Development of Itraconazole Tablets Containing Viscous KinetiSol Solid Dispersions: In Vitro and In Vivo Analysis in Dogs

The formulation factors relevant to developing immediate and controlled release dosage forms containing poorly soluble drugs dispersed in amorphous systems are poorly understood. While the utility of amorphous solid dispersions is becoming apparent in the pharmaceutical marketplace, literature reports tend to concentrate on the development of solid dispersion particulates, which then must be formulated into a tablet. Amorphous solid dispersions of itraconazole in high molecular weight hydroxypropyl methylcellulose were prepared by KinetiSol® Dispersing and tablets were formulated to immediately disintegrate or control the release of itraconazole. Formulated tablets were evaluated by two non-sink dissolution methodologies and the dosage form properties that controlled the gelling tendency of the dispersion carrier, hydroxypropyl methylcellulose, were investigated. Selected formulations were evaluated in an exploratory beagle dog pharmacokinetic study; the results of which indicate potential for a prolonged absorption phase relative to the commercially extruded control.

Hot melt extrusion versus spray drying: hot melt extrusion degrades albendazole

The purpose of this study was to enhance the dissolution properties of albendazole (ABZ) by the use of amorphous solid dispersions. Phase diagrams of ABZ-polymer binary mixtures generated from Flory-Huggins theory were used to assess miscibility and processability. Forced degradation studies showed that ABZ degraded upon exposure to hydrogen peroxide and 1 N NaOH at 80 °C for 5 min, and the degradants were albendazole sulfoxide (ABZSX), and ABZ impurity A, respectively. ABZ was chemically stable following exposure to 1 N HCl at 80 °C for one hour. Thermal degradation profiles show that ABZ, with and without Kollidon^® VA 64, degraded at 180 °C and 140 °C, respectively, which indicated that ABZ could likely be processed by thermal processing. Following hot melt extrusion, ABZ degraded up to 97.4%, while the amorphous ABZ solid dispersion was successfully prepared by spray drying. Spray-dried ABZ formulations using various types of acids (methanesulfonic acid, sulfuric acid and hydrochloric acid) and polymers (Kollidon^® VA 64, Soluplus^® and Eudragit^® E PO) were studied. The spray-dried ABZ with methanesulfonic acid and Kollidon^® VA 64 substantially improved non-sink dissolution in acidic media as compared to bulk ABZ (8-fold), physical mixture of ABZ:Kollidon^® VA 64 (5.6-fold) and ABZ mesylate salt (1.6-fold). No degradation was observed in the spray-dried product for up to six months and less than 5% after one-year storage. In conclusion, amorphous ABZ solid dispersions in combination with an acid and polymer can be prepared by spray drying to enhance dissolution and shelf-stability, whereas those made by melt extrusion are degraded.

A New Extrudable Form of Hypromellose: AFFINISOL™ HPMC HME

Hypromellose is a hydrophilic polymer widely used in immediate- and modified-release oral pharmaceutical dosage forms. However, currently available grades of hypromellose are difficult, if not impossible, to process by hot melt extrusion (HME) because of their high glass transition temperature, high melt viscosity, and low degradation temperature. To overcome these challenges, a modified grade of hypromellose, AFFINISOL™ HPMC HME, was recently introduced. It has a significantly lower glass transition temperature and melt viscosity as compared to other available grades of hypromellose. The objective of this paper is to assess the extrudability and performance of AFFINISOL™ HPMC HME (100LV and 4M) as compared to other widely used polymers in HME, including HPMC 2910 100cP (the currently available hypromellose), Soluplus®, Kollidon® VA 64, and EUDRAGIT® E PO. Formulations containing polymer and carbamazepine (CBZ) were extruded on a co-rotating 16-mm twin-screw extruder, and the effect of temperature, screw speed, and feed rate was investigated. The performance of the solid dispersions was evaluated based on Flory-Huggins modeling and characterized by differential scanning calorimetry (DSC), X-ray powder diffraction (XRD), Raman spectroscopy, Fourier-transform infrared (FTIR) spectroscopy, and dissolution. All formulations extruded well except for HPMC 2910 100cP, which resulted in over-torqueing the extruder (machine overloading because the motor cannot provide efficient energy to rotate the shaft). Among the HME extrudates, only the EUDRAGIT® E PO formulation was crystalline as confirmed by DSC, XRD, and Raman, which agreed with predictions from Flory-Huggins modeling. Dissolution testing was conducted under both sink and non-sink conditions. Sink dissolution testing in neutral media revealed that amorphous CBZ in the HME extrudates completely dissolved within 15 min, which was much more rapid than the time for complete dissolution of bulk CBZ (60 min) and EUDRAGIT® E PO solid dispersion (more than 6 h). Non-sink dissolution in acidic media testing revealed that only CBZ contained in the AFFINISOL™ HPMC HME, and EUDRAGIT® E PO solid dispersions rapidly supersaturated after 15 min, reaching a twofold drug concentration compared to the CBZ equilibrium solubility. In summary, AFFINISOL™ HPMC HME 100LV and AFFINISOL™ HPMC HME 4M are useful in the pharmaceutical HME process to increase wetting and dissolution properties of poorly water-soluble drugs like CBZ.

