Overview
DESCRIPTION Standardized Cat Hair Extract is a clear, light yellow to amber solution of the allergens of cat hair, extracted in buffered saline containing sodium chloride, sodium bicarbonate and 50% glycerol by volume. Phenol at 0.4% w/v is added as a preservative. Source material for the extract is obtained from the hair of the domestic cat The importance of surface allergens in cat allergy has...
Mechanism of Action
CLINICAL PHARMACOLOGY Positive skin tests with allergenic extract are the result of histamine release from mast cells sensitized with allergen specific IgE. The exact mechanisms by which immunotherapy relieves symptoms of allergy are still under investigation. Elevations in allergen-specific IgG antibodies and an increase in the activity of T suppressor lymphocytes appear to be some of the immunologic changes that occur from hyposensitization (4, 5, 6).
Indications
- INDICATIONS AND USAGE Studies have shown that skin tests with cat extract are useful in the diagnosis of cat allergy. As a rule, persons with cat allergy have positive skin reactions when tested with cat extract, and non-allergic individuals rarely react (7, 8, 9). However, the relationship between a positive skin test and the appearance of clinical symptoms after exposure to a cat is not absolute, i.e., some skin-test positive persons do not experience allergic symptoms after exposure (10).
Common Doses
- 0.05 mL
Dosage
DOSAGE AND ADMINISTRATION Diagnosis: Concentrated extract (10,000 BAU/mL) may be used for scratch or prick-puncture testing. Puncture tests performed with a bifurcated needle in ten cat allergic persons showed a mean wheal diameter of 6.6 mm (S.D. 1.3) with a mean sum of erythema of 57.3 mm (S.D. 10.4). Intradermal tests with serial three-fold dilution of the 10,000 BAU/mL showed the following results: Serial 3-Fold Dilutions of 10,000 BAU/mL Extract Subject 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 1 X 2 X 3 X 4 X 5 X 6 X 7 X 8 X 9 X 10 X The mean three-fold dilution eliciting a response of 50 mm...
Black Box Warning
WARNINGS This allergenic product is intended for use by physicians who are experienced in the administration of allergenic extracts and the emergency care of anaphylaxis, or for use under the guidance of an allergy specialist. Standardized Cat Hair Extract is not directly interchangeable with Standardized Cat Pelt Extract or Cat Extracts labeled in Allergy Units (AU/mL) The initial dose must be based on skin testing as described in the dosage and administration section of this insert.
Contraindications
- CONTRAINDICATIONS Standardized Cat Hair Extract should not be used for immunotherapy in persons who do not have cat related allergic symptoms and a positive skin test to the extract.
Side Effects
- ADVERSE REACTIONS Local Reactions From Skin Testing Large local reactions may result from skin tests with Standardized Cat Hair Extract. To help prevent this, a patient should be skin tested initially by the prick or scratch method. If a positive response is NOT observed, an intradermal skin test may be performed with a more dilute solution of the extract. Oral antihistamines and topical corticosteroids may be administered to relieve itching and swelling resulting from large skin test reactions.
Interactions
- No major interactions listed on the FDA label. Always consult a healthcare professional.