Design of taste masked enteric orodispersible tablets of diclofenac sodium by applying fluid bed coating technology.

Diclofenac sodium (DS) a non-steroidal anti-inflammatory drug has a bitter taste and is a local stomach irritant. The aim of this study was to formulate taste masked DS orally dispersible tablets (ODTs) with targeted drug release in the intestine. Pellets of DS were designed using sugar sphere cores layered with DS followed by an enteric coat of Eudragit L100 and a second coat of Eudragit E100 for taste masking. The produced pellets had a high loading efficiency of 99.52% with diameters ranging from 493.7 to 638.9 µm. The prepared pellets were spherical with smooth surfaces on scanning electron microscopy examination. Pellets with the 12% enteric coat Eudragit L100 followed by 5% Eudragit E 100 resulted in 1.4 ±â€¯0.5% DS release in simulated gastric fluid (SGF) and complete dissolution in simulated intestinal fluid (SIF). The pellets were then used to formulate ODTs. In vitro disintegration time of ODTs ranged from 20 ±â€¯0.26 to 46 ±â€¯0.27 s in simulated saliva fluid (SSF). Dissolution was less than 10% in SGF while complete drug release occurred in SIF. The release rate was higher for the optimized formulation (F12) in SIF than for the marketed product Voltaren® 25 mg tablets. The optimized ODTs formulation had a palatable highly acceptable taste.

Role of chitosan on controlling the characteristics and antifungal activity of bioadhesive fluconazole vaginal tablets.

Vaginal fluconazole (FLZ) prolonged release tablets containing chitosan in physical blends with other bioadhesive polymers were designed. Chitosan was mixed with hydroxypropyl methylcellulose (HPMC), guar gum or sodium carboxymethyl cellulose (NaCMC) at different ratios and directly compressed into tablets. In-vitro release profiles of FLZ were monitored at pH 4.8. Compressing chitosan with HPMC at different ratios slowed FLZ release, however, time for 80% drug release (T80) did not exceed 4.3 h for the slowest formulation (F11). Adding of chitosan to guar gum at 1:2 ratio (F3) showed delayed release with T80 17.4 h while, in presence of PVP at 1:2:1 ratio (F5), T80 was 8.8 h. A blend of chitosan and NaCMC at 1:2 ratio (F15) showed prolonged drug release with T80 11.16 h. Formulations F5 and F15 showed fair physical characteristics for the powder and tablets and were subjected to further studies. Fast swelling was observed for F15 that reached 1160.53 ±â€¯13.02% in 4 h with 2 h bioadhesion time to mouse peritoneum membrane compared with 458.83 ±â€¯7.09% swelling with bioadhesion time exceeding 24 h for F5. Extensive swelling of F15 could indicate possible dehydration effect on vaginal mucosa. Meanwhile, antifungal activity against C. albicans was significantly high for F5.

Design of liposomal colloidal systems for ocular delivery of ciprofloxacin.

Ophthalmic drug bioavailability is limited due to protective mechanisms of the eye which require the design of a system to enhance ocular delivery. In this study several liposomal formulations containing ciprofloxacin (CPX) have been formulated using reverse phase evaporation technique with final dispersion of pH 7.4. Different types of phospholipids including Phosphatidylcholine, Dipalmitoylphosphatidylcholine and Dimyristoyl-sn-glycero-3-phosphocholine were utilized. The effect of formulation factors such as type of phospholipid, cholesterol content, incorporation of positively charging inducing agents and ultrasonication on the properties of the liposomal vesicles was studied. Bioavailability of selected liposomal formulations in rabbit eye aqueous humor has been investigated and compared with that of commercially available CPX eye drops (Ciprocin®). Pharmacokinetic parameters including Cmax, Tmax, elimination rate constant, t1/2, MRT and AUC0-∞, were determined. The investigated formulations showed more than three folds of improvement in CPX ocular bioavailability compared with the commercial product.

Optimization of 5-flurouracil solid-lipid nanoparticles: a preliminary study to treat colon cancer.

