Rapidly disintegrating tablets prepared by the wet compression method: mechanism and optimization

Design of easily swallowable xerogel pill with enough physical strength through hardening-process under heating and humidification

The xerogel pill has been developed as a novel dosage form with dose-adjusting and swallow-assisting functions by using drop freeze-drying (DFD) technique. It was double-structured small sphere composed of an inner drug core and an outer dried-gel layer, however, had problem of insufficient physical strength. In this study, it was attempted to use dextrin (DEX), one of oligosaccharides, to strengthen the xerogel pill. DEX was co-dissolved in the dropping fluid in the DFD process and co-loaded in the conventional pill, which was mainly composed of mannitol (MNT) as a filler, to prepare the rigid body. DEX-loaded pill could be successfully prepared with high recovery (>90 %) by optimizing the ratio of DEX and MNT. Further, the representative pills with and without DEX (P-DEX and P-MNT, respectively) were hardening-processed under humidification. The physical strength of P-DEX pill was significantly increased when humidified under severe condition, resulting in enough hardness (>5N) and friability (<1.0 %). Processed P-DEX was found to have dense structure covered with a thick outer shell, which would be formed by interparticle bridge of DEX. It was also found that processed P-DEX pill suppressed initial drug dissolution significantly and exhibited sustained dissolution behavior, suggesting the potential function of bitter taste masking. Processed P-DEX pill had excellent sliding behavior with low friction forces as a result of lubricant effect of xanthan gum (XG) surrounding the pills. Furthermore, the sliding test also suggested that processed P-DEX pill had hard candy-like texture, in contrast unprocessed P-DEX pill had orally disintegrating (OD) tablet-like texture. Various xerogel pills with such different swallowing texture would have a potential to accommodate the children's preferences when taking medication.

Effect of post-compaction heating on characteristics of microcrystalline cellulose compacts

Compacts of microcrystalline cellulose were prepared at applied compression pressures of 21, 32, 43, 53, and 64 MPa. Compacts were subjected to elevated temperatures of 125°C, 150°C, and 175°C according to a 5-min heating program. The effect of these thermal treatments on compact volumes, densities, porosities, tensile strengths, and weight loss was determined. There was no change in the volumes of the compacts due to thermal treatments in most of the conditions. However, the densities of the compacts decreased while the porosities increased as a consequence of weight loss. Moreover, there was no difference (p > 0.05) between the tensile strengths of the compacts without heat treatment and those subjected to heat treatment in most of the conditions. This was indicative of the preservation of the magnitude of the interparticulate bonds in the compacts. Weight loss of the compacts was affected by the heat treatment temperature and their porosities.

Controlled-Release Fine Particles Prepared by Melt Adsorption for Orally Disintegrating Tablets

Melt adsorption is a manufacturing method that offers precise control of particle size distribution of granules and circumvents the disadvantages of conventional melt granulation. However, drug release from particles adsorbed with hydrophobic materials has not been fully investigated, and there are missing details as to whether particles manufactured by this technique can be applied to orally disintegrating tablets (ODT). In this report, we aimed to optimize process parameters and formulation to manufacture ODT containing melt adsorption-particles with the specific characteristic of sustained release. Melt adsorption particles containing Neusilin US2 as the adsorbent were prepared by using various waxes to determine the most suitable material for controlled release formulation. Glycerol fatty acid ester (Poem TR-FB: TR-FB) was the optimal wax examined because of its drug release pattern and tabletability. We then optimized manufacturing conditions by examining granulation time, disintegrant amount per tablet and compression force on the tablet for ODT that meet the criteria of controlled drug release, tensile strength and disintegration of the tablet. Multiple regression analysis revealed the effect of process parameters on tablet properties and drug release with increasing the granulation time affording sustained release of the drug. The analysis also showed that a high compression force crushed the granules coated by TR-FB, which impaired sustained drug release. From the regression model the optimal manufacturing conditions were determined, and the tablet prepared under these conditions concurred with the predicted values and met all criteria. This new technique should contribute to the development of ODT to improve medication adherence.

