Düşük molekül ağırlıklı heparinin oral ilaç şekli üzerine çalışmalar
Studies on the oral dosage form of low molecular weight heparin
Yazar: CANAN İSKENDEROĞLU
Danışman: PROF.DR. FÜSUN ACARTÜRK
Gazi Üniversitesi / Sağlık Bilimleri Enstitüsü / Farmasötik Teknoloji Ana Bilim Dalı
Derece: Doktora, 2007
Konu: Eczacılık ve Farmakoloji = Pharmacy and Pharmacology
Dizin: Kitosan = Chitosan

Özet:
Heparin ve duguk molekul aglrllkl~h eparin (DMAH) derin ven trombozununve pulmoner embolinin onlenmesinde ve tedavisinde yaygln olarak kullanllanantikoagulanlardlr. Heparin, oral antikoagulanlara gore tedavideki ustunlugu vedaha guvenilir olmas~ nedeniyle daha avantajl~dlr. Ancak heparininfraksiyonlanmas~ veya depolimerizasyonu ile elde edilebilen DMAH'ler, heparinegore biyoyararlan~md~a ha yuksek, kanama yapma riski daha az oldugundan daha~ otkerc ih edilmektedir.DMAH preparatlar~ sadece parenteral yoldan kullanllmaktad~r. DMAH'lnyuksek oranda negatif yuk yogunluguna sahip olmas~,~ o hkid rofilik olmas~v ebuyuk molekullu yap~da olmas~ oral biyoyararlan~m~ns~ln ~rland~rlrA. ncakparenteral uygulama hasta i ~ i n zahmetlidir ve parenteral preparatlarlnhazlrlanmaslndaki iglemler ve maliyet fazladlr. Bu nedenle alternatif uygulamayollarlna yonelik ~egitlfio rmulasyonlar aragtlrllm~gt~r.Bu ~al~gmaddaa DMAH1in, en fazla tercih edilen uygulama yolu olan oralyolla uygulanacak bir formulasyonunun geligtirilmesi ve antikoagulan etkinliginsaglanmas~ amaslanmlgtlr.Bu ama~laki tozan mikropartikul ve tabletleri, ~ozeltis, iklodekstrinli ~ozeltviealjinat boncuk lar hazlrlanm lgt~r. Kitozan i~erenfo rmulasyonlar bagarlll olmamlgtlr.Aljinat boncuklarda z3 faktoriyel tasar~m uygulanarak, etkin madde:polimeroranl, sertlegtirici madde konsantrasyonu ve sertlegtirme suresi gibi degigkenlerinsallnan ilac~n% 50'si i ~ i nge Gen sureye (f%50v) e % tutulan etkin maddeye etkisidegerlendirilmigtir.Aljinat ile CaCI2 araslndaki iyonik etkilegme sonucu boncuklarolugturulmugtur. Aljinat derigimi % 2, etkin madde:polimer oranl 1:l ve 1:2, CaCI2derigimi 0.2 ve 0.5 M ve sertlegtirme suresi 15 ve 30 dk olarak se~ilmigtir.Tutulan etkin madde oranlnln, tum formulasyonlarda % 55.8-85.4 araslndadegigtigi gozlenmigtir. Tutulan etkin madde oranl, CaCI2 derigiminin ve etkinmadde:aljinat oranlnln artmaslna bag11 olarak artmlgtlr. Sertlegtirme suresininartlrllmas~ylatu tulan etkin madde oranl ~ okku ~ukm iktarda azalmlgtlr.Boncuklarda 2 saat pH 1.2'de ard~ndan bir saat pH 6.8'de sal~m deneyiger~eklegtirilmigtir. Tum boncuk formulasyonlar~ pH 1.2'de 2 saat boyunca birmiktar gigerek -dag~lmadan- etkin maddenin % 37.7-62.0'11k klsmln~ salmlgtlr.Boncuklar pH 6.8'e allndlklar~ndai se yarlm saatte par~alanaraki ~indetu m etkinmaddenin tamamen sallnd~gg~oz lenmigtir.CaCI2 konsantrasyonu artlrlld~glndae tkin madde:aljinat oranl 1: Ii ken sal~m~ I ZdIa azalmlgtlr, ancak etkin madde