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In page Oxprenolol:

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Oxprenolol is a chiral compound, the beta blocker is used as a racemate, e. g. a 1:1 mixture of (R)-(+)-oxprenolol and (S)-(–)-oxprenolol. Analytical methods (HPLC) for the separation and quantification of (R)-(+)-oxprenolol and (S)-(–)-oxprenolol in urine and in pharmaceutical formulations have been described in the literature.[1]