Ir aqi J.Pha rm.Sc i., Vol.15 (2 ) ,2006 Fo rmulation of Rifampicin Sus pension 1 Formulation of Rifampicin Suspension Lubna A. Sabri*1 , Alaa A. Abdul-Rasool** and Muayad A. Shehab** * De partm ent of Pha rm a ce utic s, Colleg e of P ha rm a cy, Univ ersity of B agh da d Bag hda d-Iraq * *De pa rtm en t o f Ph arm ace utics, Co lle ge o f Pha rm acy , Un iv ersity of Bag hd ad ,Bag hd ad-Ira q Abstrac t Rifa mpicin is the drug of c hoice in treatment of tube rc ulosis. Als o, it is e ffec tive in trea tme nt of various bacterial infe ctions.This study was c arried out to pre pare a s ta ble sus pension for rifampicin through prepa ra tion of diffe re nt formula s of rifampicin aqueous sus pension either a s rea dy to use or as gra nular powder to be reconstituted.The selec te d formula (A) was e valua te d and c ompared with comme rc ia l brand of rifampicin (Rifac tine ®) as a re fe re nce through meas uring their diss olution rates and othe r physica l prope rties.The res ults indicated tha t the selec te d formula had be tter dis solution ra te compared with the referenc e sus pension and the rheogram showed that the se le cted formula was les s vis cous tha n the re fe rence one.Als o, it wa s found that the gra nular rifa mpicin was more stable than the ready to use suspe nsion, sinc e the e xpira tion date of granula r rifampicin was 2.6 yea rs , while the expiration date of re ady to use s uspens ion was 1.8 yea rs . K ey words :Rifampicin , Suspending a ge nt ,Powder for rec ons titution , Aque ous s uspe ns ion الخالصة مختلفة رن الرئوي وااللتهابات البكتيرية ال عالج التد ي ن هو الدواء المفضل ف سي ريفامبي راء هذه الدراسة . إن ال تم إج ق جـاهز عـل شـكل م ا ب ـم مبيسـين أ ق الريفا معـل ة ل ختلـف ة م ركيبـي ر صـيغ ت من خالل تحضي معلق ثابت للريفامبيسين ر لتحضي وق جاهز للتعل كمسح و مال أ ركيبية المختارة . يقلالستع مستحضر المرجع ) أ(أن الصيغة الت مع ال مقارنة رت للتقييم وال اختي ن( خرى من) الريفاكتي ص الفيزيائية األ وا رر و الخ رعة التح رة . خالل قياس س مختا كيبية ال غة التر أوضحت النتائج أن الصي ر عيين التدفق أظه و ت رعة تحرر مقارنة مع المستحضر المرجع جة من أعطت افضل س أن الصيغة المختارة هي اقل لزو مرجع حيث . المستحضر ال علق الجاهز لالستعمال ٬ من الم ستقرارية حبيبي هو اكثر ا مبيسين ال معلق الريفا ن كذلك وجد أ و ي هي معلق الحبيب عول ال مف هاء مدة انتهاء مف) ٦,٢(أن مدة انت عمال هيسنة بينما علق الجاهز لالست ول الم . سنة) ۸,١(ع In troduction An oral p harma ceutica l susp ens ion ha s lo ng be en one of the mo st fav ora ble dos age fo rms fo r ped ia tric patients o r pa tients una ble to to le ra te s olid dos age fo rms (1). The re a re ma ny phys ic al and che mical co nside ra tions in the p re paration and de velop ment o f a s us pension to s atisfy its pharmace utical requireme nts. So me suspe nd ing age nts are ge nerally add ed to the disp ersion me dium in o rd er that their structure s he lp to mainta in unifo rm disp ersibility (2) o r to preve nt c aking o f the d rug p article s d uring shelf-life (3). Rifampicin is bactericidal agent aga inst wide ra nge o f microorga nism (4). It is o ne of the ve ry s lightly s oluble drugs, thus is suitab le fo r s uspension dosa ge form. B ut rifa mpicin is poo rly wetted with water d ue to its hyd ro phobic na ture . El-ba ry et a l. s tudied the wettab ility of rifampic in p owde r using diffe re nt c onc entrations of v ario us s urfa ctants and po lyhydroxy co