When ciprofloxacin is administered to a client with chronic obstructive pulmonary disease taking theophylline, what interaction could occur?

When ciprofloxacin is administered to a patient who is taking theophylline, an important interaction can occur that leads to increased levels of theophylline in the bloodstream. This happens because ciprofloxacin can inhibit the metabolism of theophylline, primarily by affecting the enzymes responsible for its breakdown in the liver. As a result, when these two medications are taken together, theophylline stays in the body longer and may accumulate, leading to increased plasma levels.

Elevated levels of theophylline can result in adverse effects, such as nausea, increased heart rate, and even more serious outcomes like seizures or cardiac arrhythmias. Monitoring theophylline levels and adjusting the dose may be necessary when a patient starts or stops taking ciprofloxacin or if the dosage changes, to avoid these potential complications. This pharmacokinetic interaction emphasizes the importance of understanding how different medications can influence each other's metabolism and effects in patients, particularly those with complex health conditions like chronic obstructive pulmonary disease.