Drug Allergies & Adverse Reactions Flashcards
Type A reactions
dose-dependent and predictable
Type B reactions
not dose-dependent, and not predictable. Can be influenced by patient-specific factors. Ex. drug allergies, pseudoallergic reactions, drug intolerance, idiosyncratic reactions
True drug allergies can be classified into…
4 types
Type I reactions:
immediate (within 15-30 min of drug exposure). Ex. urticaria, bronchospasm, angioedema, anaphylaxis
Type II reactions:
minutes to hours after drug exposure. Ex. hemolytic anemia and thrombocytopenia
Type III reactions:
immune-complex reactions; occur 3-10 hour after drug exposure. Ex. drug-induced lupus erythematosus (DILE)
Type IV reactions:
delayed hypersensitivity reactions; can occur anywhere from 48 hours to several weeks after drug exposure. Ex. PPD skin test for TB (peaks at 48-72 hours)
A black boxed warning (BBW) indicates a:
risk of death or permanent disability from a drug (ex. increased risk of venous thromboembolism and death from stroke with raloxifene)
Histamine is released by…
mast cells and basophils
Contraindications indicate that..
the drug cannot be used in that patients (risk outweighs the benefit)
Adverse reactions (ADRs) refer to…
undesirable, uncomfortable or dangerous effects from a drug
Risk Evaluation and Mitigation Strategies (REMS) are…
risk management plants required by the FDA for some drugs (developed by the manufacturer and approved by the FDA) Ex. clozapine REMS, iPLEDGE for isotretinoin, and REMS to reduce the misuse of long-acting opioids
Medication Guides present important adverse events that can occur with over 300 medications and should be dispensed…
with the original Rx and with each refill. Required for many individual meds and some entire classes (including anticonvulsants, antidepressants, long-acting opioids, NSAIDs, ADHD stimulants, atomoxetine)
When an ADR occurs, the Naranjo Scale is used to…
help determine the likelihood that a drug caused an ADR. A score ≥ 9= definite ADR; 5-8= probable ADR; 1-4= possible ADR; 0= doubtful ADR
Side effects, adverse events, and allergies should be reported to the FDA’s MedWatch program, also known as..
FDA’s Adverse Event Reporting System (FAERS)
The FDA can require Phase IV (post-marketing safety surveillance programs) for…
approved drugs and biologics to collect/analyze the reports to better understand the safety profile in a real-world setting
If a FDA receive enough reports that a drug is linked to a particular problem, the manufacturer can…
be required to update the labeling (ex. package insert). In especially risky cases, a drug safety alert is issued to prescribers, usually before the labeling is changed.
Oseltamivir (Tamiflu) was initially released without any warning of unusual behavior in children. The FDA received enough reports that they issued a warning to prescribed in 2006. After many more reports, in 2008, the FDA…
required the manufacturer to update the prescribing information to include a precaution about hallucinations, confusion and other strange behavior in children
Electronic medical records allow for documentation of intolerances separate from allergies. Intolerances are less serious complaints, and the drug should be avoided if possible. For example…
a patient who had stomach upset with codeine (but not hydrocodone or other drugs in the morphine class)
Opioids cause a non-allergic release of histamine from…
mast cells in the skin, causing itching and hives in some patients. Pruritus can be reduced or avoided if the patient is premedicated with an antihistamine, such as diphenhydramine
Photosensitivity can happen when sunlight reacts with a drug in the skin and causes tissue damage that looks like a severe sunburn (usually within hours of sun exposure). A type IV (delayed hypersensitivity) reaction…
can also occur with sun exposure and some meds. It appears as a red, itchy rash that can spread to areas that were not exposed to sun and occurs within days of sun exposure.
