Characterization of nifedipine solid dispersions

Formation and Physico-Chemical Evaluation of Nifedipine-hydroxypropyl-β-cyclodextrin and Nifedipine-methyl-β-cyclodextrin: The Development of Orodispersible Tablets

The novelty in this study is the development of new orodispersible tablets containing nifedipine (NIF) as the active ingredient. Initially, the formation of inclusion complexes between nifedipine and two derivatives of beta-cyclodextrin, namely, hydroxypropyl-β-cyclodextrin (HP-β-CD) and methyl-β-cyclodextrin (Me-β-CD), was established. Inclusion complexes of nifedipine were prepared by different procedures: kneading, coprecipitation and lyophilization methods, using a 1:1 molar ratio among the drug and cyclodextrin compounds. A physical mixture was also developed for comparison, with the same molar ratio. The physicochemical and structural properties of these obtained complexes were subsequently analysed using Fourier-transform infrared spectroscopy, scanning electron microscopy, differential scanning calorimetry and X-ray diffraction techniques. The lyophilization method of preparation leads to obtaining the complete inclusion of nifedipine in the used cyclodextrin cavity, for both the derivative cyclodextrins. After that, preformulation studies and manufacturing of orodispersible tablets containing NIF-HP-β-CD and NIF-Me-β-CD, respectively, inclusion complexes were advanced. The obtained findings show that only F3 (which contains NIF-HP-β-CD) and F6 (which contains NIF-Me-β-CD) have a suitable flowability for the direct compression materials.

Hot-melt extruded hydroxypropyl methylcellulose acetate succinate based amorphous solid dispersions: Impact of polymeric combinations on supersaturation kinetics and dissolution performance

Nucleation inhibition and maintenance of drug supersaturation over a prolonged period are desirable for improving oral absorption of amorphous solid dispersions. The present study investigates the impact of binary and ternary amorphous solid dispersions on the supersaturation kinetics of nifedipine using the polymers hydroxypropylmethylcellulose acetate succinate (HPMCAS) LG, and HG, Eudragit® RSPO, Eudragit® FS100, Kollidon® VA64 and Plasdone™ K-29/32. The amorphous solubility, nucleation induction time, and particle size analysis of nifedipine in a supersaturated solution were performed with and without the presence of polymers, alone or in combination. The HPMCAS-HG and HPMCAS-HG + LG combinations showed the highest nifedipine amorphous solubility of 169.47, 149.151 µg/mL, respectively and delay in nucleation induction time up to 120 min compared to other polymeric combinations. The solid dispersions prepared via hot melt extrusion showed the transformation of crystalline nifedipine to amorphous form. The in-vitro non-sink dissolution study revealed that although the binary nifedipine/HPMCAS-LG system had shown the greater supersaturation concentration of 66.1 µg/mL but could not maintain a supersaturation level up to 360 min. A synergistic effect emerged for ternary nifedipine/HPMCAS-LG/HPMCAS-HG, and nifedipine/HPMCAS-LG/Eudragit®FS100 systems maintained the supersaturation level with enhanced dissolution performance, demonstrating the potential of polymeric combinations for improved amorphous solid dispersion performance.

Design and characterisation of an amorphous formulation of nifedipine for the treatment of autonomic dysreflexia

OBJECTIVES

Current treatment for autonomic dysreflexia (AD) involves rupturing a liquid-filled soft capsule of nifedipine to aid rapid drug release and absorption, however, this application is not covered under the manufacturer's license. The objective of the current work was to design a rapidly dissolving solid dosage formulation for the treatment of AD as an alternative to the off-license "bite and swallow" use of currently available commercial products.

METHODS

Amorphous solid dispersions (ASDs) of nifedipine were prepared by spray-drying using three different polymers: hydroxypropyl methyl cellulose (HPMC), polyvinyl pyrrolidone (PVP) and polyvinyl caprolactam-polyvinyl acetate-polyethylene glycol (Soluplus), at a 15% w/w drug loading and were formulated and compressed into tablets. Dissolution testing was performed in the paddle dissolution apparatus using either a monophasic or biphasic medium.

KEY FINDINGS

The PVP-nifedipine ASD tablets exhibited rapid dissolution, with 35% of the total nifedipine dose dissolving within 15 min in the monophasic dissolution medium. The HPMC-nifedipine ASD exhibited a very slow dissolution, while the Solupus-nifedipine system exhibited no nifedipine release over 120 min. When tested in the biphasic dissolution medium, the PVP-nifedipine ASD tablets exhibited a release profile comparable to that of the pre-split/ruptured nifedipine soft capsule product.

