[The significance of laboratory findings in long-term antiepileptic therapy]

Clinical implementation of 4-dihydroxyborylphenylalanine synthesised by an asymmetric pathway

Boron neutron capture therapy (BNCT) is an experimental therapeutic modality combining a boron pharmaceutical with neutron irradiation. 4-Dihydroxyborylphenylalanine (L-BPA) synthesised via the asymmetric pathway by Malan and Morin [Synlett. 167-168 (1996)] was developed to be the boron containing pharmaceutical in the first series of Finnish BNCT clinical trials. The final product was >98.5% chemically pure L-BPA with L-phenylalanine and L-tyrosine as the residual impurities. The solubility of L-BPA was enhanced by complex formation with fructose (BPA-F). The pH and osmolarity of the BPA-F preparation is in the physiological range. Careful attention was given to the pharmaceutical quality of the BPA-F preparations. Prior to starting clinical trials the acute toxicity of L-BPA was studied in male albino Sprague-Dawley rats. In accordance with earlier studies no adverse effects were observed. After completion of the development work L-BPA solution was administered to brain tumour patients in conjunction with clinical studies for development and testing of BPA-based BNCT. No clinically significant adverse events attributable to the L-BPA i.v. infusions were observed. We conclude that our synthesis development, complementary preclinical and clinical observations justify the safe use of L-BPA up to clinical phase III studies with L-BPA produced by the asymmetric pathway, originally presented by Malan and Morin in 1996.

Severe hepatotoxicity during valproate therapy: an update and report of eight new fatalities

Since our last report on valproate (VPA)-related hepatotoxicity in 1988, 8 other children have died of VPA-associated liver failure in Germany and Switzerland. We compared the clinical course of these children with that of 6 children with a reversible outcome of severe hepatotoxicity related to VPA. Thirty-five percent of patients with fatal liver failure were normally developed, 23.5% were receiving VPA monotherapy, and 35.3% were aged < or = 2 years. The initial clinical symptoms of VPA-related hepatotoxicity were nausea, vomiting, apathy or coma, and increasing seizures in more than 50% of patients, in combination with febrile infections at onset of symptoms. As compared with the series of German patients reported in 1988, one third of the fatalities occurred after the first 6 months of therapy as compared with 6% in the 1988 series. Clinical symptoms and laboratory findings were the same in patients with reversible and with fatal outcome. Early or immediate withdrawal of VPA after the first signs of VPA-associated hepatotoxicity may be responsible for the increased number of children who recovered after VPA-related severe liver failure. The pathogenesis of liver failure during VPA treatment remains unknown; metabolic defects and cofactors such as polypharmacy or infections have become increasingly likely to contribute by depleting intracellular CoA. Worldwide, 132 patients have died of VPA-associated liver failure and/or pancreatitis. Because a group at risk for fatalities with VPA cannot be defined precisely, patients treated with VPA and their families must be made well aware of the clinical symptoms of hepatotoxicity such as apathy, vomiting, or increased seizure frequency, especially in the presence of febrile infections. Laboratory tests and clinical controls during the first 6 months of therapy should not be neglected.