Ehab M. Elzayat

Development of modified in situ gelling oral liquid sustained release formulation of dextromethorphan

Context: Alternative strategies are being employed to develop liquid oral sustained release formulation. These included ion exchange resin, sustained release suspensions and in situ gelling systems. The later mainly utilizes alginate solutions that form gels upon contact with calcium which may be administered separately or included in the alginate solution as citrate complex. This complex liberates calcium in the stomach with subsequent gellation. The formed gel can break after gastric emptying leading to dose dumping. Objective: Development of modified in situ gelling system which sustain dextromethorphan release in the stomach and intestine. Methods: Solutions containing alginate with calcium chloride and sodium citrate were initially prepared to select the formulation sustaining the release in the stomach. The best formulation was combined with chitosan. All formulations were characterized with respect to flow, gelling capacity, gelling strength and drug release. Results: Increasing the concentration of alginate increased the gelling capacity and strength and reduced the rate of drug release in gastric conditions with 2% w/v alginate being the best formulation. However, these formulations failed to sustain the release in the intestinal conditions. Incorporation of chitosan with alginate increased the gelling capacity and strength and reduced the rate of drug release compared to alginate only system. The effect was optimum in formulation containing 1.5% w/v chitosan. The sustained release pattern was maintained both in the gastric and intestinal conditions and was comparable to that obtained from the marketed product. Conclusion: Alginate-chitosan based in situ gelling system is promising for developing liquid oral sustained release.

Investigation of in situ gelling alginate formulations as a sustained release vehicle for co-precipitates of dextromethrophan and Eudragit S 100

Abstract Alginate vehicles are capable of forming a gel matrix in situ when they come into contact with gastric medium in the presence of calcium ions. However, the gel structure is pH dependent and can break after gastric emptying, leading to dose dumping. The aim of this work was to develop modified in situ gelling alginate formulations capable of sustaining dextromethorphan release throughout the gastrointestinal tract. Alginate solution (2 %, m/m) was used as a vehicle for the tested formulations. Solid matrix of the drug and Eudragit S 100 was prepared by dissolving the drug and polymer in acetone. The organic solvent was then evaporated and the deposited solid matrix was micronized, sieved and dispersed in alginate solution to obtain candidate formulations. The release behavior of dextromethorphan was monitored and evaluated in a medium simulating the gastric and intestinal pH. Drug-polymer compatibility and possible solid-state interactions suggested physical interaction through hydrogen bonding between the drug and the polymer. A significant decrease in the rate and extent of dextromethorphan release was observed with increasing Eudragit S 100 concentration in the prepared particles. Most formulations showed sustained release profiles similar to that of a commercial sustained-release liquid based on ion exchange resin. The release pattern indicated strict control of drug release both under gastric and intestinal conditions, suggesting the potential advantage of using a solid dispersion of drug-Eudragit S 100 to overcome the problem of dose dumping after the rupture of the pH dependent alginate gels

Formulation and pharmacokinetics of multi-layered matrix tablets: Biphasic delivery of diclofenac

The rapid availability of the drug at the site of action followed by maintaining its effect for a long period of time is of great clinical importance. Thus, the purpose of the present study was to prepare and evaluate multi-layered matrix tablets of diclofenac using Eudragit RL/RS blend to achieve both immediate and sustained therapeutic effects. Diclofenac potassium (25 mg) was incorporated in an outer immediate release layer to provide immediate pain relief whereas diclofenac sodium (75 mg) was incorporated in the inner core to provide extended drug release. Wet granulation was employed to prepare the inner core of the tablets that were further layered with an immediate release drug layer in the perforated pan coater. The in-vitro and in-vivo performance of the developed formulation was compared with the marketed products Voltaren® SR 75 mg and Cataflam® 25 mg. The in-vitro drug release of the prepared formulation showed similarity (f2 = 66.19) to the marketed product. The pharmacokinetic study showed no significant difference (p > 0.05) in AUC0-24 and Cmax between the test and reference formulations. The AUC0-24 values were 105.36 ± 83.3 and 92.87 ± 55.53 μg h/ml whereas the Cmax values were 11.25 ± 6.87 and 12.97 ± 8.45 μg/ml, for the test and reference, respectively. The multi-layered tablets were proved to be bioequivalent with the commercially available tablets and were in agreement with the observed in-vitro drug release results. Stable physical characteristics and drug release profiles were observed in both long term and accelerated conditions stability studies.

Evaluation of wound healing activity of henna, pomegranate and myrrh herbal ointment blend

This study assessed the wound healing potential and antimicrobial activity of henna, pomegranate and myrrh extract formulations and their blend in excision, and dead space wound models in rats in comparison to a marketed ointment (gentamycin). The natural extracts were used in ointment formulations alone or in a combination of three extracts at a total concentration of 15% w/w in medications. The percent of wound contraction in case of henna, myrrh, pomegranate, the blend and gentamycin (10 mg/kg) were 85.90–98.5%, 88.35–99.52%, 93.55–100%, 97.30–100%, and 90.25–100% from days 16 to 20, respectively. The blended formulation showed the highest increase in the percent of wound contraction and decrease in the epithelisation period compared to other formulations and showed comparable results to the standard ointment. The histological studies of excision biopsy at day 24 showed healed skin structures with normal epithelisation, the restoration of adnexa and fibrosis within the dermis in all of the formulation- and gentamycin-treated groups while the control group lagged behind in the formation of the amount of ground substance in the granulation tissue. The formulations showed antimicrobial activity against Candida, Staphylococcus aureus, mucous membrane infections and E. coli topical infections. The study proved the wound healing potential and antimicrobial activity of the herbal extract.

