Question

Which of the following antimicrobials should not be given to a chronic asthmatic patient managed on theophylline therapy ?

• A. Erythromycin
• B. Amoxicillin
• C. Cefotaxime
• D. Cotrimoxazole

Answer 1

The Correct Option is A

In this scenario, we need to determine which antimicrobial should not be administered to a chronic asthmatic patient who is receiving theophylline therapy. Theophylline is a bronchodilator used to treat asthma, but it has a narrow therapeutic index and is metabolized by the liver enzyme cytochrome P450 3A4 (CYP3A4). Some drugs can inhibit or induce this enzyme, affecting theophylline levels.

Let's consider the options:

• Erythromycin: This is a macrolide antibiotic known to inhibit CYP3A4. It can increase the levels of theophylline in the blood, leading to potential toxicity. Therefore, it should not be given to a patient on theophylline.
• Amoxicillin: This is a penicillin antibiotic that does not significantly affect theophylline metabolism.
• Cefotaxime: This is a cephalosporin antibiotic that also does not interfere with theophylline metabolism.
• Cotrimoxazole: This is a combination of sulfamethoxazole and trimethoprim. It does not significantly interact with theophylline.

Given this information, the drug that should not be given to a chronic asthmatic patient on theophylline therapy is Erythromycin.