How to write a brand name?

Hi,

English is not my first language. I am working in marketing in the pharma business and have been taught that a brand name must always stand alone. It is maybe not gramatically incorrect but marketing wise incorrect to write 's after a brand name. Is that correct? A medical writer with English as first language says that it is perfectly correct to write a brand name with 's. I have been told that you " do not treat a brand like that". You dilute the value of the brand...

Example: Viagra's effect or the efficacy of Viagra

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