It is imperative that the physician determine the initial dose of the product by skin testing. Patients being switched from extracts not labeled in Bioequivalency Allergy Units should be started as if they were coming under treatment for the first time. Patients being switched from one lot of Standardized Cat Hair to another lot of Standardized Cat Hair (from the same or different manufacturers) should have the initial dose from the new lot reduced by 75%. Patients being switched from a Standardized Cat Pelt extract to a Standardized Cat Hair extract (both labeled in BAU/mL) should be skin tested with both extracts to determine the relative potency of the extracts and the dosage adjusted accordingly.

Recommended usual dosage and range: (Scratch or Prick Testing)

The general method of making a scratch test is to first scarify the skin and then apply a drop of extract to the scratch. Make scarifications at least 2.5 cm apart. Hold the scarifier between thumb and index finger, press the sharp edge of the instrument against the skin and twirl instrument rapidly. The scratch should disrupt the outer layers of epidermis but should not produce immediate oozing of blood. One drop (0.05 mL) of extract is rubbed or applied into each scratch. Always apply a control scratch with each test set. Sterile Diluting fluid (for a negative control) is used in exactly the same way as an active test extract. Histamine may be used as a positive control. Scratch or prick test sites should be examined at 15 and 30 minutes. To prevent excessive absorption, wipe off antigens producing large reactions as soon as the wheal appears. Record the size of the reaction. 

Recommended usual dosage and range: (Intradermal Testing)

Patients with a negative scratch or prick-puncture test:

Patients who do not react to a valid scratch or prick- puncture test should be tested intradermally with a 0.05 mL of a 50 BAU/mL extract solution. If this test is negative, a second intradermal test may be performed using a 100 BAU/mL extract dilution. The negative puncture control must be diluted appropriately for intradermal use. .

To prepare a 50 BAU/mL dilution from 10,000 BAU/mL vial:

Take 5.0 mL of the 10,000 BAU/mL + 5.0 mL of diluent =Vial A @5,000 BAU/mL.

Take 1.0 of vial A + 9.0 mL diluent = vial B @500 BAU/mL.

Take 1.0 of vial B + 9.0 mL diluent = vial C @50 BAU/mL.

Patients being suspected of being highly allergic should be tested with 0.05 mL of a 0.1 BAU/mL dilution. A negative test should be followed by repeat tests using progressively stronger concentrations until the maximal recommended strength of 100 BAU/mL is reached. The negative puncture test control must be diluted appropriately for intradermal use. To prepare this dilution follow the tenfold dilution series chart for therapeutic allergens.

Allergic response is based on measurement of wheal and erythema with respect to positive and negative control skin tests. Skin tests are graded in terms of the wheal and erythema response noted at 10 to 20 minutes. Wheal and erythema size may be recorded by actual measurement or the extent of both responses. 

Recommended dosage and range: (Therapeutic) Dosage of allergenic extracts is a highly individualized matter and varies according to the degree of sensitivity of the patient, and the clinical response and tolerance to the extract administered during the injection regimen. The dosage of allergenic extract does not vary significantly with the respiratory allergic disease under treatment. 

In patients who appear to be highly sensitive by history and skin test, the initial dose of the extract should be 0.05mL of 0.01 to 0.1 BAU/mL. Patients with lesser sensitivity may be started using 1.0 BAU/mL. The amount of allergenic extract is increased at each injection by not more than 50%-100% of the previous amount, and the next increment is governed by the response to the last injection. 

Any evidence of systemic reaction is an indication for a significant reduction (at least 50%) in the subsequent dose. Any evidence of a local or generalized reaction requires a reduction in dosage. After therapeutic injections patients should always be observed for at least 30 minutes. If adverse reactions appear, the next therapeutic injection of extract should be reduced to the dose which does not elicit a reaction and subsequent doses increased more slowly. The upper limits of dosage have not been established. Doses larger than 0.2 mL of 10,000 BAU/mL may be painful due to glycerin content. (9)

Preparation Instructions To prepare a dilution for intradermal and therapeutic use, one starts with 10,000 BAU/mL stock concentrate and makes a 1:10 dilution by adding 1.0 mL of the concentrate to 9.0 mL of sterile diluent. Subsequent dilutions are made in similar manner.

Intervals between doses: The optimal interval between doses of allergenic extract has not been definitely established. However, as it is customary practiced, injections are given once or twice per week until the maintenance dose of extract is reached. At this time, the injection interval may be increased to 2 weeks, then 3 weeks and finally to 4 weeks. If the patient does not return for 6-8 weeks after the last injection, the dose should be reduced to 25% of the last dose. If longer than 8 weeks, a dose reduction of 1,2, or 3 dilution's may be made depending on a consideration of the components and the patient's sensitivity. The dosage and the interval between injections may need to be modified according to the clinical response of the patient. When switching patients to a fresh extract the initial dose should be reduced 3/4 so that 25% of previous dose is administered.

Duration of treatment: The usual duration of treatment has not been established. A period of two or three years of injection therapy constitutes an average minimum course of treatment. 

Parenteral drug products should be inspected visually for particulate matter and discoloration prior to administration, whenever solution and container permit.