Dose adjustment of immunotherapy after prolonged missed injections
Question:
10/13/2017
We have a debate within our group about dosing reductions with allergen immunotherapy. When a patient is late on the allergy injections how much to reduce the dose. We have info from the practice parameters with dose adjustments when late up to 12 weeks. I was wondering if there was any info about dose adjusting after longer period of missed time such as 5-6 months. One says to start from the beginning of build up, the other says to reduce down 1 vial (10 fold reduction). Also should there be a difference in reductions during build up vs someone on allergen immunotherapy at maintenance for several years. Thank you. Example on maintenance since 2014 for pollen allergy. No hx asthma, no beta blocker or reaction risk factors. Last dose 4/26/2017 of 0.2mL of maintenance vial. Start over or reduce down 1 vial (10 fold) reduction?
Answer:
This question was posed in March 2016 and addressed by Dr Dennis Ledford. Please refer to his response below.
There is no definitive answer to your question but some general guidelines may help making a decision. The practice parameter discusses this issue and points out the limited evidence. The strategy I use is to reduce by one dose per week missed. I vary the magnitude of the dose reduction, following the typical build up dose increments prior to maintenance and a half-dose to one-tenth increments after maintenance. However, you elect to calculate, the starting dose would be original initiation dose after 13 month interruption.
In summary, if immunotherapy was discontinued at the beginning of pregnancy and restarted 4 months after deliver, the starting dose would approximate the original initiation dose.
I hope this information is of help to you and your patient.
All my best.
Dennis K. Ledford, MD, FAAAAI
Summary Statement 51: There is no retrospective or prospective
published evidence to support modification of doses
of allergen immunotherapy because of treatment gaps during
the build-up or maintenance immunotherapy phases. However,
it is customary to reduce the dose of allergen immunotherapy
extract when the interval between injections is
prolonged. D
There are no evidence-based guidelines on dose adjustments
for missed immunotherapy doses. During the build-up phase, it is
customary to repeat or even reduce the dose of allergen immunotherapy
extract if there has been a substantial time interval
between injections. This might depend on (1) the concentration of
allergen immunotherapy extract that is to be administered, (2)
whether there is a previous history of systemic reactions, and (3)
the degree of variation from the prescribed interval of time, with
longer intervals since the last injection leading to greater reductions
in the dose to be administered. See Table E5 in this article’s
Online Repository at www.jacionline.org for an example of an
immunotherapy dose-adjustment schedule for unscheduled gaps
in allergen immunotherapy injection intervals.
A pilot observational study of 16 missed-dose adjustment
protocols illustrated the wide variation of missed-dose adjustments
used.281 In this study half the protocols calculated the late
interval from the date of the last dose received, whereas the other
half calculated the late interval from the date of the missed scheduled
dose. The author noted that a stepwise reduction (with the
late interval beginning with the date of the missed dose) beginning
at 3 weeks late for build-up (reduce 1 dose per week late)
and 1 week late for maintenance fell within the interquartile
ranges of all protocols.
Jacqueline A. Pongracic, MD, FAAAAI