aljinat oranl 1: 2 iken sal~m~ I ZaIr tmlgtlr.Sertlegtirme suresinin sal~mh ~zlnae tkisi duguk olmakla birlikte sertlegtiricikonsantrasyonuna gore degigmigtir.Faktorlerin % tutululan etkin madde ve f%50 cevab~na etkisinin varyansanalizi ile degerlendirilmesi yapllmlgtlr, ayrlca 23 faktoriyel denemesi dogrusalmodellere uygulanmlgtlr. Sonu~tae tkin madde:aljinat oranl, CaCI2 konsantrasyonu,ve sertlegtirme suresinin etkilerinin onemli oldugu ve birbirinden bag~ms~ozlm ad~g~gozlenmigtir. Etkin madde:aljinat oranl ve CaCI2 konsantrasyonunun, sertlegtirmesuresine k~yaslad aha fazla etkili oldugu gorulmugtur.Boncuk verimi, % tutulan etkin madde oranl ve f%50c evab~a qslndan en iyisonucu, 1:2 oranlnda etkin madde:aljinat ve 0.5 M CaCI2 ile 15 dakikasertlegtirilerek hazlrlanan formulasyonun (FH7) verdigi gozlenmigtir.Aljinat boncuklarda verimin % 79.5 ile % 98.7 araslnda degigtigigozlenmigtir. Partikul boyutu 1325-1584 pm bulunmugtur.Aljinat boncuklarda DSC, X-lgln~ klrlnlm~ ve FT-IR incelemeleri sonucuDMAH'in saf oldugu ve aljinat boncuga yuklendigi gozlenmigtir. Aljinat boncuklardaSEM ol~umleri sonucu aljinat boncuklar~n ve DMAH i~eren aljinat boncuklar~nkuresel bi~imdeo lduklar~g ozlenmigtir.In vivo deneylerde 2.5-3 kg aglrl~glnda Yeni Zellanda tipi tavganlarkullanllarak, zamana karg~A Xa seviyeleri tayin edilmigtir. AUC ve Cmakdse gerlerihesaplanm~gtlr.Kitozan tablet formulasyonlar~ (1500, 3000, 5000 IUIkg DMAH) tavgalaraoral yoldan uygulanmlgtlr, etkinlik gozlenmemigtir.Absorbsiyon artlrlcl olarak dimetil-P-siklodekstrinin tercih edildigi ve %5oranlnda kullanlldlgl DMAH ~ozeltfio rmulasyonu ile 5000 IUIkg doza qkllmlgtlrancak herhangi bir etkinlik gozlenememigtir.DMAH i~eren ~ozeltiyle (5000 IUIkg), bog mikropartikullerle, sadecesiklodekstrin i~eren Cozeltiyle oral uygulama sonucu herhangi bir etkinlikgozlenmemigtir.Aljinat boncuklarla (FH7) 5000 IUIkg dozda DMAH'in tavganlarauygulanmasl sonucu iki saat sonunda anti Xa etkinligi seviyesi 0.360 IUImL'yeulagmlgtlr ve antikoagulan etkinlik saglanmlgtlr (>0.2 IUIkg).DMAH i~eren aljinat boncuklarln DMAH ~ozeltisine gore biyoyararlanlml69.3 kat artlrdlgl bulunmugtur. DMAH ~ozeltisi 100 IUIkg dozda iv olarakuygulanmlgtlr ve mutlak biyoyararlanlm hesaplanmlgtlr. Mutlak biyoyararlanlm %2.10 bulunurken, bag11 biyoyararlanlm DMAH ~ozeltisine gore % 6930bulunmugtur. Oral uygulanan DMAH Cozeltisinin mutlak biyoyararlanlml ise %0.0303 olarak hesaplanmlgtlr.Tavgan midelerinin histolojik olarak incelenmesi sonucu aljinat boncuklarlnbiyoadezif ozellik gostererek mide duvarlnl kapladlgl ve etkisinin US saat devamettigi gozlenmigtir. DMAH'in aljinat boncuk ile verilmesiyle, DMAH'in ~ozeltoi larakuygulandlglnda neden oldugu deformasyonun klsmen onlendigi belirlenmigtir.so nu^ olarak DMAH i~eren aljinat boncuklarln tavganlara oral yoldanuygulanmasl ile antikoagulan etkinlik saglanmlgtlr.

