Vasculitis induced by phenobarbital with cross-reactivity to carbamazepine

A rare case of phenobarbital-induced leukocytoclastic vasculitis

Drug hypersensitivity reactions (DHRs) manifested as vasculitis are rare. Antibiotics, non-steroidal anti-inflammatory drugs (NSAIDs), sulphonamides, diuretics, immunosupressants and anticonvulsants are the most common culprits for drug-induced leukocytoclastic vasculitis (LCV) but there is scarce information about barbiturates. We present a case of 53-year-old female with severe vasculitis after phenobarbital- and NSAIDs-containing medications use. The preliminary diagnosis of drug-induced vasculitis was made based on anamnestic and clinical data. Further examinations confirmed the diagnosis of LCV and excluded other more common causes of vasculitis. The causative significance of used medications was assessed by long-term observation of the patient after the reaction, including the drug challenge series and Naranjo's Adverse Drug Reaction Probability Scale. It was concluded that phenobarbital is the most probable culprit drug. The patient's data were included in the Armenian Registry of Patients with Severe DHRs. Since then, the patient has avoided only barbiturate-containing drugs and no reactions were noted. Thus, the case indicates that even with limited diagnostic capabilities, the final diagnosis of rare drug-induced LCV and even rarer culprit drug can be established by comparing the available data. Awareness about phenobarbital and proper recording of the case are important in the management and prevention of DHRs manifested as vasculitis.

[Drug-induced vasculitis]

INTRODUCTION

Drug-induced vasculitis is reported in almost 10-20 % of vasculitis. Several drugs may be incriminated in their occurrence. Our study aimed to study the epidemiological, clinical, histopathological and evolutionary characteristics of drug-indced vasculitis from a series of cases and to specify the different drugs involved.

METHODS

We conducted a retrospective study during the period from January 2006 to December 2015 from the cases notified to the regional pharmacovigilance center of Sousse, Tunisia. The diagnosis was established according to the criteria proposed by the group of the American college of rheumatology (ACR).

RESULTS

Our study included thirteen cases of drug-induced vasculitis over a ten-year period, with an mean incidence of 1.3 new cases per year. Mean age of patients was 40.84 years. The mean delay from the treatment onset was 14.46 days with extremes ranging from 5 days to six weeks. Most patients had pure skin involvement. Association with other extracutaneous complaints was present in five cases. Cutaneous biopsy was performed in all patients showing a pathological pattern of leukocytoclastic vasculitis, associated with fibrinoid necrosis, extravasation of red blood cells and allergic capillaritis. The outcome was favorable for all patients. The offending drugs in our series were amoxicillin, pristinamycin, rifampicin, fluconazole, metformin, glimepiride, phenobarbital, gabapentin, fenofibrate, ibuprofen, allopurinol, rituximab and tinzaparin.

CONCLUSION

Anamnestic, clinical, biological and histopathological findings allow the early recognition of drug-induced vasculitis. Adequate treatment prevents systemic spreading and a worse prognosis.