Sentence: After an initial 6 - 8 weeks of metformin , they received either letrozole ( 2.5 mg ) or clomiphene ( 100 mg ) from day 3 - 7 of their menstrual cycle .
Drug combination annotation:
[{'class': 'POS', 'spans': ['metformin', 'letrozole'], 'is_context_needed': True}, {'class': 'COMB', 'spans': [0, 2], 'is_context_needed': True}]