Towards the Future of Controlled Release Applications

Authors: Ian Campbell

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This work by Ceram is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 3.0 Unported License

Finding use in many different industrial sectors, controlled release technologies are most prevalent in the healthcare industry thanks to drug delivery and biomedical applications.

This white paper details the controlled release systems and mechanisms of release currently available and examines the materials used in this technology. The advantages of polymer and glass and ceramic materials are described, with a particular emphasis on how these and hybrid ceramic components can help to solve the challenges currently associated with controlled release technologies.

Introduction

The concept of controlled release, as opposed to instant release, refers to a gradual liberation of an agent in order to maintain its concentration or availability over a period of time. It is possible to distinguish between different types of controlled release: slow or sustained controlled release (control of the availability by delivering an agent over an extended period of time) or triggered release (tailored delivery as response of environmental stimuli permitting the selection of the conditions, time and site of delivery). There are multiple advantages associated with a prolonged delivery of active ingredients. Firstly, a more efficient action of the agent delivered is achieved, since the dosage is kept at a certain level for a continued period of time. Also, by maintaining the concentration within a certain range, any associated side effects, due to a too high, toxic, or too low, ineffective, dose, can be avoided. This, in the case of medical applications, for instance, presents a definite therapeutic benefit. Additionally, keeping a steady concentration in the bloodstream reduces the frequency of dosage, something which has a positive effect on the patient in terms of convenience and in improving their quality of life. Furthermore, the overall level of active ingredients may be reduced to achieve the same effect due to a more efficient availability; this, of course, also has a cost-saving effect. In the food industry, this type of controlled release avoids or reduces the loss of ingredients, such as vitamins and minerals, during processing. Finally, it permits the separation of incompatible or unstable compounds that are only liberated when their action is required.

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Figure 1: Controlled release vs. instant release

Applications

Controlled release is mostly associated with drug delivery and biomedical applications. However, the scope of sustained release technology is much broader and, as such, it can find applications in many different sectors. In agricultural applications the continuous supply of nutrients at a specific site over an extended time is beneficial for growth of the plants or crops. Equally, for pesticides or herbicides, the technology permits enhanced site-specific action and avoids accumulation of the compounds in soils or water streams that can cause adverse environmental and health effects.

Another area of emerging interest in sustained release technologies is that of paint coatings. In the marine industry, the release of anti-fouling agents to prevent algae proliferation and attachment on surfaces supposes a promising strategy. By reducing the surface resistance it is possible to reduce up to 60% of the energy consumption of marine vessels.In personal care and cosmetics, microencapsulation of l-menthol in soluble glass microspheres in toothpastes combines the release of the flavouring agent and elements enabling tooth remineralisation, therefore providing the benefit of a long-lasting flavour with a restorative action.

An overview and examples of applications areas of sustained release technology is presented in Table 2.

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Table 2. Examples of Areas of Applications of Controlled Release

Area of application Examples Paints Hybrid sol–gel derived films for environmentally-friendly

corrosion protection of metals Encapsulated biocides in silica networks added to coatings for

controlled delivery to reduce the amount of biocide released to the environment and maintain a minimum concentration at the coating interface, over time

Agriculture Nutrients, herbicides, fungicides, pesticides Controlled release formulations for reducing leaching of

herbicides and contamination of groundwater. Use of natural or environmentally compatible materials as carriers (of special interest in terms of economy and sustainability)

Controlled release formulations for decreasing pesticide mobility through the soil and protect from photodegradation.

