Adverse Drug Reactions Flashcards
7 cards from real PSA practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.
Read the first 7 Adverse Drug Reactions flashcards as text
A patient develops fever, rash, lymphadenopathy, and arthralgia 2 weeks after starting infliximab. Which hypersensitivity mechanism best explains this presentation?
Answer: Type III immune complex-mediated serum sickness
Serum sickness is a Type III hypersensitivity reaction caused by immune complex deposition, characteristically occurring 1-3 weeks after exposure to heterologous proteins or certain drugs.
A patient with no prior allergy receives iodinated contrast for a CT scan and develops urticaria and hypotension during administration. This reaction is best classified as:
Answer: Anaphylactoid reaction not requiring prior sensitization
Radiocontrast reactions are anaphylactoid (pseudoallergic) — they mimic anaphylaxis by directly activating mast cells without prior IgE sensitization, so no previous exposure is required.
A patient starts rituximab infusion and develops fever, rigors, and bronchospasm within the first hour. What is the most likely cause?
Answer: Cytokine release from rituximab binding CD20 on circulating B cells
Rituximab binds CD20 on circulating B cells triggering cytokine release; this infusion reaction is most severe during the first infusion when circulating B-cell burden is highest.
A patient develops DRESS syndrome 5 weeks after starting allopurinol. Which feature would NOT typically be expected in this condition?
Answer: Immediate urticaria occurring within 1 hour of dosing
DRESS is a delayed reaction occurring 2-8 weeks after drug initiation; immediate urticaria within 1 hour indicates IgE-mediated hypersensitivity, which is a distinct and incompatible diagnosis.
Long-term nitrofurantoin used for recurrent UTI prophylaxis is associated with which serious pulmonary adverse reaction?
Answer: Pulmonary fibrosis
Chronic nitrofurantoin use can cause insidious progressive pulmonary fibrosis that may be irreversible; early recognition and drug cessation are essential to limit further lung damage.
A patient receiving intravenous vancomycin too rapidly develops facial flushing, erythema over the neck and upper chest, and pruritus during the infusion. What is this reaction?
Answer: Red man syndrome
Red man syndrome is a rate-dependent, non-immune infusion reaction caused by direct mast cell degranulation when vancomycin is infused too rapidly — it is not a true allergic reaction.
Which of the following best describes a Type E adverse drug reaction in the extended Rawlins-Thompson classification?
Answer: An end-of-treatment reaction occurring upon abrupt drug withdrawal
Type E reactions (ending) occur when a drug is withdrawn abruptly, such as opioid withdrawal syndrome or rebound hypertension after stopping clonidine suddenly.