Juan Manuel Llabot

Double-layered mucoadhesive tablets containing nystatin

The objective of this work was to design a mucoadhesive tablet with a potential use in the treatment of oral candidosis. A 2-layered tablet containing nystain was formulated. Lactose CD (direct compression), carbomer (CB), and hydroxypropylmethylcellulose (HPMC) were used as excipients. Tablets were obtained through direct compression. Properties such as in vitro mucoadhesion, water uptake, front movements, and drug release were evaluated. The immediate release layer was made of lactose CD (100 mg) and nystatin (30 mg). The CB:HPMC 9∶1 mixture showed the best mucoadhesion properties and was selected as excipient for the mucoadhesive polymeric layer (200 mg). The incorporation of nystatin (33.3 mg) in this layer affected the water uptake, which, in turn, modified the erosion front behavior. Nystatin showed a first-order release. The polymeric layer presented an anomalous kinetic (n=0.82) when this layer layer was individually evaluated. The mucoadhesive tablet formulated in this work releases nystatin quickly from the lactose layer and then in a sustained way, during approximately 6 hours. from the polymeric layer. The mixture CB:HPMC 9∶1 showed good in vitro mucoadhesion. A swelling-diffusion process modulates the release of nystatin from this layer. A non-Fickian (anomalous) kinetic was observed.

Design of Peumus boldus tablets by direct compression using a novel dry plant extract.

A solid pharmaceutical dosage formulation using a novel dry plant extract of Peumus boldus MOL. (Monimiaceae) (Pb) is proposed. The botanical evaluation of plant material, through morphological and anatomical diagnosis, is presented. This evaluation permits to identify the herb to be used correctly. The analysis of the most extractive solvent mixture and the attainment of plant extract (fluid and dry) are reported. Several formulations (tablets) containing a novel dry plant extract of Pb and common excipients for direct compression are evaluated. The following formulation: dry plant extract of Pb (170 mg), Avicel PH101 (112 mg), Lactose CD (112) and magnesium stearate (6 mg), compressed at 1000 mPa, showed the best pharmaceutical performance.

Bioadhesive properties of poly(anhydride) nanoparticles coated with different molecular weights chitosan

The aim of this study was to develop and characterize the bioadhesive properties of poly(anhydride) nanoparticles coated with two types of low-molecular weight chitosan (CH20 of 20 kDa or CH50 of 50 kDa) or their thiolated conjugates. Nanoparticles were prepared by a solvent displacement method and characterized by measuring the size, zeta potential, morphology and composition. For bioadhesion studies, nanoparticles were fluorescently labelled with rhodamine B isothiocyanate. In all cases, coated nanoparticles showed a slightly higher size and lower negative zeta potential than uncoated nanoparticles. Nanoparticles coated with CH20 showed a higher adhesive capacity than uncoated nanoparticles. On the contrary, when nanoparticles were coated with CH50, the resulting carriers displayed a decreased ability to develop adhesive interactions within the gut. Finally, the coating of nanoparticles with thiolated chitosan improved their adhesive abilities. Poly(anhydride) nanoparticles coated with thiolated chitosan can be considered as promising bioadhesive particulate carriers for oral delivery strategies.

Self-dispersible nanocrystals of albendazole produced by high pressure homogenization and spray-drying.

Abstract Albendazole (ABZ) is a broad-spectrum antiparasitic drug used in the treatment of human or animal infections. Although ABZ has shown a high efficacy for repeated doses in monogastric mammals, its low aqueous solubility leads to erratic bioavailability. The aim of this work was to optimize a procedure in order to obtain ABZ self-dispersible nanocrystals (SDNC) by combining high pressure homogenization (HPH) and spray-drying (SD). The material thus obtained was characterized and the variables affecting both the HPH and SD processes were studied. As expected, the homogenizing pressure and number of cycles influenced the final particle size, while the stabilizer concentration had a strong impact on SD output and redispersion of powders upon contact with water. ABZ SDNC were successfully obtained with high process yield and redispersibility. The characteristic peaks of ABZ were clearly identified in the X-ray patterns of the processed samples. A noticeable increase in the dissolution rate was observed in the aqueous environment.

Novel Mucoadhesive Extended Release Tablets for Treatment of Oral Candidosis: “In Vivo” Evaluation of the Biopharmaceutical Performance

Mucoadhesive tablets containing nystatin (10 mg) were evaluated in vivo. The assays were carried out with 12 healthy volunteers and the concentration of nystatin in saliva was determined at different times. Tablets remained attached to the buccal mucosa during 270 min +/- 30 min. No evidence of ulceration or bleeding was observed. Typical appearance of intact human buccal mucosa was seen before and after contact with the tablet. The tablets were well accepted by the volunteers, although most of the volunteers reported a light bitter taste, probably due to nystatin. Concentration of nystatin in saliva was several times higher than MIC over a period of approximately 4.5 h, which was in agreement with the behavior observed in vitro. These results allow us to infer that the administration of these mucoadhesive tablets could be advantageous compared to conventional formulations and mucoadhesive extended-release tablets might produce better therapeutic performance than conventional formulations in the treatment of oral candidosis.

