In vitro evaluation of polyethylene glycol based microparticles containing azithromycin.

The objectives of the present investigation are (1) to screen the liquid and solid polyethylene glycol (PEG) molecules able to produce microparticles by cold or hot dispersion method either with or without other excipients, and (2) to evaluate the in vitro activities [like thermodegradation at three different storage conditions, dissolution using a membrane-free dissolution model in artificial tear fluid or phosphate buffer solution of pH 7.4, and zone-inhibition assay using Eschericella coli and red blood cells (RBC) rupturing assay] of azithromycin (AZM)-loaded microparticles in comparison to AZM alone. Adding chitosan and propylene glycol into PEG 6000 led to the formation of spherical-shaped microparticles. Keeping the drug alone in phosphate buffer solution of pH 7.4 at three different storage conditions did show degradation and thus precipitation whereas incorporating the drug into microparticles did not. The microparticles showed a drug release profile that was completely in a retarded style when compared to the release profile of drug alone. The antimicrobial activity of AZM was not affected after incorporating it into microparticles as shown in the zone-inhibition assay. Nevertheless, the microparticles reduced markedly the RBC rupturing property of the drug in comparison to drug in phosphate buffer solution of pH 7.4 (hemolysis percentage values of 27.41 ± 4.1and 43.11 ± 7.6, respectively). This indicates that the microparticles prepared based on PEG, chitosan and propylene glycol could be of a suitable carrier to protect AZM from thermodegradation, to provide retardation in drug release, to preserve antimicrobial activity, and to reduce RBC rupturing effect of the drug.

Studies on ocular and parenteral application potentials of azithromycin- loaded anionic, cationic and neutral-charged emulsions.

Ocular and parenteral application potentials of azithromycin-containing, non-phospholipid-based cationic nanosized emulsion in comparison to the phospholipid-based anionic and neutral-charged nanosized emulsions were investigated. Various physical, chemical, nonclinical toxicity and antimicrobial activity studies (mean droplet diameter, surface charge, creaming index, entrapment efficiency, accelerated, long-term and freeze-thaw cycling stabilities, TLC study, modified hen's egg chorioallantoic membrane (HET-CAM) test, in vitro hemolysis test, in vitro and in vivo myotoxicity, and in vitro antimicrobial activity) were conducted for assessing the potentials of these three types of emulsions. Following autoclave sterilization, all of these emulsions exhibited a nanometer range mean particle diameter (200 ± 29 to 434 ± 13 nm). While the anionic and cationic emulsions did show high negative (-34.2 ± 1.23 mV) and positive zeta potential (42.6 ± 1.45 mV) values, the neutral-charged emulsion did not. Even with 5 freeze-thaw cycles, the cationic emulsion remained stable whereas other two emulsions underwent phase-separation. The hen's egg chorioallantoic membrane test revealed an irritation score value that was higher for the anionic emulsion than for cationic or neutral-charged emulsion. A significantly higher % hemolysis value was also noticed for the anionic emulsion when compared to the % hemolysis value of cationic emulsion (ANOVA, P < 0.05). However, all of the emulsions showed a lesser intracellular creatine kinase (CK) release/plasma CK level in comparison to the positive control (phenytoin) indicating their lesser myotoxicity at the injection site . When compared to anionic and neutral-charged emulsions, the possible controlled drug release from cationic emulsion delayed the in vitro antimicrobial action against H.influenzae and S.pneumoniae.

Influence of acetazolamide loading on the (in vitro) performances of non-phospholipid-based cationic nanosized emulsion in comparison with phospholipid-based anionic and neutral-charged nanosized emulsions.

