How to Write a Subcutaneous Immunotherapy (SCIT) Prescription for Allergic Rhinitis

Author: V. Dimov, M.D., Allergist/Immunologist and Assistant Professor at University of Chicago
Reviewer: S. Randhawa, M.D., Allergist/Immunologist and Assistant Professor at LSU (Shreveport) Department of Allergy and Immunology

A 33-year-old AAM is referred to the allergy clinic for symptoms of allergic rhinitis and conjunctivitis. He complains of itchy watery eyes, itchy nose and nasal congestion. These symptoms occur all year but are worse in the spring and summer. He has tried intranasal steroids (INS) and oral antihistamines but does not get a lasting symptom relief and his sleep is impaired. No history of nasal polyps, eczema, food allergies, or systemic reactions to stinging insects.

Past medical history (PMH)

Allergic rhinitis and conjunctivitis.

Medications

Fluticasone (Flonase) 50 mcg/actuation nasal spray QHS, loratidine 10 mg po daily.

Social history (SH)

No tobacco or alcohol use.

Environmental history

Pets in the home: 2 dogs. Flooring: Wall-to-wall carpeting. Air conditioning: Central air. Heating: Forced hot air. Basement: Dry basement. Dust mite controls: Dust mite controls are not in place. Tobacco smoke: no exposure in the home.

Family history (FH)

Mother with asthma and allergic rhinitis. Sister with allergic rhinitis.

Physical examination

VSS
HEENT: External ears normal. Canals clear. TM's normal. Nares normal. Septum midline. Congested pale mucosa, no polyps seen. No drainage or sinus tenderness. Lips, tongue normal. Oropharynx clear.
Neck: supple, no adenopathy
CVS: RRR, normal S1/S2, no m/r/g
Chest: CTA (B)
Extremities: no c/c/e
Skin: color, texture, turgor normal. No rashes or lesions.

What is the most likely diagnosis?

Allergic rhinitis and conjunctivitis.

What tests would you order?

Skin prick test.

What happened?


Figure 1. Skin prick test results (click to enlarge).

The allergen skin test was extremely positive with multiple pseudopods described by the nurse as "pseudopods on pseudopods."

The patient developed conjunctival itching and redness, nasal congestion and discharge during the skin prick test which required administration of epinephrine 0.3 mg IM, loratidine 10 mg and prednisone 40 mg po. His symptoms resolved withing 15 minutes. A second dose of prednisone was prescribed for the next day.

Final diagnosis

Allergic rhinitis and conjunctivitis.

What treatment options would you suggest for long-term control of his symptoms?

Subcutaneous immunotherapy (SCIT).

Risks and benefits of subcutaneous immunotherapy (SCIT) for allergic rhinitis were discussed and the patient opted to start therapy.

How would you write a prescription for SCIT?


Figure 2. SCIT Instructions (click to enlarge).

Please see the SCIT instructions above. Multiallergic patiens may need 3 vials of mixed immunotherapy extracts labeled A, B and C.

Please see the table for protease activity in the SCIT instructions above. High protease activity extracts cannot mix with the low protease activity extracts because they degrade them. For example, mold and dust mite extracts can only be mixed together (and with ragweed). Ragweed extract can be mixed with all other extracts.

You must have in mind the total volume of each vial when writing a SCIT prescription. In this case, the total volume of each vial is 5 ml. The extracts can be mixed up to 5 ml in each vial. The rest of the volume is made up with diluent.

You can use a Microsoft Excel Spreadsheet or similar software to calculate the sum of the volumes for different extracts and the volume of diluent needed.


Figure 3. SCIT prescription. (click to enlarge).

You need figures 1, 2 and 3 in front of you when writing a prescription for each patient.

Figure 1 (skin prick test) determines what will be put in the mix.
Figure 2 (reminder "cheat sheet") determines how the extracts will be mixed in each vial.
Figure 3 is the actual SCIT prescription.

It is advisable to have all three figures in front of you when writing SCIT prescriptions, at least initially.

Let's look at vial A. Our patient is allergic to almost all allergens tested. We will mix in vial A the following allergens:

- Grass Mix #7, 0.4 ml
- Bermuda, 0.5 ml
- Creighton Tree Mix (or local mix for the particular area), 1.5 ml
- Short Ragweed 1.0 ml

The amount of diluent needed to constitute the vial to a total of 5 ml is 0.3 ml.

