The purpose of this study is to investigate the effect of AZD3161 on mechanical pain sensitivity and axon reflex flare in normal and ultraviolet C irradiated skin.

Inclusion Criteria:

• Healthy Caucasian male and female volunteers aged 18 to 55 years inclusive with suitable veins for venepuncture
• The subject belongs to skin type II or III according to Fitzpatrick skin type scale
• Females must have a negative pregnancy test at screening and at admission, must not be lactating and must be of non-child-bearing potential
• Have a body mass index (BMI) between 18 and 30 kg/m2 inclusive and weigh between 50 kg and 100 kg inclusive
• Male subjects should be willing to use barrier contraception ie, condoms, from the day of dosing until 3 months after dosing with investigational product.

Exclusion Criteria:

• Presence of skin disorders, tattoos or other skin conditions that may interfere with the QST measurements, as judged by the Investigator
• Recent exposure to significant amount of UV light, as judged by the Investigator.
• Use of any prescribed or non-prescribed analgesics (including paracetamol/acetaminophen or drugs affecting blood flow (including nasal anticongestants), prior to the first administration of investigational product that may interfere with the study objectives.
• History of severe allergy/hypersensitivity, or ongoing allergy/hypersensitivity as judged by the Investigator, or history of hypersensitivity to drugs with a similar chemical structure or class to AZD3161.
• Plasma donation within 1 month of screening or any blood donation/blood loss >500 mL during the 3 months prior to screening