TLDR  Three finasteride forms exist; "form X" doesn't.   
  This document is a scientific study that characterizes the different polymorphic forms of finasteride, a drug used to treat hair loss. The study uses various spectroscopic techniques to identify the different forms of finasteride and their chemical properties. The study concludes that there are three different polymorphic forms of finasteride, and that they differ slightly in their chemical properties. The study also provides information on the conformation of finasteride in its different forms. The study also confirms that the so-called "form X" of finasteride does not exist.
            5 citations
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  November 2014   in “Journal of Pharmaceutical Sciences”
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  November 2014   in “Journal of Pharmaceutical Sciences”         21 citations
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  October 2009   in “European Journal of Pharmaceutical Sciences”
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  October 2009   in “European Journal of Pharmaceutical Sciences”    Three new finasteride solvates found, change forms under different drying conditions.  
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  June 2007   in “Endocrinology and Metabolism Clinics of North America”
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  May 2007   in “Journal of Pharmaceutical Sciences”
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  May 2007   in “Journal of Pharmaceutical Sciences”    Different forms of hair loss drug can improve effectiveness.  
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  January 1999   in “Journal of Molecular Structure”
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  January 1999   in “Journal of Molecular Structure”    Finasteride's molecular and crystal structures help develop new drug formulations.  
    
  
        
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  May 2007   in “Journal of Pharmaceutical Sciences”
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  May 2007   in “Journal of Pharmaceutical Sciences”    Different forms of hair loss drug can improve effectiveness.  
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  July 2020   in “International Journal of Pharmaceutics”
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  July 2020   in “International Journal of Pharmaceutics”    Finasteride's solubility improves with native y-CDs, enhancing hair loss treatment and reducing side effects.  
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  June 2021   in “Powder Technology”
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  June 2021   in “Powder Technology”    Granules improve hair loss treatment by targeting follicles.  
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  January 2022   in “Theranostics”
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