Adverse Reactions & Pharmacovigilance

Type B Adverse Reaction

TRTip B Advers Reaksiyon
Also known as:Bizarre reaction · Non-dose-related adverse reaction

An adverse drug reaction that is not expected from the drug's known pharmacology, is largely independent of dose, and is uncommon but frequently serious.

In depth

Type B (bizarre) reactions are mainly immunological, such as anaphylaxis, severe cutaneous adverse reactions and drug-induced immune cytopenias, or idiosyncratic, reflecting genetic susceptibility, such as haemolysis in G6PD deficiency or malignant hyperthermia with volatile anaesthetics and suxamethonium. Because they occur at therapeutic doses in only a small subset of patients, they are often detected only after marketing and are a common reason for warnings and withdrawals.

Management is withdrawal of the culprit and avoidance of re-exposure, not dose reduction. Some type B reactions have become partly predictable through pharmacogenomic screening, for example HLA-B*57:01 before abacavir and HLA-B*15:02 before carbamazepine in patients of Southeast or South Asian ancestry.

Clinical pearl

Record the reaction precisely (drug, manifestation, timing) in the allergy/intolerance record, because re-challenge can be life-threatening; lowering the dose does not make re-exposure safe.

Example drugs

Benzylpenicillin Carbamazepine Allopurinol Abacavir suxamethonium Primaquine
TRIn Turkish

Tip B Advers Reaksiyon

İlacın bilinen farmakolojisinden beklenmeyen, büyük ölçüde dozdan bağımsız, seyrek görülen ancak sıklıkla ciddi seyreden advers ilaç reaksiyonudur.

Tip B (bizarre, beklenmedik) reaksiyonlar başlıca anafilaksi, ağır kutanöz advers reaksiyonlar ve ilaca bağlı immün sitopeniler gibi immünolojik ya da G6PD eksikliğinde hemoliz veya volatil anestezikler ve süksinilkolinle malign hipertermi gibi genetik yatkınlığı yansıtan idiyosenkratik reaksiyonlardır. Terapötik dozlarda hastaların yalnızca küçük bir alt grubunda görüldüklerinden çoğu zaman ancak ruhsat sonrasında saptanırlar ve uyarıların ve piyasadan çekilmelerin sık bir nedenidirler.

Yönetim, sorumlu ilacın kesilmesi ve yeniden maruziyetten kaçınılmasıdır; doz azaltma bir çözüm değildir. Bazı tip B reaksiyonlar farmakogenomik tarama sayesinde kısmen öngörülebilir hâle gelmiştir; örneğin abakavir öncesinde HLA-B*57:01, Güneydoğu veya Güney Asya kökenli hastalarda karbamazepin öncesinde HLA-B*15:02 taraması.

Reaksiyon (ilaç, klinik tablo, zamanlama) alerji/intolerans kaydına ayrıntılı olarak işlenmelidir; yeniden maruziyet yaşamı tehdit edebilir ve dozun düşürülmesi yeniden kullanımı güvenli hâle getirmez.

Diğer adları:Beklenmedik (bizarre) reaksiyon · Doza bağımlı olmayan advers reaksiyon
Updated 24.09.2026 1 views Educational reference — verify against current sources before clinical use.

Read next

Type A Adverse ReactionTip A Advers Reaksiyon

An adverse drug reaction resulting from an exaggeration of a drug's known pharmacological action; it is dose-related, predictable and usually common but rarely fatal.

 Idiosyncratic Reactionİdiyosenkratik Reaksiyon

An uncommon, qualitatively abnormal response to a drug that is not explained by its known pharmacology, occurs in only a small proportion of exposed patients and is not clearly dose-related.

 Drug Hypersensitivityİlaç Aşırı Duyarlılığı

An adverse drug reaction that clinically resembles allergy; when a specific immunological mechanism (IgE or T cells) is demonstrated it is termed drug allergy, otherwise non-allergic hypersensitivity.

 AnaphylaxisAnafilaksi

A severe, potentially life-threatening systemic hypersensitivity reaction of rapid onset that causes airway, breathing or circulatory compromise, usually but not always with skin or mucosal changes.

 Stevens–Johnson SyndromeStevens–Johnson Sendromu

A rare, severe, usually drug-induced mucocutaneous reaction with widespread keratinocyte death, blistering and mucosal erosions, in which epidermal detachment involves less than 10% of body surface area.

 HLA-B*57:01HLA-B*57:01

A human leukocyte antigen allele strongly associated with a severe, immune-mediated hypersensitivity reaction to the antiretroviral drug abacavir.