Challenges and Strategies in Thermal Processing of Amorphous Solid Dispersions: A Review

Thermal processing of amorphous solid dispersions continues to gain interest in the pharmaceutical industry, as evident by several recently approved commercial products. Still, a number of pharmaceutical polymer carriers exhibit thermal or viscoelastic limitations in thermal processing, especially at smaller scales. Additionally, active pharmaceutical ingredients with high melting points and/or that are thermally labile present their own specific challenges. This review will outline a number of formulation and process-driven strategies to enable thermal processing of challenging compositions. These include the use of traditional plasticizers and surfactants, temporary plasticizers utilizing sub- or supercritical carbon dioxide, designer polymers tailored for hot-melt extrusion processing, and KinetiSol® Dispersing technology. Recent case studies of each strategy will be described along with potential benefits and limitations.

Thermal Processing of PVP- and HPMC-Based Amorphous Solid Dispersions

Thermal processing technologies continue to gain interest in pharmaceutical manufacturing. However, the types and grades of polymers that can be utilized in common thermal processing technologies, such as hot-melt extrusion (HME), are often limited by thermal or rheological factors. The objectives of the present study were to compare and contrast two thermal processing methods, HME and KinetiSol® Dispersing (KSD), and investigate the influence of polymer type, polymer molecular weight, and drug loading on the ability to produce amorphous solid dispersions (ASDs) containing the model compound griseofulvin (GRIS). Dispersions were analyzed by a variety of imaging, solid-state, thermal, and solution-state techniques. Dispersions were prepared by both HME and KSD using polyvinylpyrrolidone (PVP) K17 or hydroxypropyl methylcellulose (HPMC) E5. Dispersions were only prepared by KSD using higher molecular weight grades of HPMC and PVP, as these could not be extruded under the conditions selected. Powder X-ray diffraction (PXRD) analysis showed that dispersions prepared by HME were amorphous at 10% and 20% drug load; however, it showed significant crystallinity at 40% drug load. PXRD analysis of KSD samples showed all formulations and drug loads to be amorphous with the exception of trace crystallinity seen in PVP K17 and PVP K30 samples at 40% drug load. These results were further supported by other analytical techniques. KSD produced amorphous dispersions at higher drug loads than could be prepared by HME, as well as with higher molecular weight polymers that were not processable by HME, due to its higher rate of shear and torque output.

Bioavailability enhancement of a BCS IV compound via an amorphous combination product containing ritonavir

Objectives

To evaluate the effect of ritonavir (RTV) co-administration on the bioavailability of an amorphous dispersion of acetyl-11-keto-beta-boswellic acid (AKBA) and to develop a pharmaceutically acceptable AKBA–RTV combination tablet.

Methods

A pharmacokinetic (PK) study in rats was conducted to evaluate the influence of RTV co-administration on the oral bioavailability of an AKBA amorphous dispersion. KinetiSol was utilized to enable production of an improved RTV formulation that facilitated the development of an AKBA–RTV combination tablet. Following in-vitro characterization, the PK performance of the tablets was evaluated in male beagles.