CONTEXT: Acetazolamide (ACZM)-loaded anionic, cationic, and neutral-charged oil-in-water nanosized emulsions were prepared and compared with their mean droplet diameter, surface charge, entrapment efficiency, freeze-thaw cycling stability, in vitro drug release, and transcorneal permeation. OBJECTIVE: The present study aims to determine the influence of ACZM loading on the performances of non-phospholipid-based cationic nanosized emulsion in comparison with phospholipid-based anionic and neutral-charged nanosized emulsions. RESULTS AND DISCUSSION: Regardless of charges, all of these emulsions exhibited a nanometer range mean particle diameter (240-443 nm) following autoclave sterilization. While the anionic and cationic emulsions did show high negative (-36.9 mV) and positive zeta potential (+41.4 mV) values, the neutral-charged emulsion did not. Presence of cryoprotectants (5% w/w sucrose + 5% w/w sorbitol) improved the stability of cationic emulsion to droplet aggregation during freeze-thaw cycling. The in vitro release kinetic behavior of drug exchange with physiological anions present in the simulated tear solution appears to be complex and difficult to characterize using mathematical fitting model equations. Augmentation in drug permeation through goat cornea, in vitro, was noticed for cationic emulsion. CONCLUSION: ACZM-loaded cationic nanosized emulsion could be suitable for topical application into eye to elicit better therapeutic effect in comparison with its anionic and neutral-charged emulsions.

Clinical concerns of immunogenicity produced at cellular levels by biopharmaceuticals following their parenteral administration into human body.

Similar to the low molecular weight traditional drugs, biopharmaceuticals are capable of producing not only therapeutic effects but also side effects provided if the dose of these compounds exceeds certain concentration and/or if the exposure duration of these compounds at subtoxic doses is being lengthened. In addition, a major drawback of biopharmaceuticals is the risk of antibody formation. Following the administration of biopharmaceuticals into human body, the formation of antidrug-antibody (ADA) or neutralizing antibody and other general immune system effects (including allergy, anaphylaxis, or serum sickness) are of clinical concern regarding therapeutic efficacy and patient safety. For example, drug-induced neutralizing antibodies to erythropoietin (EPO) result in pure red cell aplasia, whereas drug-induced acquired anti-factor VIII antibodies worsen the pathology associated with hemophilia. Since most of the already developed or under development biopharmaceuticals are to some extent immunogenic, the regulatory agencies insist to conduct potential ADA formation during the drug development process itself. This review encompasses a short overview on the clinical concerns of immunogenicity produced at cellular levels by growth hormone, interferon-alpha, EPO, factor VIII, and factor IX following their parenteral administration into human body. Clinical concerns related to immunogenicity produced by the biosimilar versions of these drugs are also presented wherever possible.

Formulation of multifunctional oil-in-water nanosized emulsions for active and passive targeting of drugs to otherwise inaccessible internal organs of the human body.

Oil-in-water (o/w) type nanosized emulsions (NE) have been widely investigated as vehicles/carrier for the formulation and delivery of drugs with a broad range of applications. A comprehensive summary is presented on how to formulate the multifunctional o/w NE for active and passive targeting of drugs to otherwise inaccessible internal organs of the human body. The NE is classified into three generations based on its development over the last couple of decades to make ultimately a better colloidal carrier for a target site within the internal and external organs/parts of the body, thus allowing site-specific drug delivery and/or enhanced drug absorption. The third generation NE has tremendous application for drug absorption enhancement and for 'ferrying' compounds across cell membranes in comparison to its first and second generation counterparts. Furthermore, the third generation NE provides an interesting opportunity for use as drug delivery vehicles for numerous therapeutics that can range in size from small molecules to macromolecules.

Carvedilol-loaded mucoadhesive buccal tablets: influence of various mucoadhesive polymers on drug release behavior.

The major objectives of the current study were (i) to prepare carvedilol-loaded buccal tablets by direct compression technique, and (ii) to study the influence of low and high proportions of sodium carboxy methylcellulose (SCMC) in conjunction with the corresponding high and low proportions of sodium alginate, polyvinyl pyrrolidone (PVP-K-30), carbopol 974P, and hydroxypropyl methylcellulose (HPMC) on the basic properties (hardness, friability, weight variation, thickness uniformity, drug content, mucoadhesive strength, surface pH, swelling property, and drug release behavior) of the tablets. Altering the polymer combinations did not affect the physical properties of the buccal tablets. However, the presence of SCMC and sodium alginate at 1:2 ratio in the tablet showed a sustained drug release. In addition, this polymer combination at 2:1 ratio did release the drug completely during the stipulated dissolution time. Swelling study indicated the tablet structure collapse over time at 2:1 polymer ratio, thus exposing the drug molecules directly to the dissolution medium to attain the complete drug release from the SCMC and sodium alginate-based tablets. On the other hand, whatever the polymer ratios, the SCMC and carbopol 974P combination always retarded the drug release in an almost similar manner. Though the SCMC- and carbopol 974P-based tablets did display an impressive mucoadhesion property, the surface pH value determined for this polymer combination was found to decrease considerably due to the liberation of the free carboxylic acid over the time period.

