▁special ty ▁dru gs ▁such ▁as ▁" new ▁cancer ▁dru gs ▁spe cially ▁form ulated ▁for ▁patients ▁with ▁specific ▁gen etic ▁markers ." ▁He ▁explained ▁the ▁high ▁cost ▁of ▁these ▁" ind ividual ized ▁medic ations ▁based ▁on ▁di agnostic ▁testing ; ▁and ▁“ bi olog ics ,” ▁or ▁medic ines ▁created ▁through ▁bi olog ic ▁processes , ▁rather ▁than ▁chem ically ▁synth es ized ▁like ▁most ▁ph arma ce ut ical s ." ▁He ▁argued ▁that ▁there ▁should ▁be ▁a ▁slight ▁increase ▁in ▁co - p ays ▁for ▁the ▁more ▁commonly ▁using ▁lower - t ier ▁medic ations ▁to ▁allow ▁a ▁lower ▁co - pay ▁for ▁those ▁who ▁" require ▁high - cost ▁special ty ▁tier ▁medic ations ." ▁ ▁Research ▁Charles ' ▁research ▁is ▁primarily ▁focused ▁on ▁movement ▁dis orders ▁including ▁Park inson ' s ▁disease , ▁cer v ical ▁d yst onia , ▁trem or , ▁sp astic ity , ▁and ▁ne uro to x in ▁in jections . ▁He ▁has ▁author ed ▁over ▁ 5 0 ▁research ▁publications ▁and ▁is ▁currently ▁the ▁principal ▁investig ator ▁in ▁the ▁only ▁F DA ▁approved ▁clin ical ▁trial ▁testing ▁the ▁effic acy ▁of ▁Deep ▁Bra in ▁Stim ulation ▁in ▁people ▁with ▁early ▁stage ▁Park inson ' s ▁disease . ▁ ▁Publications ▁His ▁most ▁c ited ▁article ▁is ▁Charles ▁D , ▁et ▁al .. ▁" Pred ict ors ▁of ▁Effect ive ▁Bil ater al ▁Sub th al am ic ▁N uc le us ▁Stim ulation ▁for ▁Park inson ’ s ▁D ise ase ."