Polymer-coated controlled release fertilizer as green fertilizer for controlling contamination in agriculture

Glasses that release slowly trace elements used as fertilizers Copper and trace element glass boluses for the slow release

of nutrients as dietary supplements in animal husbandryPharmaceuticals Ceramics, glasses and glass-ceramics for the delivery of

drugs, peptides, hormones, anti-inflammatory agents, antibiotics, vitamins, etc

Bioactive and resorbable bioceramics, glasses and glass-ceramics for coatings of implants for dental applications and bone regeneration. Used as fillers for restorative materials or as scaffolds

Controlled release of local anaesthetics and antiseptics in tissue-compatible wound dressings

Household and personal care

Nanocapsules for loading and release of antimicrobial molecules used as additives in household surface cleaning

Polyurethane hollow microcapsules sprayed on leather and textiles that release perfume when subjected to pressure

Controlled release of insecticide microcapsules for common household insect pest control

Extended release over time of fragrances for air freshener products

Active bioglasses in toothpaste formulations and tooth whitening products

Cosmetics Controlled release of retinol in anti-ageing products from silica particles

Soluble glasses as anti-ageing ingredients by releasing ions in an aqueous medium

Food Controlled release of flavours for greater intensity and for long periods of time

Thermally sensitive controlled release of flavour compounds to improve the appeal of frozen baked foods upon heating

Active packaging materials able to release antimicrobial compounds into foodstuffs to inhibit or slow down bacterial growth during storage

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State-of-the-art

The choice of the type of controlled release system and the delivery mechanism depends strongly on the physical and chemical properties of the active agent, the route of delivery and the application. The use of certain materials may be restricted by the compatibility with the active ingredients. Also, the market sector and the final use both play an important role in selecting or discarding the most promising, suitable and economically viable controlled release technology. Materials of different natures and properties have been developed up to the present day. These can be classified into two major groups:

Materials

PolymersCurrently, both organic (e.g. polylactic acid derived) and inorganic (silicone) materials are used as materials for the production of controlled release devices. Each group presents unique properties that make them suitable for their final application. The combination of both types to obtain composite and hybrid systems is common and leads to new products with enhanced benefits with respect to their constituents.

Biodegradable (natural or synthetic) and non-biodegradable polymers are widely used in controlled release applications. The most common polymer types are:

Acryl and vinyl polymers: cross linked acrylic acid-based polymers present swellable behaviour in aqueous solutions due to the presence of ionisable functional groups. Under certain pH they acquire charge and the electrostatic repulsion between these groups favours the intake of water and the expulsion of the agent. This feature makes them suitable candidates for pH-triggered controlled release, at specific sites. Some of these polymers are commercialized under the names Carbopol®.

Lactic and glycolic acid-based polymers show excellent biocompatibility and hydrophilic nature, which makes them good choices for controlled release and drug delivery.

Polysaccharides such as chitosan and its derivatives are water soluble, non-toxic, biocompatible and biodegradable. They, and their combination with poly (acrylic acid) or poly (methyl methacrylate), are mostly used to produce cross linked micro and nanoparticles for controlled release of proteins, vaccines, pharmaceutical compounds and pesticides.

Cellulose-derived polymers, which present different hydrophilicity, swelling and degradation behaviour, also offer a flexible and tuneable alternative for controlled release. Commercial examples of these materials are ETHOCEL™, METHOCEL™ and POLYOX™.

Poly (β-amino ester) polymers are also used to design pH-responsive polymer microspheres. Such systems degrade slowly at pH 7.4 but enable a fast and quantitative release (up to 90% of the encapsulated agent) in acidic conditions, which is of interest in biomedical applications to achieve specific different release rates within the physiological pH of the specific site.

Mixed inorganic-organic polymers: silicones.

Glass and CeramicsDespite the current commercial success of polymeric systems, a general trend has, in recent years, emerged from the need for alternatives to polymeric materials in controlled release applications.

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Depending on the final use, expensive tailor-made polymers are required, which, of course, raises manufacturing costs. In addition, polymer structures may display poor thermal, chemical and mechanical stability. This leads to their structure not remaining stable under certain conditions as they undergo swelling and plasticization. Furthermore, on occasion, they present problems associated with the presence of relict degradation products after use and the presence of residual organic solvents, which are required for polymer processing. For example, under certain conditions, the degradation of poly methyl methacrylate may lead to the formation of formaldehyde. This is associated with certain toxicity and presents a risk to both health and environment; hence, the growing interest in inorganic materials as substitutes.

