pH-independent immediate release polymethacrylate formulations--an observational study.

Using Eudragit® E PO (EudrE) as a polymethacrylate carrier, the aim of the study was to develop a pH-independent dosage form containing ibuprofen (IBP) as an active compound via chemical modification of the polymer (i.e. quaternization of amine function) or via the addition of dicarboxylic acids (succinic, glutaric and adipic acid) to create a pH micro-environment during dissolution. Biconvex tablets (diameter: 10 mm; height: 5 mm) were produced via hot melt extrusion and injection molding. In vitro dissolution experiments revealed that a minimum of 25% of quaternization was sufficient to partially (up to pH 5) eliminate the pH-dependent effect of the EudrE/IBP formulation. The addition of dicarboxylic acids did not alter IBP release in a pH 1 and 3 medium as the dimethyl amino groups of EudrE are already fully protonated, while in a pH 5 solvent IBP release was significantly improved (cf. from 0% to 92% release after 1 h dissolution experiments upon the addition of 20 wt.% succinic acid). Hence, both approaches resulted in a pH-independent (up to pH 5) immediate release formulation. However, the presence of a positively charged polymer induced stability issues (recrystallization of API) and the formulations containing dicarboxylic acids were classified as mechanically unstable. Hence, further research is needed to obtain a pH-independent immediate release formulation while using EudrE as a polmethacrylate carrier.

Reduction of tablet weight variability by optimizing paddle speed in the forced feeder of a high-speed rotary tablet press.

CONTEXT: Tableting is a complex process due to the large number of process parameters that can be varied. Knowledge and understanding of the influence of these parameters on the final product quality is of great importance for the industry, allowing economic efficiency and parametric release. OBJECTIVE: The aim of this study was to investigate the influence of paddle speeds and fill depth at different tableting speeds on the weight and weight variability of tablets. MATERIALS AND METHODS: Two excipients possessing different flow behavior, microcrystalline cellulose (MCC) and dibasic calcium phosphate dihydrate (DCP), were selected as model powders. Tablets were manufactured via a high-speed rotary tablet press using design of experiments (DoE). During each experiment also the volume of powder in the forced feeder was measured. RESULTS AND DISCUSSION: Analysis of the DoE revealed that paddle speeds are of minor importance for tablet weight but significantly affect volume of powder inside the feeder in case of powders with excellent flowability (DCP). The opposite effect of paddle speed was observed for fairly flowing powders (MCC). Tableting speed played a role in weight and weight variability, whereas changing fill depth exclusively influenced tablet weight. CONCLUSION: The DoE approach allowed predicting the optimum combination of process parameters leading to minimum tablet weight variability. Monte Carlo simulations allowed assessing the probability to exceed the acceptable response limits if factor settings were varied around their optimum. This multi-dimensional combination and interaction of input variables leading to response criteria with acceptable probability reflected the design space.

Efficacy of products to remove eggs of Pediculus humanus capitis (Phthiraptera: Pediculidae) from the human hair.

Head lice infestations are very common in children aged between 3 and 12 yr old. The eggs of the head louse are difficult to remove and remain firmly attached to the hair even after any head louse treatment. Solid in vitro and in vivo evidence to support the use of any of the proposed products to facilitate nit removal is scarce. The objective of the current study was to determine the efficacy of several products to remove eggshells from human hair using an objective measurement procedure. Water and ordinary hair conditioner significantly facilitated the removal of nits in vitro. We found no difference between ordinary conditioner and products specifically marketed for the purpose of nit removal. Other products such as formic acid solution and almond oil did not have a beneficial effect.

Gelucire 44/14 based immediate release formulations for poorly water-soluble drugs.

Here, we aim to evaluate Gelucire 44/14 as non-ionic surface-active excipient to produce immediate-release solid dosage forms for poorly water-soluble drugs. Gelucires are polyethylene glycol (PEG) glycerides composed of mono-, di- and triglycerides and mono- and diesters of PEG. They are inert semi-solid waxy amphiphilic excipients with surface-active properties that spontaneously form a fine dispersion or emulsion upon contact with water. Monolithic Gelucire 44/14 structures are prone to prolonged erosion times, thereby slowing down drug dissolution. To overcome this issue, we combine either granulation or spray-drying, followed by compression into tablets, with an optimized composition of disintegration promoting agents. This formulation strategy allows obtaining nearly 100% drug release within 10 min dissolution time.

