Ch. 8 Drug Allergies and Desensitization Flashcards
Type A reaction
Predictable reaction that is dose-dependent, related to the pharmacologic actions of the drug, can occur in any patient and range from mild to severe.
Most common type of reaction and account for 80% of ADRs
Ex. Orthostatic hypotension with doxazosin
Type B reaction
Unpredictable reaction that is generally not dose-dependent, is unrelated to the pharmacologic actions of the drug, and can be influenced by patient-specific susceptibility factors
Ex. drug allergies, pseudoallergic reactions (Red Man Syndrome, opioid rash), drug intolerances, and idiosyncratic reactions (SJS)
Type I reaction
Immediate (occurs with 15-30 minutes) and involves an IgE medicated immune response.
Ex. Urticaria (hives), angioedema, bronchospasm, anaphylaxis
Can range in severity from minor inconvenience to death
Type II reaction
Occur within minutes to hours after exposure
Ex. hemolytic anemia, thrombocytopenia
Type III reaction
Immune-complex reaction, which has an onset of 1-3 weeks
Ex. Serum sickness (fever, rash and arthralgias that can occur with antibody products derived from animals and some other medications)
Type IV reaction
Delayed hypersensitivity reaction that can occur from 48 hours to several weeks after exposure
Ex. PPD skin test for TB
When should MedGuides be dispensed?
With the original prescription and with each refill
What are some individual agents or drug classes that require MedGuides?
Anticonvulsants Antidepressants Long-acting Opioids NSAIDs ADHD stimulants Atomoxetine
Photosensitivity reaction
When sunlight reacts with a drug in the skin and causes tissue damage that looks like severe sunburn on sun-exposed areas
A Type IV (delayed hypersensitivity) reactions appears as a red, itchy rash that can affect areas that were not exposed to the sun
Patients should use sunscreens with UVA and UVB
Key drugs that can photosensitivity (x10)
Carbamazepine Diuretics (thiazides and loops) MTX Oral and topical retinoids Quinolones St. John's Wort Sulfa antibiotics Tacrolimus Tetracyclines Voriconazole
Thrombotic Thrombocytopenic Purpura (TTP)
A blood disorder where the clotting process consumes platelets and leads to bleeding under the skin and the formation of purpura (bruises) and petechiae (dots).
Life-threatening; should be treated immediately with plasma exchange
Drugs that cause TTP
Key Drugs: Clopidogrel Ticlopidine Other Drugs: Acyclovir, famciclovir, valacyclovir Quinine, SMZ
SJS and TENs
Epidermal detachment and skin loss that is equivalent to 3rd degree burns
Can result in severe mucosal erosions, a high body temp. and organ damage (eyes, liver, kidneys)
Occur generally within 1-3 weeks, and almost always more than 72 hours after administration
Systematic steroid use in SJS/TENS
CONTRAINDICATED in TEN, bit may be used in SJS
Drug Reaction with Eosinophilia and Systematic Symptoms (DRESS)
Includes a variety of skin eruptions accompanied by systemic sxs: fever, hepatic dysfunction, renal dysfunction and lymphadenopathy, but rarely involves mucosal surfaces
Key drugs that cause SJS/TENs/DRESS
Allopurinol, lamotrigine, PCNs, phenytoin, piroxicam, SMZ
Phytonadione, contrast media
Associated with pseudoallergic reaction (anaphylactoid reaction)
Not IgE mediated, but clinical appearance and tx similar to that of anaphylaxis
Effects of antihistamines, systemic steroids (sometimes NSAIDs), steroid injections, epinephrine in anaphylaxis
Antihistamines: counteract the histamine release that causes itching, swelling and rash
Systemic steroids (sometimes NSAIDs): decrease swelling
Steroid Injections: severe swelling
Epinephrine: reverses bronchoconstriction
Signs of anaphylaxis
Urticaria (hives) Swelling of the mouth and throat Difficulty breathing or wheezing sounds Abdominal cramping Hypotension
Treatment of anaphylaxis
Epinephrine injection +/-
Diphenhydramine +/-
Steroids +/-
IV fluids
Brand names of epinephrine pens
EpiPen EpiPen JR Adrenaclick Auvi-Q Symjepi
Symjepi Indication
For patients 30 kg and up in anaphylaxis
Duration of time EpiPen should be held in place after injection, and how long to massage it
3 seconds
10 seconds
Duration of time Adrenaclick should be held in place after injection, and how long to massage it
10 seconds
10 seconds
