Effect of levetiracetam on extracellular amino acid levels in the dorsal hippocampus of rats with temporal lobe epilepsy.

Levetiracetam (LEV) is an anticonvulsant drug with a unique mechanism of action that is not completely understood. However, its activity profile may involve effects on excitatory and/or inhibitory neurotransmission since the primary target of LEV, synaptic vesicle protein 2A, is ubiquitously expressed in all types of synaptic vesicles. Therefore, the objective of the present study was to explore the effect of LEV (300 mg/kg/day for one week, administered via osmotic mini-pumps) on neurotransmitter release and its probable selective effect on extracellular gamma-amino butyric acid (GABA), glutamate (Glu), aspartate (Asp), glutamine (Gln), taurine (Tau) and glycine (Gly) concentrations (using in vivo microdialysis under basal and high-K conditions) in the dorsal hippocampus (DH), a region that undergoes major synaptic changes during epilepsy.

Development of a UPLC-MS/MS method for the quantification of sildenafil by DBS, and its use on pediatric pulmonary hypertension.

Background: Sildenafil is used for the treatment of pediatric pulmonary hypertension. A dried blood spot (DBS)-based LC-MS method for sildenafil quantitation was developed and applied to a group of patients.

Results: DBS showed high portability and stability of samples, and the method was selective and linear for quantitation of sildenafil (5-3,000 ng/ml) and N-desmethyl-sildenafil (3-1,500 ng/ml).