CONCLUSIONS

This study demonstrates that a nifedipine-PVP ASD is a promising formulation strategy in the treatment of AD.

Hypromellose acetate succinate based amorphous solid dispersions via hot melt extrusion: Effect of drug physicochemical properties

In this study, the impact of drug and hydroxypropyl methylcellulose acetate succinate (HPMCAS) grades physicochemical properties on extrusion process, dissolution and stability of the hot melt extruded amorphous solid dispersions (ASDs) of nifedipine and efavirenz was investigated. Incorporation of drugs affected the extrusion temperature required for solid dispersion preparation. Differential scanning calorimetry and powder X-ray diffraction studies confirmed the amorphous conversion of the drugs in the prepared formulations. The amorphous nature of ASDs was unchanged after 3 months of stability testing at 40 °C and 75% relative humidity. The dissolution efficiency of the ASDs was dependent on the log P of the drug. The inhibitory effect of HPMCAS on drug precipitation was dependent on the hydrophobic interactions between drug and polymer, polymer grade, and dose of the drug. The dissolution efficiency and dissolution rate of the ASDs were dependent on the log P of the drug and solubility and hydrophilicity of the polymer grade respectively. The inhibitory effect of HPMCAS on drug precipitation was dependent on the hydrophobic interactions between drug and polymer, polymer grade, and the dissolution dose of the drug.

Effects of spray drying process parameters on the solubility behavior and physical stability of solid dispersions prepared using a laboratory-scale spray dryer

PURPOSE

The purpose of this study is to determine the process parameters of the laboratory-scale spray dryer affecting the solubility behavior and physical stability of solid dispersions.

METHODS

Solid dispersions of the model drug (nilvadipine or nifedipine) and hypromellose (HPMC) (w/w: 1/1) were prepared using the laboratory-scale spray dryer. As process parameters, nitrogen flow rate, sample concentration and pump speed were investigated. The samples were characterized by dissolution tests, powder X-ray diffraction (PXRD), differential scanning calorimetry (DSC), scanning electron microscope (SEM), and nanoscale thermal analysis (Nano-TA). The physical stability was monitored after 7 months storage at 25°C.

RESULTS

Solubility behavior and physical stability were improved by setting the low nitrogen flow rate and high sample concentration. DSC showed that the physical state depends on the spray drying conditions, whereas, every sample showed the similar morphology from SEM results. The difference of solubility behavior and physical stability were found to come from the microstructural phase separation of the spray dried particles using a novel analytical technique (Nano-TA).

CONCLUSIONS

This study demonstrated that nitrogen flow rate and sample concentration should be the critical parameters for the enhancements of the solubility and physical stability of solid dispersions.

Selection of excipient, solvent and packaging to optimize the performance of spray-dried formulations: case example fenofibrate

CONTEXT

Along with other options, solid dispersions prepared by spray drying offer the possibility of formulating poorly soluble drugs in a rapidly dissolving format. As a wide range of potential excipients and solvents is available for spray drying, it is usually necessary to carry out a comprehensive array of studies to arrive at an optimal formulation.

OBJECTIVE

To study the influence of formulation parameters such as co-sprayed excipients, solvents and packaging on the manufacture, in vitro performance and stability of spray-dried oral drug products using fenofibrate as a model drug.

MATERIALS AND METHODS

Solid dispersions of fenofibrate with different amorphous polymers were manufactured from two solvent systems by spray drying. These were characterized in terms of physicochemical properties, crystalline content and dissolution behavior in biorelevant media upon production and after storage in two packaging systems (Glass and Activ-Vials(™)).

RESULTS AND DISCUSSION

Spray drying the same formulation from two different solvents led to different physicochemical properties, dissolution behavior and long-term stability. The dissolution behavior and long-term stability also varied significantly among excipients. The viscosity of the polymer and the packaging material proved to be important to the long-term stability.

CONCLUSION

For spray-dried products containing fenofibrate, the excipients were ranked according to dissolution and stability performance as follows: PVP derivatives >> HPMC 2910/15, HPMCAS-MF, HP-β-CD >> PVP:PVA 2:8. EtOH 96% proved superior to acetone/water for spray drying with polymers. The results were used to propose a general approach to developing spray-dried formulations of poorly soluble drugs.

