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 D50.11 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 1/2 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 1/2 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 by: ALK-Abello Pharmaceuticals, Inc. #35-151 Brunel Road Mississauga, Ontario Canada L4Z 2H6. Revised June 2013.