We have located links that may give you full text access.
Solid-state transformations of ribavirin as a result of high-shear mechanical processing.
International Journal of Pharmaceutics 2017 May 31
Ribavirin (C8 H12 N4 O5 ; anti-viral agent) was crystallized as two unique, phase-pure polymorphs (R-I and R-II). Calorimetrically determined isobaric heat capacities and heat of transition data were utilized to determine the solid-state transition temperature (Ttr ), confirming enantiotropism, while R-I was determined to be kinetically stable at ambient temperature. Unprocessed samples of the low Tm polymorph, R-II, did not convert into R-I when held isothermally well above Ttr for 7days. In contrast milled R-II completely transformed to R-I after 15min at the same storage conditions, indicating that defects sustained during processing reduced the energy barrier for transformation, allowing it to occur. R-II was subjected to both cryogenic milling and impact milling at ambient temperature for various durations. Cryomilling resulted in an in situ progressive reduction of crystallinity, with complete conversion to amorphous ribavirin after 2h. Limited molecular mobility attributable to the low milling temperature (Texp =-196°C) likely inhibited recrystallization, allowing the amorphous solid to persist. In contrast, continuous impact milling at ambient temperature resulted in complete in situ conversion from R-II to R-I after 3h. The data suggested rapid conversion to R-I from highly disordered regions during extended milling, facilitated by localized heat buildup that likely exceeded Tg and/or Ttr .
Full text links
Related Resources
Get seemless 1-tap access through your institution/university
For the best experience, use the Read mobile app
All material on this website is protected by copyright, Copyright © 1994-2024 by WebMD LLC.
This website also contains material copyrighted by 3rd parties.
By using this service, you agree to our terms of use and privacy policy.
Your Privacy Choices
You can now claim free CME credits for this literature searchClaim now
Get seemless 1-tap access through your institution/university
For the best experience, use the Read mobile app