Table 2.

Characteristics of clinical studies comparing levodropropizine to controls in adults

Study	Design	Participants	Intervention vs. comparator	Condition	Outcomes
Allegra 1988	RCT ,double-blind Oral administration t.i.d. for 3 days	Adults N = 40 Age: >13 yrs	Levodropropizine vs. placebo	Bronchitis cough	Higher reduction in cough severity with levodropropizine
Catena 1997	RCT , double-blind, double-dummy, two parallel groups Oral administration t.i.d. for 5 days	Adults N = 209 Age: 18–75 yrs	Levodropropizine vs. dextromethorphan	Moderate non-productive cough	Significant reduction in cough frequency with both treatments; Levodropropizine significantly more effective in reducing nocturnal awakenings
Luporini 1998	RCT, double-blind, two parallel gropus Oral administration t.i.d. for 7 days	Adults N = 140 > 18 yrs	Levodropropizine vs. dihydrocodeine	Lung cancer cough	Significant reduction in cough severity and nocturnal awakenings with both treatments