Cat Hair

Cat Hair Manufacturers

• Alk-abello, Inc.
  

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  Cat Hair | Alk-abello, Inc.

  

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  Dilution

  Allergenic extract concentrates must be diluted before use in intradermal skin testing or the initial stages of immunotherapy. As with any parenteral product, always use careful aseptic technique in preparing dilutions, assuring that the vials, diluents, and syringes are sterile, and that the dilutions are prepared under aseptic conditions, Sterile diluents that can be used include Normal Saline, Buffered Saline, 50% glycerin or Albumin Saline (HSA).

  To obtain the concentrations required for intradermal testing or for the initial stages of immunotherapy, prepare serial 5 or 10 fold dilutions of the concentrate, to achieve the concentrations specified in Table 2 or 3, below. The relatively small 0.5 ml volume conserves the original concentrate, and is convenient because sterile diluent is readily available in prefilled 2.0 and 4.5 ml volumes.

  Table 2 Examples of Ten-fold Dilution Series Dilution
  Number
  Add This
  Volume/Dilution
  of Extract To this
  Diluent
  Volume To Obtain Extract
  at the Following
  Concentration (BAU/ml) 0
  1
  2
  3
  4
  5
  6 Concentrate
  0.5 ml concentrate
  0.5 ml dilution #1
  0.5 ml dilution #2
  0.5 ml dilution #3
  0.5 ml dilution #4
  0.5 ml dilution #5 __
  4.5 ml
  4.5 ml
  4.5 ml
  4.5 ml
  4.5 ml
  4.5 ml 10,000
  1,000
  100
  10
  1.0
  0.10
  0.01 Table 3 Examples of Five-fold Dilution Series Dilution
  Number
  Add This
  Volume/Dilution
  of Extract To this
  Diluent
  Volume To Obtain Extract
  at the Following
  Concentration (BAU/ml) 0
  1
  2
  3
  4
  5
  6 Concentrate
  0.5 ml concentrate
  0.5 ml dilution #1
  0.5 ml dilution #2
  0.5 ml dilution #3
  0.5 ml dilution #4
  0.5 ml dilution #5 __
  2.0 ml
  2.0 ml
  2.0 ml
  2.0 ml
  2.0 ml
  2.0 ml 5,000
  1,000
  200
  40
  8
  1.6
  0.32

  For each vial, record the date of dilution on the label.

  Skin Testing

  Scratch or prick-puncture testing should be performed using the 10,000 BAU/ml concentrate, a negative control (diluent) and a positive control (histamine 1.8 mg/ml). Extract for intradermal testing can be prepared by diluting the concentrate with any appropriate aqueous sterile diluent, as described above. A 100 BAU/ml concentration is also available for intradermal testing.

  The following skin testing protocol can be recommended:

  The location for both prick and intradermal testing is usually the flexor surface of the forearm. Use aseptic technique throughout.
  Perform a preliminary skin prick test with the extract concentrate, by placing a drop of the extract on the skin and then using a needle to prick the skin gently through the drop. Use a normal diluent as negative control and histamine as a positive control. Read the test after 15 minutes. Patients reacting strongly to the prick test should be considered highly sensitive to the extract, and suitable precautions should be taken. A suggested grading system appears in Table 4. If the histamine control is negative, the possibility of skin non-reactivity must be considered.
  Begin intradermal testing, generally starting at the 100 BAU/ml dilution if the prick test was negative, or at 0.1 or 0.01 BAU/ml if the test was positive or if no prick test was done. Use a separate, sterilized syringe and needle for each extract and each patient. Introduce the needle into the superficial skin layers until the bevel is completely buried, then slowly inject approximately 0.02 - 0.05 ml.
  Measure the wheal and erythema after 15 minutes, and determine the degree of response to the injection, in comparison to the negative control. A suggested grading system appears in Table 5.
  If the intradermal reaction is negative at the initial concentration, continue intradermal testing with 10-fold increments in the concentration until a clearly positive response has been obtained or a peak concentration of 100 BAU/ml has been tested, whichever occurs first. Table 4 Skin Test Grading System12 Grade Wheal Results 0
  +
  ++
  +++
  ++++ No Wheal/same size as negative
  <Half the Histamine Diameter
  Half the Histamine Diameter
  Same Size as Histamine Control
  Size of Histamine Control +2mm Table 5 Intradermal Skin Test Grading System13 Mean Diameters (mm) Grade Wheal Erythema 0
  ±
  1+
  2+
  3+
  4+ <5.0
  5.0-10.0
  5.0-10.0
  5.0-10.0
  5.0-10.0 or pseudopods
  >15.0, many pseudopods <5.0
  5.0-10.0
  11.0-20.0
  21.0-30.0
  31.0-40.0
  >40.0

  The interpretation of the skin response is based on the size of the wheal, the size of the erythema, and the appearance of irregular, spreading, pseudopodllike projections from the test area. The presence of the latter indicates marked hypersensitivity. A patient is considered sensitive to the test extract if there is a reaction of 1 + or greater at a concentration of 100 BAU/ml or less, providing that the 1 + reaction is in relation to the negative control.