Key findings

Co-administration of RTV increased oral absorption of AKBA by about fourfold over the AKBA dispersion alone and approximately 24-fold over the pure compound. The improved RTV amorphous dispersion exhibited similar purity and neutral-phase dissolution to Norvir. The AKBA–RTV combination tablets yielded a substantial increase in AKBA's bioavailability in dogs.

Conclusions

Oral absorption of AKBA is substantially limited by intestinal CYP3A activity and poor aqueous solubility. Consequently, AKBA's oral bioavailability is maximized by administration from a supersaturating formulation in conjunction with a CYP3A inhibitor. The AKBA–RTV combination tablet presented herein represents a breakthrough in the oral delivery of the compound facilitating future use as a drug therapy for broad spectrum cancer treatment.

Effect of hydrophilic additives on the dissolution and pharmacokinetic properties of itraconazole-enteric polymer hot-melt extruded amorphous solid dispersions

Hot-melt extrusion technology has been widely reported for producing amorphous solid dispersions of poorly water-soluble compounds. A number of studies revealed that enteric polymers containing ionizable groups are able to improve the physical stability and maintain drug supersaturation, thereby enhancing oral bioavailability. However, our previous studies found that itraconazole (ITZ)-enteric polymer amorphous solid dispersions are hydrophobic and poorly wettable. Moreover, drug release in an acidic environment (i.e. stomach) is very limited, indicating a narrow absorption window. In the present study, we investigated the effect of hydrophilic additives on the in vitro and in vivo performance of ITZ-enteric polymer amorphous solid dispersions. Incorporating Vitamin E TPGS into ITZ-HPMCAS amorphous solid dispersions significantly improved drug release in the acidic media. Surprisingly, a low concentration of Vitamin E TPGS also enhanced the degree of drug supersaturation in neutral pH media, which is unique as compared with other tested hydrophilic additives. This effect is not due to the solubilization of the surfactant. We further formulated the amorphous solid dispersions into tablet dosage forms and evaluated their performance in a bio-relevant dissolution media. Our optimized formulations exhibited drastically enhanced dissolution profiles as compared with the commercial ITZ product and ITZ amorphous solid dispersion without hydrophilic additive. In vivo study showed that Vitamin E TPGS induced rapid drug absorption after oral administration. Moreover, the elimination half-life of ITZ was prolonged due to the enzyme inhibition effect of Vitamin E TPGS.

Continuous twin screw melt granulation of glyceryl behenate: Development of controlled release tramadol hydrochloride tablets for improved safety

Interest in granulation processes using twin screw extrusion machines is rapidly growing. The primary objectives of this study were to develop a continuous granulation process for direct production of granules using this technique with glyceryl behenate as a binder, evaluate the properties of the resulting granules and develop controlled release tablets containing tramadol HCl. In addition, the granulation mechanism was probed and the polymorphic form of the lipid and drug release rate were evaluated on stability. Granules were prepared using a Leistritz NANO16 twin screw extruder operated without a constricting die. The solid state of the granules were characterized by differential scanning calorimetry and X-ray diffraction. Formulated tablets were studied in 0.1N HCl containing 0-40% ethanol to investigate propensity for alcohol induced dose dumping. The extrusion barrel temperature profile and feed rate were determined to be the primary factors influencing the particle size distribution. Granules were formed by a combination immersion/distribution mechanism, did not require subsequent milling, and were observed to contain desirable polymorphic forms of glyceryl behenate. Drug release from tablets was complete and controlled over 16 h and the tablets were determined to be resistant to alcohol induced dose dumping. The drug release rate from the tablets was found to be stable at 40°C and 75% relative humidity for the duration of a 3 month study.

Investigation of the interactions of enteric and hydrophilic polymers to enhance dissolution of griseofulvin following hot melt extrusion processing

Objectives

This study focuses on the application of hot melt extrusion (HME) to produce solid dispersions containing griseofulvin (GF) and investigates the in-vitro dissolution performance of HME powders and resulting tablet compositions containing HME-processed dispersions.

Methods

Binary, ternary and quaternary dispersions containing GF, enteric polymer (Eudragit L100-55 or AQOAT-LF) and/or vinyl pyrrolidone-based polymer (Plasdone K-12 povidone or S-630 copovidone) were processed by HME. Two plasticizers, triethyl citrate (TEC) and acetyl tributyl citrate (ATBC), were incorporated to aid in melt processing and to modify release of GF in neutral media following a pH-change in dissolution. Products were characterized for GF recovery, degrees of compositional amorphous character, intermolecular interactions and non-sink dissolution performance.

