Preparation and evaluation of once-a-day injectable microspheres of interferon alpha in rats

Preparation of bioactive interferon alpha-loaded polysaccharide nanoparticles using a new approach of temperature-induced water phase/water-phase emulsion

The aim of this study was to develop a temperature-induced polyethylene glycol (PEG) water phase/polysaccharide water-phase emulsion approach for preparing interferon alpha-2b (IFNα-2b)-loaded polysaccharide nanoparticles. IFNα-2b was first added to a mixture of an aqueous solution of PEG and polysaccharide. The mixture solution was stirred in a magnetic stirrer at a rate of 2000 rpm for 45 seconds at 0°C ± 0.5°C. The solution was then prefrozen at different temperatures. The polysaccharide and IFNα-2b partitioned in the polysaccharide phase were preferentially separated out as the dispersed phase from the mixture solution during the prefreezing process. Then the prefrozen sample was freeze-dried to powder form. In order to remove the PEG, the powder was washed with dichloromethane. Once IFNα-2b was loaded into the polysaccharide nanoparticles, these nanoparticles could gain resistance to vapor–water and water–oil interfaces to protect IFNα-2b. The antiviral activity of the polysaccharide nanoparticles in vitro was highly preserved (above 97%), while the antiviral activity of IFNα-2b–loaded polysaccharide nanoparticles using the control water-in-oil-in-water method was only 71%. The antiviral activity of the IFNα-2b from blood samples was also determined on the basis of the activity to inhibit the cytopathic effects of the Sindbis virus on Follicular Lymphoma cells (FL). The antiviral activity in vivo was also highly preserved (above 97%). These polysaccharide nanoparticles could be processed to different formulations according to clinical requirements.

Development of interferon alpha-2b microspheres with constant release

Interferon alpha-2b (IFNα-2b) is an important immune regulator used widely in clinic. However, frequent subcutaneous injection and substantial toxicity decrease patients' compliance. So, drug delivery with more precisely controlled drug release is urgent for IFNα-2b. Microsphere is a promising sustained drug delivery system, which has been studied widely for delivery of proteins. However, it was found difficult to keep proteins' activity and guarantee complete release. In this study, we solidified IFNα-2b as microparticles firstly by co-lyophilizing it with gelatin and ZnSO(4). Microspheres were then prepared. The preparing procedure and formulation were optimized with encapsulation efficiency and in vitro release as main parameters. Finally, the microspheres were prepared by S/O/W method with microparticle size about 5 μm and PEGT/PBT-PLGA (9:1, w/w) as matrix material. The diameter of microspheres was 28.94 μm, the encapsulation efficiency was 86.01%, the burst release was 16.69%, the cumulative release was 83.06% at 23th day, and IFNα-2b was released from microspheres with a zero-order profile. These microspheres also demonstrated sustained and steady release for about 13 days in rats. In conclusion, the procedure and formulation used in this study were supposed to be successful to keep IFNα-2b active and released constantly and completely.

Fabrication, characterization and in vivo studies of biodegradable gamma sterilized injectable microparticles for contraception

A Levonorgestrel-loaded microparticulate system was developed with gelatin and bovine serum albumin using triple emulsion technique coupled with chemical cross-linking thermal rigidization method. The formulation was optimized for various formulation variables and process parameters. The microparticulate system was characterized by scanning electron microscopy, encapsulation efficiency, moisture content, IR, DSC, XRD, residual solvent content and evaluated for sterility, abnormal toxicity and absence of pyrogens. Microparticles were sterilized by gamma irradiation at 2.5 Mrad. The system was injected intramuscularly in rabbits and drug blood levels estimated using radioimmunoassay technique. An optimized drug to polymer ratio of 0.4:0.75 w/w gave drug encapsulation efficiency of about 40%. The in vitro drug release followed Higuchi square root kinetics. In in vivo studies the AUC0-t was found to be 12849.25 pg/mL.day(-1) with mean residence time calculated to be about 16 days and Kel of 0.02 day(-1). Levonorgestrel (LNG) levels were maintained between 200 and 400 pg/mL. The pharmacokinetic results indicate that LNG is released from the injectable microparticles for a period of one-month duration.

