The primary objective of this study is to evaluate, compared to non-treatment, the impact of a titrated dose (1 mg once a day, then 1 mg twice a day and finally a full 2 mg twice a day) of ketotifen on the adverse event profile emerging from a rapid peanut desensitization protocol, in children with established peanut allergy.

The development of a safe oral peanut challenge procedure permits patients that do not have severe life threatening allergic reactions, to be safely desensitized with the ability to maintain peanut tolerance . The peanut desensitization procedure is however associated with unpleasant allergic side effects mainly gastrointestinal and cutaneous manifestations. The use of premedication drugs may lessen these side effects and facilitate the peanut desensitization procedure. Ketotifen is a fast acting, noncompetitive, H1-receptor blocker (antihistamine/inverse agonist) that also inhibits the release of mediators from mast cells involved in hypersensitivity reactions.

The study will enroll 6 (4 in the peanut treatment group, 2 in the control group) children with a known history of peanut allergies. The treated subjects will be randomized in a 2:1 ratio into either a pre-treatment group (final dose of 2 mg bid ketotifen) or a control group. All subjects will undergo a one-day peanut desensitization protocol designed to enable the subject to tolerate 50 mg of peanut flour (initial escalation phase). After the initial escalation day achieving up to 50 mg of peanut flour, the dosing build-up will occur every two weeks through 44 weeks. Subjects will ingest the 50mg and increased doses of peanut flour at home (every day for 2 weeks) between each dose escalation. The target dose is 8000 mg of peanut flour. A maintenance dose will be given for 4 weeks following the last (highest dose) visit.

Inclusion Criteria:

• Age ≥ 8 years, all of either sex, any race, any ethnicity at the time of the initial visit
• The presence of IgE specific to peanuts (a positive skin prick test to peanuts (diameter of wheal >3.0 mm) and a positive in vitro IgE [CAP-FEIA] > 7 kUA/L
• A history of significant clinical symptoms occurring within 60 minutes after ingesting peanuts
• Provide signed informed consent.

Exclusion Criteria:

1. History of severe anaphylaxis to peanut as defined by hypoxia, hypotension, or neurological compromise (Cyanosis or SpO2 < 92% at any stage, hypotension, confusion, collapse, loss of consciousness; or incontinence)
2. Currently participating in a study using an investigational new drug
3. Participation in any interventional study for the treatment of food allergy in the past 12 months
4. Subjects with a known oat or wheat (because of potential cross contamination with oat) food allergy will be excluded
5. Poor control or persistent activation of atopic dermatitis
6. Moderate to severe persistent asthma
7. Currently being treated with greater than medium daily doses of inhaled corticosteroids, as defined by the NHLBI guidelines
8. Inability to discontinue antihistamines for skin testing
9. History of epilepsy or seizures
10. Diabetes