Adverse Reactions & Pharmacovigilance

Cross-Reactivity

TRÇapraz Reaktivite
Also known as:Cross-sensitivity · Cross-allergy

The occurrence of a hypersensitivity reaction to a drug in a patient sensitised to a different drug, because both share a structural determinant or trigger the same reaction pathway.

In depth

Immunological cross-reactivity depends on recognition of a shared epitope. Among beta-lactams it is determined mainly by similarity of the R1 side chain rather than by the beta-lactam ring: cross-reactivity between penicillins and cephalosporins with dissimilar side chains is low, that with carbapenems is very low, and aztreonam cross-reacts essentially only with agents sharing its side chain, notably ceftazidime. Aromatic anticonvulsants (e.g., carbamazepine, phenytoin, lamotrigine) show clinically relevant cross-reactivity in delayed reactions.

Pharmacological cross-reactivity occurs without immune recognition, as in NSAID-exacerbated respiratory disease, where any strong COX-1 inhibitor can provoke symptoms. Conversely, cross-reactivity between sulfonamide antibiotics and non-antibiotic sulfonamides such as furosemide or thiazides is not supported by current evidence.

Clinical pearl

A history of non-severe penicillin allergy does not automatically exclude cephalosporins; choosing an agent with a dissimilar side chain lowers risk, whereas severe delayed reactions (SJS/TEN, DRESS) warrant avoiding the whole class.

Example drugs

Amoxicillin cefalexin Ceftazidime Aztreonam Carbamazepine Phenytoin
TRIn Turkish

Çapraz Reaktivite

Bir ilaca duyarlanmış hastada, ortak bir yapısal belirleyiciyi paylaşan veya aynı reaksiyon yolağını tetikleyen farklı bir ilaca karşı aşırı duyarlılık reaksiyonu gelişmesidir.

İmmünolojik çapraz reaktivite ortak bir epitopun tanınmasına dayanır. Beta-laktamlarda belirleyici olan, beta-laktam halkasından çok R1 yan zincirinin benzerliğidir: penisilinler ile farklı yan zincirli sefalosporinler arasındaki çapraz reaktivite düşük, karbapenemlerle çok düşüktür; aztreonam ise esas olarak yalnızca aynı yan zinciri taşıyan ajanlarla, özellikle seftazidimle çapraz reaksiyon verir. Aromatik antikonvülzanlar (ör. karbamazepin, fenitoin, lamotrijin) geç reaksiyonlarda klinik açıdan önemli çapraz reaktivite gösterir.

Farmakolojik çapraz reaktivite immün tanıma olmaksızın gelişir; NSAİİ ile alevlenen solunum yolu hastalığında güçlü COX-1 inhibitörlerinin tümü belirtileri tetikleyebilir. Buna karşılık sülfonamid antibiyotikler ile furosemid veya tiyazidler gibi antibiyotik olmayan sülfonamidler arasında çapraz reaktivite güncel kanıtlarla desteklenmemektedir.

Ağır olmayan penisilin alerjisi öyküsü sefalosporinleri otomatik olarak dışlamaz; farklı yan zincire sahip bir ajanın seçilmesi riski azaltır, ağır gecikmiş reaksiyonlarda (SJS/TEN, DRESS) ise tüm sınıftan kaçınılmalıdır.

Diğer adları:Çapraz duyarlılık · Çapraz alerji
Updated 24.09.2026 0 views Educational reference — verify against current sources before clinical use.

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