INDICATIONS
Allergenic extracts are indicated for use in diagnostic
testing and as part of a treatment regime for allergic disease, as established
by allergy history and skin test reactivity.
Allergenic extracts are indicated for the treatment of
allergen specific allergic disease for use as hyposensitization or
immunotherapy when avoidance of specific allergens can not be attained. The use
of allergenic extracts for therapeutic purpose has been established by
well-controlled clinical studies. Allergenic extracts may be used as adjunctive
therapy along with pharmacotherapy which includes antihistamines,
corticosteroids, and cromoglycate, and avoidance measures. Allergenic extracts
for therapeutic use should be given using only the allergen selection to which
the patient is allergic, has a history of exposure and are likely to be exposed
to again.
DOSAGE AND ADMINISTRATION
General Precautions
Parenteral drug products should be inspected visually for
particulate matter and discoloration prior to administration whenever solution
and container permits.
The dosage of allergenic extracts is dependent upon the
purpose of the administration. Allergenic extracts can be administered for
diagnostic use or for therapeutic use.
When allergenic extracts are administered for diagnostic
use, the dosage is dependent upon the method used. Two methods commonly used
are scratch testing and intradermal testing. Both types of tests result in a
wheal and flare response at the site of the test which usually develops rapidly
and may be read in 20-30 minutes.
Diagnostic Use: Scratch Testing Method
Scratch testing is considered a simple and safe method
although less sensitive than the intradermal test. Scratch testing can be used
to determine the degree of sensitivity to a suspected allergen before using the
intradermal test. This combination lessens the severity of response to an
allergen which can occur in a very sensitive patient.
The most satisfactory testing site is the patient's back
or volar surface of the arms from the axilla to 2.5 or 5cm above the wrist,
skipping the anti-cubital space. If using the back as a testing site, the most satisfactory
area are from the posterior axillary fold to 2.5 cm from the spinal column, and
from the top of the scapula to the lower rib margins.
Allergenic extracts for diagnostic use are to be
administered in the following manner: To scratch surface of skin, use a
circular scarifier. Do not draw blood. Tests sites should be 4 cm apart
to allow for wheal and flare reaction. 1-30 scratch tests may be done at a
time. A separate sterile scratch instrument is to be used on each patient to
prevent transmission of homologous serum hepatitis or other infectious agents
from one patient to another.
The recommended usual dosage for Scratch testing is one
drop of allergen applied to each scratch site. Do not let dropper touch skin.
Always apply a control scratch with each test set. Sterile Diluent (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.
Interpretation Of Scratch Test
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 as compared with positive and negative controls. A positive
reaction consists of an area of erythema surrounding the scarification that is
larger than the control site. For uniformity in reporting reactions, the
following system is recommended.6
REACTION |
SYMBOL |
CRITERIA |
Negative |
- |
No wheal. Erythema absent or very slight (not more than 1 mm diameter). |
One Plus |
+ |
Wheal absent or very slight erythema present (not more than 3 mm diameter). |
Two Plus |
++ |
Wheal not more than 3mm or erythema not more than 5mm diameter. |
Three Plus |
+++ |
Wheal between 3mm and 5mm diameter, with erythema. Possible pseudopodia and itching. |
Four Plus |
++++ |
A larger reaction with itching and pain. |
Diagnostic Use: Intradermal Skin Testing Method
Do not perform intradermal test with allergens which have
evoked a 2+ or greater response to a Scratch test. Clean test area with
alcohol, place sites 5 cm apart using separate sterile tuberculin syringe and a
25 gauge needle for each allergen. Insert needle tip, bevel up, into
intracutaneous space. Avoid injecting into blood vessel, pull back gently on
syringe plunger, if blood enters syringe change position of needle. The
recommended dosage and range for intradermal testing is 0.05 ml of not more
than 100 pnu/ml or 1:1000 w/v (only if puncture test is negative) of allergenic
extract. Inject slowly until a small bleb is raised. It is important to make
each bleb the same size.
Interpretation Of Intradermal Test:
The patient's reaction is graded on the basis of size of
wheal and flare as compared to control. Use 0.05 ml sterile diluent as a
negative control to give accurate interpretation. The tests may be accurately interpreted
only when the saline control site has shown a negative response. Observe
patient for at least 30 minutes. Tests can be read in 15-20 minutes. Edema,
erythema and presence of pseudopods, pain and itching may be observed in 4 plus
reactions. For uniformity in reporting reactions the following system is
recommended.6
REACTION |
SYMBOL |
CRITERIA |
Negative |
- |
No increase in size of bleb since injection. No erythema. |
One Plus |
+ |
An increase in size of bleb to a wheal not more than 5mm diameter, with associated erythema. |
Two Plus |
++ |
Wheal between 5mm and 8mm diameter with erythema. |
Three Plus |
+++ |
Wheal between 8 mm and 12mm diameter with erythema and possible pseudopodia and itching or pain. |
Four Plus |
++++ |
Any larger reaction with itch and pain, and possible diffuse blush of the skin surrounding the reaction area. |
Therapeutic Use: Recommended Dosage & Range
Check the listed ingredients to verify that it matches
the prescription ordered. When using a prescription set, verify the patient's
name and the ingredients listed with the prescription order. Assess the
patient's physical and emotional status prior to giving as injection. Do not
give injections to patients who are in acute distress. Parenteral drug
products should be inspected visually for particulate matter and discoloration
prior to administration, whenever solution and container permit.