mpound s .The we ttab ility of rifampic in was found to be d irec tly p rop ortional to surfac ta nt HLB a nd c onc entration (5). In this s tudy, rifampicin is formula te d as an a que ous s usp ension either a s re ady to use or a s dry po wde r and the s elec te d fo rmula is co mpa re d with the re fe re nc e suspe ns io n. Experimenta l Ma terials and Eq uipmen ts Rifampicin powd er, Po lyso rb ate 80 , Ra spberry flav or, Xantha n gum, Guar gum , Methylpa ra be n, Prop ylparab en (S upp lied b y Sama ra Drug Indus tries (SDI)). 1corresp ond in g author ema il Lub naHa ni_95@yahoo .comLub naHa ni_95@yahoo .com Rec eived 26-1 1-200 5 Accepted 24-5-2 006 mailto:LubnaHani_95@yahoo.com Ir aqi J.Pha rm.Sc i., Vol.15 (2 ) ,2006 Fo rmulation of Rifampicin Sus pension 2 Rifa ctine® susp ens ion ( Supplied by Me dical Union P ha rma eutica l, Egypt) Sod ium sa cc harin, Sorbitol 70%, So dium citra te (Supplied by Ibn- se ina Drug Re se arch Cente r, Baghd ad). Citric ac id monohydrate (Al-Rahma Pha rmace utic al Co., J ordan). Disod ium ed etate, So dium me ta bisulp hite , Hyd ro chloric acid, co lloida l Silic one d io xide (Ae ro sil), Methylc ellulo se , S odium ca rb oxymethylc ellulo se (BDH chemica ls Ltd , Poo le , England). Spe ctro photomete r (Pye -Unicom-sp -8 -1 00 mod el 2 92MK, Engla nd ). Disso lutio n app aratus (Erewka G.M.B.H. type DT6, W.Germany). pH mete r (Orchidis la boratories, France). Visco meter (Cole-pa rme r, rotationa l visc omete r U.S.A). Ove ns (Memme rt 85 4 Schwaba ch, W.Ge rmany). Method o f pr ep ara tion For mulatio n of Rifampicin Sus pe nsion : Sev eral formula s of rifa mpicin aqueo us suspe ns io n were prep ared, either as read y-to - us e aqueous suspe ns io n o r dry p owde r fo r re co nstitution. Ready-to-use aqueous Rifampicin Su spension Different fo rmula s of rifa mpicin susp ens ion were p re pared us ing d ifferent s usp ending agents a s shows in tab le (1), e ach fo rmula w as prepa re d as follows : Rifa mpicin, me thylpa ra ben a nd propylp arabe n were lev igated in a mo rtar with the pre pa re d d is persion of the s usp ending agent. The mixture wa s tritura te d with a p es tle until a s mooth p as te was fo rme d. With co ntinuous tritura ting, the pa ste was diluted with the rema ining amount o f the disp ersion of suspe nd ing agent the n tra nsfe rred to grad uated c ylinder. The re quired amo unt o f so dium s ac cha rin and d is odium ed etate o r so dium metabis ulphite we re d is solve d in a sma ll portio n of dis tille d water a nd ad ded to the gra dua te d cylinder. F inally sorbitol, glyc erol and ras pbe rry flav or were add ed fo llowe d by ad ding s ufficient distilled wa te r to ma ke up to vo lume. The suspe ns io n wa s shake n thoroughly a nd the p H wa s ad justed to 5 with few drop s of 5M s od ium c itrate. Ta ble ( 1 ) Diffe re nt Formula s of Ready-to - Use Rifampicin S uspe ns io n (% W/V) Material Fo rmula A B C D E F G R ifa mpicin 2 2 2 2 2 2 2 Agar x y Methy lc el - lu lo se x Xantha n gu m x y x SCMC x x P olysorba te 80 x x x x x x x Disodiu m edetate 0.1 0.1 0.1 0.1 0 .1 Sodium me tabisulph ite 0 .1 5 0.15 Glyc erol 5 5 5 5 So rbito l 7 0 % 5 5 5 5 Sodium saccharin 0 .2 Me thylp araben 0 .18 P ropy lp araben 0 .03 R aspbe rry flav or 0 .05 Fina l v olume 100 ml Ir aqi J.Pha rm.Sc i., Vol.15 (2 ) ,2006 Fo rmulation of Rifampicin Sus