Key findings

Binary dispersions exhibited lower maximum observed concentration values and magnitudes of supersaturated GF in neutral media dissolution in comparison with the ternary dispersions. The quaternary HME products, 1 : 2 : 1 : 0.6 GF : L100-55 : S-630 : ATBC and GF : AQOAT-LF : K-12 : ATBC, were determined as the most optimal concentration-enhancing compositions due to increased hydrogen bonding of enteric functional groups with carbonyl/acetate groups of vinyl pyrrolidone-based polymers, reduced compositional crystallinity and presence of incorporated hydrophobic plasticizer.

Conclusions

HME products containing combinations of concentration-enhancing polymers can supersaturate and sustain GF dissolution to greater magnitudes in neutral media following the pH-transition and be compressed into immediate-release tablets exhibiting similar dissolution profiles.

Effect of tablet structure on controlled release from supersaturating solid dispersions containing glyceryl behenate

The objective of this study was to evaluate the use of glyceryl behenate as a plasticizer and release modifier in solid dispersion systems containing itraconazole and carbamazepine. Amorphous solid dispersions of high molecular weight polyvinylpyrrolidone were prepared by hot-melt extrusion, the processing of which was improved by the inclusion of glyceryl behenate. Dispersions were milled and subsequently compressed into tablets. Solid dispersions were also prepared by KinetiSol Dispersing, which allowed for the manufacture of monolithic tablets of the same composition and shape as compressed tablets. Tablets without glyceryl behenate and all compressed tablets were observed to have an incomplete release profile likely due to drug crystallization within the tablet as this occurred at conditions in which dissolution concentrations were below saturation. Monolithic tablets formulated to be more hydrophobic, by including glyceryl behenate, allowed for sustained release below and above saturation conditions.

Dissolution enhancement of itraconazole by hot-melt extrusion alone and the combination of hot-melt extrusion and rapid freezing--effect of formulation and processing variables

We investigated the effects of the hot-melt extrusion (HME) process on the properties of itraconazole (ITZ) amorphous solid dispersions made by thin film freezing (TFF) technology. The ITZ-HPMCAS L (1:2) TFF composition exhibited limited drug release in acidic media. HME of the ITZ-HPMCAS TFF composition with hydrophilic carriers improved the drug release rate in acidic media. The type and level of hydrophilic carrier in the composition affected the dissolution profiles of the extrudates. A design of experiments (DoE) study was conducted to elucidate those effects. Hot-melt extrusion processing variables such as extrusion temperature and screw configuration also played a critical role on the properties of the extruded compositions. A higher degree of mixing reduced the crystallinity of semicrystalline excipients and favored the drug release in the acidic media; moreover, the drug precipitation rate in the neutral pH media was reduced.

Investigation of process temperature and screw speed on properties of a pharmaceutical solid dispersion using corotating and counter-rotating twin-screw extruders

Objective

The use of corotating twin screw hot-melt extruders to prepare amorphous drug/polymer systems has become commonplace. As small molecule drug candidates exiting discovery pipelines trend towards higher MW and become more structurally complicated, the acceptable operating space shifts below the drug melting point. The objective of this research is to investigate the extrusion process space, which should be selected to ensure that the drug is solubilized in the polymer with minimal thermal exposure, is critical in ensuring the performance, stability and purity of the solid dispersion.

Methods

The properties of a model solid dispersion were investigated using both corotating and counter-rotating hot-melt twin-screw extruders operated at various temperatures and screw speeds. The solid state and dissolution performance of the resulting solid dispersions was investigated and evaluated in context of thermodynamic predictions from Flory–Huggins Theory. In addition, the residence time distributions were measured using a tracer, modelled and characterized.

Key findings

The amorphous content in the resulting solid dispersions was dependent on the combination of screw speed, temperature and operating mode.

Conclusions

The counter-rotating extruder was observed to form amorphous solid dispersions at a slightly lower temperature and with a narrower residence time distribution, which also exhibited a more desirable shape.

