Phenytoin hypersensitivity: 38 cases.

Area of Science:

• Pharmacology
• Clinical Toxicology
• Immunology

Background:

• Phenytoin is a widely used anticonvulsant medication.
• Hypersensitivity reactions can occur with phenytoin therapy.
• Understanding the spectrum and timing of these reactions is important for patient safety.

Purpose of the Study:

• To investigate the frequency and severity of hypersensitivity reactions to phenytoin.
• To characterize the clinical manifestations and timeline of these reactions.
• To assess the impact of phenytoin hypersensitivity on healthcare utilization.

Main Methods:

• Retrospective review of 38 cases with confirmed phenytoin hypersensitivity reactions.
• Inclusion criteria: patients with reactions solely attributed to phenytoin, excluding concurrent drug use.
• Data collection focused on reaction types, timing, and patient outcomes.

Main Results:

• Rashes were the most common manifestation, followed by fever, lymphadenopathy, and eosinophilia.
• Other reported reactions included abnormal liver function tests, blood dyscrasias, serum sickness, renal failure, and polymyositis.
• The pseudolymphoma syndrome (fever, rash, lymphadenopathy) occurred in nine patients, with 35 of 38 reactions appearing within two months of starting phenytoin therapy.

Conclusions:

• Phenytoin hypersensitivity reactions present with a diverse range of symptoms, often within the first two months of treatment.
• Prompt recognition and discontinuation of phenytoin are essential for mitigating serious morbidity.
• Phenytoin sensitivity contributed significantly to inpatient days, highlighting the clinical and economic burden of these reactions.