Exploitation of capsule system for colon targeted drug delivery of biopolymer-based microparticles: in vivo and in vitro applications.

The current study was to improve and control aceclofenac delivery prepared as biopolymer-based microparticles for effective colon-targeted drug delivery using modified gelatin capsules (MGCs) at different time intervals developed in two batches (C1 and C2). Microparticles were formulated with extracted mucuna gum using liquid paraffin oil (AC.LPO) and soybean oil (AC.SO) and evaluated in vitro for physicochemical performance and in vivo in rats. Encapsulation efficiency ranges from 54.48 ± 0.21% to 82.83 ± 0.22% for AC.LPO and 52.64 ± 0.11% to 80.36 ± 0.22% for AC.SO. SEM showed oblong and irregular shapes with porous and cracked surfaces. DSC showed low enthalpy and a very broad endothermic peak depicting high amorphous property. Delayed drug release was observed in the upper gastrointestinal tract with sustained release depicted in the lower gastrointestinal tract (GIT) using 3 and 9-h batch C1 of MGCs. AC.SO exhibited significantly (p < 0.05) higher anti-inflammatory activity (86%) than AC.LPO (77%). Hence, aceclofenac colon delivery could be improved and controlled using biopolymer-based colon-targeted microparticles delivered with MGCs.

Microemulsion-based approach for oral delivery of insulin: formulation design and characterization.

Oral delivery of insulin provides a good alternative because it is non-invasive and patient-friendly. However, multiple challenges affected this route. To overcome barriers for oral delivery of insulin, we aimed to develop a novel insulin-loaded microemulsion system based on snail mucin for oral administration. The strategy in the novel system of using mucin loading insulin into the inner core of prepared water in oil microemulsion to provide sustained released, increased in vivo stability and enhanced drug absorption in the gastrointestinal tract. We report how microemulsion composed of varying ratios of snail mucin and Tween® 80 (1:9-9:1) using oil/water emulsion preparation method influenced insulin performance after oral administration. The results obtained include an encapsulation efficiency of above 70 %; in vitro release was sustained over 10 h and in vivo evaluations in diabetic rat model shows that insulin-loaded microencapsulation effectively reduced blood glucose levels over a period >8 h after oral administration. Therefore, we suggest that the developed formulation for oral insulin can be a promising alternative dosage form for oral protein delivery.

A new lipid-based oral delivery system of erythromycin for prolong sustain release activity.

Erythromycin-loaded solid lipid microparticles (SLM) based on solidified reverse micellar solution (SRMS) as an oral delivery formulation was studied. Hot homogenization technique was employed to prepare erythromycin stearate-loaded SLMs using blends of Softisan® 154 and Phospholipon® 90H or beeswax in the ratio of 1:2, and characterized in vitro. Antibacterial evaluation of the formulations was carried out by agar diffusion technique against some selected clinical isolates of bacterial. Preliminary pharmacokinetic study was performed after oral administration in male Albino rats. The results of matrix contain Softisan® 154 and phospholipon® 90H (1:2) showed that erythromycin-loaded SLM was smooth; particle size ranged from 10.3 ±â€¯11.24 µm to 18.1 ±â€¯10.11 µm and maximum encapsulation efficiency and loading capacity were 95.11 ±â€¯0.3% and 43.22 ±â€¯0.1 mg, respectively. While that of beeswax- containing matrix showed maximum particle size of 18.9 ±â€¯21.10 µm, maximum encapsulation efficiency of 89.01 ±â€¯0.11% and loading capacity of 39.02 ±â€¯0.12 mg. All the formulations had prolonged release and antibacterial activity. Significantly (p > 0.05), prolonged plasma erythromycin concentration was obtained in the optimized formulation (>14 h) compared with commercial sample of erythromycin tablet (10h). Erythromycin stearate-loaded SLMs formulation could serve as an alternative to conventional oral formulation of erythromycin.

Surface-modified mucoadhesive microgels as a controlled release system for miconazole nitrate to improve localized treatment of vulvovaginal candidiasis.

The use of conventional vaginal formulations of miconazole nitrate (MN) in the treatment of deep-seated VVC (vulvovaginal candidiasis) is limited by poor penetration capacity and low solubility of MN, short residence time and irritation at the application site. Surface-modified mucoadhesive microgels were developed to minimize local irritation, enhance penetration capacity and solubility and prolong localized vaginal delivery of MN for effective treatment of deep-seated VVC. Solid lipid microparticles (SLMs) were prepared from matrices consisting of hydrogenated palm oil (Softisan® 154, SF) and super-refined sunseed oil (SO) with or without polyethylene glycol (PEG)-4000, characterized for physicochemical performance and used to prepare mucoadhesive microgels (MMs) encapsulating MN, employing Polycarbophil as bioadhesive polymer. The MMs were evaluated for physicochemical performance and in vitro drug release in simulated vaginal fluid (pH=4.2), whereas mucoadhesive, rheological and stability tests, anticandidal efficacy in immunosuppressed estrogen-dependent female rats and vaginal tolerance test in rabbits were performed with optimized formulation. The amorphicity of 1:9 phytolipid blend (SO:SF) was increased in the presence of PEG-4000. The physicochemical properties of the SLMs and MMs indicated their suitability for vaginal drug delivery. Overall, MN-loaded PEGylated MMs exhibited significantly (p<0.05) more prolonged drug release than non-PEGylated MMs. Additionally, optimized PEGylated MMs was stable at 40±2°C over a period of 6months, viscoelastic, mucoadhesive, non-sensitizing, histopathologically safe and gave remarkably (p<0.05) higher reduction in Candida albicans load (86.06%) than Daktarin® (75.0%) and MN-loaded polymeric-hydrogel (47.74%) in treated rats in 12days. Thus, PEGylated MMs is promising for effective and convenient treatment of VVC.

