What potential effect might occur when ciprofloxacin is given to a client who is taking phenytoin?

When ciprofloxacin is administered to a client who is also taking phenytoin, a potential interaction may lead to increased levels of phenytoin in the body, resulting in toxicity. This interaction is primarily due to ciprofloxacin's ability to inhibit certain enzymes that are responsible for the metabolism of phenytoin in the liver. When these enzymes are inhibited, phenytoin levels can rise, which may lead to adverse effects associated with toxicity, such as dizziness, nystagmus, tremors, and even more severe consequences like ataxia or altered mental status. Understanding this interaction is crucial for ensuring patient safety and effective management of their medications. Monitoring phenytoin levels during concomitant therapy with ciprofloxacin is important to avoid these potential harmful outcomes.