In vitro and in vivo evaluation of single-unit commercial immediate-and sustained-release capsules compared with multiple-unit polystyrene microparticles dosage forms of indomethacin.

The objective of this study is to select a multiple-unit sustained-release formulation and to compare it with both commercial immediate and single unit sustained-release capsules and also to determine whether an in vitro-in vivo correlation exists for single- and multiple- unit formulations. Indomethacin (20-60% w/w)-loaded, multiple-unit polystyrene microparticles were prepared by emulsion-solvent evaporation method from an aqueous system. The in vitro release profiles obtained in phosphate buffer of pH 6.8 for drug-loaded polystyrene microparticles and for commercial sustained-release capsules (Indocap-SR, 75 mg) were compared. As the microparticles with 50% indomethacin load showed a release profile comparable to that of the Indocap-SR release profile, the microparticles with this drug load was considered as optimized/selected formulation and, therefore, was subjected to stability study and in vivo study in human volunteers. In spite of significantly higher C(max), Ka, and Ke, and lower T(max), t1/2a, t1/2e and AUC(0 --> infinity)) values observed with commercial Microcid immediate-release capsules, there was no sign of difference among the listed parameters between optimized microparticles and Indocap-SR capsules. Indeed, the values of retard quotient (Rdelta) calculated from half-value duration analysis did not show any statistical difference, indicating the occurrence of an almost same degree of retardation of drug release from the optimized microparticles and the Indocap-SR capsules. Furthermore, linear relationship obtained between the percentages dissolved and absorbed suggests a means to predict in vivo absorption by measuring in vitro dissolution. The results suggest that the optimized polystyrene microparticles could provide an alternative controlled-release drug delivery system for indomethacin.

The potential of lipid- and polymer-based drug delivery carriers for eradicating biofilm consortia on device-related nosocomial infections.

Microbial biofilms are microcosm attaching irreversibly to abiotic or biotic surfaces and they are promulgated as congregate of single or multiple populations. The potential of lipid- and polymer-based drug delivery carriers for eradicating biofilm consortia on device-related nosocomial infections is explored in this review. Liposomes-loaded with antimicrobial agents could effectively be applied as anti-biofilm coating to reduce microbial adhesion/colonisation onto medical devices and as drug delivery carriers to biofilm interfaces and in intracellular infection. Many polymer-based carrier systems have also been proposed, including those based on biodegradable polymers such as poly(lactide co-glycolide) as well as fibrous scaffolds and thermoreversible hydrogels and surface (properties) modified polymeric catheter materials such as antimicrobial, antiseptic or metallic substances-coated polymeric materials. Their contribution to the prevention/resolution of infection is reviewed.

Non-systemic delivery of topical brimonidine to the brain: a neuro-ocular tissue distribution study.

To date, the risks of central nervous system (CNS) side effects of topically administered ophthalmic therapeutic agents are thought to be the consequence of systemic absorption of these drugs. This paper envisions the possibility of drug delivery to the CNS following ocular application through non-systemic routes. After single instillation of 50 microl of 3H-radiolabeled Alphagan solution (0.2%) in the cul de sac of the right eye, three male albino rabbits (2-2.5 kg) were sacrificed at each time point (5, 15, 30 and 60 min). Both sides (eyes) specimens of aqueous humor, cornea, iris, lens, vitreous, conjunctiva, sclera, ciliary body, choroid, retina, optic nerve, optic tract and olfactory bulb were weighed, and blood samples were measured, before combustion in tissue oxidizer and radioactive liquid scintillation counting. Significant 3H-brimonidine levels were found in right and left optic nerves and tracts with extremely low corresponding drug levels in blood. Uveal tract (ciliary body, iris and choroid tissues) brimonidine levels were relatively high in the treated eye, and the highest among contralateral eye tissues. Our data provide the first case of good CNS availability after ocular application of conventional ophthalmic therapeutic agent, through non-systemic routes. Similar neuro-ocular pharmacokinetic studies should be adopted as a routine ocular therapeutics evaluation study.

