Pharmacokinetics of Doxycycline in Skin of Healthy Volunteers

Inclusion Criteria: Healthy males * Healthy, according to the medical history, ECG, vital signs, laboratory results and physical examination as determined by the Investigator/Sub-Investigator * Signed written informed consent prior to inclusion in the study * 18-45 years old inclusive * BMI: 18.5 to 30 kg/m2 * SBP: 100-139 mmHg * DBP: 55-89 mmHg * PR: 55-100 bpm (measured after 5 min of rest, sitting position) * ability to comprehend the full nature and purpose of the study, including possible risks and side effects * ability to co-operate with the Investigator and to comply with the requirements of the entire study * availability to volunteer for the entire study duration and willing to adhere to all protocol requirements Exclusion Criteria: Any clinically relevant abnormalities in ECG (12 leads) * Any clinically relevant abnormal physical findings * Any clinically relevant abnormal laboratory values indicative of physical illness * Ascertained or presumptive hypersensitivity to the active principle and/or formulations ingredients of the study drug or to tetracyclines in general * History of anaphylaxis to drugs or allergic reactions in general, which the Investigator considers may affect the outcome of the study * Relevant history of malignancy, of renal, hepatic, cardiovascular, respiratory, gastrointestinal, musculoskeletal, skin, haematological, endocrine or neurological diseases that may interfere with the aim of the study * Any psychiatric illnesses * Presence of any skin condition that would interfere with the placement of microdialysis probes * Any dermatological drug therapy on the surface of both thighs within 14 days before study day 1 of this study * Use of any medication(including OTC) within 1 week prior to study day 1 * Use of any enzyme-modifying drugs, including strong inhibitors of cytochrome P450 (CYP) enzymes (such as cimetidine, fluoxetine, quinidine, erythromycin, ciprofloxacin, fluconazole, ketoconazole, diltiazem and HIV antivirals) and strong inducers of CYP enzymes (such as barbiturates, carbamazepine, glucocorticoids, phenytoin, rifampin and St John's Wort) within 1 month prior to study day 1 * Participation in another clinical study investigating another IMP within 1 month prior to study day 1 * Blood donations within 1 month prior to study day 1 or planned within 1 month after the last study-related blood draw * History of drug or alcohol abuse (\>2 drinks/day, defined according to USDA Dietary Guidelines 2005) * other objections to study participation in the opinion of the Investigator