Preparation and characterization of fusion processed solid dispersions containing a viscous thermally labile polymeric carrier

The primary aim of the present study was to investigate the ability of hydroxypropyl and methoxyl substituted cellulose ethers to stabilize supersaturated concentrations of itraconazole (ITZ), a poorly water-soluble weak base, after an acid-to-neutral pH transition. A secondary aim of the study was to evaluate the effect of fusion processes on polymer stability and molecular weight. Polymer screening studies showed that stabilization of ITZ supersaturation was related to the molecular weight of the polymer and levels of hydroxypropyl and methoxyl substitution. METHOCEL E50LV (E50LV), which is characterized as having a high melt viscosity, was selected for solid dispersion formulation studies. Hot-melt extrusion processing of E50LV based compositions resulted in high torque loads, low material throughput and polymer degradation. KinetiSol Dispersing, a novel fusion based processing technique, was evaluated as a method to prepare the solid dispersions with reduced levels of polymer degradation. An experimental design revealed that polymer molecular weight was sensitive to shearing forces and high temperatures. However, optimal processing conditions resulted in significantly reduced E50LV degradation relative to HME processing. The technique was effectively utilized to prepare homogenous solid solutions of E50LV and ITZ, characterized as having a single glass transition temperature over a wide range of drug loadings. All prepared compositions provided for a high degree of ITZ supersaturation stabilization.

Evaluation of Ceolus™ microcrystalline cellulose grades for the direct compression of enteric-coated pellets

The preparation of multiparticulate tablets by direct compression of functionally coated pellets is technologically challenging. The objective was to investigate the influence of different grades of microcrystalline cellulose (Ceolus™ UF-711, PH-102, PH-200 and KG-802) as fillers on the properties of blends and tablets containing enteric pellets. Celphere™ spheres were drug-layered and then functionally coated with Eudragit(®) L 30 D-55/FS 30D dispersion. Tablets loaded with 50% pellets were prepared using pure or binary blends of microcrystalline cellulose fillers. The influence of the filler on the blend flow, segregation tendency, tablet hardness and enteric release properties were studied using a mixture design, and the optimum filler composition was determined. Rapidly disintegrating tablets, which yielded a drug release of less than 10% after 2 hours in acidic medium, could be successfully prepared. The blend composition had a significant effect on the flowability, but less on the tablet hardness which was influenced by the selection of lubricant. Blends containing celluloses with low bulk densities exhibited a reduced tendency to segregate. Pellet distribution uniformity was further improved when using Ceolus™ UF-711 blended with a high-density grade. As a conclusion, multiparticulate tablets containing enteric pellets with preserved delayed-release properties were successfully prepared using Ceolus™ microcrystalline celluloses as tableting excipients. The optimized filler blend for the direct compression of 50% enteric pellets into tablets contained Ceolus™ UF-711 as main component in combination with Ceolus™ PH-200.

Influence of plasticizer type and level on the properties of Eudragit S100 matrix pellets prepared by hot-melt extrusion

Matrix-type pellets with controlled-release properties may be prepared by hot-melt extrusion applying a single-step, continuous process. However, the manufacture of gastric-resistant pellets is challenging due to the high glass transition temperature of most enteric polymers and an unacceptably high, diffusion-controlled drug release from the matrix during the acidic phase. The objective was to investigate the influence of three plasticizers (triethyl citrate, methylparaben and polyethylene glycol 8000) at two levels (10% or 20%) on the properties of hot-melt extruded Eudragit S100 matrix pellets. Extrusion experiments showed that all plasticizers produced similar reductions in polymer melt viscosity. Differential scanning calorimetry and powder X-ray diffraction demonstrated that the solid state plasticizers were present in the amorphous state. The drug release in acidic medium was influenced by the aqueous solubility of the plasticizer. Less than 10% drug was released after 2 h at pH 1.2 when triethyl citrate or methylparaben was used, independent of the plasticizer level. Drug release at pH 7.4 resulted from polymer dissolution and was not influenced by low levels of plasticizer, but increased significantly at the 20% level. Mechanical testing by diametral compression demonstrated the high tensile strength of the hot-melt extruded pellets that decreased when plasticizers were present.

