Penicillins on the NCLEX
Penicillin class: anaphylaxis, cross-reactivity with cephalosporins, common uses.
Penicillins are a beta-lactam class. NCLEX tests anaphylaxis recognition, cross-reactivity considerations, and uses.
Common drugs
Penicillin G/VK, amoxicillin, ampicillin, piperacillin-tazobactam (Zosyn), nafcillin, oxacillin.
Allergic reactions
Anaphylaxis is the killer, laryngeal edema, hypotension, bronchospasm. Stop drug, epinephrine IM, support airway. Less severe: rash, hives.
Cross-reactivity
Cephalosporins: historically cited at 10%, actual cross-reactivity ~1-2%. Generally avoid cephalosporins in severe penicillin allergy (anaphylaxis); often safe with mild rash history.
Uses
Strep infections (PCN G/VK). Otitis media, sinusitis (amoxicillin). Endocarditis (penicillin + gentamicin). Listeria (ampicillin). Broad-spectrum (Zosyn).
Frequently asked
Patient says 'I'm allergic to penicillin', clarify?
Yes, what reaction, how long ago, was it documented? Many 'allergies' are actually GI intolerance or rash that wasn't true allergy.
Probenecid with penicillin?
Blocks renal excretion → higher penicillin levels. Used historically for STDs requiring high levels.
Quick check
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