Serum phenytoin concentrations in paediatric patients following intravenous loading

Area of Science:

• Pediatric Neurology
• Clinical Pharmacology

Background:

• Phenytoin is a key antiepileptic drug for treating acute tonic-clonic seizures in children unresponsive to benzodiazepines.
• The standard UK loading dose for phenytoin is 18 mg/kg, but evidence supporting its efficacy in pediatric patients is limited.

Purpose of the Study:

• To evaluate the effectiveness of the 18 mg/kg intravenous phenytoin loading dose in achieving therapeutic serum concentrations in pediatric patients.
• To identify any dose calculation errors or adverse events associated with this phenytoin loading regimen.

Main Methods:

• A 19-month retrospective and prospective audit of intravenous phenytoin loading doses administered to pediatric patients.
• Doses were normalized for weight, and serum phenytoin concentrations were measured between 60 and 180 minutes post-administration.
• Data on dose calculation errors and adverse events were systematically recorded.

Main Results:

• Serum phenytoin concentrations were within the therapeutic range (10-20 μg/ml) in 24 out of 31 measurements (77.4%) in 27 children.
• The median time for serum concentration measurement was 153 minutes after the loading dose.
• No dose calculation errors or adverse effects were identified during the audit.

Conclusions:

• The 18 mg/kg intravenous phenytoin loading dose generally achieves therapeutic serum concentrations in most pediatric patients.
• This established loading dose appears safe and effective for pediatric epilepsy management, warranting its continued use.