Dissolution enhancement of a drug exhibiting thermal and acidic decomposition characteristics by fusion processing: a comparative study of hot melt extrusion and KinetiSol dispersing

In this study, hot melt extrusion (HME) and KinetiSol Dispersing (KSD) were utilized to prepare dissolution-enhanced solid dispersions of Roche Research Compound A (ROA), a BCS class II drug. Preformulation characterization studies showed that ROA was chemically unstable at elevated temperatures and acidic pH values. Eudragit L100-55 and AQOAT LF (HPMCAS) were evaluated as carrier polymers. Dispersions were characterized for ROA recovery, crystallinity, homogeneity, and non-sink dissolution. Eudragit L100-55 dispersions prepared by HME required the use of micronized ROA and reduced residence times in order to become substantially amorphous. Compositions containing HPMCAS were also prepared by HME, but an amorphous dispersion could not be obtained. All HME compositions contained ROA-related impurities. KSD was investigated as a method to reduce the decomposition of ROA while rendering compositions amorphous. Substantially amorphous, plasticizer free compositions were processed successfully by KSD with significantly higher ROA recovery values and amorphous character than those achieved by HME. A near-infrared chemical imaging analysis was conducted on the solid dispersions as a measure of homogeneity. A statistical analysis showed similar levels of homogeneity in compositions containing Eudragit L100-55, while differences were observed in those containing HMPCAS. Non-sink dissolution analysis of all compositions showed rapid supersaturation after pH adjustment to approximately two to three times the equilibrium solubility of ROA, which was maintained for at least 24 h. The results of the study demonstrated that KSD is an effective method of forming dissolution-enhanced amorphous solid solutions in cases where HME is not a feasible technique.

Fusion processing of itraconazole solid dispersions by kinetisol dispersing: a comparative study to hot melt extrusion

KinetiSol Dispersing (KSD) is a novel high energy manufacturing process investigated here for the production of pharmaceutical solid dispersions. Solid dispersions of itraconazole (ITZ) and hypromellose were produced by KSD and compared to identical formulations produced by hot melt extrusion (HME). Materials were characterized for solid state properties by modulated differential scanning calorimetry and X-ray diffraction. Dissolution behavior was studied under supersaturated conditions. Oral bioavailability was determined using a Sprague-Dawley rat model. Results showed that KSD was able to produce amorphous solid dispersions in under 15 s while production by HME required over 300 s. Dispersions produced by KSD exhibited single phase solid state behavior indicated by a single glass transition temperature (T(g)) whereas compositions produced by HME exhibited two T(g)s. Increased dissolution rates for compositions manufactured by KSD were also observed compared to HME processed material. Near complete supersaturation was observed for solid dispersions produced by either manufacturing processes. Oral bioavailability from both processes showed enhanced AUC compared to crystalline ITZ. Based on the results presented from this study, KSD was shown to be a viable manufacturing process for the production of pharmaceutical solid dispersions, providing benefits over conventional techniques including: enhanced mixing for improved homogeneity and reduced processing times.

Citric acid as a solid-state plasticizer for Eudragit RS PO

The use of solid-state plasticizers for the hot-melt extrusion of pharmaceutical dosage forms has been shown to be beneficial compared with liquid plasticizers. The purpose of this study was to determine the suitability of citric acid (CA) as a solid plasticizer for the preparation of Eudragit RS PO extended-release matrix systems by a melt extrusion technique. The influence of increasing levels of CA monohydrate (CA MH) or anhydrous CA in the powder blend on the extrusion process parameters (screw speed and motor load) was determined as a function of temperature. The solubility of CA MH in extruded tablets was studied by means of modulated differential scanning calorimetry (MDSC) and powder X-ray diffraction (PXRD). Films were cast from organic solutions to demonstrate the plasticizing effect of CA MH as a change in physico-mechanical properties (tensile strength, elastic modulus and elongation). The CA release from extruded tablets was studied over 12 h. The monohydrate form was found to distinctly facilitate the extrusion of Eudragit RS PO, whereas the addition of anhydrous CA to the polymer powder was less effective. This divergent behaviour in plasticization of Eudragit RS PO was attributed to the higher solubility of the monohy-drate in the acrylic polymer. The plasticizing effect of the CA MH reached a plateau at 25% during hot-melt extrusion, which coincided with the solubility limit of the organic acid in the polymer as shown by MDSC and PXRD results. The CA MH increased the flexibility of Eudragit RS PO films, as demonstrated by a decrease in tensile strength and elastic modulus and an increase in elongation as a function of CA MH concentration. The dissolution of CA from the matrix tablets followed an extended-release profile, with CA MH exhibiting a faster dissolution rate than the anhydrous form. In conclusion, CA MH was found to be an effective plasticizer for Eudragit RS PO that facilitates the production of controlled-release matrix systems by hot-melt extrusion.