Microwave-Assisted Development of Orally Disintegrating Tablets by Direct Compression

Orally disintegrating tablets (ODTs) are challenged by the need for simple technology to ensure good mechanical strength coupled with rapid disintegration. The objective of this work was to evaluate microwave-assisted development of ODTs based on simple direct compression tableting technology. Placebo ODTs comprising directly compressible mannitol and lactose as diluents, super disintegrants, and lubricants were prepared by direct compression followed by exposure to >97% relative humidity and then microwave irradiation for 5 min at 490 W. Placebo ODTs with hardness (>5 kg/cm²) and disintegration time (<60 s) were optimized. Palatable ODTs of Lamotrigine (LMG), which exhibited rapid dissolution of LMG, were then developed. The stability of LMG to microwave irradiation (MWI) was confirmed. Solubilization was achieved by complexation with beta-cyclodextrin (β-CD). LMG ODTs with optimal hardness and disintegration time (DT) were optimized by a 2³ factorial design using Design Expert software. Taste masking using sweeteners and flavors was confirmed using a potentiometric multisensor-based electronic tongue, coupled with principal component analysis. Placebo ODTs with crospovidone as a superdisintegrant revealed a significant increase in hardness from ∼3 to ∼5 kg/cm² and a decrease in disintegration time (<60 s) following microwave irradiation. LMG ODTs had hardness >5 kg/cm², DT < 30s, and rapid dissolution of LMG, and good stability was optimized by DOE and the design space derived. While β-CD complexation enabled rapid dissolution and moderate taste masking, palatability, which was achieved including flavors, was confirmed using an electronic tongue. A simple step of humidification enabled MWI-facilitated development of ODTs by direct compression presenting a practical and scalable advancement in ODT technology.

Improvement of mechanical properties of pellet containing tablets by thermal treatment

Batches of partially spray-dried lactose tablets with three different initial tensile strength (∼20N, ∼35N, ∼50N) were made. Changes along a 24h long thermal treatment at 100°C in tensile strength, friability, individual mass, water content, disintegration time, average free volume and wetting properties were evaluated. Caffeine containing gastroresistant pellets were gained by drug layering and filmcoating of inert microcrystalline cellulose pellet cores in fluid bed equipment. Shape, size, mechanical properties, drug content and dissolution profile of the coated pellets were determined. Batches of pellet containing tablets with three different pellet-filler ratios were compressed where partially spray-dried lactose was used as a filler-binder material.Characteristics of pellet containing tablets were evaluated before and after a 24h long thermal treatment at 100°C. Results shown that the poor initial mechanical properties (friability, tensile strength) were improved by thermal exposure while there were no remarkable alterations in drug release profiles.

Hydrogel-assisted functional reconstitution of human P-glycoprotein (ABCB1) in giant liposomes

This paper describes the formation of giant proteoliposomes containing P-glycoprotein (P-gp) from a solution of small proteoliposomes that had been deposited and partially dried on a film of agarose. This preparation method generated a significant fraction of giant proteoliposomes that were free of internalized vesicles, making it possible to determine the accessible liposome volume. Measuring the intensity of the fluorescent substrate rhodamine 123 (Rho123) inside and outside these giant proteoliposomes determined the concentration of transported substrates of P-gp. Fitting a kinetic model to the fluorescence data revealed the rate of passive diffusion as well as active transport by reconstituted P-gp in the membrane. This approach determined estimates for the membrane permeability coefficient (Ps) of passive diffusion and rate constants of active transport (kT) by P-gp as a result of different experimental conditions. The Ps value for Rho123 was larger in membranes containing P-gp under all assay conditions than in membranes without P-gp indicating increased leakiness in the presence of reconstituted transmembrane proteins. For P-gp liposomes, the kT value was significantly higher in the presence of ATP than in its absence or in the presence of ATP and the competitive inhibitor verapamil. This difference in kT values verified that P-gp was functionally active after reconstitution and quantified the rate of active transport. Lastly, patch clamp experiments on giant proteoliposomes showed ion channel activity consistent with a chloride ion channel protein that co-purified with P-gp. Together, these results demonstrate several advantages of using giant rather than small proteoliposomes to characterize transport properties of transport proteins and ion channels.

