Rare case of drug-induced allergy reaction

Abstract

Introduction: Adverse drug reactions (ADRs) are broadly divided into predictable (related to pharmacological actions of the drug in otherwise normal individuals) and unpredictable reactions (related to individual’s immunological response and, on occasion, to genetic differences in susceptible patients). Drug allergy is a type of unpredictable reaction. ADRs should be differentiated from adverse drug events (ADEs). ADEs extend beyond ADRs to include harm related to medication errors and drug/food interactions. While knowledge of ADEs is important in efforts to improve patient safety, ADRs are the primary focus of regulatory agencies and post-marketing surveillance. Clinical case: We present a 73-year-old woman who was consulted in the Emergency Room and admitted in the Internal Medicine - Geriatrics Department because of a sudden syncope at home, associated with dyspnea at rest and high rhythm palpitations. Three months ago she was diagnosed with atrial fibrillation, but she stopped the treatment a week before coming to ER. The paraclinical tests showed no heart anomalies so it was decided to initiate the therapy with Propafenone. After 8 days the Propafenone is changed with Amiodarone because the EKG showed left bundle branch block (LBBB) and the laboratory analy sis presented high values of cardiac enzymes, but the patient had a worsening general condition, associating dyspnea with nervousness, coughing and increased heart rate (Sc>2=80-82%, Pulse=130bpm). so she received oxygen therapy and a beta-blocker. On the next day she presented an allergic rush spreaded all over her body and so she received Hydrocortisone hemisuccinate, but her allergy persisted and even spreaded wider. We realized that she developed this abnormal reaction to Amiodarone. Metoprolol and later to ail the administrated drugs, even on antiallergic one. Afterwards she reacted pretty well on antihistaminic medication, vitamin C and calcium. The paradox was that in absence of any medication the heart rate remained convenient. Results: A study of 141 patients with suspected drug eruptions, including histological assessment, found that 24% were in fact reactive rashes or had other causes, suggesting that drug eruptions were overdiagnosed on clinical grounds alone. Of the confirmed drug-related eruptions. 39.8% were caused by antibiotics, 21.2% by anti-inflammatories, 7.6% by contrast media and 31.4% by others (oral antidiabetics, antimycotics, antipsychotics, anti-epileptics and others). Conclusion: All drugs can cause an allergic reaction and despite the fact that allergic reaction to Amiodarone is very rare (under 1%), it still can occurs and it has to be considered when one presents immunological reaction to the treatment.