Solid lipid nanoparticle (SLNs) formulae were utilized for the release of 5-flurouracil (5-FU) inside the colonic medium for local treatment of colon cancer. SLNs were prepared by double emulsion-solvent evaporation technique (w/o/w) using triglyceride esters, Dynasan™ 114 or Dynasan™ 118 along with soyalecithin as the lipid parts. Different formulation parameters; including type of Dynasan, soyalicithin:Dynasan ratio, drug:total lipid ratio, and polyvinyl alcohol (PVA) concentration were studied with respect to particle size and drug entrapment efficiency. Results showed that formula 8 (F8) with composition of 20% 5-FU, 27% Dynasan™ 114, and 53% soyalithicin andformula 14 (20% 5-FU, 27% Dynasan™ 118, and 53% soyalithicin), which were stabilized by 0.5% PVA, as well as F10 with similar composition as F8 but stabilized by 2% PVA were considered the optimum formulae as they combined small particle size and relatively high encapsulation efficiencies. F8 had a particle size of 402.5 nm ± 34.5 with a polydispersity value of 0.005 and an encapsulation efficiency of 51%, F10 had a 617.3 ± 54.3 nm particle size with 0.005 polydispersity value and 49.1% encapsulation efficiency, whereas formula F14 showed a particle size of 343 nm ± 29 with 0.005 polydispersity, and an encapsulation efficiency of 59.09%. DSC and FTIR results suggested the existence of the lipids in the solid crystalline state. Incomplete biphasic prolonged release profile of the drug from both formulae was observed in phosphate buffer pH 6.8 as well as simulated colonic medium containing rat caecal contents. A burst release with magnitudes of 26% and 28.8% cumulative drug released were noticed in the first hour samples incubated in phosphate buffer pH 6.8 for both F8 and F14, respectively, followed by a slow release profile reaching 50% and 52% after 48 hours.

Chitosan and sodium sulfate as excipients in the preparation of prolonged release theophylline tablets.

The major objectives of this study were to monitor the effect of cross-linking of cationic chitosan in acidic media with sulfate anion during granules preparation by wet granulation method prior to tableting using theophylline (TPH) as a model drug. The prepared granules and the compressed tablets were subjected to in vitro evaluation. The properties of the prepared matrix granules and the compressed tablets were dependent on chitosan:sodium sulfate weight ratios, chitosan content, and molecular weight of chitosan. The prepared granules of all batches showed excellent to passable flowability and were suitable for compression into tablets. Most of the granules were hard and expected to withstand handling during the subsequent compression into tablets. Granules with high friabilities were only those prepared with a high amount of sodium sulfate or low amount of chitosan. Compression of granule batches yield nondisintegrating tablets that showed a decrease in tensile strength with the increase of sodium sulfate content at high chitosan:sodium sulfate weight ratio or with decrease of chitosan content. On the other hand, friability of tablets was increased in the presence of an excessive amount of sodium sulfate and low chitosan content as observed with granules. Slow TPH release from the formulated tablets was achieved at 1:0.5 and 1:1 chitosan:sodium sulfate weight ratios where all or most of the cationic chitosan and sulfate anions were used in a cross-linking reaction during wet granulation. Ratios of 1:2 and 1:3 showed fast drug release, which support the hypothesis that excessive unreacted water-soluble sodium sulfate might increase the porosity of the nondesintegrating tablets during dissolution. Slow drug release was also obtained with high molecular weight chitosan, whereas changing the hardness of the tablets did not significantly change the release profile of the drug as long as the tablets are intact during dissolution. Furthermore, slow drug release was observed as the total amount of chitosan was increased in the formulated tablets. A comparative in vivo study between the chosen formulated tablets (1:1 chitosan:sodium sulfate ratio that contains 10% high molecular weight chitosan) and the commercial Quibron tablets indicated prolonged appearance of the drug in dogs' plasma for both formulations with no significant differences (p > 0.05) in rate and extent of drug absorption. The formulated tablets showed 103.16% bioavailability relative to that of the commercial tablets.

