Solidified Reverse Micellar Solution Research Articles

PREPARATION OF LIPID-BASED FORMULATIONS USING LOCAL BEESWAX SOURCED FROM HONEYCOMBS

Solid lipids used in formulation of novel drug delivery systems in most developing countries are sourced from abroad and are quite expensive. Wax from honeycombs is readily available, and is even disposed as waste, but can be utilized as a solid lipid for the formulation of different lipid-based drug delivery systems. This study aims to formulate and compare the features of the solid lipid nanoparticle (SLNs) and nanostructured lipid carrier (NLCs) delivery systems of quinine hydrochloride made with local beeswax (that is beeswax from locally sources honeycomb waste) and other solid lipids sourced from abroad. Local beeswax was first purified by hot bath method. Solidified reverse micellar solutions (SRMS) were prepared by fusion method using Phospholipon®90H and either local beeswax, Softisan®154, foreign beeswax, or stearic acid, separately. SLNs and NLCs of quinine made with SRMS of each of these solid lipids were formulated using hot homogenization method. These SLNs and NLCs were characterized. The average particle size of SLNs and NLCs made with local beeswax was 93.60 ± 4.44 nm and 112.80 ± 3.89 nm, respectively, and was not significantly (p > 0.05) different from the sizes of formulations made from other solid lipids (SLNs: 96.64 to 118.9 ± 4.13 nm and NLCs: 99.68 ± 6.75 to 117.30 ± 4.60 nm). The particles were monodispersed having PDI ranging from 0.281±0.054 to 0.308±0.055. Encapsulation efficiency and loading capacity were generally poor, especially among the SLN formulations. However, SLNs made with local beeswax and stearic acid were able to encapsulate quinine, whereas foreign beeswax and Softisan®154 had zero encapsulation. This study reveals that the features of the SLNs and NLCs made with local beeswax where highly comparable with those formulated with the imported solid lipids. Therefore, local beeswax can serve as a suitable affordable and available alternative to other imported solid lipids for formulating different lipid drug delivery systems.

Anti-Inflammatory and Antinociceptive Activity of Herbal Lipospheres of Pentaclethra macrophylla (Fabaceae) Stem Bark Extract

Purpose: Inflammation of various degrees is common among humans. There are associated side effects with orthodox delivery systems and anti-inflammatory agents; hence, the study investigated the characteristics of herbal lipospheres and the anti-inflammatory potency of the lipospheres formulated from Pentaclethra macrophylla with the view to having a drug with a better delivery system and lesser side effects. Methods: Herbal lipospheres were formulated using solidified reverse micellar solutions (SRMS) of P90H and goat fat and characterized for particle size and morphology, pH time dependent analysis, encapsulation efficiency (EE%), and Fourier Transform infrared spectroscopy. The in vitro antinociceptive and anti-inflammatory studies were carried out using membrane stabilization by hypotonicity-induced hemolysis and the determination of anti-platelet aggregatory activity models. The in vivo antinociceptive and anti-inflammatory studies on egg albumin- and formaldehyde-induced arthritis models were conducted. A total white blood cell count and differential blood count were carried out on the rats. Results: The results showed that there was no change in pH for the PM-unloaded lipospheres and 2.5 g of PM-loaded lipospheres from day 1 to day 7, but there was a mild variation in the rest of the formulations. The EE ranged from 35.2% to 94%, increasing according to the drug concentration. The photomicrographs of the lipospheres showed that the particles were spherical in shape. The particle sizes were within the acceptable range for lipospheres. FTIR showed no interaction. In the arthritis study, PM-loaded lipospheres inhibited edema consistently throughout the duration of observation. Inhibition of the membrane increased steadily with an increase in concentration of PM in the lipospheres and the standard drug. The platelet aggregatory inhibition decreased steadily with an increase in concentration of the PM in the lipospheres as well as the standard. The T50 dose of PM had the highest percentage of WBC, and it decreased as the treatment doses increased from T100 to T200. There were no significant differences among the Neutrophil counts of the different groups. Conclusions: The study, therefore, showed that the methanol extract of Pentaclethra macrophylla formed efficient herbal lipospheres with antinociceptive and anti-inflammatory activities.

