(S)-(-)-Atenolol

Synthesis of a nano-sized chiral imprinted polymer and its use as an (S)-atenolol carrier in the bulk liquid membrane.[Pubmed:24771633]

J Sep Sci. 2014 Jul;37(14):1887-95.

In this work, nanosized chiral imprinted polymers containing (S)-atenolol ((S)-ATN) selective sites were synthesized by using suspension polymerization in silicon oil. (S)-ATN, methacrylic acid, and ethylene glycol dimethacrylate were used as enantiomerically pure template, functional monomer, and cross-linker, respectively. The prepared chiral imprinted polymers were used as the carrier elements in a bulk liquid membrane (BLM). (S)-ATN transport capability of the chiral imprinted polymers was compared with that of the nonimprinted polymer. It was shown that chiral imprinted polymers could transport (S)-ATN through the BLM more effectively than (R)-ATN, whereas no difference in the facilitated transport was observed between (R)-ATN and (S)-ATN when using nonimprinted polymer particles as the carrier element in the BLM. A kinetic model was proposed for the transportation of (S)-ATN through the chiral imprinted polymers based BLM. It was found that the extraction of ATN from the source to the membrane controls the chiral separation process. It was also found that the pH of source and receiving phases as well as the racemic ATN concentration in source phase had very crucial effect on the chiral separation efficiency.

Design, Development and Optimization of S (-) Atenolol Floating Sustained Release Matrix Tablets Using Surface Response Methodology.[Pubmed:26798171]

Indian J Pharm Sci. 2015 Sep-Oct;77(5):563-72.

The objective of this present investigation was to develop and formulate floating sustained release matrix tablets of s (-) atenolol, by using different polymer combinations and filler, to optimize by using surface response methodology for different drug release variables and to evaluate the drug release pattern of the optimized product. Floating sustained release matrix tablets of various combinations were prepared with cellulose-based polymers: Hydroxypropyl methylcellulose, sodium bicarbonate as a gas generating agent, polyvinyl pyrrolidone as a binder and lactose monohydrate as filler. The 3(2) full factorial design was employed to investigate the effect of formulation variables on different properties of tablets applicable to floating lag time, buoyancy time, % drug release in 1 and 6 h (D1 h,D6 h) and time required to 90% drug release (t90%). Significance of result was analyzed using analysis of non variance and P < 0.05 was considered statistically significant. S (-) atenolol floating sustained release matrix tablets followed the Higuchi drug release kinetics that indicates the release of drug follows anomalous (non-Fickian) diffusion mechanism. The developed floating sustained release matrix tablet of improved efficacy can perform therapeutically better than a conventional tablet.

Effect of aged garlic extract and s-allyl cysteine and their interaction with atenolol during isoproterenol induced myocardial toxicity in rats.[Pubmed:24550592]

Indian J Pharmacol. 2014 Jan-Feb;46(1):94-9.

OBJECTIVES: The study evaluates the cardioprotective effect of aged garlic extract (AGE) and its constituent; S-allylcysteine (SAC) and their interaction with atenolol during isoproterenol induced cardiac toxicity in rats. MATERIALS AND METHODS: Rats were administered AGE at two different doses of 2 ml/kg or 5 ml/kg orally whereas SAC was administered either at a dose 13.1 mg/kg or 32.76 mg/kg. The AGE or SAC was given alone or in combination with atenolol (6 mg/kg, p.o), every alternate day for three weeks. At the end of treatment, two doses of isoproterenol (150 mg/kg, s.c) were administered to rats. The electrocardiogram (ECG) was recorded followed by withdrawal of blood to estimate serum lactate dehydrogenase (LDH) and creatinine kinase-MB (CK-MB) activities. The activities of LDH, CK-MB as well as superoxide dismutase (SOD), catalase and thiobarbituric acid reactive substances (TBARS) were also determined in the heart tissue homogenate (HTH). RESULTS: The isoproterenol induced ECG changes were restored to normal in all treated groups. The AGE and SAC administration caused a decrease in serum LDH and CK-MB activities and an elevation of LDH and CK-MB activities in HTH. Atenolol alone or in combination with AGE and S-allylcsyteine demonstrated similar changes in biomarker activities. CONCLUSION: AGE showed dose-dependent cardioprotection. However, concurrent administration of SAC with atenolol (6 mg/kg, p.o) combated more effectively the myocardial dysfunction during isoproterenol induced cardiotoxicity in rats.

Stereoselective features of (R)- and (S)-atenolol: clinical pharmacological, pharmacokinetic, and radioligand binding studies.[Pubmed:8383518]

Chirality. 1993;5(1):15-9.

In a randomized, double-blind, cross-over study in 12 healthy volunteers, the effects of single oral doses of 100 mg rac-atenolol were compared during exercise to those of equal amounts of the optically pure enantiomers, i.e., 50 mg (R)- and 50 mg (S)-atenolol. The mean rate pressure product decreased with rac-atenolol (-37%; P < 0.01) and half-dosed (S)-atenolol (-35%; P < 0.01) to the same extent, whereas (R)-atenolol caused no effect. Radioligand binding studies in beta-adrenergic receptors of the guinea pig heart yielded a eudismic ratio of 46 for (S)- to (R)-atenolol. The mean AUCs, maximal plasma concentrations, and plasma half-lives of the enantiomers were similar regardless of whether they were administered as optically pure enantiomers or as racemic mixture. On the other hand, the AUC of (R)-atenolol was 1.08-fold greater (P < 0.01) than that of the (S)-enantiomer. The reason for this finding remains unclear. We conclude that only (S)-atenolol, but not (R)-atenolol, contributes to the beta-blocking effect of currently used rac-atenolol since the same effect can be elicited with the (S)-enantiomer alone.