Different HPMC viscosity grades as coating agents for an oral time and/or site-controlled delivery system: a study on process parameters and in vitro performances

Time-Based Formulation Strategies for Colon Drug Delivery

Despite poor absorption properties, delivery to the colon of bioactive compounds administered by the oral route has become a focus of pharmaceutical research over the last few decades. In particular, the high prevalence of Inflammatory Bowel Disease has driven interest because of the need for improved pharmacological treatments, which may provide high local drug concentrations and low systemic exposure. Colonic release has also been explored to deliver orally biologics having gut stability and permeability issues. For colon delivery, various technologies have been proposed, among which time-dependent systems rely on relatively constant small intestine transit time. Drug delivery platforms exploiting this physiological feature provide a lag time programmed to cover the entire small intestine transit and control the onset of release. Functional polymer coatings or capsule plugs are mainly used for this purpose, working through different mechanisms, such as swelling, dissolution/erosion, rupturing and/or increasing permeability, all activated by aqueous fluids. In addition, enteric coating is generally required to protect time-controlled formulations during their stay in the stomach and rule out the influence of variable gastric emptying. In this review, the rationale and main delivery technologies for oral colon delivery based on the time-dependent strategy are presented and discussed.

Novel self-floating tablet for enhanced oral bioavailability of metformin based on cellulose

Metformin has several problems such as low bioavailability, short half-life, and narrow absorption window, sustained and site-specific drug delivery system is required. Floating drug delivery systems are very useful to achieve these purposes. However, conventional floating systems have several limitations; lag time, a high proportion of excipient in the tablet, using non-biocompatible excipient, and requirement of a complicated procedure. To overcome these obstacles, we developed a hollow-core floating tablet (HCFT). The HCFT immediately floated in pH 1.2, 4.0, 6.8 medium, and even distilled water. The floating duration time of HCFT was>24 h. From the in vitro release study, it was confirmed that HCFT showed the sustain release profile of metformin for 12 h. Water uptake and matrix erosion were evaluated for predicting the buoyancy and drug release kinetics of HCFT in the body. Factor analysis was applied to optimize the formulation. There were significant (p < 0.05) differences in metformin plasma concentration of 4 h and 6 h between two groups. Compared with Glucophage® XR, the relative bioavailability of metformin HCFT was 123.81 ± 3.52%. The X-ray imaging of optimized formulation revealed that HCFT was constantly floating in the stomach region of the rabbit, thereby indicating improved gastric retention for>6 h. Consequently, all the findings indicate that HCFT could be an effective gastric retention system and applied extensively to other drugs with narrow absorption windows.

Evaluation of powder-layering vs. spray-coating techniques in the manufacturing of a swellable/erodible pulsatile delivery system

A swellable/erodible system for oral time-dependent release, demonstrated to provide consistent pulsatile and colonic delivery performance, has been manufactured through a range of coating techniques to achieve the functional hydroxypropyl methylcellulose (HPMC) layer. Although aqueous spray-coating has long been preferred, the processing times and yields still represent open issues, especially in view of the considerable amount of polymer required to give in vivo lag phases of proper duration. To make manufacturing of the delivery system more cost-efficient, different coating modes were thus evaluated, namely top and tangential spray-coating as well as powder-layering, using a fluid bed equipment. To this aim, disintegrating tablets of 5 mm in diameter, containing a tracer drug, were coated up to 50% weight gain with low-viscosity HPMC, either as a water solution or as a powder formulation. In all cases, process feasibility was assessed following setup of the operating conditions. Irrespective of the technique employed, the resulting dosage forms exhibited uniform coating layers able to defer the onset of release as a function of the amount of polymer applied. The structure and thickness of such layers differed depending on the deposition modes. With respect to top spray-, both tangential spray-coating and powder-layering were shown to remarkably ameliorate the process time, which was reduced to approximately 1/3 and 1/6, and to enhance the yield by almost 20 and 30%, respectively. Clear advantages associated with such techniques were thus highlighted, particularly with respect to powder-layering here newly proposed for application of a swellable hydrophilic cellulose derivative.