Health-related characteristics and unmet needs of men with erectile dysfunction: a survey in five European countries

INTRODUCTION

Data suggest that ED is still an underdiagnosed and undertreated condition. In addition, it seems that men with ED are unsatisfied about their relationship with their physician and with the available drugs.

AIM

The study aims to identify health-related characteristics and unmet needs of patients suffering from erectile dysfunction (ED) in big 5 European Union (EU) nations (France, Germany, Italy, Spain, and UK).

METHODS

Data were collected from the 2011 5EU National Health and Wellness-Survey on a population of 28,511 adult men (mean age: 47.18; SD 16.07) and was focused on men (5,184) who self-reported ED in the past 6 months. In addition, the quality of life (QoL) and work productivity/activity were explored.

MAIN OUTCOME MEASURES

Health-related QoL (HRQoL) and work productivity were measured with SF-12v2 and WPAI validated psychometric tools.

RESULTS

One in every 20 young men (age 18-39) across 5EU experienced ED in the past 6 months. About half of men (2,702/5,184; [52%]) with ED across all ages did not discuss their condition with their physician. Interestingly, among those men who did discuss their condition with their physician, 68% (1,668/2,465) do not currently use medication. These findings were more evident in the age group of 18-39 years. Only 48% (2,465/5,184) had a closer relationship with their physician, suggesting that this quality of relationship may be unsatisfactory. Compared with controls, ED patients have a significantly higher intrapsychic and relational psychopathological comorbid burden and relevant decreasing in HRQoL, with a significantly higher impairment on work productivity/activity.

CONCLUSION

Data suggest that there is a need for a new therapeutic paradigm in ED treatment which images the achievement of a new alliance between physician and patient. Hence, alternative drug delivery strategies may reduce the psychological and social impact of this disease.

Development and evaluation of fixed dose bi therapy sublingual tablets for treatment stress hypertension and anxiety

Objective:

A stress induced rise in the blood pressure. Some believe that patients with hypertension are characterized by a generalized state of increased anxiety.

Aim:

The purpose of this study is to prepare a fixed dose bi therapy using bisoprolol hemifumarate (BH) as antihypertensive drug and buspirone hydrochloride (BuHCl) as anxiolytic drug, which can be used to treat both diseases concomitantly. Using sublingual tablets is hopeful to improve the BuHCl poor oral bioavailability and to facilitate administration to patients experiencing problems with swallowing.

Materials and Methods:

A total of 5mg BH and 10mg BuHCl were selected based on compatibility study. A 3×22 full factorial design was adopted for the optimization of the tablets prepared by direct compression method. The effects of the filler type, the binder molecular weight, and the binder type were studied. The prepared formulae were evaluated according to their physical characters as hardness, friability, disintegration time (new modified method and in vivo disintegration time) and wetting properties. In vitro drugs dissolute, permeation through the buccal mucosa and the effect of storage were analyzed by a new valid high pressure liquid chromatography (HPLC) method. Bioavailability study of the selected formula study was carried out and followed by the clinical.

Results:

The optimized tablet formulation showed accepted average weight, hardness, wetting time, friability, content uniformity, disintegration time (less than 3 min). Maximum drug release could be achieved with in 10 min. In addition enhancing drug permeation through the buccal mucosa and, the maximum concentration of the drug that reached the blood was in the first 10 min which means a rapid onset of action and improved the extent of both drug's absorption.