Quinine: Redesigned and Rerouted

Quinine hydrochloride (QHCl) has remained a very relevant antimalarial drug 400 years after its effectiveness was discovered. Unlike other antimalarials, the development of resistance to quinine has been slow. Hence, this drug is to date still used for the treatment of severe and cerebral malaria, for malaria treatment in all trimesters of pregnancy, and in combination with doxycycline against multidrug-resistant malaria parasites. The decline in its administration over the years is mainly associated with poor tolerability due to its gastrointestinal (GIT) side effects such as cinchonism, complex dosing regimen and bitter taste, all of which result in poor compliance. Hence, our research was aimed at redesigning quinine using nanotechnology and investigating an alternative route for its administration for the treatment of malaria. QHCl nanosuspension (QHCl-NS) for intranasal administration was prepared using lipid matrices made up of solidified reverse micellar solutions (SRMS) comprising Phospholipon® 90H and lipids (Softisan® 154 or Compritol®) in a 1:2 ratio, while Poloxamer® 188 (P188) and Tween® 80 (T80) were used as a stabilizer and a surfactant, respectively. The QHCl-NS formulated were in the nanosize range (68.60 ± 0.86 to 300.80 ± 10.11 nm), and highly stable during storage, though zeta potential was low (≤6.95 ± 0.416). QHCl-NS achieved above 80% in vitro drug release in 6 h. Ex vivo permeation studies revealed that formulating QHCl as NS resulted in a 5-fold and 56-fold increase in the flux and permeation coefficient, respectively, thereby enhancing permeation through pig nasal mucosa better than plain drug solutions. This implies that the rate of absorption as well as ease of drug permeation through porcine nasal mucosa was impressively enhanced by formulating QHCl as NS. Most importantly, reduction in parasitaemia in mice infected with Plasmodium berghei ANKA by QHCl-NS administered through the intranasal route (51.16%) was comparable to oral administration (52.12%). Therefore, redesigning QHCl as NS for intranasal administration has great potential to serve as a more tolerable option for the treatment of malaria in endemic areas.

Assessment of the Anti-Malarial Properties of Dihydroartemisinin- Piperaquine Phosphate Solid Lipid-Based Tablets.

Artemisininbased combination therapies (ACTs) typified by dihydroartemisinin- piperaquine phosphate are first-line drugs used in the treatment of Plasmodium falciparum malaria. However, the emergence of drug resistance to ACTs shows the necessity to develop novel sustained release treatments in order to ensure maximum bioavailability. To formulate dihydroartemisinin (DHA)-piperaquine phosphate (PQ) sustained release tablets based on solidified reverse micellar solutions (SRMS). The SRMS was prepared by fusion using varying ratios of Phospholipon® 90H and Softisan® 154 and characterised. The tablets were prepared by using an in-house made and validated mould. The formulations were tested for uniformity of weight, hardness, friability, softening time, erosion time and in vitro-in vivo dissolution rate. Antimalarial properties were studied using modified Peter's 4-days suppressive test in mice. One-way analysis of variance (ANOVA) was used in the analysis of results. Smooth caplets, with average weight of 1300 ± 0.06 mg to 1312 ± 0.11 mg, drug content of 61 mg for DHA and t 450 mg for PQ. Tablet hardness ranged from 7.1 to 9.0 Kgf and softening time of 29.50 ± 1.90 min. Erosion time of 62.00 ± 2.58 to 152.00 ± 1.89 min were obtained for tablets formulated with Poloxamer 188 (Batches R2, S2 and T2) which significantly reduced the softening and erosion time (p < 0.05). In vitro release showed that the optimized formulations had a maximum release at 12 h. Formulations exhibited significantly higher parasitaemia clearance and in vivo absorption compared to marketed formulations at day 7 (p < 0.05). DHA-PQ tablets based on SRMS were much easier and relatively cheaper to produce than compressed tablets. They also showed exceptionally better treatment of malaria owing to their sustained release properties and improved bioavailability and are recommended to Pharmaceutical companies for further studies.