Influence of an acrylic polymer blend on the physical stability of film-coated theophylline pellets

The purpose of this study was to investigate the physical stability of a coating system consisting of a blend of two sustained release acrylic polymers and its influence on the drug release rate of theophylline from coated pellets. The properties of both free films and theophylline pellets coated with the polymer blend were investigated, and the miscibility was determined via differential scanning calorimetry. Eudragit RS 30 D was plasticized by the addition of Eudragit NE 30 D, and the predicted glass transition temperature (T(g)) of the blend was similar to the experimental values. Sprayed films composed of a blend of Eudragit NE 30 D/Eudragit RS 30 D (1:1) showed a water vapor permeability six times greater than films containing only Eudragit NE 30 D. The presence of quaternary ammonium functional groups from the RS 30 D polymer increased the swellability of the films. The films prepared from the blend exhibited stable permeability values when stored for 1 month at both 25 degrees C and 40 degrees C, while the films which were composed of only Eudragit NE 30 D showed a statistically significant decrease in this parameter when stored under the same conditions. Eudragit NE 30 D/Eudragit RS 30 D (1:1)-sprayed films decreased in elongation from 180% to 40% after storage at 40 degrees C for 1 month, while those stored at 25 degrees C showed no change in elongation. In coated pellets, the addition of Eudragit RS 30 D to the Eudragit NE 30 D increased the theophylline release rate, and the pellets were stable when stored at 25 degrees C for a period of up to 3 months due to maintenance of the physico-mechanical properties of the film. Pellets stored at 40 degrees C exhibited a decrease in drug release rate over time as a result of changes in film physico-mechanical properties which were attributed to further coalescence and densification of the polymer. When the storage temperature was above the T(g) of the composite, instabilities in both drug release rate and physical properties were evident. Stabilization in drug release rate from coated pellets could be correlated with the physico-mechanical stability of the film formulation when stored at temperatures below the T(g) of the polymer.

Amorphous compositions using concentration enhancing polymers for improved bioavailability of itraconazole

Amorphous engineered particle compositions of itraconazole (ITZ) and potential concentration enhancing polymers, cellulose acetate phthalate (CAP) and polyvinyl acetate phthalate (PVAP), were produced by ultra-rapid freezing to investigate the effect of these polymers on the bioavailability of ITZ solid dispersions. X-ray diffraction analyses of engineered particle compositions were shown to be amorphous. Modulated differential scanning calorimetry demonstrated that ITZ:CAP engineered particle compositions exhibited a strong correlation with the Gordon-Taylor relationship while ITZ:PVAP formulations exhibited positive deviations from predicted values attributed to hydrogen bonding interactions between the drug and polymer. Energy dispersive spectroscopy mapping demonstrated that the drug was homogenously distributed within all compositions, supporting the miscibility of the drug with the polymers. Scanning electron microscopy imaging of the particles demonstrated that the material existed in two general forms, discrete particles of approximately 5 microm and larger aggregates in excess of 30 microm, with engineered particle compositions having approximately 15 times higher measured specific surfaces areas compared to micronized ITZ. In vitro supersaturated dissolution results showed that all compositions provided significantly lower levels of supersaturation in acidic media and greater extents of supersaturation in neutral media compared to Sporanox pellets. ITZ: CAP formulations provided the greatest degree and extent of supersaturation in neutral media. Dissolution data were fitted to an exponential relationship based on a simplified model of particle growth, allowing for the determination of drug half-life in solution for evaluation of stabilization behavior. 1:2 ITZ:CAP showed superior in vitro performance compared to all other engineered particle compositions and was selected for in vivo testing. Although not fully elucidated, data indicated that the stabilization mechanism was due to interactions between the drug and polymer, primarily attributed to steric hindrance resulting from the molecular weight of the polymer chain and chemical composition of the polymer backbone relative to position of hydrogen bonding sites. In vivo testing conducted in Sprague-Dawley rats (n = 6) demonstrated a significant improvement in oral bioavailability from the 1:2 ITZ:CAP (AUC = 4,516 +/- 1,949 ng x h/mL) compared to the Sporanox pellets (AUC = 2,132 +/- 1,273 ng x h/mL) (p < or = 0.05). Additionally, the more rapid onset of action indicated superior targeting of the upper small intestines, and the prolonged half-life suggested the utility of CAP to maintain supersaturated concentrations, in vivo. These results demonstrated that amorphous compositions of ITZ and enteric concentration enhancing polymers provided improved bioavailability due to enhanced intestinal targeting and increased durations of supersaturation.