Conclusion:

The results revealed that sublingual (F6) tablets containing both drugs would maintain rapid onset of action, and increase bioavailability. BuHCl with BH can be attributed to the marked decline in DBP and SBP. That led to a reduction in the MAP.

Fast disintegrating tablets: Opportunity in drug delivery system

Fast disintegrating tablets (FDTs) have received ever-increasing demand during the last decade, and the field has become a rapidly growing area in the pharmaceutical industry. Oral drug delivery remains the preferred route for administration of various drugs. Recent developments in the technology have prompted scientists to develop FDTs with improved patient compliance and convenience. Upon introduction into the mouth, these tablets dissolve or disintegrate in the mouth in the absence of additional water for easy administration of active pharmaceutical ingredients. The popularity and usefulness of the formulation resulted in development of several FDT technologies. FDTs are solid unit dosage forms, which disintegrate or dissolve rapidly in the mouth without chewing and water. FDTs or orally disintegrating tablets provide an advantage particularly for pediatric and geriatric populations who have difficulty in swallowing conventional tablets and capsules. This review describes various formulations and technologies developed to achieve fast dissolution/dispersion of tablets in the oral cavity. In particular, this review describes in detail FDT technologies based on lyophilization, molding, sublimation, and compaction, as well as approaches to enhancing the FDT properties, such as spray drying and use of disintegrants. In addition, taste-masking technologies, experimental measurements of disintegration times, and dissolution are also discussed.

A pilot human pharmacokinetic study and influence of formulation factors on orodispersible tablet incorporating meloxicam solid dispersion using factorial design

Meloxicam (MLX) suffers from poor aqueous solubility leading to slow absorption following oral administration; hence, immediate release MLX tablet is unsuitable in the treatment of acute pain. This study aims to overcome such a drawback by increasing MLX solubility and dissolution using PEG solid dispersion (SD), then, to investigate the feasibility of incorporating the SD into orodispersible tablets (ODTs). A 2(3) full factorial design was employed to investigate the influence of three formulation variables on MLX ODTs. The selected factors: camphor (X(1)) as pore-forming material, and croscarmellose sodium (X(2)) as superdisintegrant, showed significant positive influence, while PEG content (X(3)) was proved to negatively affect both disintegration and wetting times. In addition, isomalt increased disintegration and wetting times when compared to mannitol as diluents. The pharmacokinetic assessment of the optimum ODT formulation in healthy human subjects proved that the faster MLX dissolution by using PEG solid dispersion at pH 6.8 resulted in more rapid absorption of MLX. The rate of absorption of MLX from ODT was significantly faster (p = 0.030) with a significantly higher peak plasma concentration (P = 0.037) when compared to the marketed immediate release MLX tablet with a mean oral disintegration time of 17 ± 3 s.

Maltodextrin: a novel excipient used in sugar-based orally disintegrating tablets and phase transition process

The recent challenge in orally disintegrating tablets (ODT) manufacturing encompasses the compromise between instantaneous disintegration, sufficient hardness, and standard processing equipment. The current investigation constitutes one attempt to fulfill this challenge. Maltodextrin, in the present work, was utilized as a novel excipient to prepare ODT of meclizine. Tablets were prepared by both direct compression and wet granulation techniques. The effect of maltodextrin concentrations on ODT characteristics--manifested as hardness and disintegration time--was studied. The effect of conditioning (40 degrees C and 75% relative humidity) as a post-compression treatment on ODT characteristics was also assessed. Furthermore, maltodextrin-pronounced hardening effect was investigated using differential scanning calorimetry (DSC) and X-ray analysis. Results revealed that in both techniques, rapid disintegration (30-40 s) would be achieved on the cost of tablet hardness (about 1 kg). Post-compression conditioning of tablets resulted in an increase in hardness (3 kg), while keeping rapid disintegration (30-40 s) according to guidance of the FDA for ODT. However, direct compression-conditioning technique exhibited drawbacks of long conditioning time and appearance of the so-called patch effect. These problems were, yet, absent in wet granulation-conditioning technique. DSC and X-ray analysis suggested involvement of glass-elastic deformation in maltodextrin hardening effect. High-performance liquid chromatography analysis of meclizine ODT suggested no degradation of the drug by the applied conditions of temperature and humidity. Overall results proposed that maltodextrin is a promising saccharide for production of ODT with accepted hardness-disintegration time compromise, utilizing standard processing equipment and phenomena of phase transition.

