Inter-arm and Inter-period Reproducability of the Dermal Blood Flow Response After a Histamine Skin Prick.
Inter-arm and Inter-period Reproducability of the Dermal Blood Flow Response After a Histamine Skin Prick.
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.
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.