Meral T. Ercan

Diclofenac sodium incorporated PLGA (50:50) microspheres: formulation considerations and in vitro/in vivo evaluation.

Recently, considerable interest has been focused on the use of biodegradable polymers for specialized applications such as controlled release of drug formulations; meanwhile, microsphere drug-delivery systems using various kinds of biodegradable polymers have been studied extensively during the past two decades. Poly (lactide-co-glycolide) (PLGA) polymers have been proven to be excellent drug carriers for microparticulate systems due to their advantages, e.g. biocompatibility and regulatory approval. The administration of nonsteroidal anti-inflammatory drugs (NSAIDs) into the intra-articular cavity in patients with chronic inflammatory disease is complicated due to the short duration of effect. In the present study, controlled-release parenteral formulations of diclofenac sodium (DS), a commonly used NSAID, were prepared for intra-articular administration, and evaluated in vitro for particle size, yield, drug loading, surface morphology and release characteristics. For in vivo studies, Technetium-99m labelled polyclonal human immunogammaglobulin (99m Tc-HIG) was used as the radiopharmaceutical to demonstrate arthritic lesions by gamma scintigraphy. Evaluation of arthritic lesions post-therapy in rabbits showed no significant difference in the group treated with PLGA (50:50) (mw 34000) DS microspheres compared to control groups.

In vitro and in vivo evaluation of diclofenac sodium loaded albumin microspheres

The use of polymeric carriers in formulations of therapeutic drug delivery systems has gained widespread application, due to their advantage of being biodegradable and biocompatible. Among the microparticulate systems, microspheres have a special importance since it is possible to target drugs and provide controlled release. Diclofenac sodium (DS), is a potent drug in the NSAID group having non-steroidal, anti-inflammatory properties, and is widely used in the treatment of rheumatoid arthritis, osteoarthritis and ankylosing spondylitis. In this present study, it was aimed to prepare microsphere formulations of DS using a natural biodegradable polymer as a carrier for intraarticular administration to extend the duration period of the dosage form in the knee joint. Microsphere formulations of DS which were prepared were evaluated in vitro for particle size, yield value, encapsulation efficiency, surface morphology, and in vitro drug release. Two appropriate formulations were selected for in vivo trials. For the in vivo studies, Technetium-99m labelled polyclonal human immunogammaglobulin (99mTc-HIG) was used as the radiopharmaceutical to demonstrate arthritic lesions by gamma scintigraphy. After the induction of arthritis in knee joints of rabbits, the radio-labelled microspheres loaded with DS were injected directly into the articular cavity and at specific time points gamma scintigrams were obtained to find the residence time of the microspheres in knee joints in order to determine the most suitable formulation.The use of polymeric carriers in formulations of therapeutic drug delivery systems has gained widespread application, due to their advantage of being biodegradable and biocompatible. Among the microparticulate systems, microspheres have a special importance since it is possible to target drugs and provide controlled release. Diclofenac sodium (DS), is a potent drug in the NSAID group having non-steroidal, anti-inflammatory properties, and is widely used in the treatment of rheumatoid arthritis, osteoarthritis and ankylosing spondylitis. In this present study, it was aimed to prepare microsphere formulations of DS using a natural biodegradable polymer as a carrier for intraarticular administration to extend the duration period of the dosage form in the knee joint. Microsphere formulations of DS which were prepared were evaluated in vitro for particle size, yield value, encapsulation efficiency, surface morphology, and in vitro drug release. Two appropriate formulations were selected for in vivo trials. For the in vivo studies, Technetium-99m labelled polyclonal human immunogammaglobulin (99mTc-HIG) was used as the radiopharmaceutical to demonstrate arthritic lesions by gamma scintigraphy. After the induction of arthritis in knee joints of rabbits, the radio-labelled microspheres loaded with DS were injected directly into the articular cavity and at specific time points gamma scintigrams were obtained to find the residence time of the microspheres in knee joints in order to determine the most suitable formulation.

Preparation, characterization and in vivo distribution of terbutaline sulfate loaded albumin microspheres

Terbutaline sulfate is widely used as a bronchodilator for the treatment of bronchial asthma, chronic bronchitis and emphysema. As it has a short biological half-life, a long acting terbutaline sulfate formulation is desirable to improve patient compliance. Bovine serum albumin microspheres were prepared by an emulsion polymerization method using glutaraldehyde as the crosslinking agent. All microspheres were spherical and smooth with the mean particle size in the range of 22-30 microm. Drug release from the BSA microspheres displayed a biphasic pattern characterized by an initial fast release, followed by a slower release. The released amount was decreased with an increase in the glutaraldehyde concentration. In the absence of trypsin, the time required for complete degradation of microspheres was increased from 144 to 264 h when the glutaraldehyde concentration increased from 0.1 to 0.7 ml. In the presence of trypsin, a linear relationship was obtained between the degradation rates and trypsin concentrations, indicating that saturation was not reached under the experimental conditions. Biodistribution studies indicated that the degree of uptake by the lungs was higher than that of the other organs. All these results demonstrated that terbutaline sulfate loaded microspheres can be used for passive lung targeting.

