Analytical Performance of a Fiber Optic Probe Dissolution System

Introductionissolution testing is a time-consuming and l a bo r -i nte n s i ve test proce d u re.The te c hnique re q u i res a sample of dissolution medium be re m oved from each of the te s t vessels at a specified time po i nt ( s ) .This sampling p roce d u re can be handled either manually or by means of an auto m ated sipper mechanism.Ea c h m e t h od has its own inhere nt errors assoc i ated with i t .The manual technique is subject to analyst va ria b i l i ty.Two of the most common errors assoc i ate d with the manual sampling technique are impro pe r sampling within the vessel and timing errors in s a m p l i n g.Ad d i t i o n a l l y,this is the most labo r -i nte ns i ve technique and is especially taxing fo r co nt ro l l e d -release fo rm u l at i o n s,which ofte n re q u i re 24-hour testing pe ri od s.Au to m at i c sampling techniques can save analyst labo r,but still re q u i re a good deal of mainte n a n ce and set-up t i m e.Al s o,a u to m ated sipping mechanisms are co m p l ex and co ntain many moving parts that ca n m a l f u n ct i o n ,resulting in sampling erro r s.Si p pe r mechanisms are prone to sample co nt a m i n at i o n , ca rryove r,b u b b l e s,d i l u t i o n ,f i l ter clog g i n g,a n d tubing leaks.An In-Situ dissolution technique will eliminate all of these sampling pro b l e m s.A number of re s e a rchers have inve s t i g ated this technique to s t u dy the fe a s i b i l i ty of this te c h n o l ogy ( 1 , 2 , 3 ) .Mo re re ce ntly wo rk has been done with pro bes in tra d itional sampling locat i o n ( 4 , 5 , 6 , 7 ) ,as well as with a p ro be -i n -s h a ft sampling te c h n i q u e ( 9 ) .This publication will discuss a fiber optic pro be dissolution sys tem that we have deve l o ped at Pu rdue Ph a rma LP.Wh at sets our dev i ce apart is t h at it is a fully inte g rated sys tem consisting of va l id ated hardwa re and softwa re.We have suce s s f u l y used the sys tem in our R&D labo rato ry as well as our quality co nt rol facility. System DescriptionThe UV fiber optic dissolution sys tem utilizes a dipty pe UV pro be to measure the amount of act i ve dru g released from a solid dosage fo rm .A total of 12 UV tra n s f l e ct a n ce pro be s a re placed into 12 dissolution vessels and reside insitu for the duration of the te s t .Each pro be is co n n e cted to a miniat u re Ph o to Di ode Array (PDA) s pe ct ro m e ter via a fibe r optic light guide.A pair of d e u te rium lamps are used as illumination source s.A UV spe ct rum is then a c q u i red from each of the vessels at set inte rva l s.Th e raw spe ct ral data is sto re d in a database on our s e c u red co m p u te r n e two rk ,and the re s u l t a nt dissolution po i nt is d i s p l ayed in real time.Th e d ata co nt rol co m p u te r, using our va l i d ated pro p rie t a ry softwa re packa g e RA I N B OW pe rfo rms all n e ce s s a ry ca l c u l at i o n s.Th e s ys tem co ntains no m oving parts ( Fi g u re 1).To add flex i b i l i ty to our s ys tem we used a pro be with a re m ovable flow ce l l ;a wide range of pat hlengths may be used with the sys tem ( Fi g u re 2).We a re curre ntly using pro bes with 2cm to 0.2 cm