title: Evidence-based nanoscopic and molecular framework for excipient functionality in compressed orally disintegrating tablets.
abstract: The work investigates the adhesive/cohesive molecular and physical interactions together with nanoscopic features of commonly used orally disintegrating tablet (ODT) excipients microcrystalline cellulose (MCC) and D-mannitol. This helps to elucidate the underlying physico-chemical and mechanical mechanisms responsible for powder densification and optimum product functionality. Atomic force microscopy (AFM) contact mode analysis was performed to measure nano-adhesion forces and surface energies between excipient-drug particles (6-10 different particles per each pair). Moreover, surface topography images (100 nm2-10 µm2) and roughness data were acquired from AFM tapping mode. AFM data were related to ODT macro/microscopic properties obtained from SEM, FTIR, XRD, thermal analysis using DSC and TGA, disintegration testing, Heckel and tabletability profiles. The study results showed a good association between the adhesive molecular and physical forces of paired particles and the resultant densification mechanisms responsible for mechanical strength of tablets. MCC micro roughness was 3 times that of D-mannitol which explains the high hardness of MCC ODTs due to mechanical interlocking. Hydrogen bonding between MCC particles could not be established from both AFM and FTIR solid state investigation. On the contrary, D-mannitol produced fragile ODTs due to fragmentation of surface crystallites during compression attained from its weak crystal structure. Furthermore, AFM analysis has shown the presence of extensive micro fibril structures inhabiting nano pores which further supports the use of MCC as a disintegrant. Overall, excipients (and model drugs) showed mechanistic behaviour on the nano/micro scale that could be related to the functionality of materials on the macro scale.
authors.affiliation: Aston School of Pharmacy, Aston University, Birmingham, United Kingdom; Aston Research Centre for Healthy Ageing, Aston University, Birmingham, United Kingdom.
authors.forename: Ali
authors.initials: A
authors.lastname: Al-Khattawi
authors.affiliation: Aston School of Pharmacy, Aston University, Birmingham, United Kingdom.
authors.forename: Hamad
authors.initials: H
authors.lastname: Alyami
authors.affiliation: School of Engineering and Applied Science, Aston University, Birmingham, United Kingdom; Aston Research Centre for Healthy Ageing, Aston University, Birmingham, United Kingdom.
authors.forename: Bill
authors.initials: B
authors.lastname: Townsend
authors.affiliation: School of Engineering and Applied Science, Aston University, Birmingham, United Kingdom; Aston Research Centre for Healthy Ageing, Aston University, Birmingham, United Kingdom.
authors.forename: Xianghong
authors.initials: X
authors.lastname: Ma
authors.affiliation: Aston School of Pharmacy, Aston University, Birmingham, United Kingdom; Aston Research Centre for Healthy Ageing, Aston University, Birmingham, United Kingdom.
authors.forename: Afzal R
authors.initials: AR
authors.lastname: Mohammed
mesh_terms: D002482:Cellulose / Q000737:chemistry; D002626:Chemistry, Pharmaceutical; D004339:Drug Compounding; D005079:Excipients / Q000737:chemistry*; D007052:Ibuprofen / Q000737:chemistry; D008353:Mannitol / Q000737:chemistry; D013607:Tablets / Q000737:chemistry*; D013806:Theophylline / Q000737:chemistry
chemical_list: D005079:Excipients; D013607:Tablets; D008353:Mannitol; D002482:Cellulose; D013806:Theophylline; C109691:microcrystalline cellulose; D007052:Ibuprofen