  Immunotherapy

  Administer the extract solution subcutaneously, using a suitable sterile 1 ml syringe and a 25-27 gauge 1/4 to 5/8 inch needle. The injections are typically given in the lateral aspect of the upper arm.

  Dosage of allergenic extracts is a highly individualized matter12, and varies according to the degree of sensitivity of the patient, the clinical response, and tolerance of the extract administered previously.

  A safe starting dose for any allergic patient is that dose which on intradermal testing produces a 1 + reaction. For most patients a starting dose that is 0.1 ml of 0.01 BAU/ml dilution of the extract concentrate should be well tolerated, although in some very sensitive patients a more dilute concentration may be required.

  If no untoward symptoms are observed following the initial injection, the dose can be increased gradually for each subsequent injection until the injection volume reaches 0.6 -0.8 ml. Then begin using the next more concentrated ten-fold dilution, and proceed with this dosage pattern until the maintenance dose-defined as that dose that either relieves the patient's symptoms or is the highest that the patient can tolerate is reached. Care must be taken, however, in administering a volume greater than 0.2 ml of any extract in 50% glycerin; such injections can be painful to the patient due to the glycerin content.

  After each injection, evaluate the patient's skin reaction and overall response to determine whether the next scheduled dose can be given:

  If a single dose results in more than a moderate local reaction (>50 mm wheal) within 1/2 hour, the same dose should be repeated at the next visit - or visits - until the patient has tolerated it.
  lf any systemic manifestation of sensitivity occurs during or following a visit, or if a single dose results in an excessive local reaction (> 100 mm wheal) within ½ hour, the total dosage for the next visit should be reduced to half of the dose that caused the reaction.
  Delayed local reactions (occurring 24-48 hours after injection) are relatively common, and do not appear to predict difficulties with future doses. As a rule, therefore, dosage adjustment is not required in most instances. However, at the physician's discretion and for the comfort of the patient, if delayed large local reactions over 10 mm are reported, the subsequent dose should be held at the same level as the one causing the reaction.

  The optimal interval between doses of allergenic extract has not been definitely established. However, as is customarily practiced, injections are given 1, 2, or 3 times per week until the maintenance dose of extract is reached. At this time, the injection interval may be increased to 2 weeks, then to 3 weeks and finally to 4 weeks depending on the clinical status. lf the patient does not return for 6 to 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 one, two or three dilutions 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 fresh extract, the initial dose should be reduced to one-quarter of the previous dose.

  Duration of treatment: Careful selection of allergens and cautious progression to maximally tolerated doses are important elements in the success of immunotherapy. The optimal length of treatment with allergen immunotherapy is unknown. A treatment period of 3 to 5 years is common, although continuation for longer periods may be appropriate13.

  Allergenic extracts, as any parenteral drug product should be inspected visually for evidence of foreign material or discoloration prior to administration. Some variation in color is normal and a minor level of extract precipitate may occur with some extracts, but do not use the extract if there is any question of its condition exists.

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• Allermed Laboratories, Inc.
  

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  Cat Hair | Allermed Laboratories, Inc.

  

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  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 sum of erythema diameters was 11.120 (S.D. 2.38). The number of BAU/mL required to elicit this response was 0.05 (range 0.0003 to 9.24 BAU/mL). This concentration is approximately a 1:200,000 v/v dilution of the 10,000 BAU/mL extract.
  
