Can a common cough drug dampen pain sensitivity?

Copied word for word from the study's registry entry, so the wording is the study team's rather than ours.

Inclusion Criteria: * Healthy male volunteers * Aged between 18 and 45 years * CYP2D6 Extensive and Intermediate metabolizers * Body mass index (BMI) between 19 and 30 kg/m2 * Systolic blood pressure between 100 and 150 mmHg, diastolic blood pressure between 50 and 90 mmHg, heart rate between 45 and 90 beats per minute * Without treatment during the 7 days before inclusion specially no use of analgesic and anti-inflammatory drugs * Cooperation and understanding enough to conform to the study obligations * Having given free informed written consent * Affiliated to the French Social Security * Inscription or acceptation of inscription in the national register of volunteers involved in trials. Exclusion Criteria: * Hypersensitivity to the active substance or to any of the excipients * Lactose intolerance * Hypertension * History of stroke * Severe heart failure * Severe hepatic impairment * Shortness of breath * Congenital galactosemia, glucose-galactose malabsorption, lactase deficiency * Association with linezolid * Pre-existence or history of peripheral neuropathy due to a cause different from neurotoxic chemotherapy * Diabetes (type I and II) * CYP2D6 Poor and Ultra-rapid metabolizers * AST, ALT, total bilirubin twice the average * Dextromethorphan intake during the 7 days before inclusion * Medical and surgical history incompatible with the study * Disease progression during inclusion * Excessive consumption of alcohol (\> 50g/day), tobacco (≥ 10 cigarettes/day), coffee, tea or drinks with caffeine (equivalent to more than 4 cups a day) or any addiction to drugs * Subject lacking concentration during tests training and low test results reproducibility * Subject does not meet the selection criteria for its ability to discriminate sensations to noxious stimuli during psychometric tests * Subject exclusion period, or the total allowable compensation exceeded * Subject undergoing a measure of legal protection (guardianship, supervision