Improvement in solubility of poor water-soluble drugs by solid dispersion

This article is intended to combine recent literature on solid dispersion technology for solubility enhancement with special emphasis on mechanism responsible for the same by solid dispersion, various preparation methods, and evaluation parameters. Solubility behavior is the most challenging aspect for various new chemical entities as 60% of the new potential products possess solubility problems. This is the biggest reason for new drug molecules not reaching to the market or not reaches to full potential. There are various techniques to enhance the drug solubility such as particle size reduction, nanosuspension, use of surfactants, salt formation, solid dispersion, etc. From this article it may be concluded that solid dispersion is an important approach for improvement of bioavailability of poor water-soluble drugs.

Improvement of pharmacological values of the nifedipine by means of mechanochemical complexation with glycyrrhizic acid

A new water-soluble form of the calcium blocker nifedipine (NF) with glycyrrhizic acid (GA) (with molecular ratio 1:4) has been obtained by mechanochemical synthesis. Its pharmacological advantages in comparison with nifedipine were determined. An effective dose of nifedipine in complex reduced to 10 times as compared to its therapeutic dose while high antihypertensive activity preservation and pleiotropic antiarhythmic activity enhancement. This new antihypertensive and antiarhythmic agent (complex of NF:GA = 1:4) is chemically stable and safe for parenteral administration.

Evaluation of griseofulvin binary and ternary solid dispersions with HPMCAS

The stability and dissolution properties of griseofulvin binary and ternary solid dispersions were evaluated. Solid dispersions of griseofulvin and hydroxypropyl methylcellulose acetate succinate (HPMCAS) were prepared using the spray drying method. A third polymer, poly[N-(2-hydroxypropyl)methacrylate] (PHPMA), was incorporated to investigate its effect on the interaction of griseofulvin with HPMCAS. In this case, HPMCAS can form H bonds with griseofulvin directly; the addition of PHPMA to the solid dispersion may enhance the stability of the amorphous griseofulvin due to greater interaction with griseofulvin. The X-ray powder diffraction results showed that griseofulvin (binary and ternary solid dispersions) remained amorphous for more than 19 months stored at 85% RH compared with the spray-dried griseofulvin which crystallized totally within 24 h at ambient conditions. The Fourier transform infrared scan showed that griseofulvin carbonyl group formed hydrogen bonds with the hydroxyl group in the HPMCAS, which could explain the extended stability of the drug. Further broadening in the peak could be seen when PHPMA was added to the solid dispersion, which indicates stronger interaction. The glass transition temperatures increased in the ternary solid dispersions regardless of HPMCAS grade. The dissolution rate of the drug in the solid dispersion (both binary and ternary) has significantly increased when compared with the dissolution profile of the spray-dried griseofulvin. These results reveal significant stability of the amorphous form due to the hydrogen bond formation with the polymer. The addition of the third polymer improved the stability but had a minor impact on dissolution.

Solid State and Dissolution Rate Characterization of Co-Ground Mixtures of Nifedipine and Hydrophilic Carriers

Co-ground powders of the poorly water-soluble drug nifedipine and a hydrophilic carrier, [partially hydrolyzed gelatin (PHG), polyvinylpyrrolidone (PVP), sodium dodecyl sulfate (SDS), hydroxypropyl methylcellulose (HPMC), polyethylene glycol (PEG), urea or Pluronic F108] were prepared in order to improve the dissolution rate of nifedipine. The effects of type of grinding equipment, grinding time, and type of hydrophilic carrier on the crystallinity of nifedipine (x-ray diffraction and differential scanning calorimetry) on the interaction between drug and carriers (differential scanning calorimetry), on the particle size and appearance (scanning electron microscopy), on the wettability (contact angle measurements), and on the drug release were investigated. Grinding nifedipine together with these carriers improved the dissolution rate. PHG-ground mixtures resulted in the fastest dissolution rate followed by PVP, SDS, HPMC, Pluronic, urea, and PEG. This effect was not only due to particle size reduction, which increased in the order PHG<PEG=SDS<Pluronic<drug<urea<HPMC<PVP, but also resulted from the ability of some carriers (PVP and HPMC) to prevent reaggregation of the finely divided drug particles. PVP, HPMC, and PHG formed a powder with amorphous drug. The carriers improved the wettability of the ground products in the order HPMC<drug<urea<PVP<SDS<PHG<PEG<Pluronic. Differential scanning calorimetry (DSC) measurements gave valuable information about the nature of drug crystallinity and the interactions with the carriers within the ground mixtures.