Potential use of 2-hydroxypropyl-beta-cyclodextrin for preparation of orally disintegrating tablets containing dl-alpha-tocopheryl acetate, an oily drug

To expand the application of a drug in orally disintegrating tablets, the potential use of beta-cyclodextrin (beta-CyD) and 2-hydroxypropyl-beta-cyclodextrin (HP-beta-CyD) as excipients for the tablets containing dl-alpha-tocopheryl acetate (VE), an oily drug, was evaluated. HP-beta-CyD, not beta-CyD, solubilized VE in water through the formation of higher order of complexes at the molar ratio of 1 : 2 (VE : HP-beta-CyD). When prepared under the optimal preparation conditions, the VE tablets containing lactose and 5% (w/w) of HP-beta-CyD, not beta-CyD, had high hardness more than 4 kg and rapid disintegration within 100 s both in vitro and in vivo. In addition, VE tablets containing lactose and 5% (w/w) of HP-beta-CyD, not beta-CyD, maintained the high hardness and rapid disintegration under the accelerated stability test using different conditions for 4 weeks. Therefore, these results suggest the potential use of HP-beta-CyD, not beta-CyD, as an excipient for orally disintegrating tablets containing VE, an oily drug, in the molding method.

A new formulation for orally disintegrating tablets using a suspension spray-coating method

The aim of this study was to design a new orally disintegrating tablet (ODT) that has high tablet hardness and a fast oral disintegration rate using a new preparation method. To obtain rapid disintegration granules (RDGs), a saccharide, such as trehalose, mannitol, or lactose, was spray-coated with a suspension of corn starch using a fluidized-bed granulator (suspension method). As an additional disintegrant, crospovidone, light anhydrous silicic acid, or hydroxypropyl starch was also included in the suspension. The RDGs obtained possessed extremely large surface areas, narrow particle size distribution, and numerous micro-pores. When tabletting these RDGs, it was found that the RDGs increased tablet hardness by decreasing plastic deformation and increasing the contact frequency between granules. In all tablets, a linear relationship was observed between tablet hardness and oral disintegration time. From each linear correlation line, a slope (D/H value) and an intercept (D/H(0) value) were calculated. Tablets with small D/H and D/H(0) values could disintegrate immediately in the oral cavity regardless of the tablet hardness and were considered to be appropriate for ODTs. Therefore, these values were used as key parameters to select better ODTs. Of all the RDGs prepared in this study, mannitol spray-coated with a suspension of corn starch and crospovidone (2.5:1 w/w ratio) showed most appropriate properties for ODTs; fast in vivo oral disintegration time, and high tablet hardness. In conclusion, this simple method to prepare superior formulations for new ODTs was established by spray-coating mannitol with a suspension of appropriate disintegrants.

Evaluation of Disintegrating Time of Rapidly Disintegrating Tablets by a Paddle Method

A paddle method for measurement of the disintegrating time of orally disintegrating tablets with rizatriptan benzoate as a model drug was evaluated. The paddle method employed a dissolution test assembly with tablets immersed in disintegrating medium through a fastened sinker. Paddle stirring rate, opening of the sinker sieve, and tablet crushing strength influenced disintegrating time greatly. A logarithmic relationship was observed between disintegrating time and paddle revolution speed, while disintegrating time values and tablet crushing strength were fitted to a linear equation. The paddle method values with limited deviation were in good correlation with in vivo results. The paddle method was employed to optimize the disintegrating time of rizatriptan benzoate orally disintegrating tablets using a factorial design. The best-fit quadratic equation with a regression coefficient of 0.996 was highly predictive, which was indicative that the paddle method was precise and applicable in formulation optimization.