pension 3 Powder fo r reconstitu tion Diffe re nt s us pending agents we re us ed to prepa re rifa mpicin s usp ensions as p owde r form re ad y fo r re co nstitutio n are shown in ta ble (2 ). Eac h was prep ared by tritura ting rifa mpicin pow der with the s elected c ompo nents. The pow der mixture was p as sed through a siev e (1 50 μm) b efore b eing tra nsferred to a mber glas s b ottle s (6).The re was an e xce ptio n for fo rmula I, in whic h a po wder b le nds wa s moistened with (0 .5 % po lyvinylp yrrolidone in alco hol). The da mp mass wa s then pas se d thro ugh the siev e (10 00 μm) and the gra nule s were drie d at 3 7 ˚C. The d ried gra nule s were re siev ed through the sa me siev e before be ing transferred to ambe r gla ss b ottles . The ea se of re co nstitution a nd s ta bility were e va luated to se le ct the pro pe r formula, whic h will b e subjecte d to further stud y. Table ( 2 ) Diffe re nt Formulas o f Rifa mpicin Powde r to be Re constitute d as Sus pe nsion. ( % W/V) Com para tive Studies of The S ele cte d Form ula with Rifactine® Suspen sio n: The s elected formulas (A a nd I) we re comp ared with the reference Rifactine ® utilizing the following pa ra meters: Dis so lu tion Pr ofile The diss olutio n ra te o f rifamp ic in sus pe ns ions wa s stud ie d us ing USP d is so lution app aratus . The d is so lution me dium was 0 .1 N HCl (900 ml), 5 ml s amp le o f susp ens ion was add ed. The n a sample o f diss olution med ium was withdrawn at different time interva ls (2, 5,10,15 ,3 0 and 4 5 minutes ) thro ugh a p ip ette fitte d with a filter pa pe r. Fres h d is so lution medium was a dde d to the ja r eac h time to re place withd ra wn sa mples. Eac h sa mple was suitab ly d iluted a nd as sa yed spe ctro photometric ally a t 47 5 nm for rifa mpicin co ntent. Me as ure ment of Rheo gra m Rhe ogra ms were ob ta ined a t 37 ˚C using Cole-parme r ro ta tio nal visco meter. Sed ime ntatio n Volume Mea sur eme nt Fifty ml o f ea ch s usp ension was d ilute d with dis tille d water to a vo lume of 100 ml in a stopp ered gra dua te d cylind er. The susp ens ions were sha ke n vigorously to e nsure unifo rmity, then left und is turb ed . The se dimenta tion volume was me asure d ev ery 4 ho urs for p erio d of 4 8 hours (7). Res usp end ability of Sus pen sion The tes t co ns is te d of manua lly shaking the cylind er a fter the se dimenta tion e xp erime nt was c omplete d. Ba se d on the e ffort req uire d to convert the s edime nted system to a homo ge nous susp ens io n, the prepa re d product was ra ted as : re sus pe nda ble, res us pendab le with difficulty or no t re susp end able. Stab ility Study: The acc elerated s ta bility stud y was d one in orde r to de termine the e xp iratio n date of fo rmula A a nd I b y plac ing the sa mples o f bo th fo rmula s in ove ns a t 35 ̊ C, 45 ˚C a nd 5 5 ̊ C for 120 d ays . Sa mples we re taken a nd a ss aye d fo r drug conte nt a t s uita ble time interva ls (0, 15,30 ,6 0,90,12 0 d ays) us ing UV spe ctro photometric method a t 4 75 nm. Result an d Disc ussion The nonio nic surfac ta nt (po lyso rb ate 80) was inc orporated in the formulatio n of rifa mpicin suspe ns io n a s a w etting a gent to increas e diss olutio n rate of the drug (5). In add ition, xanthan gum was a ls o use d a s a sus pe nding age nt be cause of its e xc elle nt sus pe nding