In vitro and in vivo evaluation of single-unit commercial conventional tablet and sustained-release capsules compared with multiple-unit polystyrene microparticle dosage forms of Ibuprofen.

The major aims of the present study were (1) to select a multiple-unit formulation that matched the in vitro dissolution profile of single-unit sustained-release commercial capsules, (2) to compare the sustaining/controlling efficacy of the selected multiple-unit formulation with that of the single-unit commercial conventional tablet and sustained-release capsules, and (3) to determine whether an in vitro-in vivo correlation exists for single- and multiple-unit formulations. Ibuprofen (20%-60% wt/wt)-loaded multiple-unit polystyrene microparticles were prepared by an emulsion-solvent evaporation method from an aqueous system. The in vitro release profiles obtained in phosphate buffer of pH 6.8 for drug-loaded polystyrene microparticles and for commercial sustained-release capsules (Fenlong-SR, 400 mg) were compared. Since the microparticles with 30% ibuprofen load showed a release profile comparable to that of the Fenlong-SR release profile, the microparticles with this drug load were considered to be the optimized/selected formulation and, therefore, were subjected to stability study and in vivo study in human volunteers. A single-dose oral bioavailability study revealed significant differences in C(max), T(max), t(1/2a), t(1/2e), K(a), K(e), and AUC between the conventional tablet and optimized or Fenlong-SR capsule dosage forms. However, all the parameters, with the exception of K(a) along with relative bioavailability (F) and retard quotient (R(Delta)), obtained from the optimized ibuprofen-loaded microparticles were lower than that obtained from the commercial Fenlong-SR formulation. Furthermore, linear relationship obtained between the percentages dissolved and absorbed suggests a means to predict in vivo absorption by measuring in vitro dissolution.

In vitro adsorption of plasma proteins onto the surface (charges) modified-submicron emulsions for intravenous administration.

Surface (charge) modified submicron emulsions (cationic and anionic) were prepared following the well established combined emulsification techniques and characterized for their droplet size distribution and surface charge. The effect of these emulsions on in vitro adsorption of plasma proteins was investigated by means of two dimensional polyacrylamide gel electrophoresis (2D PAGE). The presence of poloxamer 188 in tested emulsions effectively eliminated the adsorption of the larger proteins like immunoglobulins, fibrinogen, etc. However, depending on the type of surface charges, the smaller proteins such as apolipoproteins and albumin were almost completely adsorbed onto the submicron emulsions. Indeed, when compared to marketed lipofundin MCT 10%-and deoxycholic acid-based anionic emulsions, the adsorption of apolipoprotein, especially apoA-1, was approximately three times more on stearylamine-and oleylamine-based cationic emulsions and oleic acid-based anionic emulsions. In addition, the ratio between the apoA-1 and apoA-IV was found to be 1 for lipofundin MCT 10% whereas it was about 0.26 for deoxycholic acid-based anionic emulsion and above 5 for oleic acid-based anionic emulsions and cationic emulsions. This indicates that emulsions having similar surface/interfacial charge imparted by different anion-forming stabilizers (oleic or deoxycholic acids) exhibited markedly different protein adsorption patterns.

The potential of lipid emulsion for ocular delivery of lipophilic drugs.

For nearly a decade, oil-in-water lipid emulsions containing either anionic or cationic droplets have been recognized as an interesting and promising ocular topical delivery vehicle for lipophilic drugs. The aim of this review is to present the potential of lipid emulsions for ocular delivery of lipophilic drugs. The review covers an update on the state of the art of incorporating the lipophilic drugs, a brief description concerning the components and the classification of lipid emulsions. The ocular fate following topical instillation, safety evaluation experiments and the applications of lipid emulsions are thoroughly discussed.