Kinetic modelling of passive transport and active efflux of a fluoroquinolone across Caco-2 cells using a compartmental approach in NONMEM

The purpose was to develop a general mathematical model for estimating passive permeability and efflux transport parameters from in vitro cell culture experiments. The procedure is applicable for linear and non-linear transport of drug with time, <10 or >10% of drug transport, negligible or relevant back flow, and would allow the adequate correction in the case of relevant mass balance problems. A compartmental kinetic approach was used and the transport barriers were described quantitatively in terms of apical and basolateral clearances. The method can be applied when sink conditions are not achieved and it allows the evaluation of the location of the transporter and its binding site. In this work it was possible to demonstrate, from a functional point of view, the higher efflux capacity of the TC7 clone and to identify the apical membrane as the main resistance for the xenobiotic transport. This methodology can be extremely useful as a complementary tool for molecular biology approaches in order to establish meaningful hypotheses about transport mechanisms.

Development of mouth dissolving tablets of clozapine using two different techniques

Mouth dissolving tablets constitute an innovative dosage form that overcomes the problems of swallowing and provides a quick onset of action. In view of enhancing bioavailability an attempt has been made to study two different methods direct compression and sublimation in formulation of mouth dissolving tablets of clozapine. Total four formulations using various superdisintegrants and subliming agents were prepared. All prepared formulations were evaluated for physico-chemical parameters. The formulations exhibited good disintegration properties with total disintegration time in the range of 25 to 35 s. Comparative evaluation of two methods showed direct compression method is a better alternative to sublimation method as its formulations rapidly disintegrate in oral cavity. In vitro cumulative percentage drug release for formulations prepared by direct compression with explotab superdisintegrants shows 99.79 while sublimation method using camphor 93.58 release in 12 min. Kinetic studies indicated that all the formulations followed first order release with diffusion mechanism.

A study of tablet dissolution by magnetic resonance electric current density imaging

The electric current density imaging technique (CDI) was used to monitor the dissolution of ion releasing tablets (made of various carboxylic acids and of sodium chloride) by following conductivity changes in an agar-agar gel surrounding the tablet. Conductivity changes in the sample were used to calculate spatial and temporal changes of ionic concentrations in the sample. The experimental data for ion migration were compared to a mathematical model based on a solution of the diffusion equation with moving boundary conditions for the tablet geometry. Diffusion constants for different acids were determined by fitting the model to the experimental data. The experiments with dissolving tablets were used to demonstrate the potential of the CDI technique for measurement of ion concentration in the vicinity of ion releasing samples.

Effect of Formulated Ingredients on Rapidly Disintegrating Oral Tablets Prepared by the Crystalline Transition Method

The aim of this article was to determine the optimal ingredients for the rapidly disintegrating oral tablets prepared by the crystalline transition method (CT method). The effect of ingredients (diluent, active drug substance and amorphous sugar) on the characteristics of the tablets was investigated. The ingredients were compressed and the resultant tablets were stored under various conditions. The oral disintegration time of the tablet significantly depended on diluents, due to differences in the penetration of a small amount of water in the mouth and the viscous area formed inside the tablet. The oral disintegration time was 10-30 s for tablets with a tensile strength of approximately 1 MPa, when erythritol, mannitol or xylitol was used as the diluent. The increase in the tensile strength of tablets containing highly water-soluble active drug substances during storage was as large as that of tablets without active drug substances, while the increase in the tensile strength of tablets containing low water-soluble active drug substances was small. It was therefore found that highly water-soluble active drug substances were more suitable for the formulation prepared by the CT method than low water-soluble active drug substances. Irrespective of the type of amorphous sugar (amorphous sucrose, lactose or maltose) used, the porosity of tablets with 1 MPa of tensile strength was 30-40%, and their oral disintegration time was 10-20 s. The optimal ingredients for rapidly disintegrating oral tablets with reasonable tensile strength and disintegration time were therefore determined from these results.

