A drag-specific recombinant antibody sFv fragment (G5-sFv) was studied as a potential antidote for desipramine (DMI) toxicity in rats. The VH-(Gly4Ser)3-VL construct was expressed in genetically-modified tobacco NT-1 cell culture using the CaMV35s promoter and a plant 5'UTR signal peptide. Functional sFv routinely accumulated to >70 mg/L in the culture medium after 10 to 13 days of growth. Affinity for DMI was 2.4 × 108 M-1, modestly lower than that of the corresponding Fab' (5.5 × 108 M-1). Administration of 0.6 g/kg G5-sFv i.v. to rats after a toxic dose of DMI (molar ratio of G5-sFv/DMI = 0.18) increased the serum DMI concentration 16-fold, reduced the DMI free fraction from 38.4 to 5.3%, and significantly reduced the electrocardiographic QRS duration (P <0.05). One rat receiving G5-sFv died despite showing improvement in QRS duration, possibly due to the incomplete removal of endotoxin from this preparation. These data suggest that G5-sFv expressed at high levels in cultured tobacco NT1 cells may be effective in reducing DMI cardiotoxicity in rats. The use of sFv for this purpose expands the range of antibody fragments that may be useful in the treatment of drug overdose.
|Original language||English (US)|
|Number of pages||1|
|Journal||Clinical pharmacology and therapeutics|
|State||Published - 1997|