Posology : מינונים

DOSAGE AND ADMINISTRATION
Parenteral drug products should be inspected visually for particulate matter and discoloration prior to administration, whenever solution and container permit.
Skin test techniques for immediate (Type I) hypersensitivity testing fall into two major categories: percutaneous, and intracutaneous.
Percutaneous techniques: For percutaneous testing, in general, skin is scratched, punctured or pricked just before the allergen is applied or through a drop of test allergen. There are several devices available for this technique. Refer to the manufacturer or distributor’s circular for specific directions for their use.
In General:
1. It is recommended that the test areas should be placed no closer than 4 - 5 cm apart to avoid interference of reactions when several tests are applied.
2.   Skin test areas should be cleansed with alcohol and air dried.
3.   Preferably, the allergen should be placed on the volar surface of the forearm, upper arm, or the patient’s back. The patient should be placed in a comfortable position prior to testing.
4.   For scratch testing, a sharp, clean, sterile instrument is used to abrade the skin, but not to draw blood. Each scratch should be about 2 - 4 mm in length. A small drop of extract is placed on the surface of the skin.
5.   Prick testing: For prick testing, a sharp, sterile instrument is used to puncture the skin slightly, applying it at a 15 - 20° angle to the skin. The instrument is gently raised, “tenting” the skin until it pops out, generally pricking through the drop of allergen. Do not draw blood.
6.   For puncture testing, a sharp, clean, sterile instrument must be used. Puncture the skin, through the drop of allergen, perpendicular to the skin. Do not draw blood.
For all of the above techniques, a separate instrument must be used for each patient; if the instrument is to be used to pass through the allergen, to avoid cross-contamination, a separate instrument is to be used for each allergen. The test should be read in 15 minutes, measuring both wheal size and erythema.
Intracutaneous (intradermal) testing: General: Intradermal testing is more sensitive than percutaneous testing and its specificity is dependent on dose. Intradermal testing is not intended as an initial screen unless used in highly dilute solutions. Intradermal testing is usually reserved for allergens that have demonstrated either negative or equivocal percutaneous skin test response in the face of positive or unclear history.
Intradermal testing of one allergen in several serial dilutions (beginning with the weakest to the more concentrated dilutions) may also be useful in assessing degree of patient sensitivity for the establishment of a safe starting dose for immunotherapy.
Bulk extracts must be diluted for intradermal testing. Use of Sterile Diluent for Allergenic Extracts or Sterile Diluent for Allergenic Extracts Normal Saline with HSA (albumin saline) is recommended. Dilutions should be made with sterile disposable syringes using aseptic technique. Commonly 10 fold dilutions are used to achieve a desired concentration for intradermal testing and continuation of immunotherapy. For example, transferring 0.5 mL of a 10,000 PNU/mL extract into 4.5 mL of diluent will yield 5 mL of extract at 1,000 PNU/mL. For weight volume products, a 1:100 w/v dilution may be prepared from a 1:10 w/v by transferring 0.5 mL of the 1:10 w/v to 4.5 mL of diluent. Prepare as many additional serial dilutions as necessary to reach the appropriate concentration. As a general rule intradermal strength should begin at no higher than 1/100 to 1/1000 of the percutaneous strength that resulted in a negative skin test reaction.
1.   It is recommended that the test areas should be spaced no less than 5 cm apart to avoid interference with adjacent allergen or control.
2.   Skin should be cleansed with alcohol and air dried.
3.   A sterile 1 mL or 1/2 mL syringe with a 26 - 30 gauge needle should be used. A separate sterile syringe should be used for each extract and each patient.
4.   Care should be taken to eliminate air bubbles from the syringe prior to injecting the test dose. It is suggested that not more than
6 - 10 allergens of each different type be used at any one time. Very sensitive patients may show rapid response.
5.   The skin is held tensely, and the needle is inserted almost parallel to the skin, beveled side up far enough to cover the beveled portion. Slowly inject sufficient extract to make a small bleb of approximately 5 mm in diameter (0.01 - 0.02 mL).
6.   Read the test results in 15 minutes.
Selection of the proper strength for intracutaneous testing: A general rule for the prevention of untoward reactions, particularly in extremely sensitive patients, is to screen by percutaneous methods initially, and begin intradermal testing at a strength not more than 1/100 of a negative or equivocal percutaneous reaction.
Controls: In both percutaneous and intracutaneous tests, a negative control test with diluent alone should be performed because some patients exhibit dermographia, and/or other non-specific irritant responses.
As a positive control in the evaluation of allergenic skin testing, histamine 1 mg/mL (histamine base) should be used for percutaneous testing, and histamine 0.1 mg/mL (histamine base) should be used for intradermal testing.
Interpretation of results: Patient’s response is graded on the basis of the size of erythema or wheal. 6 General guidelines follow for percutaneous testing, different devices and/or techniques influence the size of the reaction, therefore it is important to refer to the device manufacturer’s or distributor’s instructions when grading reactions Percutaneous (prick or scratch) test:
0   No reaction or less than control.
+   Erythema greater than control, smaller than a nickel (21 mm diameter).
++ Erythema greater than a nickel in diameter, no wheal.
+++ Wheal and erythema without pseudopods.
++++ Wheal and erythema with pseudopods.
Intradermal test:
0   No reaction or less than negative control.
+   3-4 mm wheal with erythema, or erythema alone larger than a nickel (21 mm diameter).
++ 4-8 mm wheal and erythema, without pseudopods.
+++ Over 8 mm wheal and erythema without pseudopods.
++++ Wheal and erythema with pseudopods.