Treatment of experimental osteomyelitis by liposomal antibiotics.

OBJECTIVES: Traditional antibiotic therapy of staphylococcal osteomyelitis by a single drug or a drug combination is ineffective in producing complete sterilization of infected bones. The aim of this study was to develop a non-traditional delivery system of antibiotics for treatment of chronic experimental osteomyelitis. METHODS: In the current work, ciprofloxacin and vancomycin were encapsulated in a cationic, anionic or neutral liposomal formulation. For prolonged circulation in serum, liposomal dispersions (<100 nm in diameter) were sonicated for different times (20, 40, 60 or 80 s), and tested for antibacterial activities. RESULTS AND CONCLUSIONS: Liposomes sonicated for 40 s gave the highest antibacterial activities in vitro. Since cationic liposomes trapped the highest percentage of antibiotics, and enhanced antibacterial activity above that of the free drugs, they were used for therapeutic trials to treat chronic staphylococcal osteomyelitis induced in rabbits. Therapeutic trials with antibiotics given intravenously revealed that, free ciprofloxacin or vancomycin given alone for 14 days was ineffective in sterilizing bone. Combination therapy with free ciprofloxacin and vancomycin for 14 days was more effective. However, this group showed renal dysfunction and severe diarrhoea, which resulted in loss of 33.3% of treated animals. Treatment with liposomal forms of either drug for 7 days was ineffective. Meanwhile, combination therapy in liposomal form for 7 days was more effective. Complete sterilization of bone tissues on cultures (100% cure) was obtained only in the group treated for 14 days with the combination of both drugs in liposomal form. Moreover, liposomal formulations showed much lower nephrotoxicity and a lower incidence of severe diarrhoea than that induced by free drugs.

Aqueous preparation and evaluation of albumin-chitosan microspheres containing indomethacin.

Controlled-release egg albumin-chitosan microspheres containing indomethacin as a model drug were successfully prepared by coacervation method. The proposed method can offer a simple method for microsphere preparation in an aqueous system with the elimination of the use of organic solvents that are usually needed in conventional techniques of microencapsulation. The interaction between negatively charged egg albumin molecules in phosphate buffer, pH 7.2, or sodium hydroxide solution and positively charged chitosan molecules dissolved in diluted acetic acid to form an insoluble precipitate was the principle for the formation of the microspheres. The effects of many process variables, such as amount of formaldehyde as a cross-linking agent, stirring time, final pH of encapsulation medium, initial drug loading, and albumin concentration or albumin-to-chitosan weight ratio, on the properties of the prepared microspheres were investigated. Incorporation efficiencies of the microspheres to the drug were high in most cases and ranged between 63.3 +/- 3.6% and 92.39 +/- 3.2%, while particle sizes were 435.2 +/- 12.6 up to 693.9 +/- 34.6 microm for the different tested batches. On the other hand, the values of angles of repose and compressibility indices were in the range of 23.5 +/- 0.4 to 32.0 +/- 0.7 degrees and 11.1 +/- 0.7% to 23.6 +/- 0.7% respectively, which indicate overall good free flowing nature of the microspheres of all batches. The maximum required amount of the cross-linking agent was determined to avoid excessive unnecessary chemicals. It was also noticed that excessive time of stirring and excessive initial drug loading are not recommended as it may lead to microspheres of low properties. The pH of the encapsulation media (pH 3.77 up to pH 4.91) significantly affected the properties of the microspheres. As the pH of the encapsulation media was increased, the incorporation efficiency, particle size, and flowability decreased, along with increase of drug release rate, which could be related to incomplete cross linking of the microspheres matrix. It was also observed that high concentration of albumin solution and accordingly the increase of albumin-to-chitosan weight ratio were accompanied with increases in incorporation efficiency and particle size with improved microsphere flowability and slow indomethacin release. Thus, the proposed microspheres showed the ability to control the release of indomethacin, and their properties were highly affected by many process variables that could be controlled to obtain an optimized system.