Characterization and drug release investigation of amorphous drug-hydroxypropyl methylcellulose composites made via supercritical carbon dioxide assisted impregnation

Hydroxypropylmethyl cellulose (HPMC)-indomethacin (4:1, w/w) drug composites (DCs) were prepared via supercritical carbon dioxide (sc-CO(2)) assisted impregnation. The effect of processing temperature (at fixed pressures) on the physical and other properties of the resulting HPMC-indomethacin DCs was investigated using a range of analytical techniques, including differential scanning calorimetry (DSC), Fourier transform infrared (FTIR) spectroscopy, Raman spectroscopy, and powder X-ray diffraction (XRD) methods. The data suggest that for a 4:1 (w/w) HPMC-indomethacin ratio prepared at 130 degrees C (17.2 MPa), the indomethacin exists entirely in an amorphous dispersion within the polymer matrix. The primary interaction between HPMC and indomethacin appears to be hydrogen bonding between the carboxylic acid carbonyl group of indomethacin and hydroxyl group of HPMC. The initial (first 15 min) and overall drug release behavior within a 5h timeframe for the HPMC-indomethacin DCs, was analyzed. For the HPMC-indomethacin drug composite processed at 130 degrees C/17.2 MPa, drug release behavior obeyed a n-power law (n=0.54).

Investigations on factors affecting chitosan for dissolution enhancement of oxcarbazepine by spray dried microcrystal formulation with an experimental design approach

In the present work effect of chitosan on microcrystal formulation for dissolution enhancement of oxcarbazepine using controlled crystallization technique coupled with spray drying was explored. The work was extended for exploration of simplified approach for stable particle size reduction. The study was performed with an experimental design approach i. e. a fractional factorial design of resolution 5 (with all 2 factor interaction) for the screening of predefined independent variables drug concentration, chitosan concentration, feed rate, inlet temperature and percent aspiration for spray drying. Whereas percent drug dissolved, wettability time, flowability in terms of angle of repose and particle size were designated as response variables. Resultant models were analyzed using multiple linear regression analysis, which generated equation to plot response surface curves along with desirability function. Results showed that chitosan concentration had significant effect on dissolution enhancement of oxcarbazepine at a level of 2% w/v. Increase in drug concentration showed decreased dissolution rate however on particle size it did not show statistically significant effect. Topographical characterization was carried out by SEM which showed that feed rate, percent aspiration and inlet temperature had significant effect on particle morphology. For deriving optimized formulation results were analyzed using desirability function for the maximum percent drug dissolved and least drug polymer matrix particle size. DSC studies showed that drug was molecularly associated with chitosan matrix or particles.

Polymer-mediated disruption of drug crystallinity

Ibuprofen (IB), a BCS Class II compound, is a highly crystalline substance with poor solubility properties. Here we report on the disruption of this crystalline structure upon intimate contact with the polymeric carrier cross-linked polyvinylpyrrolidone (PVP-CL) facilitated by low energy simple mixing. Whilst strong molecular interactions between APIs and carriers within delivery systems would be expected on melting or through solvent depositions, this is not the case with less energetic mixing. Simple mixing of the two compounds resulted in a significant decrease in the differential scanning calorimetry (DSC) melting enthalpy for IB, indicating that approximately 30% of the crystalline content was disordered. This structural change was confirmed by broadening and intensity diminution of characteristic IB X-ray powder diffractometry (PXRD) peaks. Unexpectedly, the crystalline content of the drug continued to decrease upon storage under ambient conditions. The molecular environment of the mixture was further investigated using Fourier transform infrared (FT-IR) and Fourier transform Raman (FT-Raman) spectroscopy. These data suggest that the primary interaction between these components of the physical mix is hydrogen bonding, with a secondary mechanism involving electrostatic/hydrophobic interactions through the IB benzene ring. Such interactions and subsequent loss of crystallinity could confer a dissolution rate advantage for IB.

Sudden Rise of Crystal Growth Rate of Nifedipine near Tg without and with Polyvinylpyrrolidone

The crystal growth of nifedipine in the beta polymorph has been measured from T(g) + 50 to T(g) - 20 K, where T(g) = 315 K is the glass transition temperature. A sudden 10-fold rise of growth rate was observed as the temperature decreased from above to below T(g) accompanied by a change of growth morphology. This is the same phenomenon reported by Oguni and coworkers [Hikima T, Adachi Y, Hanaya M, Oguni M. 1995. Phys Rev B 52:3900-3908] for other compounds of lower T(g). The phenomenon persisted in the presence of 1% polyvinylpyrrolidone (PVP). The presence of 1% or 2% PVP had little effect on the growth rate near T(g) + 50 K, but reduced the growth rate by 100-fold at T(g) + 9 K. These kinetic features are relevant to predicting the stability of amorphous drugs.

