Study to Investigate Safety With Special Emphasis on ECG Effects and Tolerability After Oral Doses of Dextromethorphan Hydrobromide Monohydrate in Healthy Male and Female Subjects

The primary objective of the current study is to investigate the safety with special emphasis on ECG effects, and tolerability of dextromethorphan hydrobromide monohydrate (2mg/mL syrup) in healthy male and female subjects following oral administration of 30 mg q.i.d. and 90 mg q.i.d. for 2 days followed by a single morning dose (extensive metabolisers of CYP 2D6) and for 10 days followed by a single morning dose (poor metabolisers of CYP 2D6). Additionally pharmacokinetic properties of dextromethorphan and its main metabolites dextrorphan, 3-hydroxymorphinan, and 3-methoxymorphinan will be investigated