<prompt> A patient of bronchial asthma is on theophylline. Which of the following drugs should not be indicated to treat the upper respiratory tract infection in the same patient?CiprofloxacinAmoxicillinAmpicillinAll of the above  <response>: Drugs like ciprofloxacin, erythromycin and cimetidine are powerful microsomal enzyme inhibitors, predisposing to toxicity of theophylline. 