Multiple response optimization of processing and formulation parameters of Eudragit RL/RS-based matrix tablets for sustained delivery of diclofenac

Abstract Context: Multiple response optimization is an efficient technique to develop sustained release formulation while decreasing the number of experiments based on trial and error approach. Objective: Diclofenac matrix tablets were optimized to achieve a release profile conforming to USP monograph, matching Voltaren®SR and withstand formulation variables. The percent of drug released at predetermined multiple time points were the response variables in the design. Statistical models were obtained with relative contour diagrams being overlaid to predict process and formulation parameters expected to produce the target release profile. Materials and methods: Tablets were prepared by wet granulation using mixture of equivalent quantities of Eudragit RL/RS at overall polymer concentration of 10–30%w/w and compressed at 5–15KN. Results and discussion: Drug release from the optimized formulation E4 (15%w/w, 15KN) was similar to Voltaren, conformed to USP monograph and found to be stable. Substituting lactose with mannitol, reversing the ratio between lactose and microcrystalline cellulose or increasing drug load showed no significant difference in drug release. Using dextromethorphan hydrobromide as a model soluble drug showed burst release due to higher solubility and formation of micro cavities. Conclusion: A numerical optimization technique was employed to develop a stable consistent promising formulation for sustained delivery of diclofenac.

Rosuvastatin calcium nanoparticles: Improving bioavailability by formulation and stabilization codesign

Purpose Rosuvastatin calcium (ROSCa) is a poorly soluble drug with bioavailability not exceeding 20%. Decreasing the particle size may enhance its solubility, dissolution rate and bioavailability. Therefore, the aim of the current study is to prepare ROSCa nanoparticles by wet milling technique using planetary ball mill. The codesign between formulation and stabilization of nanoparticles was studied to achieve both high dissolution as well as bioavailability. Methodology ROSCa nanosuspensions was prepared by wet milling technique using planetary ball mill, by applying milling ball size of 0.1 mm at speed of 800 rpm for 3 cycles each cycle composed of 10 minutes. HPMC, PVP k-30, pluronic F-127, Tween 80 and PEG 6000 were used as stabilizers. The nanosuspensions were then freeze-dried, and the dried nanoparticles were evaluated for particle size, zeta potential, in-vitro dissolution test, XRPD and in-vivo study. Results ROSCa nanoparticles stabilized with 10% PVP (P3) had a good stability with smallest particle size, which in turn enhanced the dissolution rate. The particle size of the leading formula was 461.8 ± 16.68 nm with zeta potential of -31.8 ± 7.22 mV compared to untreated drug that has a particle size of 618μm. The percent of ROSCa dissolved after 1 hour enhanced significantly which reached 72% and 58.25% for leading nanoparticle formula and untreated ROSCa, respectively (P < 0.05). The in-vivo study of ROSCa from the leading nanoparticle formula showed a significant enhancement in the Cmax after 2 h (82.35 ng/ml) compared to 9.2 ng/ml for untreated drug. Conclusion Wet milling technique is a successful method to prepare ROSCa nanoparticles. From different stabilizer used, PVP (10%) was able to produce stable nanoparticle with small particle size which significantly enhance the dissolution rate and pharmacokinetics parameters of ROSCa.

Influence of the microwave technology on solid dispersions of mefenamic acid and flufenamic acid

The present studies were undertaken to develop solvent-free solid dispersions (SDs) for poorly soluble anti-inflammatory drugs mefenamic acid (MA) and flufenamic acid (FFA) in order to enhance their in vitro dissolution rate and in vivo anti-inflammatory effects. The SDs of MA and FFA were prepared using microwaves irradiation (MW) technique. Different carriers such as Pluronic F127® (PL), Eudragit EPO® (EPO), polyethylene glycol 4000 (PEG 4000) and Gelucire 50/13 (GLU) were used for the preparation of SDs. Prepared MW irradiated SDs were characterized physicochemically using differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), Fourier transform infra-red (FT-IR) spectroscopy, powder X-ray diffraction (PXRD) and scanning electron microscopy (SEM). The physicochemical characteristics and drug release profile of SDs were compared with pure drugs. The results of DSC, TGA, FT-IR, PXRD and SEM showed that SDs were successfully prepared. In vitro dissolution rate of MA and FFA was remarkably enhanced by SDs in comparison with pure MA and FFA. The SDs of MA and FFA prepared using PEG 400 showed higher drug release profile in comparison with those prepared using PL, EPO or GLU. The dissolution efficiency for MA-PEG SD and FFA-PEG SD was obtained as 61.40 and 59.18%, respectively. Optimized SDs were also evaluated for in vivo anti-inflammatory effects in male Wistar rats. The results showed significant % inhibition by MA-PEG (87.74% after 4 h) and FFA-PEG SDs (81.76% after 4 h) in comparison with pure MA (68.09% after 4 h) and pure FFA (55.27% after 4 h) (P<0.05). These results suggested that MW irradiated SDs of MA and FFA could be successfully used for the enhancement of in vitro dissolution rate and in vivo therapeutic efficacy of both drugs.