Sentence: For example , the renal excretion of methotrexate by glomerular filtration and tubular secretion is affected by a number of weak organic acids , such as probenecid , salicylates and penicillin , which compete for tubular secretion , resulting in delayed clearance of methotrexate .
Drug combination annotation:
[{'class': 'POS', 'spans': ['methotrexate', 'probenecid'], 'is_context_needed': False}, {'class': 'POS', 'spans': [0, 2], 'is_context_needed': False}, {'class': 'POS', 'spans': [0, 3], 'is_context_needed': False}]