pro pe rtie s and also a s an e ffec tive floc culating agent a t re la tive ly lo w conce ntra tion(8). An inc re as e in the conce ntra tion of xanthan gum (as in fo rmula Mate rial Fo rmula I II III IV Rifampic in 2 2 2 2 Gua r gu m x y 2y SCMC x Ae rosil x x p olys orbate 80 x S ucrose 2 0 S odium sa cc harin 0.08 Metylparabe n 0.18 Propylparabe n 0.03 Disod ium e deta te 0 .1 S odium citra te 0.06 Citric ac id 0.03 Raspberry fla vor 0.05 Ir aqi J.Pha rm.Sc i., Vol.15 (2 ) ,2006 Fo rmulation of Rifampicin Sus pension 4 B) gave no s ub stantial cha nge in flo cc ulatio n be hav io r a nd a visc ous susp ens io n wa s obta ined which pour with d iffic ulty. On the other ha nd, sod ium ca rb oxymethylc ellulo se (SCMC) was us ed a s in fo rmula D. It ga ve good diss olutio n prope rties a nd it prod uce d se diment la ye r that was e as ily redisp erse d by s haking. Furthermore, a c ombina tion o f xa ntha n gum and SCMC re sulted in to o visc ous suspe ns io n, which po ured with d ifficulty. Methylc ellulo se utilized in formula E produce d a s us pe nsion with low d is so lution ra te a s shown in figure (1 ). Fina lly, a ga r was utilized as thic kening age nt and to c ontrol flocc ulatio n. Good res ults were ac hieve d with fo rmula F but ha rd c ake wa s fo rme d with formula G. Fo rmula A ga ve the mos t o ptimum physica l stability a nd re markab le re le as e profile, therefore it w as chose n fo r exte ns iv e stud y a nd to be co mpared with re fe re nc e suspe ns io n. On the o ther hand, rifa mp ic in s us pe ns io n (as dry powde r) when prepa re d using guar g um as a single suspending age nt ( formula II) resulted in a suspe nsio n tha t sho wed low se dimenta tion volume (0.2) but was easily re disperse d. The addition of a erosil to formula III and IV re sulted in eas ily re dispersed suspens ions with high sed iment v olume (0.8 and 0 .9 for III a nd IV, respectively). Be ing fine ly divided , aerosil a ggre gates to form thre e dimensional network toge ther with its ability to absorb large a mount o f wate r, hence it p revents ca king (6). In ad dition sodium ca rboxymethylcellulose was used as a suspe nd ing age nt in c omb inatio n with po lyso rbate 80 to enhance the d isso lution (formula I). This for mula was prepared as granule s using a lcoho lic PVP so lution as a granula ting age nt. The granules were found to be fre e flowing and not bulky . Also , rifamp ic in granule s were found to be good in app eara nce and their pa rticles we re uniform in size. Fo rmula I was c hos en s ince it gave goo d stability although it prod uce d sed ime nt layer with ea sily re dispe ra bility by s ha king. Figure (2) s hows the d is so lution rate of rifa mpicin suspe ns io n for formulas A and I comp ared with the reference rifac tine sus pe ns ion. The results s ho wed tha t rifamp ic in re le ase d from formula A wa s higher tha n that from o thers. Fo rmula I after re constitution sho wed the lowes t diss olutio n ra te and this may be due to granulation proc ess , s ince PVP was used a s granulating age nt which is water solub le binder a nd has go od swe lling and hyd ra tion cap acity (9). The se p ro pertie s re sult in high visco us re gion surrounding the drug partic le . Rhe ograms o f the prod uc ts a re rep re sente d in figure (3). The grap h showed that the vis co sity of rifampicin sus pe nsions wa s s he ar ra te dep end ent a nd increa sed in the fo llowing order: Formula A < Rifa ctine < Formula I The re sults illus tra te d that the p re pa red fo rmula s (A a nd I) e xhib ited ps eudop la stic flow prope rties due to the s us pending agents use d, whic h were xanthan gum and sod ium carbo xymethylce llulo se . 