Injection Molded Capsules for Colon Delivery Combining Time-Controlled and Enzyme-Triggered Approaches

A new type of colon targeting system is presented, combining time-controlled and enzyme-triggered approaches. Empty capsule shells were prepared by injection molding of blends of a high-amylose starch and hydroxypropyl methylcellulose (HPMC) of different chain lengths. The dissolution/erosion of the HPMC network assures a time-controlled drug release, i.e., drug release starts upon sufficient shell swelling/dissolution/erosion. In addition, the presence of high-amylose starch ensures enzyme-triggered drug release. Once the colon is reached, the local highly concentrated bacterial enzymes effectively degrade this polysaccharide, resulting in accelerated drug release. Importantly, the concentration of bacterial enzymes is much lower in the upper gastrointestinal tract, thus enabling site-specific drug delivery. The proposed capsules were filled with acetaminophen and exposed to several aqueous media, simulating the contents of the gastrointestinal tract using different experimental setups. Importantly, drug release was pulsatile and occurred much faster in the presence of fecal samples from patients. The respective lag times were reduced and the release rates increased once the drug started to be released. It can be expected that variations in the device design (e.g., polymer blend ratio, capsule shell geometry and thickness) allow for a large variety of possible colon targeting release profiles.

Engineering of Naproxen Loaded Polymer Hybrid Enteric Microspheres for Modified Release Tablets: Development, Characterization, in silico Modelling and in vivo Evaluation

BACKGROUND

Naproxen (NP) is a non-steroidal anti-inflammatory drug with poor aqueous solubility and low oral bioavailability, which may lead to therapeutic failure. NP causes crucial GIT irritation, bleeding, and peptic and duodenal ulcers.

PURPOSE OF THE STUDY

This study aimed to engineer and characterize polymer hybrid enteric microspheres using an integrated (experimental and molecular modelling) approach with further development to solid dosage form with modified drug release kinetics and improved bioavailability.

MATERIALS AND METHODS

NP loaded polymer hybrid enteric microspheres (PHE-Ms) were fabricated by using a modified solvent evaporation technique coupled with molecular modelling (MM) approach. The PHE-Ms were characterized by particle size, distribution, morphology, crystallinity, EE, drug-polymer compatibility, and DSC. The optimized NP loaded PHE-Ms were further subjected to downstream procedures including tablet dosage form development, stability studies and comparative in vitro-in vivo evaluation.

RESULTS

The hydrophobic polymer EUD-L100 and hydrophilic polymer HPMC-E5 delayed and modified drug release at intestinal pH while imparting retardation of NP release at gastric pH to diminish the gastric side effects. The crystallinity of the NP loaded PHE-Ms was established through DSC and P (XRD). The particle size for the developed formulations of PEH-Ms (M1-M5) was in the range from 29.06 ±7.3-74.31 ± 17.7 μm with Span index values of 0.491-0.69, respectively. The produced NP hybrid microspheres demonstrated retarded drug release at pH 1.2 and improved dissolution at pH 6.8. The in vitro drug release patterns were fitted to various release kinetic models and the best-followed model was the Higuchi model with a release exponent "n" value > 0.5. Stability studies at different storage conditions confirmed stability of the NP loaded PHE-Ms based tablets (P<0.05). The molecular modelling (MM) study resulted in adequate binding energy of co-polymer complex SLS-Eudragit-HPMC-Naproxen (-3.9 kcal/mol). In contrast to the NP (unprocessed) and marketed formulations, a significant increase in the Cmax of PHE-MT1 (44.41±4.43) was observed.

CONCLUSION

The current study concludes that developing NP loaded PHE-Ms based tablets could effectively reduce GIT consequences with restored therapeutic effects. The modified release pattern could improve the dissolution rate and enhancement of oral bioavailability. The MM study strengthens the polymer-drug relationship in microspheres.

Hot-melt extruded filaments based on pharmaceutical grade polymers for 3D printing by fused deposition modeling

Fused deposition modeling (FDM) is a 3D printing technique based on the deposition of successive layers of thermoplastic materials following their softening/melting. Such a technique holds huge potential for the manufacturing of pharmaceutical products and is currently under extensive investigation. Challenges in this field are mainly related to the paucity of adequate filaments composed of pharmaceutical grade materials, which are needed for feeding the FDM equipment. Accordingly, a number of polymers of common use in pharmaceutical formulation were evaluated as starting materials for fabrication via hot melt extrusion of filaments suitable for FDM processes. By using a twin-screw extruder, filaments based on insoluble (ethylcellulose, Eudragit(®) RL), promptly soluble (polyethylene oxide, Kollicoat(®) IR), enteric soluble (Eudragit(®) L, hydroxypropyl methylcellulose acetate succinate) and swellable/erodible (hydrophilic cellulose derivatives, polyvinyl alcohol, Soluplus(®)) polymers were successfully produced, and the possibility of employing them for printing 600μm thick disks was demonstrated. The behavior of disks as barriers when in contact with aqueous fluids was shown consistent with the functional application of the relevant polymeric components. The produced filaments were thus considered potentially suitable for printing capsules and coating layers for immediate or modified release, and, when loaded with active ingredients, any type of dosage forms.

