Oxiracetam

Oxiracetam, a cyclic derivative of gamma-aminobutyric acid (GABA), is used as a nootropic drug to improve memory and learning.

Comparative pharmacokinetic studies of racemic oxiracetam and its pure enantiomers after oral administration in rats by a stereoselective HPLC method.[Pubmed:25886392]

J Pharm Biomed Anal. 2015;111:153-8.

Oxiracetam (ORC), a nootropic drug used for improving the cognition and memory, has an asymmetric carbon in its structure and exists as (S)- and (R)-ORC. The pharmacokinetic profiles of racemic Oxiracetam and its pure enantiomers in rats were evaluated and compared by enantioselective high-performance liquid chromatography, which was performed on a Chiralpak ID column with a mobile phase of hexane-ethanol-trifluoroacetic acid (78:22:0.1, v/v/v). The method was validated with respect to selectivity, linearity, accuracy and precision, stability and the limit of quantification. The validation acceptance criteria were met in all cases. A saturating phenomenon of (S)-ORC was observed when the dosage ranged from 200 mg/kg to 800 mg/kg. The two enantiomers showed similar profiles in the absorb phase, and reached the maximum concentration at 2h after oral administration. However, compared with the racemate group, the AUC/dose and Cmax/dose ratios of (S)-ORC were higher and Cl/f was lower in enanpure (S)-ORC group. The Cmax of (S)-ORC decreased from 21.3 +/- 5.0 mug/ml to 13.2 +/- 4.2 when (R)-ORC was co-administrated at the dose of 200mg/kg. AUC0-t values of (S)-ORC were different after oral administration of 200 mg/kg (S)-ORC and 400 mg/kg racemic ORC (96.7 +/- 15.5 and 50.1 +/- 16.3 mug h/ml). The higher absorption and slower elimination suggest that enantiopure (S)-ORC could be a promising drug that efficiently reduces clinical dosage, improves therapeutic indices, decreases toxicology risks, and results in increased therapeutic ration.

Enantioselective HPLC determination of oxiracetam enantiomers and application to a pharmacokinetic study in beagle dogs.[Pubmed:25978861]

J Chromatogr B Analyt Technol Biomed Life Sci. 2015 Jul 1;993-994:9-13.

An enantioselective high-performance liquid chromatography method was developed and validated for the determination of Oxiracetam enantiomers, a cognition and memory enhancer, in beagle dog plasma. The plasma samples were prepared by methanol extraction from 200muL plasma, and then the baseline resolution was achieved on a Chiralpak ID column (250mmx4.6mm, 5mum) with mobile phase of hexane-ethanol-trifluoroacetic acid (78:22:0.1, v/v/v) at flow rate of 1.0mL/min. The column elute was monitored using ultraviolet detection at 214nm. The method was linear over concentration range 0.50-100mug/mL for both enantiomers. The relative standard deviation values for intra- and inter-day precision were 0.78-13.61 and 0.74-8.92% for (R)- and (S)-Oxiracetam, respectively. The relative error values of accuracy ranged from -4.74 to 10.48% for (R)-Oxiracetam and from -0.19 to 11.48% for (S)-Oxiracetam. The method was successfully applied to a pharmacokinetic study of individual enantiomer and racemic Oxiracetam in beagle dogs after oral administration. The disposition of the two enantiomers was not stereoselective and chiral inversion was not observed in beagle dogs. The pharmacokinetic profiles of (S)-Oxiracetam were similar with racemic Oxiracetam in beagle dogs.

Pharmacokinetic comparisons of S-oxiracetam and R-oxiracetam in beagle dogs.[Pubmed:27279070]

Acta Pharm. 2016 Jun 1;66(2):279-87.

A pharmacokinetic comparison and conformational stability study of S-Oxiracetam (S-ORT) and R-Oxiracetam (R-ORT) in beagle dogs was used to investigate the possible mechanism of different effects of two Oxiracetam enantiomers through a random crossover design. After drug administration to beagle dogs, blood samples were collected at different time points for pharmacokinetic analysis using the UPLC-ESI-MS/MS method. Parts of plasma samples were used for conformation transformation studies using a normal phase high performance liquid chromatographic (NP HPLC) method. The study showed that Oxiracetam enantiomers maintained their original conformation when administered orally to beagle dogs. Concentrations of S-ORT were significantly higher than R-ORT 1.5 and 2 h after administration; the AUC0-infinity of S-ORT after oral administration tended to be higher than that of R-ORT, which showed that the different effects between S-ORT and R-ORT may be partly associated with their distinctive absorption at least.

Oxiracetam can improve cognitive impairment after chronic cerebral hypoperfusion in rats.[Pubmed:27741481]

Psychiatry Res. 2016 Dec 30;246:284-292.

Chronic cerebral hypoperfusion (CCH) induces cognitive deficits. Although CCH can be improved, cognitive impairment is not improved accordingly. To date, many studies have focused on investigating the pathophysiological mechanisms of CCH; however, the treatment of the induced cognitive impairment remains ineffective. Thus, the mechanisms underlying cognitive impairment after CCH and potential agents for treating this impairment need to be explored further. Oxiracetam is a nootropic drug that improves clinical outcomes for some central nervous system (CNS) disorders. Whether it can improve cognitive impairment after CCH is unknown. In this study, we used behavioural methods, electrophysiology, biochemistry, histopathological staining and transmission electron microscope to investigate rat's cognitive impairment by CCH, and found that Oxiracetam could improve CCH-induced cognitive impairment and prevent deficits of neural plasticity, white matter lesions, and synaptic ultrastructure. These results suggest that Oxiracetam may be effective as a potential agent against CCH-induced cognitive impairment.

Oxiracetam is a cyclic derivative of γ-aminobutyric acid (GABA) which has been commonly used as nootropic drug to treat cognitive impairments.

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