Hello everyone my name is hannah and today i’m going to be talking about penicillin allergy and desensitization in children so my objectives for today are to describe the epidemiology and characteristics of a true ige mediated penicillin allergy explain the process of drug desensitization and when it should be used analyze the current literature surrounding the use of
Penicillin desensitization in pediatric patients and discuss the risks and benefits of drug desensitization as well as the use of pre-medications so i’d like to begin by talking about the epidemiology of true penicillin allergies so approximately 10 percent of patients in the united states report having a penicillin allergy when in reality less than one percent of
The population is actually truly allergic to penicillins with a true ige mediated reaction based on this we can conclude that a thorough history should be obtained in order to establish a true diagnosis of penicillin allergy in patients so what do the characteristics of a true type 1 or ige mediated reaction look like well these reactions occur usually immediately
Or within one hour of administration of the drug patients may present with hives so that includes red or pink raised areas on the skin usually associated with itching patients may also present with angioedema so this looks like that localized swelling that can occur in several different parts of the body patients also may experience shortness of breath wheezing
Or cough and lastly they may experience anaphylaxis which involves two organ systems at least or the development of hypotension after drug exposure so if a patient presents with a history that is consistent with this possible immediate reaction to penicillin or amoxicillin then it is recommended that skin testing should be performed as a first-line investigation
However penicillin skin testing has a very low sensitivity and high specificity meaning that you are at risk for false negatives so should a negative test occur with the penicillin skin test and this should be followed by a drug provocation test or dpt newer studies suggest that dpt may also be considered even without this preemptive skin testing for children
That just have mild reactions limited to the skin overall skin testing is considered to be safe but noted to be rather unpleasant and sometimes difficult to perform in younger children if a patient presents with a true penicillin allergy and penicillin is the preferred agent of choice drug desensitization may be considered this is the process of administering
Increasing doses of a drug to which a patient had a known or highly suspected hypersensitivity reaction and this usually occurs on a predetermined time schedule with the goal of achieving tolerance to the agent while the exact mechanisms and molecular targets of drug desensitization are not fully known it is thought to temporarily modify the immune response to
The medication in the hopes that the patient will temporarily and safely be able to use that medication that they are allergic to so when should drug desensitization be used well this is indicated in patients that have that ige mediated drug-induced allergic response specifically for those patients that there is no equally efficacious alternative treatment
Option or if the alternative treatment option produces greater toxicity than the preferred option this should also be considered in patients that do not have any comorbidities that would put them at an increased risk during the procedure and in patients that had a previous drug reaction that was not considered to be severe or life-threatening i mean this would
Include reactions such as stevens-johnson syndrome i will note here that there have been a few case reports of successful desensitization procedures in patients with some of these more severe reactions so when considering using drug desensitization in a patient physicians should really evaluate the risks and benefits of performing this procedure and patients
Should be aware that acute hypersensitivity reactions may occur during the drug desensitization in general these procedures vary widely based on the agent and the route of administration but usually the drug desensitization procedure can be completed within 4-12 hours for most patients additionally these procedures should only be performed by physicians that
Are familiar with the process and patients should be constantly monitored for any signs or symptoms of anaphylaxis and appropriate treatment should be readily available if anaphylaxis were to occur additionally patients should be in a stable clinical condition before performing the procedure and any medications that they were previously on to treat any underlying
Disease states should be continued with the exception of beta blockers if the cardiologist allows and this is because they may actually interfere with the treatment of severe hypersensitivity reactions additionally the desensitization procedures for more severe reactions such as anaphylaxis should be performed in the icu and the medications should be administered
Through the same route that is required for the therapeutic purposes so what we’ve seen in this study so far is that oral and parental routes seem to be equally effective however the oral route seems to be safer easier and less expensive and it’s also the preferred route in children specifically so any time that penicillin desensitization occurs it should always
Be performed through the oral route when possible i would like to point out that there is a lack of controlled studies of desensitization protocols for children so most of the evidence that we have in children is derived from meta-analyses of case reports in pediatric patients or the pediatric protocols are adapted from adult data and so usually these pediatric
Protocols just differ in the total cumulative dose that’s given which should be ideally the daily dose used for adequate therapy so taking a look at the desensitization protocols for penicillin specifically most protocols have around 12 steps but it can vary from anywhere from 4 to 16 steps and the dose escalations typically occur at factors of 2 to 3 times the
Previous dose usually these are administered every 15 to 20 minutes over the course of several hours although some studies have recommended anywhere from 45 to 60 minute intervals for some oral desensitization protocols the starting dose should be determined based on the severity of the patient’s reaction so if patients have more severe anaphylactic history of
Reactions um those doses may be much lower than the therapeutic dose than patients that had more mild to moderate reactions the initial dose should be based on the final therapeutic dose with increases in doses at each step until this dose is achieved so this is an example of a proposed penicillin desensitization protocol specifically for oral penicillin i mean
You can see that the initial dose starts out pretty low at 100 units and then goes all the way up on 14 steps although just a reminder this initial dose should be based on the indication for the antibiotic as well as the patient’s weight and the final therapeutic dose that is to be achieved i would like to point out that about a third of patients will experience
An allergic reaction during the desensitization procedure however most of these reactions tend to be mild in severity even if the reactions are mild appropriate treatment should not be delayed and medications to treat these allergic reactions should be kept close by and patients continuously monitored i would also like to touch on the role of pre-medication in
Drug desensitization procedures as its role is somewhat controversial there’s a little bit of debate in the literature about whether pre-medications should be used or not as systemic corticosteroids and antihistamines may sometimes mask the early signs and symptoms of hypersensitivity reactions so premedication protocols vary widely based on the specific drug
Being given and by the institution some studies propose that medications may be used alone or in combination to help reduce the risk and severity of these types of reactions that occur during desensitization these medications include drugs like diphenhydramine famotidine or renitidine which are typically given 20 minutes prior to the procedure or drugs like
Dexamethasone which may be given the night before and the morning of the procedure so like i said it varies widely based on what institution you’re at what literature you read but some studies recommend either giving one or a combination of these agents to help prevent some of those more severe reactions lastly i’d like to talk a little bit about long-term
Tolerance and the success rates so really what’s important to understand here is that desensitization procedures only provide temporary tolerance so this tolerance is only going to remain for about 24 to 36 hours after the drug is discontinued so if the patient needs this medication again in the future they are likely going to need to repeat the desensitization
Protocol again lastly in general i’ll say that beta lactam desensitization success rates are relatively high and there’s an estimated range of around 58 to 100 percent so in conclusion overall i believe that drug desensitization is a method that can be considered to overcome penicillin allergies in children with sub-optimal alternative treatment options and
Generally it’s considered a relatively safe and effective procedure the penicillin desensitization strategies should be tailored to the individual patient so the final therapeutic dose that is your goal of the penicillin desensitization should be based on the indication as well as the patient’s weight lastly we are in need of standardized protocols and specific
Pediatric drug desensitization guidelines and this will just help us optimize treatment in the future and implement this into common practice is a list of my references and if you have any questions about anything please feel free to contact me my email is on the screen thank you so much for listening
Transcribed from video
Penicillin Desensitization in Children By TTUHSC Peds Rotation Abilene