Spray dried microspheres based on chitosan: A promising new carrier for intranasal administration of polymeric antigen BLSOmp31 for prevention of ovine brucellosis

Previous studies have demonstrated that parenteral immunization with polymeric antigen BLSOmp31 induced a strong immune response and conferred protection against Brucella ovis in rams. This work describes the development of a novel formulation strategy for the delivery of BLSOmp31 in the nasal mucosa. Chitosan microparticles were prepared by spray-drying technology processes and recombinant chimera BLSOmp31 was loaded by passive adsorption onto chitosan microspheres, which were characterized by means of the evaluation of size, zeta potential, morphology, and loading and release rate of BLSOmp31. The mucoadhesive properties of microspheres were evaluated by studying the interaction between microparticles and mucin. The antigen BLSOmp31 integrity was investigated by SDS-PAGE. The yield of production of spray-drying process was 68.95%. Microspheres had a good sphericity, 1-10 μm of particle size and had a positive charge. The loading capacity was found to be 45.19%. The initial fast release of BLSOmp31 from chitosan microparticles was 60%. The BLSOmp31 integrity was not affected by passive adsorption (ionic interaction). The amount of mucin adsorbed on the surface of CMs-BLSOmp31 was lower than on the surface of blank CMs at neutral pH. In vivo studies were carried out in rams. Intranasal immunization induced systemic and local antibodies. In conclusion, the use of BLSOmp31-loaded chitosan spray-drying microspheres offers a promising way for nasal mucosal vaccination in sheep against brucellosis.

RP-HPLC method development for the simultaneous determination of timolol maleate and human serum albumin in albumin nanoparticles

An isocratic high-performance liquid chromatographic method was developed and validated for the simultaneous determination of human serum albumin (HSA) and timolol in albumin nanoparticles. This method involved a reversed-phase-C18 column thermostated at 25 °C, UV detection at 276 nm, flow rate of 1.0 ml/min and a mobile phase compounded by 0.05% (v/v) trifluoroacetic acid in water/0.05% (v/v) trifluoroacetic acid in an acetonitrile (40:60, v/v) solution. The elution times for albumin and timolol were 1.84 ± 0.05 min and 2.67 ± 0.04 min, respectively. Calibration curves were linear from 0.2 to 100 mg/ml for HSA and 0.01 to 1 mg/ml for timolol. Limits of quantification were 0.2 mg/ml for HSA and 0.01 mg/ml for timolol. The values of accuracy and precision of intra- and inter-day variation studies were within acceptable limits, according to the US Food and Drug Administration Guidance for Industry. The described method has proved to be useful to give accurate measurements of human serum albumin and timolol from albumin nanoparticles to determine the percentage of encapsulation and the process yield.

New Mucoadhesive Polymeric Film for Ophthalmic Administration of Acetazolamide

This article reports the results concerning the design and manufacture of a novel polymeric film for ocular administration of acetazolamide (AZM), and a patent document presented to INPI- National Institute of Industrial/Intelectual Property. The system was designed using mucoadhesive polymers, such as carbomer (CB974P) and sodium carboxymethylcellulose (NaCMC), combined with the poloxamer (POL407) which behaves as a swelling modulator, surfactant and slightly plasticizer. The maximum amount of AZM to be incorporated without loss of homogeneity or precipitation of the drug, was 0.04 mg AZM/mg of the film. The addition of a polymeric coating based on Eudragit RSPO (cationic permeable polymethacrylate polymer) allowed optimizing drug release. The coating in a proportion of 10% (determined as percentage of total weight of the film) seemed to be the most adequate, since 80% of controlled drug release was achieved along 240 minutes. This coating membrane did not affect the mucoadhesive properties of the swellable polymers. Thus, the system obtained, showed good efficiency and the intra ocular pressure (IOP) decreased according to the results derived from in vivo studies performed on normotensive rabbits. Finally, irritation scored studies demonstrated that these systems were not irritant for rabbit´s ocular mucosa.

Hyaluronan-Itaconic Acid-Glutaraldehyde Films for Biomedical Applications: Preliminary Studies.

New hyaluronic acid–itaconic acid films were synthesized as potential materials with biomedical applications. In this work, we explored the homogeneous cross-linking reactions of hyaluronic acid using glutaraldehyde in the presence of itaconic acid and triacetin as plasticizers. Biomechanical properties were assessed in terms of stability by measuring swelling in aqueous environments, investigating wettability using contact angle tests, and evaluating bioadhesive performance. The ductility of the materials was evaluated through stress-strain measurements and the morphology was explored by scanning electron microscopy. The results show that the incorporation of itaconic acid improved most of the desirable properties, increasing adhesiveness and reducing wettability and swelling. The use of triacetin enhanced the strength, bioadhesiveness, and ductility of the material.

Human serum albumin nanoparticles for ocular delivery of bevacizumab

Bevacizumab-loaded nanoparticles (B-NP) were prepared by a desolvation process followed by freeze-drying, without any chemical, physical or enzymatic cross-linkage. Compared with typical HSA nanoparticles cross-linked with glutaraldehyde (B-NP-GLU), B-NP displayed a significantly higher mean size (310 nm vs. 180 nm) and a lower negative zeta potential (-15 mV vs. -36 mV). On the contrary, B-NP displayed a high payload of approximately 13% when measured by a specific ELISA, whereas B-NP-GLU presented a very low bevacizumab loading (0.1 μg/mg). These results could be related to the inactivation of bevacizumab after reacting with glutaraldehyde. From B-NP, bevacizumab was released following an initial burst effect, proceeded by a continuous release of bevacizumab at a rate of 6 μg/h. Cytotoxicity studies in ARPE cells were carried out at a single dose up to 72 h and with repeated doses over a 5-day period. Neither bevacizumab nor B-NP altered cell viability even when repeated doses were used. Finally, B-NP were labeled with 99mTc and administered as eye drops in rats. 99mTc-B-NP remained in the eye for at least 4 h while 99mTc-HSA was rapidly drained from the administration point. In summary, HSA nanoparticles may be an appropriate candidate for ocular delivery of bevacizumab.