Glass and ceramic materials have unique properties that make them excellent candidates as carriers for sustained release. They present controllable thermal and chemical resistance, especially in strong acid and alkaline environments, which may help to prevent the degradation of the active agent(s). They do not react with solvents (e.g. gastric resistance) to which most of polymers are susceptible. This opens up, for instance, new delivery routes, such as enteral delivery. Also, compared to polymers, they do not swell or change structure under pH or temperature variations, avoiding potential dose-dumping problems. Upon processing into a micro-porous or nano-porous form, they provide numerous sites for hosting functional compounds. Depending on their composition, the solubility of glasses and ceramics can be tailored to suit the requirements of delivery. This property makes them very interesting, not only in controlled release, but also as temporary scaffolds for the regeneration of hard and soft tissues.

Another intrinsic advantage of ceramics and glasses is that they can be designed with compatible chemistry with the target tissue. For instance, a calcium phosphate ceramic is in essence hydroxyapatite. Modified hydroxyapatite is the main mineral of enamel and dentine and it also constitutes up to 50% of bone composition. This ensures good compatibility and low toxicity.

Two main possibilities exist for the production of glass and ceramic materials for controlled release applications: fusion and sol-gel routes. Traditional fusion-derived glasses are prepared by melting mixtures of the glass components in the appropriate ratios at high temperatures followed by cooling into a glassy solid structure. Further processing may involve grinding to obtain particles of the desired size, which can be further sintered or shaped into the proper format for delivery. This synthesis route permits the incorporation of specific elements into the glass structures as active ingredients (e.g. Cu-containing glasses present anti-fouling properties and Ag-containing glasses are used as anti-microbial materials); this is in addition to their potential as matrixes or carriers for other active compounds.

Sol-gel techniques comprise the transformation from a solution containing the glass precursors into a solid network. By adding sacrificial agents it is possible to obtain porous structures to be loaded with the agent to be released. Compared to fusion derived glasses, sol-gel glasses and ceramics present bioactive properties which are not solely determined by the composition and the choice of the precursor materials but also by the final porous and ordered structure.

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In a similar way to polymeric systems, it is possible to design stimuli-responsive glasses by selecting the organosilane precursors to incorporate different organic functional groups in sol-gel preparation. The proper combination of hydrophilic amino groups and hydrophobic organic moieties enables control of the non-covalent interactions with water (reversible swelling and shrinkage upon intake and expulsion of water molecules respectively). The advantage over polymers is that sol-gel derived glasses offer a cost-effective method with the ability to control structure and composition at a molecular level. The resulting glasses may show expansion/shrinkage when a stimulus is applied. Alkoxodisilane precursors with long-chain spacer units allow formation of materials with enlarged pores, which are more likely to exhibit pronounced structural changes due to an increased retention of water in the network.

Controlled Release Systems

Reservoir SystemsThese are based on the confinement of an active agent within a porous or non-porous barrier or shell that protects it temporarily or permanently from the external environment. Shell materials can present different properties in terms of permeability, and can range from being permeable to impermeable. The core materials of the microcapsules can be solid, liquid or gas. The thickness of the barriers, the permeability and the area all affect the release rate. When placed in contact with a different medium, the core compounds are released at a determined rate that also depends on properties of the core compound itself affecting its diffusion and mobility. If the reservoir contains the active agent in excess of the concentration of the environment, the release rate is constant following zero-order kinetics.