Characterization of the molecular distribution of drugs in glassy solid dispersions at the nano-meter scale, using differential scanning calorimetry and gravimetric water vapour sorption techniques

The molecular distribution in fully amorphous solid dispersions consisting of poly(vinylpyrrolidone) (PVP)-diazepam and inulin-diazepam was studied. One glass transition temperature (T(g)), as determined by temperature modulated differential scanning calorimetry (TMDSC), was observed in PVP-diazepam solid dispersions prepared by fusion for all drug loads tested (10-80 wt.%). The T(g) of these solid dispersions gradually changed with composition and decreased from 177 degrees C for pure PVP to 46 degrees C for diazepam. These observations indicate that diazepam was dispersed in PVP on a molecular level. However, in PVP-diazepam solid dispersions prepared by freeze drying, two T(g)'s were observed for drug loads above 35 wt.% indicating phase separation. One T(g) indicated the presence of amorphous diazepam clusters, the other T(g) was attributed to a PVP-rich phase in which diazepam was dispersed on a molecular level. With both the value of the latter T(g) and the DeltaC(p) of the diazepam glass transition the concentrations of molecular dispersed diazepam could be calculated (27-35 wt.%). Both methods gave similar results. Water vapour sorption (DVS) experiments revealed that the PVP-matrix was hydrophobised by the incorporated diazepam. TMDSC and DVS results were used to estimate the size of diazepam clusters in freeze dried PVP-diazepam solid dispersions, which appeared to be in the nano-meter range. The inulin-diazepam solid dispersions prepared by spray freeze drying showed one T(g) for drug loads up to 35 wt.% indicating homogeneous distribution on a molecular level. However, this T(g) was independent of the drug load, which is unexpected because diazepam has a lower T(g) than inulin (46 and 155 degrees C, respectively). For higher drug loads, a T(g) of diazepam as well as a T(g) of the inulin-rich phase was observed, indicating the formation of amorphous diazepam clusters. From the DeltaC(p) of the diazepam glass transition the amount of molecularly dispersed diazepam was calculated (12-27 wt.%). In contrast to the PVP-diazepam solid dispersions, DVS-experiments revealed that inulin was not hydrophobised by diazepam. Consequently, the size of diazepam clusters could not be estimated. It was concluded that TMDSC enables characterization and quantification of the molecular distribution in amorphous solid dispersions. When the hygroscopicity of the carrier is reduced by the drug, DVS in combination with TMDSC can be used to estimate the size of amorphous drug clusters.

Preparation and characterization of nanocrystals for solubility and dissolution rate enhancement of nifedipine

Poorly water-soluble drugs such as nifedipine (NIF) (approximately 20 microg/ml) offer challenging problems in drug formulation as poor solubility is generally associated to poor dissolution characteristics and thus to poor oral bioavailability. In order to enhance these characteristics, preparation of nifedipine nanoparticles has been achieved using high pressure homogenization. The homogenization procedure has first been optimized in regard to particle size and size distribution. Nanoparticles were characterized in terms of size, morphology and redispersion characteristics following water-removal. Saturation solubility and dissolution characteristics were investigated and compared to the un-milled commercial NIF to verify the theoretical hypothesis on the benefit of increased surface area. Crystalline state evaluation before and following particle size reduction was also conducted through differential scanning calorimetry (DSC) and powder X-ray diffraction (PXRD) to denote eventual transformation to amorphous state during the homogenization process. Through this study, it has been shown that initial crystalline state is maintained following particle size reduction and that the dissolution characteristics of nifedipine nanoparticles were significantly increased in regards to the commercial product. The method being simple and easily scaled up, this approach should have a general applicability to many poorly water-soluble drug entities.