When dispensing medications that can cause photosensitivity, it is important to…
counsel the patient and/or their caregivers to limit sun exposure and to used sunscreens that block both UVA and UVB radiation
Drugs most commonly associated with photosensitivity include:
- amiodarone
- diuretics (thiazide and loop)
- methotrexate
- oral and topical retinoids
- quinolones
- St. John’s Wort
- sulfa antibiotics
- tacrolimus
- tetracyclines
- voriconazole
Other drugs that can cause photosensitivity include:
- antihistamines (1st gen)
- carbamazepine
- chloroquine
- coal tar
- fluorouracil
- griseofulvin
- NSAIDs
- quinidine
- tigecycline
Counsel patients to apply sunscreen liberally and reapply…
at least every 2 hours and after swimming/sweating
Thrombotic thrombocytopenic purpura (TTP) is…
a blood disorder in which clots form throughout the body. The clotting process consumes platelets and leads to bleeding under the skin and formation of purpura (bruises) and petechiae (dots)
TTP can be fatal and should be treated…
immediately with plasma exchange
Drugs that are associated with TTP include:
- oral P2Y12 inhibitors (ex. clopidogrel)
- ticlopidine (older P2Y12 inhibitor)
- sulfamethoxazole
- Others: acyclovir, famciclovir, quinine, valacyclovir
Hematomas are a collection of blood under the skin due to trauma to a blood vessel, resulting in blood leaking into the surrounding tissue. Drugs that can cause hematoma include…
heparin, low molecular weight heparin (LMWH), some other anticoagulants and phytonadione (vitamin K) if given mistakenly as an IM injection
Steven-Johnson Syndrome (SJS) and Toxic Epidermal Necrolysis (TEN) involve…
epidermal detachment and skin loss that is equivalent to 3rd degree burns. SJS and TEN generally occur 1-3 weeks after drug administration, and almost always more than 72 hours after drug administration.
SJS and TEN are commonly classified by the % of skin detachment. The key to treating both is to…
stop the offending agent ASAP. Also, patients will receive fluid and electrolyte replacement, wound care and pain medications
Systemic steroids are C/I in TEN, but may be used in TEN, although…
benefit is controversial. Due to the severity of the mucosal involvement, antibiotics are often necessary to prevent or treat an infection
DRESS can include a variety of skin eruptions accompanied by…
systemic symptoms such as fever, liver dysfunction, kidney dysfunction, and lymphadenopathy
Treatment of DRESS consists of…
stopping the offending drug, although symptoms may continue to worsen for a period of time after the drug has been stopped
For a true drug allergy to occur…
the person must have taken the drug before. Initial exposure will cause a Type I hypersensitivity reaction, causing IgE production, which primes the body to release excessive histamine at the next drug exposure.
Key drugs commonly associated with severe skin reactions include…
- abacavir
- allopurinol
- carbamazepine
- ethosuximide
- lamotrigine
- modafinil
- nevirapine
- penicillins
- phenytoin
- sulfamethoxazole
In a drug allergy, antihistamines can be used to counteract the histamine release that causes itching, swelling, and rash. Also…
systemic steroids, and sometimes NSAIDs, can be used to decrease swelling. Severe swelling may necessitate a steroid injection. Epinephrine is used to reverse bronchoconstriction if the patient is wheezing or has other signs of trouble breathing
Drugs associated with SJS (rash <10% of BSA) and TENS (rash> 30% of BSA) include:
- acetaminophen
- amiodarone
- bupropion
- caspofungin
- celecoxib
- clindamycin
- clopidogrel
- darbepoetin
- darunavir
- deferasirox
- epoetin alfa
- etravirine
- fosphenytoin
- hydroxychloroquine
- ibuprofen
- isavuconazonium
- isoniazid
- macrolides
- metronidazole
- minocycline
- oseltamivir
- oxcarbazepine
- peramivir
- phenobarbital
- piroxicam
- quinine
- quinolones
- terbinafine
- tiagabine
- varenicline
- voriconazole
- zonisamide
Drugs associated with DRESS include…
- doxycycline
- fosphenytoin
- gabapentin
- lacosamide
- minocycline
- olanzapine
- oxcarbazepine
- sulfasalazine
- terbinafine
- valproate
- vancomycin
Anaphylaxis is a…
severe, life-threatening allergic reaction that occurs within seconds to minutes of drug exposure. Signs may include urticaria (hives), swelling of the mouth/throat, difficulty breathing or wheezing sounds, abdominal cramping and hypotension
An anaphylactic reaction required immediate emergency medical care. Call 911. Treatment includes:
epinephrine injection +/- diphenhydramine +/ steroids +/ IV fluids
Epinephrine auto-injectors generally available in 1 mg/mL dose:
EpiPen, EpiPen Jr., Auvi-Q, Adrenaclick, Symjepi, or generic equivalent
The pediatric dose of epinephrine is for patients 15-30 kg (EpiPen Jr.)