Designing polymeric particles for antigen delivery.

By targeting dendritic cells, polymeric carriers in the nano to lower micron range constitute very interesting tools for antigen delivery. In this critical review, we review how new immunological insights can be exploited to design new carriers allowing one to tune immune responses and to further increase vaccine potency (137 references).

Layer-by-layer incorporation of growth factors in decellularized aortic heart valve leaflets.

Aortic heart valve disease is a growing health problem and a tissue-engineered aortic heart valve could be a promising therapy. In this paper, decellularized porcine aortic heart valve leaflets are used as scaffolds and loaded with growth factor and heparin via layer-by-layer electrostatic deposition (LbL technique) with the final purpose to stimulate and control cellular processes. Binding and subsequent release of heparin and basic fibroblast growth factor (bFGF) from aortic valve leaflets were assessed qualitatively by immunohistochemistry and quantitatively by radioactive labeling methods. It was observed that the amount of heparin and bFGF bound to aortic heart valve leaflets was directly proportional to the concentration of heparin and bFGF in the incubation medium. Release of heparin and bFGF from the decellularized heart valve leaflets at physiological conditions was sustained over 4 days while preserving the biological activity of the released growth factor.

Polymeric multilayer capsules in drug delivery.

Recent advances in medicine and biotechnology have prompted the need to develop nanoengineered delivery systems that can encapsulate a wide variety of novel therapeutics such as proteins, chemotherapeutics, and nucleic acids. Moreover, these delivery systems should be "intelligent", such that they can deliver their payload at a well-defined time, place, or after a specific stimulus. Polymeric multilayer capsules, made by layer-by-layer (LbL) coating of a sacrificial template followed by dissolution of the template, allow the design of microcapsules in aqueous conditions by using simple building blocks and assembly procedures, and provide a previously unmet control over the functionality of the microcapsules. Polymeric multilayer capsules have recently received increased interest from the life science community, and many interesting systems have appeared in the literature with biodegradable components and biospecific functionalities. In this Review we give an overview of the recent breakthroughs in their application for drug delivery.

Optimisation of an enteric coated, layered multi-particulate formulation for ileal delivery of viable recombinant Lactococcus lactis.

Layering of pellets with recombinant Lactococcus lactis Thy 12 was optimised for the production of a dosage form with a high load of viable recombinant L. lactis. Shear stress induced during the atomisation and the type of carrier used for the layering process did not influence the viability. A 5% lactose matrix resulted in the highest viability of L. lactis (8.9+/-1.7%) which could be maintained for at least 12 months at -20 degrees C. A higher bacterial cell load on the pellets was obtained using a longer process time, but the addition of 10% skim milk was essential to maintain the stabilising capacity of the matrix. Increasing the load of viable L. lactis was also possible using a higher bacterial cell concentration of the layering suspension and increasing the amount of stabilising matrix to 10% lactose/20% skim milk, yielding a formulation with 1.7 x 10(9)cfu/100 mg pellets. To protect the bacteria during gastric passage and to obtain ileum targeting, the formulation was enteric coated with 5% Eudragit FS30D, but after coating and gastric residence for 2 h HCl about 1% of the bacteria remained viable. Application of a subcoating, previous to enteric coating, did not result in a higher viability.

In-vitro and in-vivo evaluation of enteric-coated starch-based pellets prepared via extrusion/spheronisation.