Abstract:
Heparin and low molecular weight heparin (LMWH) are widely usedanticoagulants for the treatment and prevention of deep vein thrombosis andpulmonary embolism. Because heparin is safer and more effective than other oralanticoagulants, its use has certain advantages. However, because in comparisonwith heparin, LMWHs, which are obtained by fractioning or de-polymerization ofheparin, have a higher bioavailability and lower risk of bleeding, they are chosenmore frequently than heparin.LMWH preparations are currently available to patients only by parenteraladministration. Because LMWH is highly negatively charged, highly hydrophilic andhas large a molecular structure, its oral bioavailability is limited. However,parenteral administration is painful for patients and parenteral preparations aremore difficult and more expensive. Therefore, various formulations are beinginvestigated for alternative routes of administration.The aim of this study is to develop a formulation for the oral administrationof LMWH, which would be effective as an anticoagulant. For this purpose, chitosanmicroparticles and tablets, solution with and without cyclodextrin and alginatebeads were prepared. The formulations containing chitosan were unsuccessful.Using Z3 factorial design, the effect on the duration for 50 % of the drug tobe released (f50%) and encapsulation efficiency of parameters such as activesubstance:polymer ratio, concentration of the hardening agent and hardening timewas investigated.Beads were formed based on the ionic interactions between alginate andCaCI2. Concentration of alginate was 2 %, active substance:polymer ratio was 1:land 1:2, CaCI2 concentration was 0.2 and 0.5 M and hardening duration was 15and 30 minutes.Through all formulations, encapsulation efficiencies varied between 55.8and 85.4 %. The encapsulation efficiencies increased related to increasing CaCI2ratio and active substancelalginate ratio. With increasing hardening duration,encapsulation efficiency decreased to an insignificant degree.Drug release studies were carried out on beads using pH 1.2 for 2 hoursand then using pH 6.8 for one hour. All bead formulations, at pH 1.2, swelledslightly, but did not disintegrate and released 37.7-62.0 % of their active substancein 2 hours. On the other hand, when those beads were placed in pH 6.8 solutions,all the active substance was released in half an hour.When the active substance:alginate ratio was 1:2, LMWH release rateincreased with increasing CaCI2 concentration. However, when the activesubstance:alginate ratio was I :I, the release rate decreased with increasing CaC12concentration.Therefore, release rate was affected only to an insignificant degree byhardening duration but was affected by concentration of the hardening agent.Variance analysis was used to establish the effect of independent factors ondependent factors such as encapsulation efficiency and f50%. In addition, 23factorial design was applied to linear models. Therefore, we observed that activesubstancelalginate ratio, CaCI2 concentration and hardening duration have asignificant effect.Active substancelalginate ratio and CaCI2 concentration have a moresignificant effect than hardening duration.The formulation (FH7) consisting of 1:2 active substance:alginate andhardened using 0.5 M CaCI2 for 15 minutes gave the best result in terms ofencapsulation efficiency, t50% and bead yield. The yield of all formulations variedbetween 79.5 and 98.7 %. Alginate bead size measured 1325-1 584 vm.DSC, X-ray diffraction and FT-IR tests on alginate beads showed thatLMWH was pure and that is was loaded on alginate beads.