In vitro--in vivo evaluation of tableted caseinchitosan microspheres containing diltiazem hydrochloride.

Casein-chitosan microspheres containing diltiazem hydrochloride (DTZ.HCL) were prepared using aqueous coacervation technique. The formed microspheres were not suitable for tableting by direct compression due to their poor binding properties. The effect of hydroxypropylmethylcellulose (HPMC), ethylcellulose (EC), carbopol 940 and egg albumin as dry binders at different concentrations on the properties of the tablets was studied. Each blend of microspheres with dry binder and 2% w/w magnesium stearate as glidant was hand-filled into the die cavity of a single punch tablet machine to ensure constant amount of drug (90 mg) in each tablet. The compression force was adjusted to produce tablets with hardness value about 7.73 +/- 0.79 Kp. The prepared tablets showed good appearance and low friability. The tested binders HPMC (10 and 30% w/w) and EC (20 and 30% w/w) gave fast tablet disintegration with high initial drug release (burst effect) while, carbopol 940 (5 and 10% w/w) and egg albumin (30% w/w) gave non-disintegrating tablets with low initial drug release. Tableted microspheres prepared with 30% egg albumin showed drug release profile similar to one of the commercial tablets (Dilzem retard, 90 mg) and was chosen for in-vivo study. Tableted microspheres and commercial tablets were administered orally in different occasions to six beagle dogs and diltiazem was assayed in dog plasma. The pharmacokinetic parameters including maximum drug concentration (Cmax) and time to reach that maximum (Tmax) were 106.24 +/- 17.96 ng.ml-1 and 5.8 +/- 2.04 hours, respectively, for the commercial sustained release DTZ tablets while, those were 107.9 +/- 12.89 ng.ml-1 and 3.6 +/- 1.36 hours, respectively for tableted microspheres. The elimination half-lives were nearly the same for the commercial and the formulated tablets (8.22 +/- 4.19 and 7.95 +/- 4.28 hours, respectively). No statistical differences (P > 0.05) were found between the two treatments for area under the plasma concentration curve (AUC0 infinity), mean residence time (MRT) and rate of drug absorption (Cmax/AUC0 infinity) indicating comparable extent and rate of drug absorption for both formulations. It was concluded that the formulated tableted microspheres provide an acceptable delivery for DTZ over an extended period of time.

Effect of inclusion complexation with cyclodextrins on photostability of nifedipine in solid state.

Nifedipine is a highly photosensitive drug that requires restricted protection from light during manufacturing, storage and handling of its dosage forms. Inclusion complexation of nifedipine with cyclodextrins (CDs) could be advantageous in protecting the drug against the effect of light. In this study, solid inclusion complexes of nifedipine with beta-cyclodextrin (beta-CD), hydroxypropyl-beta-cyclodextrin (HP-beta-CD) and dimethyl-beta-cyclodextrin (DM-beta-CD) were prepared using the coprecipitation method. The obtained solid inclusion complexes have been confirmed by differential scanning calorimetry (DSC), X-ray diffraction and infrared spectroscopy (IR). The IR spectra indicated partial inclusion of nifedipine molecules into CD cavities through the dihydropyridine ring. Inclusion complexation was also associated with a dramatic enhancement of drug dissolution with magnitudes depended on the type of CD. The effect of exposure to fluorescent lamp and sunlight on the photodegradation of uncomplexed and complexed nifedipine was tested. Photodegradation of nifedipine was monitored using a high performance liquid chromatographic (HPLC) assay method. Inclusion complexation of nifedipine showed to retard drug photodegradation as indicated by degradation rate constant lowering with values depended on light source and type of complexing agent. This effect was the least with beta-CD compared with that of modified beta-CD. It was also interesting to notice that inclusion complexation of nifedipine offered much higher protection against the effect of fluorescent lamp than that of sunlight. The obtained results suggests that the design of solid dosage forms of nifedipine such as a fast dissolving nifedipine tablets is possible with the advantages of low required light protection.