Management of Drug Hypersensitivity in Pediatric

Flashcards covering the definition, diagnosis, types, and management protocols for pediatric drug hypersensitivity, including specific conditions like SJS, TEN, and anaphylaxis.

Adverse Drug Reaction (WHO Definition)

A response to a drug which is noxious, and unintended, which occurs at doses normally used in man for prophylaxis, diagnosis or therapy of disease, or for the modification of physiological function.

Type A Adverse Drug Reaction

Reactions related to the drug's pharmacological action, such as hepatic failure with high dose acetaminophen or sedation in antihistamines.

Type B Adverse Drug Reaction

Reactions unrelated to the drug's pharmacological action, occurring in susceptible individuals.

Immediate Reaction (Phenotype)

Hypersensitivity reactions appearing within minutes to 6 hours after exposure, typically IgE mediated or through direct mast cell/basophil activation.

Delayed Reaction (Phenotype)

Hypersensitivity reactions appearing more than 6-12 hours after exposure, typically T cell specific.

HLA-B15:02

An HLA haplotype associated with Carbamazepine-SJS drug-hypersensitivity reactions in Asiatic populations.

HLA-B31:01

An HLA haplotype associated with Carbamazepine-SJS drug-hypersensitivity reactions in Northern European populations.

HLA-B57:01

An HLA haplotype associated with Abacavir hypersensitivity syndrome.

Skin Prick Testing (SPT)

The primary mode of skin testing for immediate IgE-mediated allergy; considered positive if the induration is $>3mm$ larger than the negative control.

Intradermal Testing (IDT)

A test relevant to both immediate IgE-mediated allergy and delayed-type hypersensitivity; induration is positive if it is $>3mm$ larger than the mark at 0 minutes.

Patch Testing

A test conducted mainly by dermatologists relevant to contact hypersensitivity and some forms of delayed-type hypersensitivity; not relevant for immediate IgE-mediated allergy.

Oral Challenge Positive Criteria

The test is positive if clinical symptoms appear during the 3-hour observation period (fast phase) or within 5 days (delayed phase).

Mild Drug Reactions

Localized skin manifestations without systemic involvement, such as localized urticaria ($<10\%$ body surface), limited angioedema, or localized pruritus.

Diphenhydramine pediatric dose (Mild Reaction)

$1\,mg/kg$ IV/IM for first-generation antihistamine management.

Anaphylaxis (WAO 2020 Criteria)

Highly likely with acute onset (minutes to hours) of skin/mucosal involvement plus either respiratory compromise, reduced BP/end-organ dysfunction, or severe GI symptoms.

Epinephrine (Adrenaline) dosage

Intramuscular injection in the mid-anterolateral thigh at $0.01\,mg/kg$ of a $1:1,000$ ($1\,mg/ml$) solution; maximum of $0.5\,mg$ in adults or $0.3\,mg$ in children.

DRESS Syndrome

Drug Reaction with Eosinophilia and Systemic Symptoms; characterized by fever, lymphadenopathy, skin eruption, and internal organ involvement (hepatitis, pneumonitis, etc.).

Stevens-Johnson Syndrome (SJS) BSA involvement

A severe cutaneous adverse reaction involving skin detachment of less than $10\%$ of the total body surface area.

SJS/TEN Overlap BSA involvement

A severe cutaneous adverse reaction involving skin detachment between $10\%$ and $30\%$ of the total body surface area.

Toxic Epidermal Necrolysis (TEN) BSA involvement

A severe cutaneous adverse reaction involving skin detachment of greater than $30\%$ of the total body surface area.

ALDEN Score

Algorithm for assessment of Drug causality in SJS and toxic epidermal necrolysis, based on time latency, drug presence in the body, and prechallenge/rechallenge info.

SCORTEN

A severity-of-illness score for TEN based on 7 prognostic factors, calculated within 24 hours after admission to assess the risk of mortality.

Nikolsky sign

A clinical sign where the top layers of the skin slip away from the lower layers when rubbed, found to be positive in SJS, TEN, and SSSS.

Staphylococcal Scalded Skin Syndrome (SSSS)

A differential diagnosis for SJS/TEN in infants, characterized by widely spread erythema, perioral/nares crusting, superficial desquamation, and no mucous membrane involvement.