Evaluation of rapidly disintegrating tablets manufactured by phase transition of sugar alcohols

The aim of the present study was to assess the properties of rapidly disintegrating (RD) tablets manufactured by the phase transition method. RD tablets were produced by compressing powder containing erythritol (melting point: 122 degrees C) and xylitol (melting point: 93 approximately 95 degrees C), and then heating at about 93 degrees C for 15 min. The hardness and oral disintegration time of the heated tablets increased with an increase of the xylitol content. These results suggested that the heating process and xylitol content might influence the properties of RD tablets. Then we evaluated the physicochemical properties of the RD tablets, including the median pore size, crystallinity, hardness, and oral disintegration time of tablets made with and without heating. After heating, the median pore size of the tablets was increased and tablet hardness was also increased. The increase of tablet hardness with heating and storage did not depend on the crystal state of the lower melting point sugar alcohol. It is concluded that a combination of low and high melting point sugar alcohols, as well as a phase transition in the manufacturing process, are important for making RD tablets without any special apparatus.

The preparation of orally disintegrating tablets using a hydrophilic waxy binder

The demand for rapidly disintegrating tablets (RDT) has been growing during the last decade especially for elderly and children who have swallowing difficulties. The problem of certain RDT is their low physical resistance and high friability. This work describes a new approach to prepare RDT with sufficient mechanical integrity, involving the use of a hydrophilic waxy binder (Superpolystate, PEG-6-stearate). Superpolystate is a waxy material with a melting point of 33-37 degrees C and an HLB value of 9. So it will not only act as a binder and increase the physical resistance of tablets but will also help the disintegration of the tablets as it melts in the mouth and solublises rapidly leaving no residues. The incorporation of Superpolystate in the formulation of RDT was realised by means of two different granulation methods: wet granulation by using an emulsion of this waxy binder as granulating liquid and melt granulation where the molten form of the binder was used. Granule size distributions of both wet and melt granules of crystallised Paracetamol and D-mannitol were compared using laser light diffractometer. Scanning electron microscopy (SEM) was used to examine their morphological characteristics. The potential of the intragranular addition of croscarmellose sodium as a disintegrating agent was also evaluated. The subsequent step encompassed the preparation and the evaluation of the tablets, including the effect of the extragranular introduction of croscarmellose sodium. An improvement in tablet hardness and friability was observed with both granulation methods where we were able to obtain RDT with a disintegration time of 40 +/- 2 s and a hardness of 47.9 +/- 2.5N.

Preparation and Evaluation of High Drug Content Particles

To determine how to prepare high drug content particles using a Wurster fluidized bed to determine realizing the miniaturization of solid dosage forms, aspirin was selected as the model drug and granulated without any additive. In this study, the emphasis was on evaluating the key operation factors of airflow rate and atomizing flow volume. The properties of the resulting particles, such as the average diameter, particle strength, appearance, and compressibility using different airflow rates and atomizing flow volumes, were investigated. Furthermore, detailed optimization of the operation conditions was conducted by artificial neural network (ANN) analysis. The relationship between the controlling factors (powder supplied, concentration of spray liquid, the amount of consumed spray liquid, and spray rate) and the response variables (product yield, median diameter, angle of repose, and degradation of aspirin) was investigated after evaluating the airflow rate and atomizing flow volume effects. The resulting granules under optimum operation conditions showed excellent physicochemical properties such as particle size uniformity, flowability, and compressibility.