  Extract for intradermal testing should be used as follows:
  

  Patients with a positive scratch or prick test to Standardized Cat Hair Extract. It is not advisable to perform an intradermal skin test in these patients. Patients with a negative scratch or prick test to Standardized Cat Hair Extract. Patients who do not react to a scratch or prick test with the 10,000 BAU/mL concentrate maybe tested intradermally with 0.05 mL of a 1:2,000 v/v dilution of the concentrate (5 BAU/mL). If the test is negative, a second test should be performed with 0.05 mL of a 1:200 v/v dilution of concentrate (50 BAU/mL). Patients tested only by the intradermal method with Standardized Cat Hair Extract. Patients suspected of being highly allergic to cats should be tested with 0.05 mL of a 1:200,000 v/v dilution (0.05 BAU/mL) of the concentrate. A negative test should be followed by repeat tests using 10 fold stronger concentrations until the maximum dose of 0.05 mL of a 1:200 v/v dilution (50 BAU/mL) is reached.

  Interpretation Of Skin Tests:
  The interpretation of skin tests should be based on the size of the erythema and wheal response to the allergen compared to a negative saline control. A suggested method of scoring skin tests is shown below. Measurements refer to the longest (single), diameter of erythema and wheal response.
  
  Scratch and Prick Test
  A negative test shows only a slight red area at the site of scarification or prick penetration. Positive tests are scored as follows:
    1 + Erythema with a 5 mm wheal
    2 + Erythema with a 5 -10 mm wheal
    3 + Erythema with a 10 - 15 mm wheal
    4 + Erythema with a wheal 15 mm (or larger) with pseudopodia
  
  Intradermal Test
  A negative test shows no change in the appearance and size of the 5mm wheal created by the I.D. injection of 0.05 mL of extract. Positive tests are scored as follows:
    1 + Erythema 10 - 20 mm with a 5 -10 mm wheal
    2 + Erythema 20 - 30 mm with a 5 -10 mm wheal
    3 + Erythema 30 - 40 mm with a 10 - 15 mm wheal
    4 + Erythema greater than 40 mm with a 15 mm wheal (or larger) with pseudopodia
  
  Immunotherapy
  Allergenic extract should be administered subcutaneously in the outer aspect of the upper arm using a sterile tuberculin syringe and needle. The skin should be cleaned with 70% alcohol and aseptic technique should be observed in removing the extract from the vial. Care must be taken to avoid injecting the extract into a blood vessel because of the potential hazard of anaphylaxis.
  Standardized Cat Hair Extract must be diluted before administration to new patients. As a precaution against overdose, a skin test with the intended starting dose should be done to help evaluate the patient's sensitivity to the product. If the skin response is larger than 5/15 mm (edema/erythema), the extract should be diluted before it is given subcutaneously. The doses shown in the Dosage Schedule may be followed unless the patient's skin test response and allergic history indicate that more dilute extract should be used.
  Little is known about the required accumulated dosage of Fel d1 (and other allergens that may be present in cat extract) that is needed to relieve symptoms. However, studies with other allergenic substances have shown that high dose immunotherapy is most efficacious in the treatment of allergic rhinitis and asthma. The amount of cat extract that is tolerated during immunotherapy depends upon the sensitivity of the patient. In one study in which patients with cat asthma were treated for a period of one year, the accumulated dose of Fel d1 varied from 3.6 to 115.8 (median 46.2) units13. A burning sensation immediately following the injection of extract from the concentrate is due to the glycerol in the extract. It should not be interpreted as an adverse allergic response.
  Patients who have received allergenic extract for maintenance therapy SHOULD NOT be given the same dose from a fresh vial of extract. IT IS ADVISABLE TO REDUCE THE DOSAGE OF FRESH EXTRACT TO ONE-FOURTH THE AMOUNT GIVEN FROM A PREVIOUS LOT.
  
  

  Dosage Schedule for Standardized Cat Hair Extract (The safety and efficacy of this schedule has not been determined by well-controlled clinical trials.) [BAU = Bioequivalent Allergy Units per mL]   Vial #1
  0.05 BAU Vial #2
  0.5 BAU Vial #3
  5 BAU Vial #4
  50 BAU Vial #5
  500 BAU Vial #6
  5,000 BAU   frequency twice weekly No. mL mL mL mL mL mL 1 0.05 0.05 0.05 0.05 0.05 0.05 2 0.1 0.1 0.1 0.1 0.1 0.1 3 0.2 0.2 0.2 0.2 0.2 0.2 4 0.3 0.3 0.3 0.3 0.3 0.3 5 0.4 0.4 0.4 0.4 0.4 0.4 v/v dilutions of concentrate containing 10,000 BAU per mL required to make the above concentrations. BAU per mL v/v Dilution of Concentrate 0.05 1:200,000 0.5 1:20,000 5.0 1:2,000 50.0 1:200 500.0 1:20 5,000.0 1:2

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