Exploratory Study for Allergy Relief Onset

Inclusion Criteria:

- Ambulatory healthy male and female subjects between 18 to 65 years of age inclusive;

- Self-reported to have seasonal allergic rhinitis for at least 2 years prior

- Documented positive skin prick test response to common ragweed (ambrosia
artemisiifolia) pollen; prick with wheal > 4mm larger than the diluent within the
previous 12 months

- Total Symptom Score (TSS) ≥ 40 mm at the 90 or 120 minute time point during one of the
Priming Visits and at 90 or 120 minute time points during ragweed challenge Symptom
Induction Phase of each Treatment Visit;

- Body Mass Index (BMI) in the range of 18 to 30 kg/m2

- Female subjects of childbearing potential must be using a medically acceptable form of
birth control for at least 1 month prior to screening (3 months on oral
contraceptives), e.g., oral or patch contraceptives, intrauterine device, injectable
contraceptive (e.g. Depo-Provera®), or a double barrier and have a negative pregnancy
test at Screening and prior to IMP administration on Day 1 and Day 7 ± 1 day. Female
subjects of non-childbearing potential must be amenorrheic for at least two years or
had a hysterectomy and/or bilateral oophorectomy

Exclusion Criteria:

- Evidence or self-reported history of significant medical condition which, in the
judgment of the investigator, is a contraindication to the use of chlorpheniramine, or
might interfere with the trial. These may include thyroid disease (e.g.,
hyperthyroidism, hypothyroidism), uncontrolled diabetes mellitus, coronary heart
disease, ischemic heart disease , symptomatic prostatic hypertrophy, bladder neck
obstruction, hepatic insufficiency, narrow-angle glaucoma, pyloroduodenal obstruction,
or stenosing peptic ulcer;

- Known allergy to chlorpheniramine, dexchlorpheniramine, or any of its inactive
ingredients

- Self-reported non-responders (lack of therapeutic effect) to antihistamines

- Administration of epinephrine is contra-indicated;

- Current use of oral steroids, including prednisone and prednisolone;

- Females who are pregnant or lactating

- A history of anaphylaxis to ragweed allergen

- Subjects with a history of asthma, lower respiratory tract disease, emphysema or
chronic bronchitis; At the discretion of the investigator, subjects with self-reported
mild intermittent asthma or exercise induced asthma may be included.