Pellet cores containing modified starch (high-amylose, crystalline and resistant starch) as the main excipient were enteric-coated with an Eudragit L30 D-55 based dispersion. The polymer weight gain was from 15% to 30% (w/w). Pellet cores were prepared using piroxicam (2.5% w/w, poor water solubility) and anhydrous theophylline (2.5% and 25% w/w, coarse and micronised powder, medium water solubility) as model drugs. Next to the water solubility, particle size and concentration of the model drugs, the influence of sorbitol (0% and 10%, w/w) and drying method (oven and fluid-bed) on pellet yield, size (Feret mean diameter), sphericity (aspect ratio, AR and two-dimensional shape factor, e(R)), friability, surface morphology and drug release were evaluated. Binder (HPMC) and granulation liquid (water) concentration were optimised to obtain maximum yield (size fraction between 900 and 1400 microm) and acceptable sphericity (AR<1.2). Pellet friability was <0.01% for all formulations, while the mean pellet diameter was lower for pellets with sorbitol and the ones dried in an oven. Mercury intrusion porosimetry combined with scanning electron microscopy revealed an influence of drying method and sorbitol level on the surface structure: the surface of fluid-bed dried pellets without sorbitol and with 2.5% of model drug was cracked, which correlated with a Hg-intrusion peak at the 6-80 microm pore size range. Due to improved mechanical properties of the wet mass, sorbitol addition smoothened the pellets as the main peak of Hg-intrusion shifted to a smaller pore size range. Using a higher drug concentration and micronised theophylline shifted the main peak of Hg-intrusion further towards the smaller pore size range. Oven-dried pellets showed no Hg-intrusion and no cracks were observed. When applying the highest coating thickness (30% weight gain), all theophylline pellet formulations were successfully coated (<10% drug release after 2h in acid dissolution medium), while pellets with the lowest coating thickness (15% weight gain) released from 5% to about 30% theophylline. The extent of drug release depended on the pellet composition and drying method as these factors determined the surface properties. Piroxicam release in acid medium was less than 1% irrespective of the surface characteristics, due to its poor water solubility. In basic medium (phosphate buffer, pH 6.8) all pellets released the drug in less than 45 min. The bioavailability of coated and uncoated piroxicam pellets was determined after oral administration to six dogs. Values of AUC(0-->72h), C(max) and t(max) after oral administration of piroxicam pellets to dogs were not significantly different from the values obtained for immediate release capsules (P>0.05).

Development of starch-based pellets via extrusion/spheronisation.

A modified starch (high-amylose, crystalline and resistant starch) was evaluated as an alternative excipient to microcrystalline cellulose for pellets prepared via extrusion/spheronisation. Theophylline anhydrous (25%, w/w) was used as a model drug. A binder was necessary to obtain an acceptable yield and the addition of sorbitol improved the surface properties of the pellets. A surface response design with three formulation variables (binder, sorbitol and water level) and one process variable (spheronisation speed) was used to optimise the process and to evaluate pellet yield, sphericity (aspect ratio and two-dimensional shape factor, e(R)), size (mean Feret diameter), friability and disintegration properties. Mixer torque rheometry and solid-state NMR revealed a significant influence of sorbitol on wet mass consistency and pellet properties. A high pellet yield (>90%), acceptable sphericity (AR<1.2), low friability (<0.01%), fast disintegration (<10 min) and complete drug release in less than 20 min for all formulations, demonstrated the potential of this modified starch in formulations intended for extrusion/spheronisation.

Correlation between the permeability of metoprolol tartrate through plasticized isolated ethylcellulose/hydroxypropyl methylcellulose films and drug release from reservoir pellets.

The present study investigates if drug diffusion through plasticized isolated ethylcellulose (EC)/hydroxypropyl methylcellulose (HPMC) films prepared by solvent casting can be used as a tool to develop spray-coated dosage forms. In particular, the importance of the level and type of plasticizers was investigated. The permeability of the model drug metoprolol tartrate through plasticized isolated films could be adjusted by selecting the type and amount of plasticizer in the films due to the different hydrophilicity of the plasticizers. The release of metoprolol tartrate from coated pellets is consistent with the drug diffusion through the films made up of the same polymer blends. This indicated that it is useful to test isolated films for early predictions and for formulation optimization.

The use of a new hydrophilic polymer, Kollicoat IR, in the formulation of solid dispersions of Itraconazole.