PEGylated aceclofenac solid lipid microparticles homolipid-based solidified reverse micellar solutions for drug delivery

Aceclofenac is a non-steroidal anti-inflammatory drug with poor aqueous solubility and a short half-life resulting in low bioavailability. Aceclofenac-loaded solid lipid microparticles based solidified reverse micellar solution (SLMs-SRMS) for oral drug delivery was investigated to improve the bioavailability and control drug release. Hot homogenization method was adopted to prepare the SLMs using a homolipid irvingia fat and Phospholipon® 90H with or without propylene glycol 6000 (PEGylation) in different ratios and characterized in vitro. The in vivo anti-inflammatory activity of the drug was determined on mice inflamed with carrageenan as phlogistic agent. Results showed that the morphology and particle sizes of the SLMs were spherical and smooth and ranged between 5.24 ± 0.01–97.44 ± 0.18 μm. EE % ranged between 67 - 81 %. A significant (p < 0.05) viscosity of 490 mPasec-1 was obtained. FTIR spectra indicated compatibility amongst the constituents. DSC showed a broad peak which depicted an imperfect matrix resulting in a deformation of crystal arrangement creating many spaces for drug entrapment. Delayed drug release was observed in almost all the formulations in SIF (pH, 6.8). Anti-inflammatory activity showed a significant inhibitory effect (p < 0.05, up to 90 %). Hence, the aceclofenac-loaded SLMs-SRMS showed desirable characteristics and could be used for controlled delivery of aceclofenac and thus alternative to conventional aceclofenac oral formulation.

Intranasal artesunate-loaded nanostructured lipid carriers: A convenient alternative to parenteral formulations for the treatment of severe and cerebral malaria

Early treatment with parenteral antimalarials is key in preventing deaths and complications associated with severe and cerebral malaria. This can be challenging in ‘hard-to-reach’ areas in Africa where transit time to hospitals with facilities to administer drugs parenterally can be more than 6 h. Consequently, the World Health Organization has recommended the use of artesunate (ATS) suppositories for emergency treatment of patients, however, this treatment is only for children under 6 years. The intranasal route (INR) can provide a safe and effective alternative to parenteral and rectal routes for patients of all ages; thus, reducing delays to the initiation of treatment. Hence, we designed ATS-loaded nanostructured lipid carriers (NLCs) for intranasal administration. ATS-NLCs were formulated using varying concentrations of lipid matrices made up of solidified reverse micellar solutions (SRMS) comprising a 1:2 ratio of Phospholipon ® 90H and lipids (Softisan ® 154 or Compritol ®). ATS-NLCs were spherical, and the small sizes of ATS-NLCs obtained for some formulations (76.56 ± 1.04 nm) is an indication that ATS-NLCs can pass through the nasal mucosa and reach the brain or systemic circulation. Encapsulation efficiency of ATS in NLCs was ≥70% for all formulations. ATS-NLCs achieved up to 40% in vitro drug release in 1 h, while ex vivo permeation studies revealed that formulating ATS as NLCs enhanced permeation through pig nasal mucosa better than drug solution. Most importantly, the activity and reduction in parasitaemia [in mice infected with Plasmodium berghei ANKA in a murine cerebral malaria model] by ATS-NLCs administered through the INR (54.70%, 33.28%) was comparable to intramuscular administration (58.80%, 42.18%), respectively. Therefore, intranasal administration of NLCs of ATS has great potentials to serve as a satisfactory alternative to parenteral administration for the treatment of severe and cerebral malaria in both adults and children in remote areas of sub-Saharan Africa.

Sustained-Release Glibenclamide-Loaded Solid Lipid Microparticles from Micellar Solutions of Homolipids

Fat from Capra hircus (goat fat) has been widely used for drug delivery. In this work, 1:1, 1:2, and 2:1 of goat fat and Softisan® 142 were melted together, cooled at room temperature, and the resultant matrix further modified with Phospholipon 90G (4:1) to obtain solidified reverse micellar solutions (SRMS). SRMS were used to prepare solid lipid microparticles (SLMs) loaded with or without glibenclamide, a poorly water soluble antidiabetic drug by hot melt homogenization. Particle size, morphology, thermal behavior, drug encapsulation efficiency, in vitro release study, and in vivo fate in diabetogenic rats were investigated. We report here an improved drug holding capacity (70.35%) of the lipid matrix of SRMS 2:1 due to imperfection of the lipid mixtures showing lower transition temperatures (117.0 °C) and enthalpies (−12.5 mW/mg). In vitro drug diffusion showed 66.98% drug release from SLM 2:1 exhibiting non-Fickian diffusion model (anomalous behavior) and almost zero-order kinetic. SLM 2:1 also gradually released 56.98% of glibenclamide under 16 h and maintained a steady state till 24 h; generally lowering blood glucose from 600 to 120 mg/dL unlike SLM 1:2 which showed burst glibenclamide release of 22.66% within 30 min with consequent rise in blood sugar. The 2:1 micellar solution (SRMS) of homolipids could deliver glibenclamide in a sustained form better than the conventional tablet form.

