INDICATIONS
Hyposensitization (injection) therapy is a treatment for
patients exhibiting allergic reactions to seasonal pollens, dust, molds, animal
danders, various other inhalants, and in situations where the offending allergen
cannot be avoided.
Prior to initiation of therapy, the clinical sensitivity
should be established by careful evaluation of the patient's history confirmed
by diagnostic skin testing. Hyposensitization should not be prescribed for sensitivities
to allergens which can easily be avoided.
DOSAGE AND ADMINISTRATION
Parenteral drug products should be inspected visually for
particulate matter and discoloration prior to administration, whenever solution
and container permit.
When diluting bulk extracts, 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 initiation 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.
Starting dose for immunotherapy is related directly to a
patient's sensitivity as determined by carefully executed skin testing. Degree
of sensitivity can be established by determination of D5011.
A general rule is to begin at 1/10 of the dose that produces sum of erythema of
50 mm (approximately a 2+ positive skin test reaction).
For example, if a patient exhibits a 2+ intradermal
reaction to 1 AU/mL, the first dose should be no higher than 0.05 mL of 0.1
AU/mL. Dosage may be increased by 0.05 mL each time until 0.5 mL is reached, at
which time the next 10-fold more concentrated dilution can be used, beginning
with 0.05 mL, if no untoward reaction is observed.
Interval between doses in the early stages of
immunotherapy is no more than once to twice a week, and may gradually be
increased to once every two weeks. Generally, maintenance injections may be
given as infrequently as once every two weeks to once a month.
Injections are given subcutaneously, preferably in the
arm. It is advantageous to give injections in alternate arms and routinely in
the same area. In some patients, a local tolerance to the allergen may develop
thus preventing a possible severe local reaction.
Formal stability studies for diluted and undiluted forms
of unstandardized extracts have not been performed; therefore, it is
recommended that minimal amounts of the concentrate be diluted so that the diluted
product is used up within a relatively short period of time; i.e., preferably
not more than four weeks.
Pre-Seasonal Method Of Treatment
Treatment of hay fever by the pre-seasonal method should
be started 6-10 weeks prior to the usual onset of symptoms. Therapy should be
started early enough to permit a graduated series of doses at 2-7 day
intervals. It is recommended that the larger doses be spaced 5-7 days apart.
Some physicians continue therapy into or through the
season by repeating a reduced or MAINTENANCE dose at weekly or biweekly
intervals. If during the season, hay fever symptoms develop, relief may be
provided by giving supplemental treatment. If the last dose was well-tolerated and
not more than 2 weeks has elapsed since it was given, this dose may be given
again and repeated every 4 to 7 days.
Perennial Treatment
The patient's tolerance to the offending pollen or pollens
is first established by the injection of a series of graduated doses as
outlined in the PRE-SEASONAL METHOD, not necessarily given preseasonally, since
perennial therapy may be begun at any time. After completion of the ascending
series of injections, from 1/4 to ½ of the highest well-tolerated dose is
continued at 2 to 3 week intervals throughout the year. Shortly before the
usual onset of symptoms (4 to 5 weeks prior to the season) the interval between
injections is shortened and the dosage is gradually increased, according to the
Pre- Seasonal schedule, until maximum well-tolerated dose is again attained.
This top dose should be reached just before the usual onset of symptoms at
which time the treatment is discontinued. If patient's symptoms persist,
therapy may be continued at a reduced dosage level, usually 1/4 to ½ of the
top dose.
Dosage Adjustments
For Products Containing Short Ragweed.
In transferring patients from unstandardized to
standardized product, the physician should establish the potency relationships,
perhaps by comparative skin testing, prior to injecting the first standardized
dose.
AgE is important in adjusting dosage of Short Ragweed
extracts to accurately transfer a patient from older extracts to fresher
material. In such cases, the dosage of AgE should be considered in addition to the
W/V dilution or protein nitrogen units. Antigen E concentration continuously
declines in Short Ragweed Pollen extracts at a rate that varies with the
formulation of the product. Aqueous extracts retain Antigen E potency less
effectively than glycerin 50% (v/v) extracts. These differences are reflected
in the expiration date declared on the vial. The continuous decline should be
considered. Also, where ragweed is a component of an allergen mixture, clinical
response to the other components must be considered in adjustment of dosage
based on AgE content alone. The usual course of immunotherapy is three to five
years.
Caution
A small percent of individuals allergic to Short Ragweed
are more sensitive to minor antigens such as Ra3 Ra5 than AgE. There is no
correlation between the amount of these antigens and either AgE or PNU content.
NOTE
For extracts of Short Ragweed or equal part mixture of
Short and Tall Ragweed refer to AgE dosage schedule. The AgE content for those
products is indicated on the vial label. The physician may use the formula
below to determine the AgE dosage for each injection.
AgE dosage can be monitored by using the following
formula:
W/V compounded products:
Labeled AgE X Dose (mL) = dose in AgE
PNU compounded products:
Labeled AgE/mL X dose in PNU = dose in AgE
Labeled PNU/mL
HOW SUPPLIED
- Treatment Sets: 3 and 4 vial sets in serial dilutions
prepared for therapy.
- Maintenance vials: 5 mL and 10 mL vials.
- Concentrate in multiple dose vials: 10 mL and 50 mL,
single antigens or specified mixtures, potency expressed in PNU/mL (up to and
including 100,000 PNU/mL) or W/V (up to and including 1:10 W/V), aqueous or in
50% glycerin, to be diluted prior to use. 1:10 w/v short ragweed extracts contain
≥ 300 units/mL of AgE.
- Sterile Diluent for Allergenic Extracts (Phenol Saline)
is supplied in vials of 4.5 mL, 9.0 mL, 30 Ml and 100 mL.
Storage
To maintain stability of allergenic extracts, proper
storage conditions are essential. Bulk concentrates and diluted extracts are to
be stored at 2° to 8° C even during use. Bulk or diluted extracts are not to be
frozen. Do not use after the expiration date shown on the vial label.
REFERENCES
11. Turkeltaub, P.C., Rastogi, S.C., Baer, H., et al: A
standardized quantitative skin-test assay of allergen potency and stability:
studies on the allergen dose-response curve and effect of wheal, erythema, and
patient selection on assay results, J. Allergy Clin. Immunol. 70:343, 1982.
Distributed in Canada by: ALK-Abello Pharmaceuticals,
Inc., #35-151 Brunel Road, Mississauga, Ontario, Canada L4Z 2H6. Revised : Jun
2013