Cytotoxicity of 5-fluorouracil entrapped in gelatin microspheres

Gelatin microspheres were prepared by water/oil emulsion polymerization and by cross-linking with glutaraldehyde. For the microsphere preparation procedure, two different gelatin (5 or 10% w/v) and three different glutaraldehyde (5, 0.5 or 0.1% v/v) concentrations were used. The influence of preparation compositions on microsphere recovery, particle size and morphology, swelling and degradation, 5-fluorouracil loading and release, and cytotoxicity were investigated. The concentrations of gelatin and glutaraldehyde influenced the size and surface properties of microspheres. The decrease in gelatin concentration and the increase in glutaraldehyde concentration resulted in the formation of smaller (140.82-71.47 microm for gelatin microspheres with a 5% gelatin content; 297.67-97.44 microm for gelatin microspheres with a 10% gelatin content) microspheres with smoother surface properties. Swelling values were decreased as the amount of glutaraldehyde was increased. In particular, for microspheres with a high glutaraldehyde content (5% v/v), only about 15% were degraded in 12 days, whereas for those with 0.5% (v/v) glutaraldehyde, almost 97% degradation occurred in the same period. The most rapid 5-fluorouracil release was observed from uncross-linked microspheres (about 88% in 4 h), whereas a particular slower release (about 36% in 4 h) profile was obtained for the highly cross-linked ones. Cytotoxicity tests of free and entrapped 5-fluorouracil were carried out with MCF-7 breast cancer cell line. Free 5-fluorouracil produced an immediate effect, whereas entrapped 5-fluorouracil showed a prolonged cytotoxic effect.

Hydrophilic biodegradable microspheres of interferon-alpha and its pharmacokinetics in mice

The goal of this research was to prepare a kind of hydrophilic sustained release microspheres of interferon-alpha (IFN-alpha), alginate-chitosan microspheres (ACM) of IFN, and investigate its pharmacokinetics in mice. Alginate microspheres of IFN-alpha were first prepared by an emulsion method and further incubated in chitosan to form IFN-ACM. The influences of isopropanol, bovine serum albumin (BSA), and pH adjustment by isoelectric point of IFN were studied. The optimized IFN-ACM was obtained with smooth and round morphology, size of 2.18 +/- 0.43 microm and entrapment efficiency of 40%. All the concentrations of IFN-alpha were determined by IFN assay kits. Finally the pharmacokinetics of IFN-ACM suspension was studied in ICR mice by intramuscular (I.M.) routes. Compared with IFN solution, C(max) of IFN-ACM reduced 2.3-fold, and time to achievement of maximum serum concentrations (T(max)) increased 4-fold. Meanwhile the area under the concentration-time curve (AUC) was the same as that of solution. The concentration-time profiles presented the prolonged serum levels of IFN from IFN-ACM.

Transdermal delivery of interferon alpha-2B using microporation and iontophoresis in hairless rats

PURPOSE

To demonstrate transdermal delivery of interferon alpha-2b (IFNalpha2b) in hairless rats through aqueous microchannels (micropores) created in the skin and enhanced by iontophoresis.

MATERIALS AND METHODS

The Altea Therapeutics PassPort System was configured to form an array of micropores (2.0 cm(2); 72 micropores/cm(2)) on the rat abdomen. The transdermal patch (Iomed TransQ1-GS-hydrogel) was saturated with an IFNalpha2b solution (600 microg/ml) and applied for 4 h. Delivery was evaluated with and without cathodic iontophoresis (0.1 mA/cm(2)). Intravenous delivery (0.4 microg/100 g body weight) was performed to support pharmacokinetic calculations.