Formulation, characterization and evaluation of the effect of polymer concentration on the release behavior of insulin-loaded Eudragit(®)-entrapped mucoadhesive microspheres.

INTRODUCTION: The aim of this study was to use Eudragit(®) RL 100 (pH-independent polymer) and magnesium stearate (a hydrophobic droplet stabilizer) in combination to improve the controlled release effect of insulin-loaded Eudragit(®) entrapped microspheres prepared by the emulsification-coacervation technique. MATERIALS AND METHODS: Mucoadhesive insulin-loaded microspheres containing magnesium stearate and varying proportions of Eudragit(®) RL 100 were prepared by the emulsification-coacervation technique and evaluated for thermal properties, physicochemical performance, and in vitro dissolution in acidic and subsequently basic media. RESULTS: Stable, spherical, brownish, discrete, free-flowing and mucoadhesive insulin-loaded microspheres with size range of 14.20 ± 0.30-19.80 ± 0.60 µm and loading efficiency of 74.55 ± 1.05-75.90 ± 1.94% were formed. After 3 h, microspheres prepared with insulin: Eudragit(®) RL 100 ratios of 1:4, 1:6, and 1:8 released 73.40 ± 1.38, 66.20 ± 1.59, and 71.30 ± 1.27 (%) of insulin, respectively. CONCLUSION: The physicochemical and physico-technical properties of the microspheres developed in this study demonstrated the effectiveness of the Eudragit(®) RL entrapped mucoadhesive microspheres (prepared by the emulsification-coacervation technique using varying polymer concentration) as a carrier system for oral insulin delivery.

Investigation of novel solid lipid microparticles based on homolipids from Bos indicus for the delivery of gentamicin.

BACKGROUND: The aim of this study was to formulate solidified reverse micellar solution (SRMS)-based solid lipid microparticles (SLMs) using homolipids from tallow fat (Bos indicus) and evaluate its potential for enhanced delivery of gentamicin. MATERIALS AND METHODS: SLMs were formulated by melt-emulsification using SRMS (15% w/w Phospholipon(®) 90G in 35% w/w Bos indicus), polyethylene glycol 4000 (PEG) and gentamicin (1.0, 2.0, 3.0% w/w), and characterized with respect to size, morphology, encapsulation efficiency % and pH-dependent stability. The in vitro release of gentamicin from the SLMs was performed in phosphate buffer (pH 7.4) while bioevaluation was carried out using clinical isolates of Staphylococcus aureus and Escherichia coli. RESULTS: Results showed that the lipid matrix accommodated gentamicin in a concentration-dependent manner, and that stable and spherical SLMs with size range of 18.62 ± 1.24-20.59 ± 1.36 µm and 21.35 ± 1.57-50.62 ± 2.37 µm respectively for unloaded and drug-loaded formulations were obtained. The in vitro drug release studies revealed that SRMS-based SLMs could better be used to control the release of gentamicin than gentamicin injection. Results of sensitivity test revealed that the SLMs time-dependently and capacity-limitedly produced greater inhibition zone diameters (IZDs) than the standards, an indication of improved bioactivity against the test organisms, with greater IZDs against S. aureus than E. coli. Overall, SLMs containing 2% w/w SRMS, 3% w/w gentamicin and PEG 4000 entrapped the highest amount of drug, achieved complete drug release and gave highest IZD against the organisms within 420 min, while plain gentamicin gave the least. CONCLUSION: This research has shown that SLMs based on Bos indicus and P90G is a potential carrier system for dissolution and bioactivity enhancement of gentamicin.

Evaluation of the anti-candidal activity of methanolic leaf extract of cleistopholis patens (fam. Annonaceae) on candida species isolated from stage II HIV patients.