Application of SRMS 154 as Sustained Release Matrix for the Delivery of Stavudine: In vitro and in vivo Evaluation and Effect of Poloxamer 188 on the Properties of the Tablets.

Stavudine is an antiretroviral therapy with so many side effects and has a short half-life of 1.5 h. It degrades to thymine under hydrolytic, oxidative and photolytic conditions hence has major formulation challenges. To formulate sustained release lipid based stavudine and to study the properties of the formulations by in vitro and in vivo methods. Stavudine tablets were formulated by moulding using validated tablets moulds. The carrier used were solidified reverse micellar solution (SRMS) made up of varying ratios of hydrogenated palm oil and Phospholipid admixtures. Evaluation tests were carried out on the tablets using both Pharmacopoeial and non Pharmacopoeial test. Drug release was studied in both simulated gastric fluid (SGF, pH 1.2) and simulated intestinal fluid (SIF, pH 7.2). In vivo release was studied using Wistar rats. The results showed that stavudine tablets exhibited weight range of 372 ± 0.14 to 386 ± 0.52 mg, friability ranged from 0.00 to 0.13 % and hardness ranged from 4.27 ± 0.25 to 5.30 ± 0.21 Kgf. Tablets formulated with SRMS 1:2 had erosion time range of 60.80 ± 1.23 to 87.90 ± 2.33 min and was affected significantly by the presence of Poloxamer 188 (p < 0.05). The formulations exhibited T100 % at 10 to13 h in SIF. Stavudine tablets showed the area under the curve (AUC) of 854.0 μg/h/ml, significantly higher than the AUC of the reference (p < 0.05). Stavudine SRMS-based tablets had good stability and sustained release properties. Formulations containing 1 % Poloxamer 188 exhibited enhanced in vivo absorption and hence could be used once daily in order to enhance the bioavailability of this drug.

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 ± 11.24 μm to 18.1 ± 10.11 μm and maximum encapsulation efficiency and loading capacity were 95.11 ± 0.3% and 43.22 ± 0.1 mg, respectively. While that of beeswax- containing matrix showed maximum particle size of 18.9 ± 21.10 μm, maximum encapsulation efficiency of 89.01 ± 0.11% and loading capacity of 39.02 ± 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.

Novel solidified reverse micellar solution-based mucoadhesive nano lipid gels encapsulating miconazole nitrate-loaded nanoparticles for improved treatment of oropharyngeal candidiasis

Objective: To develop and evaluate solidified-reverse-micellar-solution (SRMS)-based oromucosal nano lipid gels for improved localised delivery of miconazole nitrate (MN).Methods: Phospholipon® 90G and Softisan® 154 (3:7) were used to prepare SRMS by fusion. Solid lipid nanoparticles (SLNs, 0.25–1.0% w/w MN) formulated with the SRMS by high shear homogenisation were employed to prepare mucoadhesive nano lipid gels. Physicochemical characterisation, drug release in simulated salivary fluid (SSF) (pH 6.8) and anti-candidal activity were carried out.Results: The SLNs were spherical nanoparticles, had mean size of 133.8 ± 6.4 to 393.2 ± 14.5 nm, low polydispersity indices, good encapsulation efficiency (EE) (51.96 ± 2.33–67.12 ± 1.65%) and drug loading (DL) (19.05 ± 2.44–24.93 ± 1.98%). The nano lipid gels were stable, spreadable, pseudoplastic viscoelastic mucoadhesive systems that exhibited better prolonged release and anti-candidal properties than marketed formulation (Daktarin® oral gel) (p < 0.05).Conclusion: This study has shown that SRMS-based nano lipid gels could be employed to prolong localised oromucosal delivery of MN.

