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In Goodman & Gilman's The Pharmacological Basis of Therapeutics, 12e R,S-citalopram is referred to. The problem is that from what I am aware of citalopram only has one stereocentre, and hence I am forced to ask were the author having a stroke when they added the comma and really meant the racemic mixture of R and S stereoisomers?
Figure 1: Screenshot of the Relevant Page in Goodman and Gilman
Figure 2: Citalopram
(The latter has the stereocentral carbon highlighted)
It seems fairly clear that the authors intended to refer to the racemic mixture there. You're right that a comma would normally be used to separate the locants of distinct stereocenters when multiple ones are present, but then the individual chiral carbons would have to be numbered, which obviously isn't the case here.
