ing ▁agent ▁az ath iop r ine ▁may ▁replace ▁it ▁once ▁th era pe ut ic ▁effect ▁has ▁been ▁achieved . ▁IV IG ▁may ▁be ▁used ▁with ▁a ▁degree ▁of ▁effect iveness . ▁Pl asma ▁exchange ▁( or ▁pl as map her esis ), ▁the ▁removal ▁of ▁pl asma ▁prote ins ▁such ▁as ▁ant ib od ies ▁and ▁replacement ▁with ▁normal ▁pl asma , ▁may ▁provide ▁improvement ▁in ▁ac ute ▁severe ▁weak ness . ▁Again , ▁pl asma ▁exchange ▁is ▁less ▁effective ▁than ▁in ▁other ▁related ▁conditions ▁such ▁as ▁my as then ia ▁gra vis , ▁and ▁additional ▁imm unos upp ress ive ▁medic ation ▁is ▁often ▁needed . ▁ ▁Other ▁Three ▁other ▁treatment ▁modal ities ▁also ▁aim ▁at ▁impro ving ▁LE MS ▁sympt oms , ▁namely ▁py rid ost ig mine , ▁ 3 , 4 - d iam in opy rid ine ▁( am if am pr id ine ), ▁and ▁gu an id ine . ▁They ▁work ▁to ▁improve ▁neur om us cular ▁transmission . ▁ ▁T ent ative ▁evidence ▁supports ▁ 3 , 4 - d iam in opy rid ine ] ▁at ▁least ▁for ▁a ▁few ▁weeks . ▁The ▁ 3 , 4 - d iam in opy rid ine ▁base ▁or ▁the ▁water - sol ub le ▁ 3 , 4 - d iam in opy rid ine ▁ph osph ate ▁may ▁be ▁used . ▁Both ▁ 3 , 4 - d iam in opy rid ine ▁form ulations ▁delay ▁the ▁rep olar ization ▁of ▁n erve