Drug Allergies and Beta-Lactam Allergies Flashcards
How common are antibiotic allergies?
Reported antibiotic allergies are common however TRUE allergies are less common
Why is labelling someone with a drug allergy dangerous?
Labelling someone with a drug allergy can be dangerous if they subsequently require that drug in the future and are denied access to it
Labelling someone with a drug allergy is dangerous that they may require them later in the future and a 2nd line antibiotic is broader spectrum with more s/e
Describe a beta-lactam allergy
If the allergy is to the beta-lactam ring, the patient will be allergic to all beta-lactams
Allergy may also occur to the side chain (R1) in which case allergy will be to the specific drugs that share that side chain
Can you give a cepahlosporin to a person allergic to penicillin?
Carpbapenems?
Cephalosporin and penicillin cross-sensitivity rate often quoted as up to 10% ,however it is not that high; more like 1-3% or even less
Carbapenems have ~ 1% cross-reactivity with penicillins
A person allergic to both (cross-sensitivity) is rare –> In majority of patients, safe to give cephalosporin to someone with penicillin allergy
What are some of s/e of a penicillin adverse event?
When does it usually occur?
Is it a true allergy?
What drugs are safe?
Diffuse non-itchy rash, GI upset, headache –> Most common s/e
Diffuse non-itchy rash occurs in < 10% of patients taking penicillin –> Not an ALLERGY
Usually begin after 2-5 days of therapy and may last several days up to a week
Rashes may come slightly after the end (days after stopping meds a rash occurs)
Not IgE mediated (occur within an hour)
Safe to give penicillins and cephalosporins
What are some severe adverse effects of penicillin?
Stevens-Johnson syndrome, toxic epidermal necrolysis (TENS), interstitial nephritis, hemolytic anemia, serum sickness
Not IgE mediated
All beta-lactams are contraindicated (penicllins, cephalopsorins, carbenems)
Skin testing , desensitization and graded challenges are not recommended- could be harmful
Describe a true penicillin allergy.
- IgE mediated allergy
Itchy rash or hives –> Major itching
Angioedema, hypotension, bronchospasm
Can be life-threatening
Usually occur < 1 hour after dose
Anaphylaxis
What is a pharmacists role in antibiotic allergies?
Sulfonamide antibiotics are different than any other sulfa containing moieties
Most people who have a sulfa antibiotic allergy are not allergic to these other drugs and its safe to give them
If someone gets a skin rxn to a sulfa, the rash is significant
More releuctant to give someone a sulfa if they had a rash with a sulfa before –> Absoultely do not if associated with fever or swollen lymph nodes