Formulation design, in vitro characterizations and anti-malarial investigations of artemether and lumefantrine-entrapped solid lipid microparticles

Context: Poor aqueous solubility of artemether and lumefantrine makes it important to seek better ways of enhancing their oral delivery and bioavailability.Objective: To formulate and carry out in vitro and anti-malarial pharmacodynamic evaluations of solidified reverse micellar solutions (SRMS)-based solid lipid microparticles (SLMs) of artemether and lumefantrine for oral delivery and improved bioavailability.Materials and methods: Rational blends of Softisan®154 and Phospholipon®90H lipid matrices, and different concentrations of artemether and lumefantrine were used to formulate several batches of SLMs. Drug-free SLMs were also formulated. Morphology, particle size, encapsulation efficiency (EE%) and pH studies were performed. In vitro release studies were performed in alcoholic buffer, simulated gastric fluid (SGF) and simulated intestinal fluid (SIF) without enzymes. Anti-malarial pharmacodynamic studies were conducted in mice.Results: Stable, smooth and spherical particles with sizes ranging from 4.2 ± 0.02 to 9.3 ± 0.8 µm were formed. EE% of 92.2–97.3% and 30.2–84.7% and pH of 3.0 ± 0.02 to 4.9 ± 0.12 and 3.0 ± 0.02 to 5.8 ± 0.05 were obtained for artemether and lumefantrine SLMs, respectively. Release of 100, 88.28 and 75.49%, as well as 63.26, 34.31 and 56.17% were recorded for artemether and lumefantrine in alcoholic buffer, SGF and SIF, respectively. Pharmacodynamic studies indicated very significant (p < 0.05) clearance of parasitaemia in plasmodium-infected mice by the drug-loaded SLMs.Conclusion: Oral delivery and bioavailability of artemether and lumefantrine could be improved using SRMS-based SLMs.

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 Gentamicin-Entrapped Solid Lipid Microparticles Formulated with a Biodegradable Homolipid from &lt;i&gt;Capra hircus&lt;/i&gt;

Purpose: To formulate solidified reverse micellar solutions (SRMS)-based solid lipid microparticles (SLMs) using homolipid from Capra hircus, and evaluate its suitability for the delivery of gentamicin. Methods: SLMs were formulated by melt-emulsification using SRMS (15 % w/w Phospholipon® 90G in 35 % w/w Capra hircus), PEG 4000 and gentamicin (1.0, 2.0 and 3.0 % w/w), and characterized with respect to size, morphology, encapsulation efficiency (EE) and pH-dependent stability. 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 Pseudomonas aeruginosa and Staphylococcus aureus. Results: Stable and discrete SLMs of size range 1.47 ± 0.02 to 3.55 ± 0.09 µm were obtained. The SLMs showed a biphasic pattern of drug release 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, released 99 % of drug and gave the highest inhibitory zone diameter (IZD) against the organisms within 420 min, while plain gentamicin gave the least. Conclusion: SRMS-based SLMs prepared with homolipid from Capra hircus offers a suitable delivery system for gentamicin.

Formulation in vitro and in vivo evaluation of SRMS-based heterolipid-templated homolipid delivery system for diclofenac sodium

The sole objective of this work was to design successful dosage oral forms of diclofenac sodium (DiNa)-loaded solid lipid microparticles (SLM) based on solidified reverse micellar solution (SRMS). Hot homogenization technique was employed to prepare DicNa SLM using a mixture goat fat and Phospholipon® 90 G as lipid matrix and Tween®-80 as mobile surfactant. Characterization based on percentage yield, morphology, particle size, zeta potential, percentage encapsulation, pH and stability of SLMs were investigated. Anti-inflammatory, gastrointestinal tract (GIT) sparing effect and pharmacokinetics were carried out in rat model after oral administration. Results showed that the SLMs were spherical and smooth. The optimized formulation (SLM-4) had particle size of 79.40 ± 0.31 µm, polydispersity index of 0.633 ± 0.190, zeta potential of −63.20 ± 0.12 mV and encapsulation efficiency of 91.2 ± 0.1% with good stability after 8 months of storage. The DicNa SLM had sustained release effect with good anti-inflammatory activity. Higher and prolonged plasma DicNa concentration was shown by the SLM-4 compared to pure drug and a conventional sample. These studies demonstrate that DicNa-loaded SLM based on SRMS could be a promising oral formulation for enhanced bioavailability, pharmacologic activity and gastrointestinal sparing effect of the NSAID, DicNa.