Film coatings for oral pulsatile release

Pulsatile delivery is generally intended as a release of the active ingredient that is delayed for a programmable period of time to meet particular chronotherapeutic needs and, in the case of oral administration, also target distal intestinal regions, such as the colon. Most oral pulsatile delivery platforms consist in coated formulations wherein the applied polymer serves as the release-controlling agent. When exposed to aqueous media, the coating initially performs as a protective barrier and, subsequently, undergoes a timely failure based on diverse mechanisms depending on its physico-chemical and formulation characteristics. Indeed, it may be ruptured because of the gradual expansion of the core, swell and/or erode due to the glassy-rubbery polymer transition or become permeable thus allowing the drug molecules to diffuse outwards. Otherwise, when the coating is a semipermeable membrane provided with one or more orifices, the drug is released through the latter as a result of an osmotic water influx. The vast majority of pulsatile delivery systems described so far have been prepared by spray-coating, which offers important versatility and feasibility advantages over other techniques such as press- and dip-coating. In the present article, the design, manufacturing and performance of spray-coated pulsatile delivery platforms is thus reviewed.

Development of pH- and enzyme-controlled, colon-targeted, pulsed delivery system of a poorly water-soluble drug: preparation and in vitro evaluation

BACKGROUND

As conventional pH-controlled colon-targeted system used for oral drug delivery often shows a poor performance, a more effective way to preserve poorly water-soluble drug from releasing in upper gastrointestinal tract should be researched.

METHOD

The objective of this study was to develop a novel colon-targeted drug delivery system using guar gum and Eudragit as enzyme- and pH-based materials. Lansoprazole, a poorly water-soluble drug was used as model drug. Under three different conditions, the in vitro drug release behaviors of this newly developed system was evaluated, using β-mannanase, rat cecal content, and human fecal media to simulate the pH and enzyme during intestinal transit to the colon.

RESULTS

The released amount of lansoprazole in simulated small intestine fluid (pH 6.8) after 5 hours was less than 10% from the pH- and enzyme-controlled tablets compared with 80.01±0.3% in rat cecal content medium (pH 7.4).The degradation ability of human fecal slurries on PECCT-PT was independent of human age and gender. β-Mannanase did not have a similar effect on the degradation of polysaccharide as rat cecal enzymes and human fecal enzymes in our study. Scanning electron microscope study indicated that the dissolution mechanism of PECCT-PT should be corrosion.

CONCLUSION

The above results indicated this system could be served as a potential carrier to deliver poorly water-soluble drug specifically to the colon.

Oral colon delivery of insulin with the aid of functional adjuvants

Oral colon delivery is currently considered of importance not only for the treatment of local pathologies, such as primarily inflammatory bowel disease (IBD), but also as a means of accomplishing systemic therapeutic goals. Although the large bowel fails to be ideally suited for absorption processes, it may indeed offer a number of advantages over the small intestine, including a long transit time, lower levels of peptidases and higher responsiveness to permeation enhancers. Accordingly, it has been under extensive investigation as a possible strategy to improve the oral bioavailability of peptide and protein drugs. Because of a strong underlying rationale, most of these studies have focused on insulin. In the present review, the impact of key anatomical and physiological characteristics of the colon on its viability as a protein release site is discussed. Moreover, the main formulation approaches to oral colon targeting are outlined along with the design features and performance of insulin-based devices.

A new application of lipid nanoemulsions as coating agent, providing zero-order hydrophilic drug release from tablets

The objective of the present investigation was to evaluate potential of nanoemulsions as a coating material for the tablets. The nanoemulsion of size less than 100 nm was prepared using a simple and low-energy spontaneous emulsification method. Conventional tablets containing theophylline as a model hydrophilic drug were prepared. The theophylline tablets were coated with the nanoemulsion using a fluid bed coater. The effect of different levels of the nanoemulsion coating on the theophylline release was evaluated. The theophylline tablets containing different levels of the nanoemulsion coating could be successfully prepared. Interestingly, the coating of tablet with the nanoemulsion resulted in zero-order release of theophylline from the tablets. The noncoated theophylline tablets release the entire drug in less than 2 minutes, whereas nanoemulsion coating delayed the release of theophylline from tablets. This investigation establishes the proof of concept for the potential of nanoemulsions as a coating material for tablets.