Preparation and evaluation of combination tablet containing incompatible active ingredients

Combination preparation plays an important role in clinical treatment because of its better and wider curative synergism and weaker side effects. However, the existence of incompatibility between active ingredients or between active ingredients and excipients presents a serious obstacle in the preparation of such combination solid dosage forms. In this study, aspirin and ranitidine hydrochloride, between which there existed a chemical interaction, were selected as model drugs. Aspirin powders without any additives were granulated with hydroxypropyl methyl cellulose (HPMC) water solution as a binder using a Wurster coating apparatus and the operation conditions were optimized by Artificial Neural Network (ANN) analysis. Under these conditions, the aspirin granules prepared showed good flowability and compressibility. On the other hand, ranitidine hydrochloride was coated with Aquacoat (ethyl cellulose aqueous dispersion) after preliminary granulation with the Wurster coating apparatus. The aspirin granules and coated ranitidine hydrochloride particles were compressed into tablets with suitable excipients. The combination tablets showed good dissolution, content uniformity and improved stability of active ingredients.

Cold extrusion as a continuous single-step granulation and tabletting process

The potential of cold extrusion as a continuous granulation/tabletting technique was investigated. Extrudates (X, 9 mm) were produced using twin-screw extrusion, cut manually into tablets (thickness, 4 mm) and dried at 25 degrees C for 20 h. alpha-Lactose monohydrate (200 M) was used as an excipient, PVP (Kollidon K30) and water as binders, and hydrochlorothiazide as the model drug. The influence of formulation (water content, PVP addition, drug incorporation) and process (total input rate and screw speed) parameters on the process (torque, die pressure, visual evaluation of tablets) and on the tablet properties (tensile strength, friability, disintegration time, porosity) was evaluated. Formulation, as well as process parameters, affected the process feasibility, but had only a minor effect on the tablet properties at conditions that allowed continuous tablet production. All alpha-lactose monohydrate tablets formulated without and with PVP and produced at optimum conditions showed tensile strengths above 0.7 and 1.5 MPa, friabilities below 1.0 and 0.9%, and disintegration times below 1 and 8 min, respectively. This technique allows single-step granulation/tabletting of pure alpha-lactose monohydrate, indicating that cold extrusion could be used as alternative tablet production technique for ingredients with poor compaction properties. As the tablets prepared by extrusion have a much higher porosity compared with conventional tablets, this technique could also be useful for tablet production of formulations with poor disintegrating properties.

In vitro, ex vivo, and in situ intestinal absorption characteristics of the antiviral ester prodrug adefovir dipivoxil

Caco-2 monolayers (in vitro), rat intestinal sheets mounted in modified Ussing Chambers (ex vivo), and in situ intestinal perfusion of rat ileum were used as models to determine and compare the absorption characteristics of the antiviral agent 9-[2-(phosphonomethoxy)ethyl]adenine (PMEA, adefovir) and its bis(pivaloyloxymethyl)-ester prodrug [bis(POM)-PMEA, adefovir dipivoxil]. Although metabolism of adefovir dipivoxil was more pronounced in the ex vivo and in situ models than in the Caco-2 system, the transport of 'total adefovir' [= adefovir dipivoxil and its metabolites mono(POM)-PMEA and adefovir] was comparable in the three models. Compared with transport of the parent compound (adefovir), use of adefovir dipivoxil resulted in a significant increase in transport of total adefovir in the in vitro ( approximately 100-fold) and the in situ ( approximately 10-fold) models; in contrast, the ex vivo method failed to demonstrate a remarkable transport enhancement when using the ester prodrug. Similar to the results obtained in the Caco-2 model, the inclusion of the P-glycoprotein inhibitor verapamil resulted in transport enhancement during in situ perfusion of rat ileum with adefovir dipivoxil; however, no effect of verapamil could be observed in the ex vivo model. The results of this study confirm the utility of both the in vitro and in situ models to assess intestinal transport and metabolism of adefovir dipivoxil. The ex vivo model appeared to be less appropriate because of its inability to discriminate transport following administration of adefovir or adefovir dipivoxil and because of the absence of an effect of verapamil on transport when using adefovir dipivoxil.