Kollicoat IR, a new pharmaceutical excipient developed as a coating polymer for instant release tablets, was evaluated as a carrier in solid dispersions of Itraconazole. The solid dispersions were prepared by hot stage extrusion. Modulated temperature differential scanning calorimetry and X-ray powder diffraction were used to evaluate the miscibility of the drug and the carrier. The pharmaceutical performance was evaluated by dissolution experiments, performed in simulated gastric fluid without pepsin (SGF(sp)). In the X-ray diffractograms no Itraconazole peaks were visible; the polymer on the other hand appeared to be semi-crystalline. Moreover, its crystallinity increased during the extrusion process due to exposure to heat and shear forces. Modulated temperature differential scanning calorimetry analysis showed that the drug and the polymer formed a two phase system. Separate clusters of glassy Itraconazole were present for drug loads of 40% or higher, indicating further phase separation. Dissolution measurements demonstrated a significantly increased dissolution rate for the solid dispersions compared to physical mixtures. Interestingly the physical mixture made up of glassy Itraconazole and Kollicoat IR (20/80, w/w) showed a dissolution rate and maximum that was much higher than that of the physical mixture made up of crystalline Itraconazole and that of pure glassy Itraconazole. The results of this study show that Kollicoat IR is a promising excipient for the formulation of solid dispersions of Itraconazole prepared by hot stage extrusion.

Elucidation and visualization of solid-state transformation and mixing in a pharmaceutical mini hot melt extrusion process using in-line Raman spectroscopy.

Mixing of raw materials (drug+polymer) in the investigated mini pharma melt extruder is achieved by using co-rotating conical twin screws and an internal recirculation channel. In-line Raman spectroscopy was implemented in the barrels, allowing monitoring of the melt during processing. The aim of this study was twofold: to investigate (I) the influence of key process parameters (screw speed - barrel temperature) upon the product solid-state transformation during processing of a sustained release formulation in recirculation mode; (II) the influence of process parameters (screw speed - barrel temperature - recirculation time) upon mixing of a crystalline drug (tracer) in an amorphous polymer carrier by means of residence time distribution (RTD) measurements. The results indicated a faster mixing endpoint with increasing screw speed. Processing a high drug load formulation above the drug melting temperature resulted in the production of amorphous drug whereas processing below the drug melting point produced solid dispersions with partially amorphous/crystalline drug. Furthermore, increasing the screw speed resulted in lower drug crystallinity of the solid dispersion. RTD measurements elucidated the improved mixing capacity when using the recirculation channel. In-line Raman spectroscopy has shown to be an adequate PAT-tool for product solid-state monitoring and elucidation of the mixing behavior during processing in a mini extruder.

Melt granulation using a twin-screw extruder: a case study.

The purpose of this study was to use a twin-screw extruder for melt granulation. Polyethylene glycols (PEG 400 and 4000) were used as binders for the development of a drinking water formulation with immediate drug release. The effect of drug content, PEG 400/4000-ratio, surfactant (type and concentration) and granulation temperature on granule properties and dissolution characteristics was determined. The granulation temperature had an important influence on the granule formation. High yield (95% of the granules <1400 microm) was obtained only at a temperature near the melting point of PEG 4000. During granulation the drug of BCS class II was finely dispersed in the PEGs, creating a micro-environment around the drug particles enhancing the dissolution rate. To obtain complete drug release within 10 min for a formulation containing 10% drug, the addition of 2% (w/w) surfactant (polysorbate 80 or Cremophor RH40) was required. At a higher drug content (20%), the PEG 4000 concentration had to be increased to 20% to improve granule properties and 4% polysorbate 80 was required to obtain 100% drug release. X-ray diffractograms showed distinct peaks of crystalline drug, the crystallinity of the drug did not change after 50 days, independent of the storage conditions.

Co-extrusion as a processing technique to manufacture a dual sustained release fixed-dose combination product.

