<prompt> Which anti-asthma drug is avoided with erythromycin?SalbutamolIpratropiumTheophyllineTerbutaline.  <response>: Erythromycin decreases the plasma clearance of theophylline hence may manifest theophylline toxicity. Theophylline follows zero order kinetics. It is metabolised by microsomal enzymes. hence prone to drug interaction. ENZYME INHIBTORS -Agents which inhibit its metabolism are - Erythromycin Ciprofloxacin Cimetidine Oral contraceptive Allopurinol ENZYME INDUCERS - Like rifampicin increases its clearance hence higher dose is required for action. Smoking Phenytoin phenobarbitone 