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/cm2.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.

Solidified Reverse Micellar Solution (SRMS)-Based Indomethacin Sustained-Release Tablets: Formulation and &lt;i&gt;In vitro&lt;/i&gt; Evaluation

Purpose: To formulate and evaluate sustained-release indomethacin tablets based on solidified reverse micellar solution (SRMS).Methods: SRMS consisting of mixtures of phospholipid (Phospholipon® 90H) and triglyceride (Softisan® 154) were prepared in the ratios of 1:1, 2:1 and 1:2, respectively. SRMS-based tablets containing 75 mg of indomethacin each were prepared using a validated plastic mould. The physicochemical properties of the tablet formulations were studied. In vitro release study was carried out in simulated intestinal fluid (SIF, pH 7.5).Results: The results showed that the physicochemical properties of the tablet formulations were significantly affected by the composition/ratio of the lipid matrix used (p &lt; 0.05). Tablet hardness ranged from 5.00 ± 0.39 to 5.60 ± 0.36 kgf for tablets formulated with SRMS 1:2 and 2:1 (N3 and N2), respectively. The tablets exhibited friability of &lt; 1 % (p &lt; 0.05). Erosion time in SIF ranged from 124.0 ± 0.5 to 180.0 ± 1.1 min while drug release from the tablets reached a maximum in 8 – 11 h for all thebatches.Conclusion: Indomethacin tablets based on SRMS exhibited good sustained-release properties and can be further developed to achieve once daily administration for improved patient adherence to therapy.Keywords: Solidified reverse micellar solution, Phospholipid, Triglyceride, Indomethacin, Sustained release.

Solidified reverse micellar solutions (SRMS): A novel approach for controlling drug release from various lipids based drug delivery systems

Solidified reverse micellar solutions (SRMS) are reverse micelles containing lecithin and a triglyceride, for example, SOFTISAN ® 142, which is hydrogenated coco glyceride. SRMS transform into a lamellar mesophase after melting on contact with water; this transformation enables controlled release of solubilized drugs. They offer potentials for sustained drug delivery of both hydrophilic and lipophilic drugs. SRMS have the advantage of providing more flexibility in controlling the drug release and protecting the encapsulated ingredients from chemical degradation. SRMS based systems influence the absorption of active ingredients through different mechanisms to modify the release of active ingredients, and improve drugs bioavailability. The types of SRMS-based drug delivery systems include solid lipid nanoparticles (SLN), solid lipid microparticles (SLM), tablets and suppositories amongst others. The work exhaustively reviews the advances in SRMS based carriers. Its formulation methods, characterisation and delivery systems were discussed in details. Key words : Solidified reverse micellar solutions (SRMS), lipids, wide angle X-ray diffraction analysis (WAXD), small angle X-ray diffraction analysis (SAXD), lipid absorption.

English

Recently, advances in pharmaceutical research is focused on new delivery systems utilizing new devices to achieve modification of delivery time, targeting, as well as improve the in vivo solubility and hence bioavailability of poorly soluble drugs. Lipid based drug delivery systems (LDDS) consists of diverse group of formulations, each consisting of varying functional and structural properties that are amenable to modifications achieved by varying the composition of lipid excipients and other additives. LDDS has evolved, overtime, from micro- to nano-scale enhancing the efficacy and therapeutic application of these systems. LDDS are accepted, proven, commercially viable strategies for formulating challenging pharmaceutical molecules and can be tailored to meet a wide range of product requirements. Generally, most lipid drug delivery systems used as drug carriers have high stability, high carrier capacity, feasibility of incorporating both hydrophilic and hydrophobic substances and feasibility of variable routes of administration, including oral, topical, parenteral and pulmonary routes. LDDS can also be designed to allow modified drug release from matrices. LDDS could be broadly grouped into four: solid lipid particulate dosage forms, emulsion based systems, solid lipid tablets, and vesicular systems. Modifications from these four types include: lipospheres, solid lipid nanoparticles (SLNs), nano structured lipid carriers (NLC), lipid drug conjugate nanoparticles (LDC), self emulsifying formulations (SEFs), pickering emulsions, dry emulsions, micro and nano-emulsions, solidified reverse micellar solution (SRMS) based tablets, liposomes, herbosomes, cryptosomes and transferosomes amongst others. This work exhaustively reviewed the advances in LDDS and also drew comparison between the different types based on history, methods of manufacture, applications, advantages and disadvantages. Key words: Cryptosomes, lipospheres, lipoplexes, solid lipid tablets, pharmacosomes, virosomes, vesosomes.