0 10 20 30 40 50 60 70 80 90 100 0 5 10 15 20 25 30 35 40 45 50 55 60 Time (min) % R if a m p ic in r e le a s e d 50 55 60 65 70 75 80 85 90 95 100 0 5 10 15 20 25 30 35 40 45 50 55 60 Time (min) % D is s o lv e d o f R if a m p ic in Rifactine Formula A Formula I Fig ure (1) : Dis so lution ra te profile o f rifa mp ic in s us pe nsion (formula E) in 0 .1 N HCl a t 37 º Figure (2) : Dis so lution rate profile of rifa mpicin suspe ns io n (formulas A and I) a nd rifac tine in 0 .1 N HCl at 37 ˚C. Ir aqi J.Pha rm.Sc i., Vol.15 (2 ) ,2006 Fo rmulation of Rifampicin Sus pension 5 . Tab le s (3 and 4) show the s edimentatio n volume a nd res usp endab ility after s ettling of rifampic in s us pensions, res pe ctiv ely. The d ata indica te d that fo rmula A, which wa s prepa re d with xa ntha n gum, ha d s ed ime ntation volume eq ual to 2. This res ult wa s a ttrib uted to the ne two rk o f flo cs formed in the s us pension , which wa s s o loo se and fluffy tha t ca n b e exte nde d thro ughout extrave hicle. The sa me re sult was rep orte d by J awad (10). Table ( 3 ) Se dime ntatio n Volume o f Rifa mpicin Suspe ns io ns (fo rmulas A, I and Rifactine ) Ta ble ( 4 ) Re suspe ndability of Rifampicin Suspe ns io ns (fo rmu la s A,I and R ifac tine ) Products Res us pe ndability Rifa ctine ea sily resuspended F ormula A No sedimenta tion Fo rmula I ea sily resuspended Rifa ctine ea sily resuspended In the s ta bility stud y of rifa mpicin sus pe ns ion and granular rifamp ic in figures (4 and 5) sho wed tha t the de grada tion o f rifamp ic in for fo rmula s A a nd I res pe ctiv ely, whic h fo llows firs t orde r kinetics s ince straight line s we re obtaine d by plotting the lo garithm o f perce nt re maining o f rifamp ic in v ersus time . Pro duc ts Se dime nta tion v olume F = Hu / Ho F Rifac tine 45 /50 0.9 Fo rmula A 1 00/50 2 Formula I 20 /50 0.4 0 25 50 75 100 125 150 175 200 225 0 50 100 150 200 250 Shear stress (dyne/cm 2 ) S h e a r ra te ( s e c . -1 ) Rifactine Formula A Formula I 1.93 1.94 1.95 1.96 1.97 1.98 1.99 2 2.01 0 30 60 90 120 150 Time (days) L o g % R if a m p ic in r e m a in in g 35 C 45 C 55 C o o o Figure (3) : Rheo gram at 3 7˚C o f rifampic in s us pe nsions fo rmu la s and rifa ctine . Whe re : Hu is u ltimate he ig ht of the se dime nt a s s us pe nsion settle Ho is the initial he ight of the to ta l suspe ns io n. Figure (4) :Deg radatio n curve o f re ady-to- use rifa mpicin s uspe ns ion (formula A) a t diffe re nt te mpe ra tures . Ir aqi J.Pha rm.Sc i., Vol.15 (2 ) ,2006 Fo rmulation of Rifampicin Sus pension 6 The d egra dation rate co nstants (K) at d ifferent te mpe ra ture s were ca lc ulated fro m the s lo pe s of the s traight line s and the y were listed in ta ble (5). Ta ble ( 5 ) De grada tion Ra te Cons ta nts of Rifa mpicin Sus pe nsions Rea dy -to-Use (For mula A) a nd Gra nular Sus pe nsion (For mula I). Arrhe nius plots were then c ons tructed and are shown in figures (6 and 7 ) fo r fo rmula I and A, res pec tive ly. The linearity o f the c urve s