In vitro evaluation and intra-articular administration of biodegradable microspheres containing naproxen sodium

The dispersion of non-steroidal antiinflammatory drugs (NSAIDs) into biodegradable polymeric matrices have been accepted as a good approach for obtaining a therapeutic effect in a predetermined period of time meanwhile minimizing the side effects of NSAIDs. In the present study, it was aimed to prepare Naproxen Sodium (NS), (a NSAID) loaded microsphere formulation using natural Bovine Serum Albumin (BSA) and synthetic biodegradable polymers such as poly(lactide-co-glycolic acid) (PLGA) (50:50 MW 34,000 and 88,000 Da) for intra-articular administration, and to study the retention of the drug at the site of injection in the knee joint. NS incorporated microspheres were evaluated in vitro for particle size (the mean particle size; for BSA microspheres, 10.0 +/- 0.3 microm, for PLGA microspheres, 9.0 +/- 0.2 and 5.0 +/- 0.1 microm for MW 34,000 and 88,000 Da, respectively), yield value, drug loading, surface morphology and drug release. For in vivo studies, monoarticular arthritis was induced in the left knee joints of rabbits by using ovalbumin and Freunds Complete Adjuvant as antigen and adjuvant. A certain time (4 days) is allowed for the formation of arthritis in the knee joints, then the NS loaded microspheres were injected directly into the articular cavity. At specific time points, gamma scintigrams were obtained to determine the residence time of the microspheres in knee joints, in order to determine the most suitable formulation. This study indicated that PLGA, a synthetic polymer, is more promising than the natural type BSA microspheres for an effective cure of mono-articular arthritis in rabbits.

The use of commercial pectinase in fruit juice industry. Part I: viscosimetric determination of enzyme activity

The kinetics of commercial pectinase, Pectinex Ultra SP-L, in a batch reactor was studied. The change in viscosity of pectin solution was followed by an enzymatic assay to determine pectolytic activity of the enzyme preparation. The pectolytic activity of Pectinex Ultra SP-L was measured at pH 3.5 and 35°C and found to be 0.025 pectin % (w/v)/sec/enzyme % (v/v). The Michaelis-Menten constant (Km) of enzyme preparation was found to be 1.137 pectin % (w/v). The temperature dependence of the reaction rate was obeying the Arrhenius Law. The activation energy of the biochemical reaction catalysed by commercial pectinase was calculated as 9.316 kcal mol−1.

In-vivo studies on dexamethasone sodium phosphate liposomes

Dexamethasone Sodium Phosphate (DSP) is a water soluble anti-inflammatory steroid commonly used in the therapy of serious types of ophthalmic inflammation. It has been demonstrated that unless the corneal epithelium is damaged, DSP is poorly absorbed by the cornea (Kupferman et al. 1974). Thus, it is doubtful whether such a drug would cure inflammation of the anterior segments. For this purpose, several liposomal DSP formulations containing phospholipid: charge inducer: cholesterol in molar ratios of 10:1:4 were investigated. Both gel state (PL 90H: SA: Cho1) and liquid state (PL 100: SA: Cho1) liposomes were prepared. For the preparation of liposomes, the film method followed by bath sonication was used. Liposomes were labelled with (99m)-Tc and administered intra-ocularly to New Zealand white rabbits weighing 2.5-3 kg for in vivo experiments. The biodistribution of the labelled liposomes were determined. For this purpose, eye segments (such as cornea, lens, iris, ciliar body, vitreous, aqueous humor, conjuctiva and sclera) and RES organs (such as liver, pancreas, spleen) were removed at fixed time intervals. In the present study, the efficiency of liposomes for the delivery of water-soluble drugs was evaluated in rabbit eyes using DSP as a model drug in different liposomal formulations.

