A Study to Assess the Clinical Effects of Navarixin in Participants With Psoriasis (MK-7123-009)

Inclusion Criteria

• Body Mass Index (BMI) 19 to 34, BMI = weight (kg)/height (m^2).
• Must have a diagnosis of psoriasis vulgaris (PASI >8) present for at least 1 year. Participants with an on-therapy PASI 8 following washout of their current psoriasis therapy.
• Target lesion selected must be located on the head, trunk, arms or legs and be at least 10 cm^2 in size. The lesion's total numerical ratings for erythema, infiltration, and desquamation must be at least 6 out of the possible 12. Severity score for desquamation must be at least 2.
• Vital sign measurements (taken after ~3 minutes in a supine position) must be within the following ranges: oral body temperature between 35.0°C to 37.5°C; systolic blood pressure, 90 to 160 mm Hg; diastolic blood pressure, 45 to 90 mm Hg; pulse rate, 40 to 100 bpm.
• Have stable disease (ie, off treatment PASI during Screening period and Baseline PASI should not differ by more than 40%).
• Clinical laboratory tests (CBC, blood chemistries, and urinalysis) must be within normal limits or clinically acceptable to the investigator/sponsor. Participants must have a neutrophil count of at least 2 x 10^9/L to be included.
• Free of any clinically significant disease (other than psoriasis).
• Willing to give written informed consent and able to adhere to dose and visit schedules.
• For female participants: Negative serum pregnancy test (beta-hCG) and urine pregnancy test. Agree to use medically accepted methods of contraception during and for an appropriate pre-study period while receiving protocol specified medication, and for 1 month after stopping medication. Female participants of non-childbearing potential must be surgically sterilized or be postmenopausal.
• Male subject must agree to use an adequate form of contraception for the duration of the study.
• At Screening, ECG conduction intervals must be within gender specific normal range (ie, QTc for males <430 msec and females <450 msec) or if not within the normal range, the values must be considered clinically insignificant by the investigator and sponsor.

Exclusion Criteria

• Female participants who are pregnant, intend to become pregnant (within 3 months of ending the study), or are breastfeeding.
• Participants who, in the opinion of the investigator, will not be able to participate optimally in the study.
• Any surgical or medical condition which might significantly alter the absorption, distribution, metabolism or excretion of any drug.
• History of any infectious disease within 4 weeks prior to drug administration and/or are positive for hepatitis B surface antigen, hepatitis C antibodies or human immunodeficiency virus (HIV).
• Immunocompromised participants.
• Positive screen for drugs with a high potential for abuse or have a history of drug or alcohol abuse in the past 2 years.
• History of mental instability or who have been treated for mood disorders.
• Donated blood in the past 60 days.
• Previous treatment with study medication.
• Currently participating in another clinical study or have participated in a clinical study within 30 days.
• Part of the study staff personnel or family members of the study staff personnel.
• Demonstrated clinically significant (requiring intervention) allergic reactions or who are known to be allergic to components of local anesthetics.