A common method to obtain reservoir-type carriers for controlled release is microencapsulation. Encapsulated substances include compounds of varied natures such as drugs, pigments, nutrients, fragrances, anti-microbial compounds, etc. The main advantage of microencapsulation is the separation of the active agent from the medium of storage. This ensures good compatibility and stability of the compounds prior to use, thereby avoiding undesired reactions and facilitating handling which, in turn, increases the lifetime of the product. 6

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Figure 2: Release profile of an active agent in sol-gel glass carriers with the same composition but different physical properties and morphologies related to the synthesis parameters

Different techniques and processes permit microcapsules of various morphologies, sizes and structures to be obtained. They can be classified as chemical methods (e.g. in-situ reactions at the interface of emulsions), physico-chemical processes (e.g. sol-gel encapsulation: entrapment of a medium containing the active agent by the solidification of a solution into a solid shell structure) and physico-mechanical techniques (e.g. spray drying of a polymer solution containing the core agents which is sprayed in a hot chamber causing the solidification of the shell material).

Matrix SystemsThe agents are dispersed or dissolved homogeneously throughout a material which is processed into the desired shape and geometry. The geometry of the carrier, the type of material and the concentration of the active agent affect the release rate.

Mechanisms of Release

Diffusion-Controlled ReleaseThe agent is confined in a matrix consisting of a degradable or non-degradable material. The mechanisms for release involve migration and diffusion within the reservoir to the surface of the matrix followed by the distribution of the active compound between the interface between the matrix and the surrounding medium and, finally, the transport away from the surface into the medium. The dose and release rate depend on the chemical and physical properties of the system, which can be adjusted and tailored for the specific application by controlling compositional and non-compositional parameters during synthesis. For porous systems, diffusion is the rate-limiting step in administration and it can be modified and adjusted by changing the polymer structure (cross linking, crystallinity), the thickness of the barrier and the solubility of the degradable material (addition of additives and plasticizers). In the case of degradable materials the delivery is enhanced by the degradation of the carrier shell. These release mechanisms are characteristic of reservoir and matrix systems.

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Figure 3: Silica microcapsules synthesized via sol-gel as controlled released carriers for an over-the-counter drug

Figures 4 and 5: Examples of porous and non-porous silica carriers including a dispersed over-the-counter drug

Solvent-Activated ReleaseSome materials exhibit reversible swelling/shrinkage in water due to changes in hydrophobicity and altered interactions between the organic groups present. When in contact with water they undergo a transition from glassy to a gel state, in contrast to diffusion controlled systems in which the membrane remains unaltered. This behaviour increases the mobility of the structural chains favouring the diffusion and release of the agent molecules.

Osmotically-controlled ReleaseSo-called osmotic systems are very promising for the delivery of poorly soluble compounds. They are based on the effect of osmotic pressure, caused by the flow of

water through a semi-permeable membrane into a solution containing a solute (osmotic agent) that cannot permeate through the membrane. This facilitates the ejection of an active ingredient (different from the osmotic agent) that is dispersed in a polymeric matrix but cannot normally diffuse through it. Upon water intake, directly proportional to the solute concentration,

the internal pressure increases and, thus forces the active ingredient out of its confinement in opposition of the inward flow of water. An advantage of these systems is that the delivery is independent of the properties of the active agent and the pH of the environment. It can be pulsed or delayed by finely tuning and by the concentration of the osmotic agent, as well as by the porosity and the thickness of the semi permeable membrane. Therefore it is suitable for the delivery of agents of different nature and sizes, ranging from ions to macromolecules. However, the complexity and the possibility of a burst release, due to structural defects of the carriers, are the main drawbacks of these systems.

Stimulus-responsive ReleaseSmart materials capable of adapting their response to changes in environmental parameters show great potential for controlled release. Reversible swelling/shrinkage behavior can be affected by the presence of salts, pH, ionic strength or temperature. Also the active ingredient may be released by physical pressure on the barrier/shell covering the core where it is contained. Some inorganic modified silica-based gels undergo swelling when exposed to salts and shrinkage when exposed to water. The swelling correlates linearly with the salt concentration due to the increased intake of ions along with water. Also, at low pH, the protonation of the amino groups in the silica network also causes the intake of water molecules leading to expansion of the gel. Polymeric hydrogels based on poly (N-isopropylacrylamide) also present a reversible swelling/shrinkage in response to changes in temperature, which permits a certain control of the release rate.

