Chapter 77: Drug Allergies & Adverse Drug Reactions

Question 1

What is an ADR

Answer 1

unintended pharmacologic effect

Question 2

ADRs are categorized into which two types

Answer 2

Type A: predictable (most ADRs)
Type B: unpredictable

Question 3

ADRs are different from medication erros because…

Answer 3

the drug is being administered correctly (dose, indication, etc) and someone then has an ADR

Question 4

Type A reactions are dependent on

Answer 4

dose
account for 80% of ADRs

Question 5

Type B reactions depend on ____ and include

Answer 5

patient specific factors (unrelated to pharmacologic mechanism)
- idiosyncratic reactions (e.g., SJS)
- pseudoallergic reactions (e.g., redman syndrome with rapid vanco infusion, itching after opioid administration)
- Drug intolerances (e.g., nausea with codeine)
- Drug allergies (immune mediated responses)

Question 6

Type I allergic reactions occur how long after drug exposure

Answer 6

within 60 min

Ex) urticaria, bronchospasm, angioedema, anaphylaxis

Question 7

Type II allergic reactions occur how long after drug exposure

Answer 7

Several days (5-8 days)

Ex) hemolytic anemia and thrombocytopenia

Question 8

Type III allergic reactions occur how long after drug exposure

Answer 8

immune complexes ≥ 1 week

Ex) DILE

Question 9

Type IV allergic reactions occur how long after drug exposure

Answer 9

48 hours to several weeks

Ex) SJS

Question 10

REMS are developed by ____ and approved by ____ to ensure the benefits of the drug outweighs the risk

examples

Answer 10

Manufacturer
FDA

clozapine REMS, isotretinoin IPLEDGE

Question 11

T/F: if a medication has a MedGuide, it only needs to be dispensed with the original Rx and it’s optional to dispense it with each refill

Answer 11

False - it must be dispensed with the original rx and each refill

Question 12

When an ADR occurs, which scale can help determine the likelihood that a drug caused an adverse reaction

Answer 12

Naranjo Scale

0 = doubtful ADR; ≥9 = definite ADR

Question 13

SE, adverse events and allergies should be reported to the ____

Answer 13

FDAs MedWatch program, which is called the FDA Adverse Event Reporting System (FAERS)

Question 14

Post-marketing safety surveillance programs is also known as

Answer 14

Phase IV trials

Question 15

upset stomach/nausea is ____

Answer 15

an intolerance, not an allergy

Question 16

When dispensing medications that can cause photosensitivity, it is important to advise patients to use sunscreens that block both UVA and UVB, which are labeled as

Answer 16

Broad-spectrum

Question 17

Drugs most commonly associated with photosensitivity

Answer 17

Amiodarone
Diuretics (thiazide and loop)
MTX
Oral and topical retinoids
Quinolones
St. John's Wort
Sulfa antibiotics 
Tacrolimus
Tetracyclines
Voriconazole

Question 18

What is TTP

Answer 18

a blood disorder in which clots form throughout the body

Question 19

Key drugs associated with TTP

Answer 19

Oral P2Y12 inhibitors (e.g., Plavix)
Sulfamethoxazole

Question 20

What is the key to treating SJS and TEN

Answer 20

stop the offending drug
then fluid and electrolyte replacement, woudn care, pain medications

Question 21

Which medications are CI in TEN, but may be used in SJS

Answer 21

Systemic steroids

Question 22

DRESS management

Answer 22

stop offending agent

Question 23

Anaphylaxis occurs within what time frame of drug exposure

Answer 23

seconds to minutes

Question 24

Treatment for anaphylaxis

Answer 24

Epinephrine injection +/- Benadryl +/- steroids +/- IV fluids

Question 25

Key drugs that are commonly associated with severe skin reactions

Answer 25

``` Abacavir Allopurinol Carbamazepine Ethosuximide Lamotrigine Modafinil Nevirapine PCNs Phenytoin SMX ```

Question 26

Dose for EpiPen

Answer 26

1 mg/mL

Question 27

Where should EpiPen be injected

Answer 27

into the middle of the outer thigh

Question 28

At what angle should an EpiPen be injected

Answer 28

90 degree only

Question 29

How long should the EpiPen needle be held in place when injecting

Answer 29

3 seconds

Question 30

After removing the EpiPen needle, how long should you massage the area for

Answer 30

10 seconds

Question 31

T/F: to know you have injected the full amount of EpiPen, there should be no liquid in the device after using

Answer 31

False - there may be liquid remaining in the device after injection

Question 32

T/F: A second dose of EpiPen can be given in the opposite leg if needed prior to arrival of medical help

Answer 32

True

Question 33

T/F: EpiPen CANNOT be injected through clothing

Answer 33

False - it can

Question 34

On the NAPLEX, if a patient is allergic to PCNs, all PCN classes should be avoided, with the exception of:

Answer 34

Acute otitis media; use of a 2nd or 3rd gen cephalosporin in patients with non-severe PCN allergy (cefdinir, cefpodoxime, ceftriaxone, or cefuroxime)

Question 35

Which medication is considered safe in patients with PCN allergies

Answer 35

Aztreonam

Question 36

In which disease state should a pregnant person or a person with HIV & a PCN allergy be desensitized and still receive PCN

Answer 36

Syphilis - PCN G Benzathine (Bicillin LA)

Question 37

Which drugs/classes contain a warning or CI for use in patients with sulfa allergies

Answer 37

``` Thiazide & loop diuretics Sulfonylureas Acetazolomide Zonisamide Celecoxib Darunavir ```

Question 38

T/F: Sulfite or sulfate allergies cross react with sulfonamides

Answer 38

False - they do not cross react

Question 39

Contrast media used in CT scans can cause

Answer 39

Anaphylactoid reactions and delayed skin reactions

Question 40

Drugs to avoid with a peanut or soy allergy

Answer 40

Clevidipine Propofol

Question 41

Patients who have true allergy to eggs should avoid which drugs

Answer 41

Clevidipine Propofol Yellow Fever vaccine

Question 42

T/F: if a severe reaction occurs to an influenza vaccine, regardless of which ingredient is suspected, the patient should not receive further doses of any influenza vaccine formulation

Answer 42

True | if egg allergy, no matter how severe, can get any flu vaccine indicated

Question 43

What is the most common drug allergy in the US

Answer 43

PCN allergy

Question 44

What is the goal of penicillin skin testing

Answer 44

To identify patients who are at the greatest risk of a Type I hypersensitivity reaction

Question 45

Skin testing only predicts what kind of reaction

Answer 45

IgE-mediated

Question 46

How is desensitization done

Answer 46

A very small dose of the medication is administered and the dose is increased in increments at regular time intervals up to the target dose

Question 47

What happens if doses are missed during desensitization

Answer 47

The drug-free period allows the immune system to re-sensitize to the drug and serious hypersensitivity reactions could occur with subsequent doses

Question 48

Desensitization should NEVER be attempted if an agent has previously caused which reactions

Answer 48

SJS or TEN