half of adult dose (0.15 mg). Auvi-W is also available in 0.1 mg (for patients weighing 7.5-14 kg). The patient’s emergency kit should also include emergency contact info. and diphenhydramine tablets (25 mg x 2), which should be taken if there is no tongue/lip swelling
If patient has a penicillin allergy, must desensitize and use the drug to treat syphilis in…
pregnant or HIV-infected patients
Reactions are most commonly reported with sulfamethoxazole, and the patient should…
avoid using sulfasalazine, sulfadiazine, and sulfisoxazole.
Sulfite or sulfate allergies do not cross react with sulfonamides. Meds that contain sulfites include…
rotigotine patch, orphenadrine injection, the Rowasa mesalamine enema, some dobutamine formulations and some eye drops
The risk for cross-reactivity with sulfamethoxazole thiazides and loop diuretics is…
very low, and in clinical practice, the reaction is usually not considered significant when these drugs are needed
The package labels for “non-arylamine” sulfonamides such as…
thiazide diuretics, loop diuretics (except ethacrynic acid), sulfonylureas, acetazolamide, zonisamide, and celecoxib, cidofovir, darunavir (Prezista), fosamprenavir, and tipranavir containing warnings or C/Is for use in patients with sulfa allergy (but it’s rare)
Contrast media (used in CT scans) can cause anaphylactoid reactions and delayed skin reactions.
Systemic steroids and antihistamines can be used to prevent reactions if contrast media is needed in a patient who has had a prior rxn.
Reactions to NSAIDs, including aspirin, can either be a drug sensitivity or a true allergic rxn. A drug sensitivity can cause rhinitis, mild asthmatic-type reactions, or skin reactions. If a true allergy is present, the patient will..
experience urticaria, angioedema, and occasionally anaphylaxis. COX-2 selective NSAIDs may be used in practice (but avoid all NSAIDS on the NAPLEX)
Peanut and soy are in the same family and can have cross-reactivity. Parents of children with peanut allergies should be…
CPR-trained and have ready access to an epinephrine auto-injector.
Drugs to avoid with a peanut or soy allergy include…
clevidipine (Cleviprex), propofol (Diprivan), and progesterone in Prometrium capsules
Drugs to avoid with a peanut or soy allergy include…
- clevidipine (Cleviprex)
- propofol (Diprivan)
- progesterone in Prometrium capsules
If a patient has a true allergy to eggs, they cannot use…
- clevidipine (Cleviprex)
- propofol (Diprivan)
- Yellow fever vaccine (chicken eggs used)
Flublok is made using recombinant techniques and…
contains no egg protein and is an option in patients with severe reactions to eggs (but is not preferentially recommended by ACIP)
For influenza vaccine, ACIP states that…
even patients who have had more severe symptoms when consuming eggs can receive any indicated inactivated vaccine
A penicillin allergy is the most common drug allergy, reported in…
~10% of the general population
Desensitization must take place…
in a medical setting where emergency care can be provided
Desensitization should never be attempted if…
an agent has previously caused SJS or TEN
The goal of penicillin skin testing is to…
identify patients who are at the greatest risk of a Type I hyper sensitivity reaction if exposed to a systemic penicillin
Pre-Pen (benzylpenicilloyl polylysine injection) contains…
the major determinants of penicillin allergy and is used with very dilute solutions of penicillin G
