Formulation strategies for achieving high delivery efficiency of thymoquinone-containing Nigella sativa extract to the colon based on oral alginate microcapsules for treatment of inflammatory bowel disease.

Nigella sativa extract (NSE) was incorporated in alginate microcapsules using aerosolisation and homogenisation methods, respectively, with the aim of delivering high concentrations of the active species, thymoquinone (TQ), directly to sites of inflammation in the colon following oral administration. Encapsulation of NSE was accomplished either by direct loading or diffusion into blank microparticles. Microcapsules in the size range 40-60 µm exhibited significantly higher NSE loading up to 42% w/w and encapsulation efficiency (EE) up to 63% when the extract was entrapped by direct encapsulation compared with 4.1 w/w loading, 6.2% EE when NSE was incorporated by diffusion loading. Sequential exposure of samples to simulated intestinal fluids (SIFs) revealed that the microcapsules suppressed NSE release in simulated gastric fluid (SGF) for 2 h and SIF for 4 h and liberated most of the NSE content (80%) in simulated colonic fluid (SCF) over 18 h. NSE released in SCF at 12 h exhibited antioxidant activity, when measured using the 1,1-diphenyl-2-picryl-hydrazyl (DPPH) assay at levels comparable with the activity of unencapsulated extract. These findings demonstrate the potential of oral alginate microcapsules as highly efficient, targeted carriers for colonic delivery of NSE in the treatment of inflammatory bowel disease.

Sustained Simultaneous Delivery of Metronidazole and Doxycycline From Polycaprolactone Matrices Designed for Intravaginal Treatment of Pelvic Inflammatory Disease.

Poly(ɛ-caprolactone) (PCL) intravaginal matrices were produced for local delivery of a combination of antibacterials, by rapidly cooling a mixture of drug powders dispersed in PCL solution. Matrices loaded with different combinations of metronidazole (10%, 15%, and 20% w/w) and doxycycline (10% w/w) were evaluated in vitro for release behavior and antibacterial activity. Rapid "burst release" of 8%-15% of the doxycycline content and 31%-37% of the metronidazole content occurred within 24 h when matrices were immersed in simulated vaginal fluid at 37°C. The remaining drug was extracted gradually over 14 days to a maximum of 65%-73% for doxycycline and 62%-71% for metronidazole. High levels of antibacterial activity up to 89%-91% against Gardnerella vaginalis and 84%-92% against Neisseria gonorrhoeae were recorded in vitro for release media collected on day 14, compared to "nonformulated" metronidazole and doxycycline solutions. Based on the in vitro data, the minimum levels of doxycycline and metronidazole released from PCL matrices in the form of intravaginal rings into vaginal fluid in vivo were predicted to exceed the minimum inhibitory concentrations for N. gonorrhea (reported range 0.5-4.0 µg/mL) and G. vaginalis (reported range 2-12.8 µg/mL) respectively, which are 2 of the major causative agents for pelvic inflammatory disease.

Evaluation of polycaprolactone matrices for the intravaginal delivery of metronidazole in the treatment of bacterial vaginosis.

Microporous, poly (ɛ-caprolactone) (PCL) matrices loaded with the antibacterial, metronidazole were produced by rapidly cooling suspensions of drug powder in PCL solutions in acetone. Drug incorporation in the matrices increased from 2.0% to 10.6% w/w on raising the drug loading of the PCL solution from 5% to 20% w/w measured with respect to the PCL content. Drug loading efficiencies of 40-53% were obtained. Rapid 'burst release' of 35-55% of the metronidazole content was recorded over 24 h when matrices were immersed in simulated vaginal fluid (SVF), due to the presence of large amounts of drug on matrix surface as revealed by Raman microscopy. Gradual release of around 80% of the drug content occurred over the following 12 days. Metronidazole released from PCL matrices in SVF retained antimicrobial activity against Gardnerella vaginalis in vitro at levels up to 97% compared to the free drug. Basic modelling predicted that the concentrations of metronidazole released into vaginal fluid in vivo from a PCL matrix in the form of an intravaginal ring would exceed the minimum inhibitory concentration of metronidazole against G. vaginalis. These findings recommend further investigation of PCL matrices as intravaginal devices for controlled delivery of metronidazole in the treatment and prevention of bacterial vaginosis.

PLGA microspheres for the delivery of a novel subunit TB vaccine.

Biodegradable poly(dl-lactide-co-glycolide) microspheres were prepared using a modified double emulsion solvent evaporation method for the delivery of the subunit tuberculosis vaccine (Ag85B-ESAT-6), a fusion protein of the immunodominant antigens 6-kDa early secretory antigenic target (ESAT-6) and antigen 85B (Ag85B). Addition of the cationic lipid dimethyl dioctadecylammonium bromide (DDA) and the immunostimulatory trehalose 6,6'-dibehenate (TDB), either separately or in combination, was investigated for the effect on particle size and distribution, antigen entrapment efficiency, in vitro release profiles and in vivo performance. Optimised formulation parameters yielded microspheres within the desired sub-10 microm range (1.50 +/- 0.13 microm), whilst exhibiting a high antigen entrapment efficiency (95 +/- 1.2%) and prolonged release profiles. Although the microsphere formulations induced a cell-mediated immune response and raised specific antibodies after immunisation, this was inferior to the levels achieved with liposomes composed of the same adjuvants (DDA-TDB), demonstrating that liposomes are more effective vaccine delivery systems compared with microspheres.