Inclusion complexes and self-assembled cyclodextrin aggregates for increasing the solubility of benzimidazoles

Albendazole and fenbendazole are imidazole derivatives that exhibit broad spectrum activity against parasites, but the low solubility of these drugs considerably reduces their effectiveness. Complexation of albendazole and fenbendazole with cyclodextrins (ß-cyclodextrin and hydroxypropyl-ß-cyclodextrin) in both water and an aqueous solution of polyvinylpyrrolidone (PVP-k30) was studied to determine if it could increase the solubility and dissolution rate of the drugs. In an aqueous solution, ß-cyclodextrin increased the solubility of albendazole from 0.4188 to ~93.47 µg mL-1 (223×), and of fenbendazole from 0.1054 to 45.56 µg mL-1 (432×); hydroxypropyl-ß-cyclodextrin, on the other hand, increased solubility to ~443.06 µg mL-1 (1058×) for albendazole and ~159.36 µg mL-1 (1512×) for fenbendazole. The combination of hydroxypropyl-ß-cyclodextrin and polyvinylpyrrolidone enabled a solubility increase of 1412× (~591.22 µg mL-1) for albendazole and 1373× (~144.66 µg mL-1) for fenbendazole. The dissolution rate of the drugs was significantly increased in binary and ternary systems, with hydroxypropyl-ß-cyclodextrin proving to be more effective. The presence of the water-soluble PVP-k30 increased the dissolution rate and amorphization of the complexes. Analysis of the changes in displacement and the profile of the cyclodextrin bands in the 1H NMR spectra revealed a molecular interaction and pointed to an effective complexation in the drug/cyclodextrin systems. Monomeric forms and nanoclusters of cyclodextrins were observed in the drug/cyclodextrin systems, suggesting that the increase in solubility of the drugs in the presence of cyclodextrins should not be attributed only to the formation of inclusion complexes, but also to the formation of cyclodextrin aggregates

Cyclodextrins and ternary complexes: technology to improve solubility of poorly soluble drugs

Cyclodextrins (CDs) are cyclic oligosaccharides composed of D-glucopyranoside units linked by glycosidic bonds. Their main property is the ability to modify the physicochemical and biological characteristics of low-soluble drugs through the formation of drug:CD inclusion complexes. Inclusion complexation requires that host molecules fit completely or partially within the CD cavity. This adjustment is directly related to the physicochemical properties of the guest and host molecules, easy accommodation of guest molecules within the CD cavity, stoichiometry, therapeutic dose, and toxicity. However, dosage forms may achieve a high volume, depending on the amount of CD required. Thus, it is necessary to increase solubilization efficiency in order to use smaller amounts of CD. This can be achieved by adding small amounts of water-soluble polymers to the system. This review addresses aspects related to drug complexation with CDs using water-soluble polymers to optimize the amount of CD used in the formulation in order to increase drug solubility and reduce dosage form volume.

Ciclodextrinas (CDs) são oligossacarídeos cíclicos, compostos por unidades D-glicopiranosídicas ligadas entre si por meio de ligações glicosídicas e sua principal propriedade está na capacidade de alterar as características físico-químicas e biológicas de fármacos com baixa solubilidade por meio da formação de complexos de inclusão fármaco:CD. Para a formação dos complexos de inclusão a molécula hospedeira necessita ajustar-se total ou parcialmente no interior da cavidade da CD, onde este ajuste está diretamente ligado a propriedades físico-químicas da molécula hóspede e hospedeira, facilidade de alojamento da molécula hóspede no interior da cavidade da CD, estequiometria, dose terapêutica e toxicidade. No entanto, as formas farmacêuticas podem atingir um elevado volume, em função da quantidade de CD requerida, sendo necessário aumentar sua eficiência de solubilização para que seja possível utilizar menores quantidades das mesmas. Isso pode ser obtido com a inclusão de pequenas quantidades de polímeros hidrossolúveis ao sistema. Nessa revisão, são abordados aspectos relacionados à complexação de fármacos com ciclodextrinas empregando-se polímeros hidrossolúveis para otimização da quantidade de CD utilizada na formulação, com a finalidade de aumentar a solubilidade do fármaco e reduzir o volume das preparações.

Utilização de ciclodextrinas na formação de complexos de inclusão de interesse farmacêutico / Use of cyclodextrins to form inclusion complexes of pharmaceutical interest

As ciclodextrinas (CDs) constituem uma nova classe de excipientes farmacêuticos com capacidade para formar complexos de inclusão reversíveis com moléculas apolares. A habilidade das CDs em encapsular fármacos tem conseguido melhoras na biodisponibilidade, estabilidade e segurança de inúmeras fórmulas farmacêuticas atualmente comercializadas. Esta revisão bibliográfica compila os principais procedimentos empregados para a obtenção de complexos de inclusão em solução e em estado sólido utilizando CDs, discutindo seus diferentes aspectos. As técnicas utilizadas para caracterização e controle são analisadas criticamente quanto a suas aportações e limitações. Os aspectos relacionados à sua utilização pela indústria farmacêutica também são abordados

Cyclodextrins (CDs) have found application in a new family of pharmaceutical excipients with the ability to form reversible inclusion complexes with non-polar molecules. CDs capable of encapsulating drugs have led to improvements in the bioavailability, stability and safety of several dosage forms on the market. The main procedures employed to produce CD inclusion complexes, both in dissolved and solid forms, are brought together in this review of the literature and several aspects of these methods are examined. The techniques used in research and quality control of CD formulations are analysed critically with respect to their particular features and limitations. Aspects of their use in the drugs industry are also discussed.

Avaliaçäo biofarmacêutica da interaçäo de ciclodextrinas e fármacos pouco solúveis em água: revisäo / Biopharmaceutical evaluation of interaction of cyclodextrins and poorly soluble drugs: review

Este artigo corresponde à revisäo das características de formaçäo do complexo de inclusäo de ciclodextrinas e fármacos pouco solúveis em meio aquoso, que possibilita o incremento da sua liberaçäo e absorçäo, com base em formas farmacêuticas.

Evaluation of ketoprofen B-cyclodextrin inclusion complex formulated into tablets, capsules and suppositories

Ketgoprofen beta Cyclodextrin [beta CD] inclusion complexes prepared by co-grinding, freeze drying and evaporation under vacuum were formulated into tablets, capsules and suppositories. The prepared ketoprofen dosage forms were evaluated with regard to their dissolution, behavior and compared to comercial ketoprofen dosage forms. Directly compressed ketoprofen beta -CD tablets showed relatively better dissolution characteristics than a commercial ketoprofen capsule dosage from. Manually filled hard gelatin capsules of either the spray dried complex or the ground mixture showed a very fast dissolution rate compared to the tested commercial ketoprofen capsules. on the other hand, suppositories containing ether the freeze dried complex or the ground mixture gave rise to a relatively faster in vitro release than those containing non-treated ketopfrofen or the tested commercial ketoprofen suppositories