OBJECTIVES: This study aimed to design a fixed-dose combination dosage form which provides a sustained release profile for both the freely water-soluble metformin HCl and the poorly soluble gliclazide, two antidiabetic compounds used to treat diabetes mellitus. METHODS: Hot-melt co-extrusion was used as an innovative manufacturing technique for a pharmaceutical fixed-dose combination product. In this way, a matrix formulation that sustained metformin release could be developed, despite the high drug load in the formulation and the freely soluble nature of the drug. KEY FINDINGS: It was clear that co-extrusion was perfectly suited to produce a fixed-dose combination product with adequate properties for each of the incorporated APIs. A coat layer, containing at least 30% CAPA(®) 6506 as a hydrophobic polymer, was necessary to adequately sustain the release of the highly dosed freely soluble drug from the 70% metformin HCl-loaded CAPA(®) 6506 core of the co-extrudate. To obtain a complete gliclazide release over 24-h solubilization in Kollidon(®) VA, added as a second polymer to the CAPA(®) 6506 in the coat, was needed. CONCLUSIONS: Both active pharmaceutical ingredients (APIs), which have different physicochemical characteristics, were formulated in a single dosage form, using co-extrusion.

Stearic acid and high molecular weight PEO as matrix for the highly water soluble metoprolol tartrate in continuous twin-screw melt granulation.

Granules with release-sustaining properties were developed by twin screw hot melt granulation (HMG) using a combination of stearic acid (SA) and high molecular weight polyethylene oxide (PEO) as matrix for a highly water soluble model drug, metoprolol tartrate (MPT). Earlier studies demonstrated that mixing molten SA and PEO resulted in hydrogen bond formation between hydroxyl groups of fatty acid molecules and ether groups in PEO chains. These molecular interactions might be beneficial in order to elevate the sustained release effect of drugs from a SA/PEO matrix. This study aims to investigate the continuous twin screw melt granulation technique to study the impact of a SA/PEO matrix on the dissolution rate of a highly water soluble drug (MPT). Decreasing the SA/PEO ratio improved the release-sustaining properties of the matrix. The solid state of the granules was characterized using differential scanning calorimetry (DSC), nuclear magnetic resonance (NMR), X-ray diffraction (XRD), Raman spectroscopy, Fourier transform infrared (FTIR) and near infrared chemical imaging (NIR-CI) in order to understand the dissolution behavior. The results revealed a preferential interaction of the MPT molecules with stearic acid impeding the PEO to form hydrogen bonds with the stearic acid chains. However, this allowed the PEO chains to recrystallize inside the stearic acid matrix after granulation, hence, elevating the release-sustaining characteristics of the formulation.

The use of rheology to elucidate the granulation mechanisms of a miscible and immiscible system during continuous twin-screw melt granulation.

Twin-screw hot melt granulation (TS HMG) is a valuable, but still unexplored alternative to granulate temperature and moisture sensitive drugs in a continuous way. Recently, the material behavior of an immiscible drug-binder blend during TS HMG was unraveled by using a rheometer and differential scanning calorimetry (DSC). Additionally, vibrational spectroscopic techniques proved the link between TS HMG and rheology since equal interactions at molecular level did occur in both processes. This allowed to use a rheometer to gain knowledge of the material behavior during hot melt processing of an immiscible drug-binder blend. However, miscibility of a drug-binder formulation and drug-binder interactions appear to influence the rheological properties and, hence conceivably also the granulation mechanism. The aim of this research was to examine if the TS HMG process of a miscible formulation system is comparable with the mechanism of an immiscible system and to evaluate whether rheology still serves as a useful tool to understand and optimize the hot melt granulation (HMG) process. The executed research (thermal analysis, rheological parameters and spectroscopic data) demonstrated the occurrence of a high and broad tan(δ) curve without a loss peak during the rheological temperature ramp which implies a higher material deformability without movement of the softened single polymer chains. Spectroscopic analysis revealed drug-polymer interactions which constrain the polymer to flow independently. As a result, the binder distribution step, which generally follows the immersion step, was hindered. This insight assisted the understanding of the granule properties. Inhomogeneous granules were produced due to large initial nuclei or adhesion of multiple smaller nuclei. Consequently, a higher granulation temperature was required in order to get the binder more homogeneously distributed within the granules.

