Figure 13. Overlay plots of ζ -potential: ( a ) inlet temperature and drug–mannitol ratio, ( b ) inlet temperature and drug– Figure 13. Overlay plots of ζ -potential: ( a ) inlet temperature and drug–mannitol ratio, ( b ) inlet temperature and drug– stabilizer ratio, ( c ) drug–mannitol and drug–stabilizer ratio. stabilizer ratio, ( c ) drug–mannitol and drug–stabilizer