indica te s their utility in pred ic ting the rate of de grada tion a t lowe r tempe ra tures . The rate co ns ta nts at 25 ˚C, obta ined fro m those plots fo r read y-to -use (formula A) a nd granular sus pe ns io n (formula I) were e qual to 0.15 3 x 10-3 a nd 0 .1 09 x 10 -3 (d ays-1) re spe ctiv ely. Since the degra dation o f the d rug fo llowe d first order kinetics , the e xpiratio n da te t1 0% at 2 5˚C could be c alcula te d us ing the fo llowing equatio n: 0.10 5 t1 0% = K25˚C Te mpe ra tu re (˚C) K x1 0-3 ( da y-1) For mula A For mula I 55 1 .206 0 .822 45 0 .619 0 .429 35 0 .318 0 .224 25 0 .153 0 .109 1.95 1.96 1.97 1.98 1.99 2 2.01 0 30 60 90 120 150 Time (days) L o g % R if a m p ic in r e m a in in g 35 C 45 C 55 C o o o 0.1 1 10 3 3.1 3.2 3.3 3.4 (1/T) x 1000 (Kelvin-1) K x 1 0 -3 ( d a y -1 ) 0.1 1 10 3 3.1 3.2 3.3 3.4 (1/T) x 1000 (Kelvin-1) K x 1 0 -3 ( d ay -1 ) Figure (5 ): Deg ra dation c urve of gra nula r rifa mpic in s us pe nsion (fo rmula I) at diffe re nt te mpe ra tures Figure (6) :Arrhe nius p lo t fo r e xpira tion date e stima tion o f rifa mpicin suspe ns io n formula I a t 25˚C. Fig ure (7) : Arrhe nius plot for expiration da te e stima tion o f rifampicin suspe ns io n fo rmu la A at 25˚C. Ir aqi J.Pha rm.Sc i., Vol.15 (2 ) ,2006 Fo rmulation of Rifampicin Sus pension 7 The e xpiratio n d ates fo r formula A and fo rmula I were 1.8 and 2.6 ye ars re spe ctively, indica ting tha t rifampicin is mo re s ta ble whe n it is p re pared as granula ted p owde r for re co nstitution, as a ls o indicate d b y P atankar and Bajaj (11) Referen ces 1. Ans el H.C., Allen L.V. and P opo vich, N.G., Pha rmace utic al dos age fo rms a nd d rug de live ry s yste m, 17 th e d., 1 999 ,c hap ter 13 , p. 347 -3 64. 2. Kawa shima Y. and Iwa moto T., Prep ara tio n and charac te riza tion of a new c ontrolle d re le as e ib uprofen s us pension for improving . suspe nd ability, Int. J. Pharm., 199 1, 7 5 (Aug 30), 2 5-35. 3. Zatz J.L., Sc hnitze r L. and Sa rp otdar P ., Flocc ulation of sulfame ra zine s us pension b y a ca tionic po lymer. J. P harm. Sc i., 1 979 , 68, 149 1-149 4. 4. Physician Des k Reference, c omp act d is k, 200 1. 5. El-Ba ry A.A., El- Mone m H.A. a nd Naim O., Fo rmula tion a nd Bioa vailability of rifa mpicin suspe ns io n, Egyp t J. P harm. Sc i., 199 2, 3 3 (5 -6 ), 997 -10 12 . 6. El – Khes hen S.A. , Ba dawi S .S . and Bada wi A.A., Optimization of rec ons titutab le sus pe ns ion of rifa mpicin using 24 fac to rial des ign , drug De v .Ind .Pha rm.,19 96 , 22(7),6 23 -63 0 . 7. Lac hman L., Lieb erman H.A. and Kanig J.L., The Theory and P rac tic e o f Indus trial Pha rma cy,3 rd ed., 1 986 ,c hap ter 16 a nd 18 , p. 480 -4 88, 535 . 8. F elmeister A., Kuc htya k G., Kozio l S. and Felmeis te r C., Po lymer induced flocc ulation of pha rma ce utical suspe ns io ns , J. Pharm. Sc i., 197 3, 62 (12), 1972 -1 973 . 9. Aulto n-M.E, Pha rma ceutic s: The sc ie nce of d osa ge form de sign, 19 88,chapte r 15 and 1 8, p.264 , 26 9-278 , 31 8-320 . 10. J awa d F .J ., A co mbine d formulation of dilo xanid e furo ate and metronida zo le b enzoa te as a s usp ension, thes is , Co llege of Pharmac y, Baghda d Unive rs ity, 20 00. 11. P atankar, L. and Bajaj, A., F ormulatio n of rifa mpicin and iso niazid gra nules for re constitution, Indian J . Pharm. Sc i, 199 4 ,56 (5 ), 1 69 -17 3.