Sentence: 2 . The two combination treatment regimes lowered the 12 h post-dose blood pressure more effectively than did atenolol alone , but the high dose nifedipine combination was no more effective than the low dose nifedipine combination .
Drug combination annotation:
[{'class': 'POS', 'spans': ['atenolol', 'nifedipine'], 'is_context_needed': True}]