The primary hypothesis of the study is single doses of MK-8351 will reduce the baseline early asthmatic response (EAR) as assessed by area under the curve from 0-3 hours (AUC0-3hr) of forced expiratory volume (FEV1) when compared to placebo.

This is a randomized, placebo-controlled, 4-period study. Eligible patients will undergo a single-blind phase in Period 1, followed by 3 periods during which they will receive low-dose MK-8351, high-dose MK-8351, or matching placebo as a single dose in a random sequence crossover study design.

Inclusion Criteria:

• Females of non-childbearing potential (at least 1 year post-menopausal, post-hysterectomy, post-oophorectomy, or with tubal ligation);
• Males with a female partner of childbearing potential must agree to use a medically acceptable method of contraception during and up to 120 days after the last dose of study medication;
• Body Mass Index (BMI) >=17 kg/m^2 and <=33 kg/m^2
• Non-smoker and non-user of nicotine or nicotine-containing products for at least 6 months prior to enrollment;
• History of allergen-induced asthma for at least 6 months prior to enrollment;
• Able to perform reproducible pulmonary function testing;
• Positive methacholine challenge test prior to receiving study medication;
• Allergic response to house dust mite allergen or standardized cat pelt or hair allergen extract;
• Ability to tolerate sputum induction and to produce adequate sputum.

Exclusion Criteria:

• History of clinically significant disease or disorder;
• History of malignancy;
• History of significant multiple and/or severe allergies;
• History of milk or lactose allergies or intolerance;
• History of anaphylactic reaction or significant intolerability to prescription or non-prescription drugs or food;
• Positive for human immunodeficiency virus (HIV), hepatitis B surface antigen, or hepatitis C antibodies;
• History of major surgery within 3 months prior to enrollment;
• Participation in another investigational trial within 4 weeks of screening;
• Lactating females;
• Inability to refrain from, or anticipates the use of, any medication including herbal remedies during the trial period;
• History of receiving anti-immunoglobulin E (IgE) or immunotherapy;
• History of serious allergies to drug or a history of hypersensitivity to inhaled salbutamol, antihistamines, or any other potential asthma/anaphylaxis rescue medication;
• History of hospitalization for asthma-related illness within 3 months of screening;
• History of emergent care more than twice in the last 12 months for asthma-related illness;
• History of life-threatening asthma;
• Consumes >4 glasses of alcoholic beverage per day;
• Consumes >6 servings of coffee, tea, cola, energy drinks or other caffeinated beverages per day;
• History or or current use of illicit drugs within past 24 months.