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Figure 6: The osmotic pressure is created by the flow of fluid into the dosage form. The rate of release of the drug from the dosage form is directly proportional to the osmotic pressure created by the fluid

Chemically-activated ReleaseDrug release in biodegradable polymers takes place by hydrolysis of the initially non-soluble polymers into smaller non toxic molecules. The rate of hydrolysis depends on the chemistry, environmental factors (pH, temperature, etc) and the physical features such as the morphology, the degree of cross linking and the molecular weight distribution, among others. The degradation of the polymeric structure can occur either at the surface or in bulk. In the latter case there is normally an uptake of the aqueous medium into the structure followed by a cleavage of chemical bonds. As a result, the active agent, which can be entrapped, dissolved or bonded to the polymer matrix, is released at a determined rate accompanied by the resulting hydrolysis products, which are non toxic and can be eliminated via common metabolic routes.

Hydrolysis can take place by different mechanisms - either by cleavage of covalent bonds in the network backbone or cross-links or by ionisation of the side-groups, which result in the solubilisation of the resulting molecules.

Patented Controlled Release Technologies

Considerable attention is given to the development of controlled release delivery systems. New systems may enable novel routes of administration with increased dosage intervals of certain agents, permitting protection against degradation and a more targeted delivery to a specific site. This is the case, for instance, in the administration of proteins which have a short half life and low oral bioavailability. Traditionally, proteins have been administered by injections directly into the bloodstream – this can result in fluctuations of the concentration in the blood and therefore a loss of efficiency of the treatment. With a controlled release system, the frequency of administration can be reduced and the therapeutic concentration maintained.

Multiple controlled release technologies have been patented and are present in the marketplace. These include oral, transdermal, injectable and implantable forms. Some of the patented controlled release osmotic systems are listed in the table below.

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Table1. Patented Controlled Release Technologies

Technology Route DescriptionPort® Oral Two dosage formats: tablet or capsule. A polymeric matrix

containing the drug is coated by a semi permeable polymer rate-controlling polymer. An initial dosage is released followed by the release of a second dosage of the agents contained in a gelatine core coated with a semi permeable membrane. When placed in contact with an aqueous medium, the water diffuses and increases the osmotic pressure and therefore ejects the agent after a lag time depending on the coating thickness.

Flamel Oral Capsules or tablets containing microparticles which are liberated in the stomach and pass into the small intestine, where each microparticle delivers the drug. Effective control of release of multiple drugs and for delayed/extended delivery of small molecules with a narrow window of absorption.

Oros® Oral A semi permeable membrane surrounds a tablet core consisting of a drug layer containing a poorly soluble drug that is enclosed by a sacrificial push layer containing a water swellable polymer as osmotic agent. Upon contact with an aqueous medium, the osmotic agent facilitates the ejection of the confined drug.

EnSotrol™ Oral Delivery is caused by water entering the core of a reservoir through a membrane where there is a solubility enhancer that helps to dissolve the compound. The solution containing the active agent of interest is then delivered through the exit orifice.

Duros™Injectable Through osmosis, water from the body is slowly drawn

through a semi-permeable membrane. An osmotic agent expands and displaces a piston-like structure to dispense small amounts of drug formulation from the drug reservoir through the orifice.

DermaSal™ Transdermal Patch consisting of a rate-controlling polymeric matrix.

MicroSal™ Oral/implantsHydrophobic microspheres in the form of a free-flowing powder. They provide high retention of ingredients and can be utilized for sustained release, targeted delivery, and heat triggered release. It can be incorporated in both aqueous and anhydrous products in applications such as healthcare, household, personal care and food.