In-vivo studies in the treatment of oral ulcers with liposomal dexamethasone sodium phosphate

Liposomes are man-made organelles composed of bimolecular lipid layers enclosing aqueous compartments. Dexamethasone Sodium Phosphate (DSP) was encapsulated in MLV liposomes and served as the test solution. DSP in solution served as control. Both were labeled with 99mTc. The rats were divided into three groups: typical application group, intramucosal injection and control group. Oral mucosal ulcers were produced by silver nitrate and was monofocal. Rats were killed at three and 24 h, respectively, after application. Ulcerated mucosa, intact adjacent mucosa and distant mucosa were excised. Biodistribution was determined by radiotracer technique in the three mucosal parts as well as in the blood, liver, spleen and brain. Liposomes increase local and decrease systemic drug concentration. Another finding was that liposomes localize the drug in the ulcerated area. In conclusion, liposomes may be useful in the treatment of oral ulcers.

Evaluation of 99mTc-dextran as a lymphoscintigraphic agent in rabbits

Dextran (clinical grade, average mol. wt. 82,200) was labelled with 99mTc and the labelling efficiency was checked by paper and thin-layer chromatography and electrophoresis. The amount of free 99mTcO4-was always less than 1%. The radiopharmaceutical was injected ID into the web space in hind legs of ten rabbits (200–600 μCi/0.05 ml). Scintigrams were taken at 10-min intervals up to 3 h in three rabbits. The injection site and the hind legs were massaged after injection in the other seven rabbits and scintigrams were taken at 10-min intervals up to 2 h. Blood samples were obtained at 5, 15, 30, 90 and 120 min in both groups. In addition a 180-min sample, was also taken in the first group. At the end of the study the rabbits were killed and the popliteal lymph nodes and the organs were removed to be weighed, and counted. Our results indicated a high concentration of radioactivity in the popliteal lymph nodes and massage at the injection site increased the average uptake of the popliteal lymph node from 1.12%±0.77% to 4.28%±1.57% at 3 and 2 h, respectively (P<0.001). In scintigrams the lymph channels and the nodes were very well visualised. The blood radioactivity levels were too low to present a background problem. With massage 30% of the injected dose was removed from the injection site in 2 h. We have shown that 99mTc-dextran is a good radiopharmaceutical for the visualisation of the lymph system and deserves further experimental and clinical studies.

Characterization, in vitro and in vivo studies on primaquine diphosphate liposomes

In this study, several Primaquine diphosphate (PQ) liposomal formulations containing phospholipid, charge inducer and with or without cholesterol in molar ratios of 7:1:(2) and 10:1:(4) were investigated. Gel state (DPPC:CHEMS:CHOL and PL-100H:CHEMS:CHOL) and liquid-crystalline state (PL-100:CHEMS:CHOL and PL-90G:CHEMS:CHOL) liposomes were prepared. The film method followed by sonication and extrusion through polycarbonate membrane was used. Particle size distribution, percentage of entrapped active substance, content of phospholipid and bilayer type and composition were determined. Lamellarity was determined by 31P-NMR technique. In vitro release of PQ was investigated at 37 degrees C, 35 rpm and in Tris (pH: 7.4) buffer. In vitro release and its fit to kinetic models were investigated. Liposomes were labelled by 99mTc and injected intravenously to Swiss Albino mice.

99mTc-citrate versus 67Ga-citrate for the scintigraphic visualization of inflammatory lesions.

Citric acid was labeled with 99mTc with an efficiency of > 99%. The biodistribution of 99mTc-citrate was studied in mice with turpentine-induced abscesses in comparison to 67Ga-citrate. The max. abscess/muscle concentration ratios were 4.61 +/- 1.92 (3 h) for 99mTc-citrate and 4.76 +/- 2.04 (4 h) for 67Ga-citrate. Arthritis was induced in 10 rabbits by intra-articular injection of ovalbumin Scintigrams obtained 4 days later and at 3 h post-injection of 99mTc-citrate showed increased activity involving the synovium. The max. arthritic/contralateral knee ratio was 3.19 +/- 1.29 (3 h) and 6.47 +/- 3.71 (24 h) for 99mTc- and 67Ga-citrate, respectively. The blood clearance curve of 99mTc-citrate in rabbits was biexponential with a fast (T1/2 = 36 min) and a slow (T1/2 = 18 h) component, compared to mono-exponential clearance of 67Ga-citrate (T1/2 = 23 h). In 10 patients with rheumatoid arthritis whole-body scintigrams and spot images of involved joints indicated localization of the tracer in inflamed tissues. The mean target-to-soft tissue ratios were 3.04 +/- 0.81 and 4.95 +/- 2.56 for 99mTc-citrate and 99mTc-MDP, respectively. Renal clearance of radioactivity was evident from the scintigrams. Our results demonstrated that 99mTc-citrate is effective as a radiopharmaceutical for the visualization of inflammatory lesions and may be preferred to 67Ga-citrate due to the ideal physical characteristics of the radionuclide, easy preparation, low cost, early accumulation and the preference for the renal route of excretion.