Let's look at vial B. We will mix in vial B the following allergens (all with high protease activity):

- Mite Mix, 0.3 ml
- Cockroach, 0.5 ml
- Mold Mix AHP, 2.0 ml
- Minor Mold Mix, 2.0 ml

All the allergens above have high protease activity and can be mixed together. They should not be mixed with low protease activity extracts.

Mixing allergen extracts with high protease content

Mnemonic

M

Mold

Mite - cockroach has even more proteases than mite

Mixing problems - proteases degarade grass extracts in particular and decrease their potency

The amount of diluent needed to constitute the vial to a total of 5 ml is 0.2 ml.

Let's look at vial C. We will mix in vial C the following allergens:

- Cat Hair, 2.0 ml
- Dog Hair, 2.0 ml

Cat and dog hair require relatively larger volumes (2 ml each) compared to other allergens. Therefore, relatively fewer allergens are mixed in vial C.

The amount of diluent needed to constitute the vial to a total of 5 ml is 1.0 ml.

When a patient is "multiallergic," the goal should be to maximize the dose of extracts for which we have the best evidence for effectiveness: grass, ragweed and dust mite. Allergen immunotherapy with dog hair is generally less effective than the one with cat hair.

It is difficult for children to tolerate 3 SCIT injection, therefore every effort should be made to combine the extracts in 1-2 vials.

What is the starting dose of SCIT?

The patient had a hypersensitivity reaction during the skin prick testing, therefore we decided to start with the lowest dose listed in figure 3 at a dilution of 1:10,000. The dose will be administered weekly.


Vials A, B and C - mixed.

What are the 4 standardized allergen extracts?

(A) Dog

(B) Trees

(C) Cat

(D) Molds

(E) Dust Mite

(F) Grass

(G) Ragweed

The 4 standardized extracts are Cat, Dust Mite, Grass and Ragweed.

Allergen immunotherapy was introduced by Leonard Noon 100 years ago and is the only disease-modifying treatment for allergic individuals (Allergy, 2012). Allergists should provide an EpiPen prescriptions to all patients on SCIT.

References

Allergen immunotherapy: A practice parameter second update. JACI, 2007 (PDF).
Allergen Immunotherapy. AFP, 2004.
Allergy Immunotherapy for Primary Care Physicians. J . Stokes , T . Casale. The American Journal of Medicine , Volume 119 , Issue 10 , Pages 820 - 823 (2006). Link via MDConsult.
Position Statement on the Administration of Immunotherapy Outside of the Prescribing Allergist Facility. ACAAI.
Allergen injection immunotherapy. John M Weiner. MJA 2006; 185 (4): 234.
Use of Immunotherapy in a Primary Care Office. AFP, 1998.
Advances in upper airway diseases and allergen immunotherapy in 2007. Saltoun C, Avila PC. J Allergy Clin Immunol. 2008 Aug 9.
Sublingual Immunotherapy. Anthony J. Frew. NEJM, Volume 358:2259-2264, May 22, 2008.
Talking Points on Sublingual Immunotherapy (SLIT) for Physicians Practicing in the United States. ACAAI.

Allergen-specific immunotherapy for respiratory allergies: From meta-analysis to registration and beyond. JACI, 2010.

SCIT ("allergy shots") is at least as potent as pharmacotherapy in controlling the symptoms of allergic rhintis as early as the first season of therapy. JACI, 2011.
Allergen immunotherapy practice in the United States: guidelines, measures, and outcomes (2011) http://goo.gl/xHYjG

Video

Immunotherapy Rx, Part 1 and 2, Jay Portnoy, MD. Conferences Online For Allergy, Children's Mercy Hospitals & Clinics, 2009.
Immunotherapy. Linda Cox, MD. Conferences Online For Allergy, Children's Mercy Hospitals & Clinics, Feb 4, 2009.
Allergy shots by Dr. Y. Patel.

Patient Information

What is immunotherapy and how does it work? AAAAI, 2006.

Published: 02/24/2009
Updated: 09/26/2011