Anti-inflammatory, antinociceptive and ulcerogenic properties of indomethacin tablets based on solidified reverse micellar solution (SRMS)

The aim of the present study was to evaluate in vivo the anti-inflammatory, antinociceptive and ulcerogenic properties of indomethacin tablets based on solidified reverse micellar solution (SRMS). SRMS consisting of mixtures of phospholipid (Phospholipon® 90H) and triglyceride (Softisan® 154) were prepared in the ratios of 1:1, 2:1 and 1:2, respectively. SRMS based tablets containing 75 mg of indomethacin each were prepared using validated plastic mould. The physicochemical properties of the tablet formulations were studied using both official and unofficial tests. Anti-inflammatory, analgesic/antinociceptive and ulcerogenic properties of indomethacin tablets based on SRMS were studied. The results showed that the physicochemical properties of the tablet formulations were significantly affected by the composition/ratio of the lipid matrix used. The softening time in SIF ranged from 53.7 ± 0.5 to 102.6 ± 0.5 min. Results of analgesic/antinociceptive properties showed that indomethacin tablets formulated with the SRMS 1:1 had an increase in pain reaction time at 7 h significantly (p < 0.05) different from the results exhibited by tablets formulated with the lipid matrices, SRMS 1:2 and 2:1 and the reference, which showed a decrease in pain reaction time at 7 h. Indomethacin tablets based on SRMS had good anti-inflammatory properties and also inhibited the ulcerogenicity of indomethacin by 70 to 80%. Therefore, indomethacin tablets based on SRMS could be used for improved oral bioavailability of indomethacin and to enhance patient’s compliance due to inhibition of gastric irritation effect of this drug. Key words: Non steroidal anti-inflammatory drugs (NSAIDS), solidified reverse micellar solutions (SRMS), tablets, ulcerogenicity, antinociception, lipids.

Formulation and evaluation of novel solid lipid microparticles as a sustained release system for the delivery of metformin hydrochloride

The low encapsulation efficiency of conventional solid lipid microparticles (SLMs) especially for hydrophilic drugs has remained a challenge to drug formulation experts. This work seeks to address the issue of inefficient delivery of metformin hydrochloride (MTH), a potent hydrophilic oral antihyperglycemic agent, using novel SLMs based on solidified reverse micellar solutions (SRMS) prepared by melt-emulsification using a lipid derived from Capra hircus and Phospholipon® 90H. Characterization based on size, morphology, zeta potential, polydispersity index, encapsulation efficiency (EE%), loading capacity (LC) and time-resolved stability were carried out on the SLMs. The in vitro release of MTH from the SLMs was performed in phosphate buffer (pH 7.4) while the in vivo antidiabetic properties were investigated in alloxan-induced diabetic rats. Stable, spherical and smooth SLMs were obtained. Loading of MTH into the SLMs had no effect on the surface charge of the particles. The SLMs with 1.0%w/w PEG 4000 resulted in significantly (p < 0.05) higher EE% while those with 2.0%w/w gave the least. The LC values ranged from 20.3 to 29.1 and 14.6 to 24.1 for SLMs containing 500 mg and 250 mg of MTH, respectively. The in vitro release studies revealed significant release of MTH from the SLMs whereas the in vivo antidiabetic studies indicated that novel SLMs containing 500 mg of MTH gave significantly (p < 0.05) higher glucose reduction than glucophage®. This research has shown that SLMs based on SRMS offer a new and better approach of delivering MTH, thus encouraging further development of this formulation.