A novel injection-molded capsular device for oral pulsatile delivery based on swellable/erodible polymers

The feasibility of injection molding was explored in the preparation of a novel capsular device for oral pulsatile/delayed delivery based on swellable/erodible polymers. For this purpose, a mold intended to be coupled with a bench-top injection-molding press was designed. This was expected to enable the preparation of matching capsule cap and body items within a single manufacturing cycle and the selection of differing shell thicknesses (300, 600, and 900 μm). Hydroxypropylcellulose (Klucel(®) EF, LF, and GF) was employed as the release-controlling polymer in admixture with polyethylene glycol 1500 (10%, w/w) as the plasticizer. After preliminary trials aimed at the setup of operating conditions, Klucel(®) EF and LF capsule shells with satisfactory technological properties were manufactured. The performance of capsular devices filled with a tracer drug powder was studied by means of a modified USP31 disintegration apparatus. Typical in vitro delayed release patterns were thereby obtained, with lag time increasing as a function of the wall thickness. A good correlation was found between the latter parameter and t (10%), i.e., the time to 10% release, for both polymer grades employed. On the basis of the overall results, the investigated technique was proven suitable for the manufacturing of an innovative pulsatile release platform.

Formulation and development of release modulated colon targeted system of meloxicam for potential application in the prophylaxis of colorectal cancer

The objective of the present study was to develop a colon targeted system of meloxicam for potential application in the prophylaxis of colorectal cancer. Efficacy of selective cyclooxygenase-2 inhibitors has been proven in colorectal cancer. Meloxicam is a selective cyclooxygenase-2 inhibitor with pH-dependent solubility. To achieve pH-independent drug release of meloxicam, pH modifying agents (buffering agents) were used. Meloxicam tablets containing polyethylene oxide were dually coated with ethyl cellulose containing hydrophilic material, polyethylene glycol as an inner coating layer and methyl acrylate, methyl methacrylate, and methacrylic acid copolymer (Eudragit® FS 30D) as outer coating layer for colon targeting. Optimized tablet formulations demonstrated good potential to deliver the drug to the colon by successfully exhibiting a lag time of 5 h during in vitro drug release study. An in vivo evaluation study conducted to ascertain pharmacokinetic parameters in rabbits revealed that the onset of drug absorption from the coated tablets (T(lag time) = 4.67 ± 0.58 h) was significantly delayed compared to that from the uncoated tablets. The AUC(0→)(t) and AUC(0→∞) for coated tablets were lower than of uncoated tablets, although the difference was not significant (p > 0.01). The roentgenography study revealed that the tablet remained intact, until it reached the colon (5 h), which demonstrates that the system can efficiently deliver the drug to the colon. This study demonstrated that a meloxicam-loaded colon targeted system exhibited promising targeting and hence may be used for prophylaxis of colorectal cancer.

Comparison of release-controlling efficiency of polymeric coating materials using matrix-type casted films and diffusion-controlled coated tablet

Polymeric coating materials have been widely used to modify release rate of drug. We compared physical properties and release-controlling efficiency of polymeric coating materials using matrix-type casted film and diffusion-controlled coated tablet. Hydroxypropylmethyl cellulose (HPMC) with low or high viscosity grade, ethylcellulose (EC) and Eudragit(R) RS100 as pH-independent polymers and Eudragit S100 for enteric coatings were chosen to prepare the casted film and coated tablet. Tensile strength and contact angle of matrix-type casted film were invariably in the decreasing order: EC> Eudragit S100> HPMC 100000> Eudragit RS100>HPMC 4000. There was a strong linear correlation between tensile strength and contact angle of the casted films. In contrast, weight loss (film solubility) of the matrix-type casted films in three release media (gastric, intestinal fluid and water) was invariably in the increasing order: EC < HPMC 100000 < Eudragit RS100 < HPMC 4000 with an exception of Eudragit S100. The order of release rate of matrix-type casted films was EC > HPMC 100000 > Eudragit RS100 > HPMC 4000 > Eudragit S100. Interestingly, diffusion-controlled coated tablet also followed this rank order except Eudragit S100 although release profiles and lag time were highly dependent on the coating levels and type of polymeric coating materials. EC and Eudragit RS100 produced sustained release while HPMC and Eudragit S100 produced pulsed release. No molecular interactions occurred between drug and coating materials using (1)H-NMR analysis. The current information on release-controlling power of five different coating materials as matrix carrier or diffusion-controlled film could be applicable in designing oral sustained drug delivery.