Lipoparticle™

Topical Microencapsulation of an active agent. Either in a capsule of a shell material surrounding a single droplet or particle of a hydrophobic core material or consisting of many small droplets of material entrapped in a polymer matrix. Suitable for the incorporation of both hydrophobic and hydrophilic materials.

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Challenges

In general terms, the reduction of manufacturing and processing costs, together with improved efficiency and the beneficial effects of controlled release technology, represent key drivers for further developments in this area. However, one of the main challenges particular to controlled release technology is the achievement of time and site specific well-ordered delivery of one or multiple agent at a desired dosage and rate to avoid local and systemic side effects of the agents in other locations. For certain applications, besides the fundamental function as carrier of an active ingredient, an intrinsic functionality, such as good biocompatibility and bioactivity of the materials enclosing the active agents, is also highly desirable. In other cases, it is important to have an inert and stable structure, or alternatively, uniform biodegradability of the carrier is preferred, in order to eliminate any relict material.

In pharmaceutical/medical applications, besides the common ideal requirements of a site and time localised delivery, large molecules (DNA, proteins, vaccines, growth factors and alike) present some specific challenges to overcome. The carrier system must ensure the stability of the agents by enabling the transport and storage at room temperature, thus eliminating complexity and costs. Also, good solubility must be ensured and the drug precipitation or degradation during manufacturing and storage must be prevented

In the case of oral release products there are certain technology gaps and opportunities to fulfil. For instance, an increase of the residence time of the drug in the stomach to prolong its life time in the body and permit its enteric absorption would be advantageous. Another goal is the efficient loading and delivery of poorly soluble Active Pharmaceutical Ingredients (APIs). For particular therapies, such as the administration of antiretroviral drugs for HIV/AIDS treatment, controlled release tablets and ceramic implants, among others, have been developed and evaluated to both overcome problems with drug solubility and to improve targeting of the required sites. Although some reasonable success has been achieved, by using techniques such as spray drying and emulsification to increase their solubility, the question of performance, when incorporated in a conventional controlled release technology platform, still remains.

Accurate control over the release over time is of extreme importance in the case of the delivery of two or more agents in the same formulation. Also, the systems must be safe from accidental release or dose-dumping, which may cause dangerous side effects.

In addition to all of the previous qualities, an ideal system should be easy to fabricate, administer and, if necessary, remove.

Future

The technologies most likely to be developed beyond research stage are the ones that can offer low-cost solutions, are simple to commercialise and/or meet an unmet need. For instance, protein delivery by non-invasive methods (e.g. inhalation of insulin) has not succeeded because no therapeutic benefits compared to the parenteral (intravenous) administration have been confirmed. Therefore, this method has not progressed and substituted the conventional administration routes and will not do so, unless it can be proven to be economically viable.

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In terms of materials, glasses and ceramics have been gaining more and more attention over recent years. One reason is the possibility of creating different types by modifying their compositions. For instance, new glasses including N have been recently developed and have a high potential to be used in future both as fertilizers (source of N) as well as matrixes for the controlled release of other substances. Another example is the incorporation of trace elements, such as zinc and strontium, in common (bio) glass formulations. Upon glass dissolution, the release of these elements show enhanced bone grafting and regeneration for the treatment of osteoporosis.

In some cases, glasses and ceramics have a dual function due to their intrinsic bioactivity, which presents an added value with respect to an inert matrix in special biomedical and pharmaceutical applications.

Furthermore, compared to traditional polymeric systems, glasses and ceramics show a more reproducible control of the dissolution rate which provides a more reliable sustained release over an extended period of time. For example, porous silica-calcium phosphate ceramics are excellent carriers for the delivery of anti-cancer pharmaceuticals. Implants containing an anti-tumour agent show an initial drug burst release in the first 24 hours followed by a sustained release over 32 days (maintaining the therapeutic dose).