RESULTS

IFNalpha2b was not delivered through intact skin by itself (passive delivery) or during iontophoresis. However, passive delivery through micropores was achieved in vivo in rats. A dose of 397 +/- 67 ng was delivered over 6 h, with steady state serum concentrations reaching a plateau at 1 h post-patch application. These levels dropped rapidly after patch removal, and returned to baseline within 2 h of patch removal. Iontophoresis-enhanced delivery through micropores resulted in a two-fold increase in the dose delivered (722 +/- 169 ng) in the hairless rat.

CONCLUSIONS

In vivo delivery of IFNalpha2b was demonstrated through micropores created in the outer layer of the skin. Iontophoresis enhanced delivery through microporated skin in hairless rats.

Prolonged cytotoxic effect of colchicine released from biodegradable microspheres

One the main problems of cancer chemotherapy is the unwanted damage to normal cells caused by the high toxicities of anticancer drugs. Any system of controlled drug delivery that would reduce the total amount of drug required, and thus reduce the side effects, would potentially help to improve chemotherapy. In this respect, biodegradable gelatin microspheres were prepared by water/oil emulsion polymerization and by crosslinking with glutaraldehyde (GTA) as the drug-carrier system. Microspheres were loaded with colchicine, a model antimitotic drug, which was frequently used as an antimitotic agent in cancer research involving cell cultures. Microsphere sizes, swelling and degradation properties, drug-release kinetics, and cytotoxities were studied. Swelling characteristics of microspheres changed upon changing GTA concentration. A decrease in swelling values was recorded as GTA crosslink density was increased. In vitro drug release in PBS (0.01M, pH 7.4) showed rapid colchicine release up to approximately 83% (at t = 92 h) for microspheres with low GTA (0.05% v/v), whereas a slower release profile (only approximately 39%) was obtained for microspheres with high GTA (0.50% v/v) content, for the same period. Cytotoxicity tests with MCF-7, HeLa and H-82 cancer cell lines showed that free colchicine was very toxic, showing an approximately 100% lethal effect in both HeLa and H-82 cell lines and more than 50% decrease in viability in MCF-7 cells in 4 days. Indeed, entrapped colchicine indicated similar initial high toxic effect on cell viability in MCF-7 cell line and this effect became more dominant as colchicine continued to be released from microspheres in the same period. In conclusion, the control of the release rate of colchicine from gelatin microspheres was achieved under in vitro conditions by gelatin through the alteration of crosslinking conditions. Indeed, the results suggested the potential application of gelatin microspheres crosslinked with GTA as a sustained drug-delivery system for anticancer drugs for local chemotherapy administrations.

Alginate in drug delivery systems

Alginates are established among the most versatile biopolymers, used in a wide range of applications. The conventional use of alginate as an excipient in drug products generally depends on the thickening, gel-forming, and stabilizing properties. A need for prolonged and better control of drug administration has increased the demand for tailor-made polymers. Hydrocolloids like alginate can play a significant role in the design of a controlled-release product. At low pH hydration of alginic acid leads to the formation of a high-viscosity "acid gel." Alginate is also easily gelled in the presence of a divalent cation as the calcium ion. Dried sodium alginate beads reswell, creating a diffusion barrier decreasing the migration of small molecules (e.g., drugs). The ability of alginate to form two types of gel dependent on pH, i.e., an acid gel and an ionotropic gel, gives the polymer unique properties compared to neutral macromolecules. The molecule can be tailor-made for a number of applications. So far more than 200 different alginate grades and a number of alginate salts are manufactured. The potential use of the various qualities as pharmaceutical excipients has not been evaluated fully, but alginate is likely to make an important contribution in the development of polymeric delivery systems. This natural polymer is adopted by Ph.Eur. It can be obtained in an ultrapure form suitable for implants. This review discusses the present use and future possibilities of alginate as a tool in drug formulation.