Effects of roller compaction settings on the preparation of bioadhesive granules and ocular minitablets.

An experimental factorial design was employed to evaluate bioadhesive granules and bioerodible ocular minitablets (6 mg and Psi 2 mm). The purpose of this study was to compare minitablets prepared using roller compacted granules with an optimised minitablet formulation, manufactured on laboratory scale by direct compression. The formulation consisted of drum dried waxy maize starch, Carbopol 974P, and ciprofloxacin in a ratio of 90.5/5/3 (w/w/w). Three roller compactor parameters were varied, i.e. the roller speed, the horizontal screw speed and the compaction force, while the vertical screw speed was kept constant. Afterwards, the ribbons were milled to obtain granules suitable for compression. The friability, the flow properties, the bulk material characteristics (apparent and tap density and porosity) and the particle size distributions of two granule sieve fractions (90-125 and 125-355 microm) were investigated. The roller speed and the compaction force have the largest influence on the granule characteristics, followed by the horizontal screw speed. The physical properties of non- and gamma-irradiated minitablets were determined. From the tablet strength, friability and dissolution results, a low compaction force and a high roller speed were shown to be preferable to prepare granules which can be further tabletted into adequate ocular minitablets.

Development of an enteric-coated, layered multi-particulate formulation for ileal delivery of viable recombinant Lactococcus lactis.

Layering of recombinant hIL-10 producing Lactococcus lactis (L. lactis Thy12) on inert carriers is a promising technique for the preparation of a multi-particulate formulation of viable, hIL-10 producing L. lactis. To improve viability after layering and storage, L. lactis Thy12 was layered in different matrices (10% skim milk and/or 2.5, 5, 10% inulin). After layering, the highest viability was obtained in the 10% skim milk supplemented with 5% inulin matrix (8.7%). However, upon storage, 10% skim milk alone yielded the highest viability. Thereby, layered L. lactis Thy12 showed superior long term stability in comparison with freeze-dried L. lactis Thy12. The layering process was performed during 3h without encountering technical problems, with good layer consistence and constant viability. Enteric properties were obtained with a 30% Eudragit L30D-55 or 15% Eudragit FS30D coating and maintained during an initial six months storage period (-20 degrees C/20% RH). After in vitro simulation of the gastric stage, only 5% of the bacteria remained viable in Eudragit L30D-55 coated pellets, contrary to 85% in Eudragit FS30D coated pellets, indicating its superior protective capacity against gastric fluid. After eight months storage (-20 degrees C), 80% of the initial L. lactis Thy12 remained viable in the Eudragit FS30D coated pellets.

In vitro evaluation of coating polymers for enteric coating and human ileal targeting.

Recombinant interleukin-10 producing Lactococcus lactis is an alternative therapy for Crohn's disease. For in vivo interleukin-10 production, thymidine, the essential feed component of these recombinant bacteria should be coadministered. Different coating polymers were evaluated in vitro for enteric properties and targeting suitability to the ileum, the major site of inflammation in Crohn's disease. To guarantee ileal delivery, the polymer must dissolve from pH 6.8 and allow complete release within 40 min. Aqoat AS-HF coated pellets (15%) showed poor enteric properties and thymidine was released below pH 6.8. Eudragit FS30D coated pellets (15%) showed good enteric properties, but no thymidine was released within 40 min at pH 6.8. Eudragit S coated pellets (15%) showed good enteric properties after curing at elevated temperature while no thymidine was released within 40 min at pH 6.8. In another approach to pass the proximal small intestine intact, pellets were coated with 30% Eudragit L30D-55. At pH 6.0, they showed a lag-phase of 20 min. No influence of layer thickness was seen above pH 6.5. Alternatively, pellets were coated with a mixture of Eudragit FS30D/L30D-55 but they showed poor enteric properties and thymidine was released below pH 6.8. In conclusion, none of the tested polymers/mixtures ensured enteric properties and ileal targeting.