Ceramics (halloysite and related) have also been used for controlled release of opioids in cancer treatment. Experimental results have demonstrated that the active agent is released over a reproducible extended period of time (3hours) and that these carriers do not present the undesired dose-dumping effect when used in a tablet dosage form, even when crushed (simulating chewing in oral intake). This excellent property makes them especially suitable for oral administration for pain relief treatment and thus enables self-administration by the patient, thereby eliminating hospitalisation; a benefit for the patient and a reduction in costs for the healthcare system.

Sometimes, there is no single material than can provide all the properties desired. Despite their potential and the features described above, glasses and ceramics do not always completely fulfil the criteria required for certain applications. The two main weaknesses of these materials are their brittleness and their low mechanical strength when used as monoliths. In order to overcome these drawbacks, their combination with a low amount of polymers improves the toughness and processability of the resulting hybrid material. Nevertheless, the best results are obtained in hybrid materials containing a high content of ceramic component (up to 80%) with the purpose of preventing the instability of properties of polymeric systems. Some examples of hybrid materials include bioactive glass – polysulfone composites and sol-gel glasses or ceramics combined with gelatine or, polylactic acid or dextran composite scaffolds, which present a well-ordered porous structure that permits the loading of pharmaceutical active substances. Hybrid materials resulting from combination of different glasses and ceramics (e.g. apatite and calcium sulphate in equal amount nanocomposites) also present improved properties with respect to their constituents, in terms of better biocompatibility and a slower release of active compounds.

In conclusion, glasses and ceramics (either on their own or in combination with other compounds to create hybrid materials) seem to address some of the current existing challenges listed above and offer good prospects for controlled release in new areas.

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References

1. Recent patents on drug delivery and formulation 1 (2007) 236-255.

2. Angewandte Chemie International Edition 40 (2001) 1707–1710.

3. Journal of Sol-gel Science and technology 26 (2003) 553-560.

4. Medical Engineering and Physics 31 (2009) 1205-1213

5. European Journal of Pharmaceutics and Biopharmaceutics. 70 (2008) 697-710.

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About Ceram

Ceram is an independent expert in innovation, sustainability and quality assurance of materials.

With a long history in the ceramics industry, Ceram has diversified into other materials and other markets including aerospace and defence, medical and healthcare, minerals, electronics and energy and environment.

Partnership is central to how we do business; we work with our clients to understand their needs so that we can help them overcome materials challenges, develop new products, processes and technologies and gain real, tangible results.Headquartered in Staffordshire, UK, Ceram has approved laboratories around the world.

About the Author

Ian CampbellExpertise in: Glass Technology; Controlled ReleaseProject Leader

Ian has a first class Degree from Staffordshire University in Ceramic Science and Engineering and holds a Licentiateship of the Institute of Ceramics. As a trained expert witness Ian has a Cardiff University Bond Solon Expert Witness Certificate.

In addition to extensive experience in the field of materials and ceramics manufacture, Ian has specialist knowledge of glass and glaze composition and development. This expertise incorporates all product types including vitreous enamel and unique glass formulations for both traditional and non-traditional applications, especially in the coating, sealing and joining of materials with glass. Ian has also developed glass materials with functional properties related to the chemistry and controlled solubility of materials.

Glassy materials in powder or granulate form are employed, or have the potential to be employed in almost every area of technology from traditional ceramic glaze and vitreous enamels, to sealing and coating of electronic components, biomedical applications, cosmetics etc. Glasses may be stable and relatively inert or formulated to provide selected reactivity. The nature of the glassy state enables this wide range of properties to be developed for many applications. By using knowledge of the complex interactions of the glass constituents Ian is able to design and produce glassy materials with properties tuned for specific applications.

Ian has twenty-five years of industry experience in production, materials supply, research, development and consultancy. During his career, he has conducted numerous product development and troubleshooting projects for organisations in various sectors of the manufacturing and supply industry.

A regular lecturer at various institutes worldwide, Ian is an authority in the development, production, service and performance of ceramic products and glassy materials.

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