inter-arm and inter-period reproducability of the dermal blood flow response after a histamine skin prick.

Conditions: Pruritus

Summary: to evaluate the inter-arm and inter-period reproducibility of the dermal blood flow response induced by a skin prick of histamine, subjects will receive histamine (10 mg/ml) and negative control skin pricks on the volar surface of both forearms during two subsequent study visits to allow an intra-individual comparison. changes in dermal blood flow will be measured during the hour after the skin pricks with laser doppler and/or laser speckle contrast imaging.


Eligibility criteria:
inclusion criteria: * subject is a white male ≥ 18 and ≤ 45 years of age at the time of screening * subject is a nonsmoker for at least 6 months prior to the study start * subject has a body mass index ≥ 18 and ≤ 30 kg/m2 * subject has a clear increase in histamine-induced dermal blood flow * subject is judged to be in good health on the basis of medical history, physical examination and vital signs * subject understands the procedures and agrees to comply with them for the entire length of the study by giving written informed consent exclusion criteria: * subject has excessive hair growth on the volar surface of the forearm * subject has a past or present history of diffuse dermatological conditions including eczema, scleroderma, psoriasis, urticaria, dermatographism and dermatitis * subject has any abnormality on the skin of the forearm, possibly interfering with the study assessments including tattoos, keloids, tumors, ulcers, burns, flaps and grafts * subject cannot avoid excessive tanning (any exposure to sunlight or a tanning bed which would cause a sunburn reaction) throughout the study and cannot cover the forearms 24 hours before and after each study visit * subject currently uses lotions, oils, depilatory preparations, makeup or other topical treatments on the arms and on a regular basis which cannot be discontinued for the duration of the study; subject has used any topical treatments within 7 days of the start of the study * subject has a past or present history of (symptomatic) asthma * subject has a history of severe allergic reactions to food or drugs or adverse experiences of a serious nature related to the administration of either a marketed or investigational drug, including histamine * subject currently uses any prescription or nonprescription drugs on a regular basis which cannot be discontinued for the duration of the study; subject has used any prescription or nonprescription medication within 14 days of the start of the study * subject is a habitual and heavy consumer of coffee or caffeinated beverages (more than approximately 4 cups of tea, coffee or cola per day) at the time of the study. subjects who have reduced their consumption to ≤ 4 cups per day at least 1 week prior to enrollment may participate. subjects who cannot refrain from caffeinated beverages 24 hours before the study visit; * subject is unable to refrain from drinking alcohol 24 hours prior to histamine application, is currently a regular user (including "recreational use") of any illicit drugs, or has a history of drug (including alcohol) abuse. a drug screen will include amphetamines/ methamphetamines, methylenedioxymethamphetamine, benzodiazepines, barbiturates, cocaine, cannabis, tricyclic antidepressants, methadone and opiates * subject cannot refrain from being around second hand smoke 24 hours prior to histamine application or uses nicotine-containing products. ex-smokers should have ceased smoking at least 6 months prior to screening * subject has any of the following vital sign measurements at screening: heart rate ≤ 40 or ≥ 100 beats/min, diastolic blood pressure ≤ 50 or ≥ 89 mmhg and/or systolic blood pressure ≤ 90 or ≥ 139 mmhg * subject has been involved in testing an investigational drug in another clinical study within the last 4 weeks or 5 half-lives * subject has evidence of a clinically significant active infection, fever of 38°c or above at the time of the study visits * subject has a history or current cardiovascular, respiratory, hepatic, renal, gastrointestinal or neurological disorders capable of significantly altering the absorption, metabolism or elimination of drugs * subject is in a situation or has a condition, which, in the opinion of the investigator, may interfere with safe and optimal participation in the study * subject has a history of any illness or disorder, which, in the opinion of the investigator, might confound the results of the study.