Dosage of allergenic extracts is a highly individualized
matter and varies according to the degree of sensitivity of the patient, his
clinical response and tolerance to the extract administered during the early phases
of an injection regimen. The dosage must be reduced when transferring a patient
from nonstandardized or modified extract to standardized extract. Any evidence
of a local or generalized reaction requires a reduction in dosage during the
initial stages of immunotherapy as well as during maintenance therapy. After
therapeutic injections patients should be observed for at least 20 minutes for reaction
symptoms.
Suggested Dosage Schedule
The following schedule may act as a guide. This schedule
has not been proven to be safe or effective. Sensitive patients may begin
with smaller doses of weaker solutions and the dosage increments can be less.
STRENGTH |
DOSE |
VOLUME |
Vial #1 |
1 |
0.05 |
1:100,000 w/v |
2 |
0.10 |
10 pnu/ml |
3 |
0.15 |
1 AU/ml |
4 |
0.20 |
1 BAU/ml |
5 |
0.30 |
|
6 |
0.40 |
|
7 |
0.50 |
Vial #2 |
8 |
0.05 |
1:10,000 w/v |
9 |
0.10 |
100 pnu/ml |
10 |
0.15 |
10 AU/ml |
11 |
0.20 |
10 BAU/ml |
12 |
0.30 |
|
13 |
0.40 |
|
14 |
0.50 |
Vial #3 |
15 |
0.05 |
1:1,000 w/v |
16 |
0.10 |
1,000 pnu/ml |
17 |
0.15 |
100 AU/ml |
18 |
0.20 |
100 BAU/ml |
19 |
0.30 |
|
20 |
0.40 |
|
21 |
0.50 |
Vial #4 |
22 |
0.05 |
1:100 w/v |
23 |
0.07 |
10,000 pnu/ml |
24 |
0.10 |
1,000 AU/ml |
25 |
0.15 |
1,000 BAU/ml |
26 |
0.20 |
|
27 |
0.25 |
Maintenance Refill |
28 |
0.25 |
1:100 w/v |
29 |
0.25 |
10,000 pnu/ml |
30 |
0.25 |
1,000 AU/ml |
31 |
0.25 |
1,000 BAU/ml |
32 |
0.25 |
subsequent doses |
33 |
0.25 |
Preparation Instructions
All dilutions may be made using sterile buffered diluent.
The calculation may be based on the following ratio:
Volume desired x Concentration desired = Volume needed
x Concentration available.
Example 1: If a 1:10 w/v extract is available and it is
desired to use a 1:1,000 w/v extract substitute as follows:
Vd x Cd = Vn x Ca
10ml x 0.001 = Vn x 0.1
0.1 ml = Vn
Using a sterile technique, remove 0.10 ml of extract from
the 1:10 vial and place it into a vial containing 9.90 ml of sterile diluent.
The resulting ratio will be a 10 ml vial of 1:1,000 w/v.
Example 2: If a 10,000 pnu/ml extract is available and it
is desired to use a 100 pnu/ml extract substitute as follows:
10ml x 100 = Vn x 10,000
0.1 ml = Vn
Using a sterile technique, remove 0.10 ml of extract from
the 10,000 pnu/ml vial and place it into a vial containing 9.90 ml of sterile
diluent. The resulting concentration will be a 10 ml vial of 100 pnu/ml.
Example 3: If a 10,000 AU/ml or BAU/ml extract is
available and it is desired to use a 100 AU/ml or BAU/ml extract substitute as
follows: Vd x Cd = Vn x Ca
10ml x 100 = Vn x 10,000
0.1 ml = Vn
Using a sterile technique, remove 0.10 ml of extract from
the 10,000 AU/ml or BAU/ml vial and place it into a vial containing 9.90 ml of
sterile diluent. The resulting concentration will be 10ml vial of 100 AU/ml or
BAU/ml.
Intervals Between Doses
The optimal interval between doses of allergenic extract
has not been definitely established. 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. There
are three generally accepted methods of pollen hyposensitizing therapy.
Preseasonal
Treatment starts each year 6 to 8 weeks before onset of
seasonal symptoms. Maximal dose reached just before symptoms are expected.
Injections discontinued during and following season until next year.
Co-Seasonal
Patient is first treated during season with symptoms. Low
initial doses are employed to prevent worsening of condition. This is followed
by an intensive schedule of therapy (i.e. injections given 2 to 3 times per
week). Fewer Allergists are resorting to this Co-seasonal therapy because of
the availability of more effective, symptomatic medications that allow the
patient to go through a season relatively symptom free.
Perennial
Initially this is the same as pre seasonal. The allergen
is administered twice weekly or weekly for about 20 injections to achieve the
maximum tolerated dose. Then, maintenance therapy may be administered once a
week or less frequently.
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.
HOW SUPPLIED
Allergenic extracts are supplied with units listed as:
Weight/volume (W/V), Protein Nitrogen Units (PNU/ml), Allergy Units (AU/ml) or
Bioequivalent Allergy Units (BAU/ml).
Sizes
Diagnostic Scratch: 5 ml dropper application vials
Diagnostic Intradermal: 5 ml or 10 ml vials.
Therapeutic Allergens: 5 ml, 10 ml, 50 ml multiple dose
vials.
Storage
The expiration date of allergen extracts is listed on the
container label. Store extracts upon arrival at 2° to 8°C and keep them in this
range during office use.
WARRANTY: We warrant that this product was prepared
and tested according to the standards of the FDA and is true to label. Because
of biological differences in individuals and because allergenic extracts are
manufactured to be potent and because we have no control over the conditions of
use, we cannot and do not warrant either a good effect or against an ill effect
following use.
REFERENCES
6. Lockey, R.F., Bukantz, S.C., Allergen Immunotherapy.
New York,NY: Marcel Dekker Inc., 1991.
Nelco Laboratories, Inc Revised: Dec 2009