Physicochemical properties of film-coated melt-extruded pellets

The purpose of this study was to investigate the physicochemical properties of poly(ethylene oxide) (PEO) and guaifenesin containing beads prepared by a melt-extrusion process and film-coated with a methacrylic acid copolymer. Solubility parameter calculations, thermal gravimetric analysis (TGA), scanning electron microscopy (SEM), modulated differential scanning calorimetry (MDSC), X-ray powder diffraction (XRPD) and high performance liquid chromatography (HPLC) were used to determine drug/polymer miscibility and/or the thermal processibility of the systems. Powder blends of guaifenesin, PEO and functional excipients were processed using a melt-extrusion and spheronization technique and then film-coated in a fluidized bed apparatus. Solubility parameter calculations were used to predict miscibility between PEO and guaifenesin, and miscibility was confirmed by SEM and observation of a single melting point for extruded drug/polymer blends during MDSC investigations. The drug was stable following melt-extrusion as determined by TGA and HPLC; however, drug release rate from pellets decreased upon storage in sealed HDPE containers with silica desiccants at 40 degrees C/75% RH. The weight loss on drying, porosity and tortuosity determinations were not influenced by storage. Recrystallization of guaifenesin and PEO was confirmed by SEM and XRPD. Additionally, the pellets exhibited a change in adhesion behaviour during dissolution testing. The addition of ethylcellulose to the extruded powder blend decreased and stabilized the drug release rate from the thermally processed pellets. The current study also demonstrated film-coating to be an efficient process for providing melt-extruded beads with pH-dependent drug release properties that were stable upon storage at accelerated conditions.

Compression of Controlled-Release Pellets Produced by a Hot-Melt Extrusion and Spheronization Process

The purpose of this study was to investigate the physicomechanical and dissolution properties of tablets containing controlled-release pellets prepared by a hot-melt extrusion and spheronization process. A powder blend of anhydrous theophylline, Eudragit Preparation 4135 F, and functional excipients was melt-extruded, pelletized, and then spheronized. The pellets were compressed into tablets using forces of 5, 10, 15, and 20 kN. Tablet diluents included microcrystalline cellulose, a mixture of spray-dried lactose and microcrystalline cellulose, modified food starch, and soy polysaccharides. The effective porosity of the compressed pellets was measured using mercury porosimetry and helium pycnometry, while the surface area was determined using Brunauer, Emmett, and Teller (BET) analysis. The disintegration time, hardness, and friability of compacts were determined. Drug release studies were performed according to USP 27 Apparatus 3 guidelines in 250 mL of medium (pH 1.0, 3.0, 5.0, 6.8, and 7.4) 37 degrees C and 20 dpm. Samples were analyzed by high pressure-liquid chromatography (HPLC). Effective porosity and surface area determinations of the melt-extruded pellets were not influenced by compression. The percent of theophylline released from rapidly disintegrating tablets was not affected by compression force or excipient selection, but tablets with prolonged disintegration times exhibited delayed drug release in acidic media. However, dissolution profiles of uncompressed pellets and all compacts were identical after transition from 0.1 N HCl to media increasing in pH from 3.0 to 7.4. Furthermore, pellet to filler excipient ratio and filler excipient selection did not influence the rate of drug release from compacts.