Optimization of budesonide compression-coated tablets for colonic delivery

The purpose of this study was to formulate budesonide (BUD) compression-coated tablets for colonic specific delivery. Pectin and guar gum were used as enzyme-dependent polymers. For comparison purposes, both pH- and time-dependent polymers were also tried. In vitro release studies were carried out at different pH (1.2, 6.8, and 7.4). Therapeutic efficacy of the prepared tablets compared to commercially available capsules and enema were evaluated in trinitrobenzenesulfonic acid-induced rabbit colitis model. In pH-dependent polymers, Eudragit (EUD) S100/EUD L100 (1:1) released 45.58% in the target area (colon). For time-dependent polymers, decreasing cellulose acetate butyrate (CAB) ratio increased the release in both pH 6.8 and 7.4 till it reached 40.58% and 93.65%, respectively, for 25% CAB. In enzyme-dependent polymers, increasing pectin ratio to 75% retarded the release (4.59% in pH 6.8 and 54.45% in pH 7.4) which was significantly enhanced to 99.31% using pectinolytic enzyme. Formula F14 coated with 75% pectin significantly reduced the inflammatory cells in the connective tissue core of the colon of the treated group and significantly decreased myeloperoxidase activity (3.90 U/g tissue weight). This study proved that BUD compression-coated with 75% pectin may be beneficial in the treatment of inflammatory bowel disease.

Oral pulsatile delivery systems based on swellable hydrophilic polymers

Upon contact with aqueous fluids, swellable hydrophilic polymers undergo typical chain relaxation phenomena that coincide with a glassy-rubbery transition. In the rubbery phase, these polymers may be subject to swelling, dissolution and erosion processes or, alternatively, form an enduring gel barrier when cross-linked networks (hydrogels) are dealt with. Because of the peculiar hydration and biocompatibility properties, such materials are widely exploited in the pharmaceutical field, particularly as far as hydrophilic cellulose derivatives are concerned. In oral delivery, they have for long been employed in the manufacturing of prolonged release matrices and, more recently, for pulsatile (delayed) release devices as well. Pulsatile delivery, which is meant as the liberation of drugs following programmed lag phases, has drawn increasing interest especially in view of emerging chronotherapeutic approaches. In pursuit of pulsatile release, various design strategies have been proposed, chiefly including reservoir, capsular and osmotic formulations. In most cases, water-swellable polymers play a key role in the overall delivery mechanism after being activated by physiological media. Based on these premises, the aim of the present review is to survey the main oral pulsatile delivery systems, for which swelling, dissolution and/or erosion of hydrophilic polymers are primarily involved in the control of release.

Different HPMC Viscosity Grades as Coating Agents for an Oral Time and/or Site‐Controlled Delivery System: An Investigation into the Mechanisms Governing Drug Release

When used as release-controlling coating agents for tableted core-based pulsatile delivery systems, three different hydroxypropyl methylcellulose (HPMC) grades, Methocel E5, E50, and K4M, provided lag phases of varying duration (Methocel K4M > E50 > E5) and a prompt and quantitative model drug release. Dissolution/mechanical erosion, permeability increase and disruption of the hydrated polymeric layer were assumed to participate in the definition of the overall release pattern. Based on these premises, we investigated what process(es) might prevail in the release-controlling mechanism for each HPMC grade. The polymers were evaluated for dissolution and swelling, while the finished systems were concomitantly evaluated for drug release and polymer dissolution. The obtained results indicated likely similarities between Methocel E5 and E50 performances, which we hypothesized to be mainly dissolution/erosion-controlled, and a clearly different behavior for Methocel K4M. This polymer indeed proved to yield higher viscosity and slower dissolving gel layer, which was able to withstand extensive dissolution/erosion for periods that exceeded the observed lag phases. The particular characteristics of swollen Methocel K4M were shown to be associated with possible drug diffusion phenomena, which might impair the prompt and quantitative release phase that is typical of pulsatile delivery.

