms associated with this condition. The action involves reducing the population of bacteria that produce ammonia through protein digestion.

For preoperative bowel surgery, aminoglycosides are administered orally to help reduce bowel flora, minimizing the risk of postoperative infections. This is particularly important before surgeries that could expose the bowel to the external environment, where harmful bacteria could lead to complications.

These uses highlight the unique role that oral aminoglycosides play in managing specific medical conditions rather than being utilized for systemic infections or other common bacterial infections, where parenteral routes are preferred due to their effectiveness in achieving therapeutic levels in the bloodstream.