- Healthy males aged 18 to 55 years (inclusive).
- Body mass index (BMI) of 18 to 30 kg/m2.
- Non-smokers and smokers of up to 5 cigarettes or equivalent per day.
- Must be able to abstain from smoking during residential periods.
- Demonstration of positive hyperalgesia as defined by an area of hyperalgesia = 15 cm2
15 minutes after ID administration of 100 µg capsaicin.
- Demonstration of negative hyperalgesia as defined by an area of hyperalgesia 15 minutes after ID administration of capsaicin vehicle.
- Subject with a skin type compatible with the measures, and without significant skin
allergies, pigmentary disorders, or any active dermatological conditions that might
interfere with the conduct of the study.
- Subject has had a clinically significant illness in the 4 weeks before screening.
- Use of prescribed medications and herbal supplements in the 7 days prior to dosing or
over the counter preparations, including multivitamins and paracetamol, in the 48 h
- Subject has a significant history of drug/solvent abuse (within 2 years prior to Day
1), or a positive drugs of abuse test at screening.
- Subject with a history of alcohol abuse or currently drinks in excess of 28 units per
week (males), or has a positive breath alcohol test at the Screening visit or on Day
- Subject has a Heat pain tolerance threshold (HPTT) of = 50°C at screening.
- Subjects who do not develop erythema at the highest intensity of UV-B light used to
establish Minimum erythema dose (MED).
- Known allergy or intolerance to capsaicin or hot peppers.
- Subjects who have any skin trauma, scars or other skin disorder or tattoos on their
forearms or on the front of their thighs.
- Subject with active chronic pain conditions or a history of chronic pain conditions.
- Any condition that might interfere with the absorption, distribution, metabolism,
and/or excretion of drugs.
- Previous ingestion of ICA-105665.
- Considering or scheduled to undergo any surgical procedure during the duration of the
- Prolonged QT/QTc interval (repeatedly = 450 msec). Received any agent known to alter
hepatic or renal clearance (e.g., erythromycin, cimetidine, barbiturates,
phenothiazines, clarithromycin, troleandomycin, ketoconazole, miconazole, fluconazole,
itraconazole, etc.) for a period of 30 days prior to Day 1.
- History of risk factors for Torsades de Pointes (family history of long QT syndrome,
heart failure, hypokalemia).
- Subject is unable to tolerate being blindfolded.
- Subject has participated in a clinical study involving capsaicin within 1 year of the
- Subject has a history of skin cancer.
- Subject has a clinically significant history of anemia.