BACKGROUND: Candida species (sp) is implicated in causing opportunistic disseminated mycotic complications in stage II HIV patients. Cleistopholis patens is a West African medicinal tree reported to have significant antifungal activity against C. albicans. OBJECTIVES: This study aimed to determine the anti-candidal activity of methanolic leaf extract of Cleistopholis patens against Candida species isolated from stage II HIV patients. METHODS: The minimum inhibitory concentration (MIC) of the extract and Nystatin®® was determined by agar dilution method. The killing rate studies of the plant extract and Nystatin® were also determined. RESULTS: The extract had activity against all Candida isolates, with the MIC against the five isolates ranging from 6.0 - 9.8 mg/ml. Nystatin® also demonstrated plausible activity against the isolates with MICs ranging from 0.3125 - 25 mg/ml. Candida albicans strain 2 was the most sensitive to both extract and Nystatin® with MIC values of 6 and 0.3125 mg/ml respectively. Candida krusei was the least sensitive with MIC values of 9.8 and 25 mg/ml for the extract and Nystatin® respectively. The killing rate values for the extract ranged from -0.029 to -0.091 min(-1) and that of Nystatin® ranged from -0.076 to -0.11216 min(-1). CONCLUSIONS: The results indicate that the methanolic extract of Cleistopholis patens is a promising clinical alternative besides Nystatin® in the treatment of infections caused by Candida species in stage II HIV patients.

Influence of magnesium stearate on the physicochemical and pharmacodynamic characteristics of insulin-loaded Eudragit entrapped mucoadhesive microspheres.

Effective oral insulin delivery has remained a challenge to the pharmaceutical industry. This study was designed to evaluate the effect of magnesium stearate on the properties of insulin-loaded Eudragit® RL 100 entrapped mucoadhesive microspheres. Microspheres containing Eudragit® RL 100, insulin, and varying concentrations of magnesium stearate (agglomeration-preventing agent) were prepared by emulsification-coacervation method and characterized with respect to differential scanning calorimetry (DSC), morphology, particle size, loading efficiency, mucoadhesive and micromeritics properties. The in vitro release of insulin from the microspheres was performed in simulated intestinal fluid (SIF, pH 7.2) while the in vivo hypoglycemic effect was investigated by monitoring the plasma glucose level of the alloxan-induced diabetic rats after oral administration. Stable, spherical, brownish, mucoadhesive, discrete and free flowing insulin-loaded microspheres were formed. While the average particle size and mucoadhesiveness of the microspheres increased with an increase in the proportion of magnesium stearate, loading efficiency generally decreased. After 12 h, microspheres prepared with Eudragit® RL 100: magnesium stearate ratios of 15:1, 15:2, 15:3 and 15:4 released 68.20 ± 1.57, 79.40 ± 1.52, 76.60 ± 1.93 and 70.00 ± 1.00 (%) of insulin, respectively. Reduction in the blood glucose level for the subcutaneously (sc) administered insulin was significantly (p ≤ 0.05) higher than for most of the formulations. However, the blood glucose reduction effect produced by the orally administered insulin-loaded microspheres prepared with four parts of magnesium stearate and fifteen parts of Eudragit® RL 100 after 12 h was equal to that produced by subcutaneously administered insulin solution. The results of this study can suggest that this carrier system could be an alternative for the delivery of insulin.

Solid lipid micro-dispersions (SLMs) based on PEGylated solidified reverse micellar solutions (SRMS): a novel carrier system for gentamicin.

The purpose of this study was to formulate and evaluate novel PEGylated solidified reverse micellar solutions (SRMS)-based solid lipid microparticles (SLMs) for improved delivery of gentamicin. Lipid matrix (SRMS) [consisting of 15% w/w Phospholipon® 90G (P90G) in 35% w/w dika wax (Irvingia gabonensis) was formulated and characterized by differential scanning calorimetry (DSC). SLMs were formulated by melt-emulsification using the SRMS, PEG 4000 and gentamicin (1.0, 2.0, 3.0% w/w), and their physicochemical as well as pharmacokinetic parameters determined. In vitro permeation of gentamicin from the SLMs through artificial membrane (0.22 µm pore size) was carried out using Franz's cell and phosphate-buffered saline (PBS, pH 7.4) as acceptor medium, while bioevaluation was performed using clinical isolates of Pseudomonas aeruginosa and Staphylococcus aureus. Stable and irregularly-shaped gentamicin-loaded SLMs of size range 34.49 ± 2.56 to 53.52 ± 3.09 µm were obtained. The SLMs showed sustained drug permeation and exhibited time-dependent and capacity-limited bioactivity. Overall, SLMs containing 2% w/w SRMS, 3% w/w gentamicin and PEG 4000 entrapped the highest amount of drug, gave highest IZD against the test organisms and highest permeation flux (5.239 µg/cm(2).min) and permeation coefficient (1.781 × 10(-6)cm/min) within 420 min, while pure gentamicin gave the least. Preliminary in vivo pharmacokinetic studies also showed an AUC-24 of 1507 µg/h/ml for the optimized formulation, while that of oral drug solution was 678 µg/h/ml. This showed a 2.2-fold increase in the systemic bioavailability of gentamicin from the optimized formulation. PEGylated SRMS-based SLMs prepared with heterolipid from Irvingia gabonensis would likely offer a reliable delivery system for gentamicin.