Physical properties and dissolution behaviour of nifedipine/mannitol solid dispersions prepared by hot melt method

Solid dispersions of nifedipine (NIF) with mannitol in preparations containing 10 and 50% (w/w) of drug were manufactured by the hot melt method. Physical properties and the dissolution behaviour of binary systems as physical mixtures and solid dispersions were investigated. In all samples, the crystal structure of NIF was confirmed using differential scanning calorimetry (DSC) and scanning electron microscopy (SEM). Fourier transform infrared spectroscopy (FTIR) revealed, there was no interaction between drug and carrier, however, FTIR spectra indicated formation of thermodynamically less stable polymorph of mannitol. The dissolution rate of NIF from solid dispersions was markedly enhanced, the effect being stronger at higher drug loading (50%, w/w, NIF). The dissolution rate enhancement was attributed to improved wetting of NIF crystals due to mannitol particles, attached on the surface, as inspected by means of SEM. Thermal stability of NIF, mannitol and two other potential carbohydrate carriers (lactose and saccharose) during the hot melt procedure was investigated using 1H NMR. NIF was found to be thermically stable under conditions applied. As expected, among carriers only mannitol demonstrated suitable resistance to high temperature used in experiments.

Establishment of new preparation method for solid dispersion formulation of tacrolimus

The aim of this study was to establish a new preparation method for solid dispersion formulation (SDF) of tacrolimus, a poorly water-soluble drug, without dichloromethane, because no use of dichloromethane is recommended by ICH harmonized tripartite guideline. To select the appropriate carrier, three different SDFs with polyethylene glycol 6000 (PEG 6000), polyvinylpyrrolidone (PVP) and hydroxypropylmethylcellulose (HPMC) were prepared by the conventional solvent method, in which tacrolimus and the carrier were completely dissolved in the mixture of dichloromethane and ethanol. Powder X-ray diffraction (XRD) and differential scanning calorimetry (DSC) patterns indicated that tacrolimus exists in an amorphous state in all three SDFs. The supersaturated dissolution profiles of tacrolimus were observed in all SDFs, and the highest level of supersaturation for tacrolimus was obtained and maintained for 24h from SDF with HPMC. On the other hand, the supersaturated level from SDF with PEG 6000 or PVP decreased rapidly. The in vivo oral absorption study in dogs showed that bioavailability of tacrolimus from SDF with HPMC was remarkably improved compared with the crystalline powder. It was clarified that HPMC is the most appropriate carrier for SDF of tacrolimus. Then, SDF of tacrolimus was prepared by the new method, which allows us to make SDF of tacrolimus by swelling HPMC with ethanol, in which tacrolimus was completely dissolved. This new method does not need dichloromethane. The physicochemical properties of SDF with HPMC prepared by the new method were the same as those of SDF prepared by the conventional solvent method. Furthermore, SDF with HPMC prepared by the new method was still stable after stored at 40 degrees C for 3 months. The pharmacokinetic parameters after oral administration in monkeys showed no significant difference (P>0.01) between SDFs with HPMC prepared by the two methods. In conclusion, we have established the new preparation method for SDF of tacrolimus with HPMC and the new method makes it possible to prepare SDF of tacroliumus without dichloromethane.

Incorporation of Lipophilic Drugs in Sugar Glasses by Lyophilization using a Mixture of Water and Tertiary Butyl Alcohol as Solvent

In this study, a new and robust method was evaluated to prepare physically stable solid dispersions. Trehalose, sucrose, and two inulins having different chain lengths were used as carrier. Diazepam, nifedipine, Delta(9)-tetrahydrocannabinol, and cyclosporine A were used as model drugs. The sugar was dissolved in water and the drug in tertiary butyl alcohol (TBA). The two solutions were mixed in a 4/6 TBA/water volume ratio and subsequently freeze dried. Diazepam could be incorporated at drug loads up to 63% w/w. DSC measurements showed that, except in some sucrose dispersions, 97-100% of the diazepam was amorphous. In sucrose dispersions with high drug loads, about 10% of the diazepam had crystallised. After 60 days of exposure at 20 degrees C and 45% relative humidity (RH), diazepam remained fully amorphous in inulin dispersions, whereas in trehalose and sucrose crystallization of diazepam occurred. The excellent physical stability of inulin containing solid dispersions can be attributed to the high glass transition temperature (T(g)) of inulin. For the other drugs similar results were obtained. The residual amount of the low toxic TBA was only 0.1-0.5% w/w after freeze drying and exposure to 45% RH and 20 degrees C. Therefore, residual TBA will not cause any toxicity problems. This study provides a versatile technique, to produce solid dispersions. Inulin glasses are preferred because they provide an excellent physical stability of the incorporated amorphous lipophilic drugs.