Study on the Colon Specific Delivery of Prednisolone Using Chitosan Capsules

In this study, we examined the effectiveness of chitosan capsules for the colon-specific delivery of prednisolone in rats. We also evaluated the effectiveness and side effects of prednisolone using chitosan capsules compared with the conventional dosage form (gelatin capsules). We found a significant increase in the concentration of prednisolone in the large intestinal mucosa when prednisolone was administered orally using chitosan capsules, as compared with the case using gelatin capsules. On the other hand, the plasma concentrations of prednisolone after oral administration using chitosan capsules were much lower than those in the case of gelatin capsules. We also assessed the effectiveness of prednisolone for the healing of trinitrobenzene sulfonic acid-induced colitis by measuring myeloperoxidase (MPO) activity and colon wet weight/body weight (C/B) ratio. MPO activities and C/B ratios were significantly reduced when prednisolone was administered orally using chitosan capsules, in comparison with the case of gelatin capsules. Moreover, the weight of the thymus, which is an index of the side effects of prednisolone, markedly decreased after oral administration of prednisolone using gelatin capsules, whereas its weight did not change as much when prednisolone was administered orally using chitosan capsules. These findings indicate that chitosan capsules might be useful for the colon-specific delivery of prednisolone and its enhanced effectiveness for the healing of colitis in rats. Moreover, chitosan capsules might be also effective in reducing the side effects of prednisolone due to its decreased intestinal transfer to the systemic circulation.

Time-controlled oral delivery systems for colon targeting

In recent years, many research efforts have been spent in the achievement of selective delivery of drugs into the colon following oral administration. Indeed, colonic release is regarded as a beneficial approach to the pharmacological treatment or prevention of widespread large bowel pathologies, such as inflammatory bowel disease and adenocarcinoma. In addition, it is extensively explored as a potential means of enhancing the oral bioavailability of peptides, proteins and other biotechnological molecules, which are known to be less prone to enzymatic degradation in the large, rather than in the small, intestine. Based on these premises, several formulation strategies have been attempted in pursuit of colonic release, chiefly including microflora-, pH-, pressure- and time-dependent delivery technologies. In particular, this review is focused on the main design features and release performances of time-controlled devices, which rely on the relative constancy that is observed in the small intestinal transit time of dosage forms.

Properties of sustained release hot-melt extruded tablets containing chitosan and xanthan gum

The aim of this study was to investigate the influence of pH, buffer species and ionic strength on the release mechanism of chlorpheniramine maleate (CPM) from matrix tablets containing chitosan and xanthan gum prepared by a hot-melt extrusion process. Drug release from hot-melt extruded (HME) tablets containing either chitosan or xanthan gum was pH and buffer species dependent and the release mechanisms were controlled by the solubility and ionic properties of the polymers. All directly compressed (DC) tablets prepared in this study also exhibited pH and buffer species dependent release. In contrast, the HME tablets containing both chitosan and xanthan gum exhibited pH and buffer species independent sustained release. When placed in 0.1N HCl, the HME tablets formed a hydrogel that functioned to retard drug release in subsequent pH 6.8 and 7.4 phosphate buffers even when media contained high ionic strength, whereas tablets without chitosan did not form a hydrogel to retard drug release in 0.1N HCl. The HME tablets containing both chitosan and xanthan gum showed no significant change in drug release rate when stored at 40 degrees C for 1 month, 40 degrees C and 75% relative humidity (40 degrees C/75% RH) for 1 month, and 60 degrees C for 15 days.

Oral pulsatile drug delivery systems

In the field of modified release, there has been a growing interest in pulsatile delivery, which generally refers to the liberation of drugs following a programmable lag phase from the time of administration. In particular, the recent literature reports on a variety of pulsatile release systems intended for the oral route, which have been recognised as potentially beneficial to the chronotherapy of widespread diseases, such as bronchial asthma or angina pectoris, with mainly night or early morning symptoms. In addition, time-dependent colon delivery may also represent an appealing related application. The delayed liberation of orally administered drugs has been achieved through a range of formulation approaches, including single- or multiple-unit systems provided with release-controlling coatings, capsular devices and osmotic pumps. Based on these premises, the aim of this review is to outline the rational and prominent design strategies behind oral pulsatile delivery.

Innovative therapeutics: from molecules to medicines. 27 June-7 July 2004, Parma, Italy

The Socrates Intensive Programme offers annual courses focusing on the specific aspects of innovative therapeutics. The 2004 meeting was coordinated by the University of Parma and covered various subjects in the field of advanced drug delivery and pharmaceutical technology, including sessions on biopharmaceutics, pharmacokinetics, polymers, oral delivery, colloidal vectors, peptide and protein delivery, vaccines, oligonucleotide delivery, gene delivery, non-conventional routes of administration, and a graduate student symposium. The meeting had a highly interactive character and provided a unique opportunity for young scientists to present and discuss their work in an international setting.