Drug Allergies & Beta-Lactam Allergies

Question 1

Why is it dangerous to label someone with a drug allergy?

Answer 1

they may subsequently require that drug in the future and are denied access to it

Question 2

True or false: antibiotic allergies are usually from the past so when the patient presents with a new antibiotic Rx they will not generally have signs or symptoms

Answer 2

true

Question 3

In which scenarios would a patient be allergic to all beta-lactams? What would be a scenario where the patient is only allergic to x specific beta-lactam?

Answer 3

all beta-lactams: if the allergy is to the beta-lactam ring
specific: if the allergy is due to the side chain

Question 4

What is the rate of cross-sensitivity between penicillins and cephalosporins?

Answer 4

quoted up to 10%, however it is more like 1-3% or less

Question 5

What are the three groups of reactions to beta-lactams?

Answer 5

penicillin adverse effects
severe penicillin adverse effects
true IgE mediated allergy

Question 6

What would you expect to see happen to someone who is experiencing penicillin adverse effects?

Answer 6

diffuse non-itchy rash, GI upset, headache
usually begins after 2-5 days of therapy

Question 7

Are penicillin adverse effects IgE mediated?

Answer 7

no
safe to give penicillins and cephalosporins

Question 8

What would you expect to see happen to someone who is experiencing severe penicillin adverse effects?

Answer 8

SJS, TENS, interstitial nephritis, hemolytic anemia, serum sickness

Question 9

Are severe penicillin adverse effects IgE mediated?

Answer 9

no
however all beta-lactams are contraindicated

Question 10

What would you expect to see happen to someone who has a true IgE mediated allergy to penicillins?

Answer 10

itchy rash or hives
angioedema, hypotension, bronchospasm
can be life threatening
usually <1hr after dose
anaphylaxis

Question 11

What is the management of penicillin allergies?

Answer 11

stop the offending agent
ABC-assess airway, breathing, circulation
CPR if required
treat the acute reaction-epinephrine

Question 12

What is the epinephrine dosing for adults? What about children?

Answer 12

adults: 0.3-0.5mg/kg
children: 0.01mg/kg
IM every 5-15 minutes up to 3 injections

Question 13

What could you do if someone has a negative skin test to penicillin?

Answer 13

can safely give cephalosporins and penicillins

Question 14

What should you do if someone has a positive skin test to pencillin or a skin test is not available?

Answer 14

avoid penicillin
choose cephalosporin with dissimilar side chain
use alternative agent

Question 15

What are some sulfonamide drugs?

Answer 15

antibiotics
thiazide and loop diuretics
oral hypoglycemic
COX-2 inhibitors
CA inhibitors
antivirals (amprenavir, fosampenivir, darunavir)
tamsulosin
probenecid
triptans
zonisamide

Question 16

True or false: it is highly likely that there will be cross reactivity between sulfonamide antibiotics and non-antibiotics

Answer 16

false

Question 17

What are immune mediated sulfonamide reactions dependent on?

Answer 17

production of reactive metabolites in the liver

Question 18

True or false: true IgE mediated sulfa allergies are more common than delayed cutaneous reactions

Answer 18

false
immune mediated IgE reactions are rare
delayed cutaneous reactions are more common
-fever followed by rash (morbilliform)
-may also result in SJS or TEN

Question 19

What are the questions to ask when taking a detailed allergy history?

Answer 19

when did the reaction take place?
how old was the patient at the time of reaction?
does the patient recall the reaction? if not, who informed them of the reaction?
does the patient remember which medication?
what was the medication prescribed for?
what was the route of administration?
how long after starting the medication did the reaction begin?
describe the reaction.
did the patient seek medical care due to the reaction?
was the medication discontinued? if so, what happened upon dc?
did the patient have any ongoing medical problems?
what other medications was the patient taking?
has the patient taken similar medications before or after reaction?
has the patient ever experienced this reaction without intake of the suspected medication?
what antibiotics have been safely used before?