Exclusion Criteria:(1) Clinically relevant systemic diseases such as psychiatric, neurological, and dermatological conditions interfering with the collection and interpretation of study data (2) History of addiction (3) Allergy to study medication (4) Chronic intake of medication potentially interfering with pain processing (except oral contraceptives) (5) Intake of over-the-counter analgesics within the two days prior to study (6) Reynaud's disease (7) Pregnancy (8) Participation in other study within last 30 days (9) Personnel with direct access to addicting drugs