Validation study of the unguator, an apparatus for compounding dermatological preparations.

A study was conducted at the Laboratory of Pharmaceutical Technology, University of Liege, Belgium, of the performance of the Unguator Mixing System, an instrument belonging to a new generation of electronic mortar and pestle apparatus, which was designed to improve pharmaceutical compounding, provide pharmaceutically elegant preparations, and reduce nonproductive time. The goal of this study was to verify that preparations that met the actual quality criteria established by the United States Pharmacopeia, the Therapeutic Compounding Formulary, and the British Pharmacopoeia could be achieved by using the Unguator Mixing System. To achieve this goal, the optimal conditions, such as speed, mixing time, and order of addition of the components, were determined for each of several representative preparations. Two different systems were studied, the Unguator 2000 and the Unguator E/S, and effectiveness of standard and disposable blades was examined. Formulations prepared during the study were tested for appearance, microscopic appearance, and, when judged necessary, uniformity of content. Study results revealed that both models tested were less suitable for preparation of gel bases than for other types bases. Very positive and reproducible results were obtained with compositions containing a low content of active ingredient in hydrophobic ointment or hydrophilic cream. A hydrophobic drug such as clioquinol can be mixed effectively in a hydrophilic carbomer gel with either model, as quantitative assays of different batches showed perfect homogeneity, and microscopic examination found no large agglomerates. Special conditions were required for a material such as benzoyl peroxide which consists of large and hard agglomerates. Salicylic acid hydrophobic 10% ointment can be prepared without any difficulty with both models. Both systems provided full protection for the operator against dust inhalation, since all preparation steps, with the exception of weighing the ingredients, occur in closed containers.

Nasal mucoadhesive drug delivery: background, applications, trends and future perspectives.

Nasal drug delivery has now been recognized as a very promising route for delivery of therapeutic compounds including biopharmaceuticals. It has been demonstrated that low absorption of drugs can be countered by using absorption enhancers or increasing the drug residence time in the nasal cavity, and that some mucoadhesive polymers can serve both functions. This article reviews the background of nasal mucoadhesive drug delivery with special references to the biological and pharmaceutical considerations for nasal mucoadhesive drug administration. Applications of nasal mucoadhesives for the delivery of small organic molecules, antibiotics, proteins, vaccines and DNA are also discussed. Furthermore, new classes of functionalized mucoadhesive polymers, the characterization and safety aspects of nasal drug products as well as the opportunities presented by nasal drug delivery are extensively discussed.

Mucosal response in African catfish after administration of Vibrio anguillarum O2 antigens via different routes.

The aim of this study was to investigate the possibility of mucosal vaccination in African catfish (Clarias gariepinus) with Vibrio anguillarum O2 bacterins. The antigen was administered via different routes: anal intubation, oral administration, intraperitoneal injection and immersion. To monitor the antigen uptake, a competitive ELISA was used. The antibody response was measured using an indirect ELISA. Increased antibody levels were found in bile and mucus upon anal intubation, which was not the case after intraperitoneal injection. The data indicate that oral vaccination of fish may be possible when antigens can reach the second gut segment in sufficient quantities and in the right form as confirmed by the recorded substantial induction of systemic and mucosal immunity. The results obtained are a strong indication for mucosal immune response and the two compartmental models for immune response in fish.

Intravaginal gels as drug delivery systems.

Recently, there has been a great deal of interest in the design and application of different dosage forms via the vaginal route. Several studies have proven that the vagina is an effective route for drug administration intended mainly for local action, but systemic effects of some drugs also can be attained. The major advantages of this route include accessibility, good blood supply, the ability to bypass first-pass liver metabolism, and permeability to large molecular weight drugs, such as peptides and proteins. Among the delivery systems proposed for this route is the use of intravaginal gels, which have been found to be potential vaginal drug delivery systems. The bioadhesives used in the formulation of gels play a key role in the release of the drug through the attachment to the vaginal mucosa, where the drug diffuses from the gel to the mucus.

Oral vaccination of African catfish with Vibrio anguillarum O2: effect on antigen uptake and immune response by absorption enhancers in lag time coated pellets.

The impact on antigen uptake and antibody response by the addition of absorption enhancers to Vibrio anguillarum O2 antigen was studied in oral vaccination trials of African catfish (Clarias gariepinus). Oral vaccination was achieved by feeding lag time coated pellets. The lag time coat prevents premature release of the encapsulated vaccine in the tank, before ingestion of the pellets by the fish. To monitor the antigen uptake, a competitive ELISA was used. The antibody response was measured using an indirect ELISA. Feeding of bacterin-layered pellets without absorption enhancers resulted in a rather low antigen uptake and antibody levels. The addition of absorption enhancers such as sodium salicylate, sodium caprate and vitamin E TPGS increased the serum antigen levels and specific antibody levels in the systemic circulation. Skin mucus antibody levels were higher after oral vaccination compared to the IP and control group. The addition of absorption enhancers in the oral groups further increased the antibody levels obtained in the skin mucus.

Metabolism and absorption enhancement of methionine enkephalin in human nasal epithelium.

The objective of this study was to investigate absorption enhancing approaches for systemic delivery of methionine enkephalin via the nose. Absorption promotion of methionine enkephalin in the presence of protease inhibitors (bestatin, puromycin) and absorption enhancers (glycocholate, dimethyl-beta-cyclodextrin) were investigated in human nasal epithelium. Co-administration of the peptide with protease inhibitors and absorption enhancers resulted in a remarkable increase in Met-Enk permeation (4- to 94-fold). The increase was proportional to transepithelial resistance reduction and permeation of paracellular marker dye. Perturbation of the epithelial tight junctions seen in vitro may not occur in vivo due to mucus protection and mucociliary clearance.

In vitro polarized transport of L-phenylalanine in human nasal epithelium and partial characterization of the amino acid transporters involved.

PURPOSE: The purpose of this study was to provide functional and molecular evidence to support the existence of large neutral amino acid transporters in human nasal epithelium using nasal primary cell culture model. METHODS: L-Phenylalanine was used as a model substrate to characterize carrier-mediated permeation of amino acids across human nasal epithelium. The influence of temperature, concentration, other amino acids, metabolic/transport inhibitors, and polarity/stereo-selectivity on transport of the model compound was investigated. Reverse transcriptase polymerase chain reaction was used for molecular characterization of the existence of the transporters. RESULTS: The transport of L-phenylalanine across the human nasal epithelium was polarized (apical --> basolateral >> basolateral --> apical), saturable (Km = 1.23 mM; Vmax = 805.1 nmol/mg protein/min) and stereo-selective (permeation of L-phenylalanine >> D-Phenylalanine). Its permeation was significantly (< 0.05) reduced by cationic, small and large neutral amino acids, oubain, amiloride, sodium-free medium, and temperature lowering. Reverse transcriptase polymerase chain reaction revealed the presence of the broad-scope cationic-dependent amino acid transporter gene (y+LAT-2) in the human nasal epithelium. CONCLUSIONS: Based on the results of this study, one may postulate that the human nasal epithelium expresses L-amino acid transporters. More studies are necessary for detailed characterization of the transporters.

Mechanistic appraisal of the effects of some protease inhibitors on ciliary beat frequency in a sequential cell culture system of human nasal epithelium.

The aim of this study was to investigate the suitability of a sequential monolayer-suspension culture system as a model to screen subacute effects of drug excipients on ciliary beat frequency (CBF). The CBF of the cultured cells was measured by computerized microscope photometry. Protease inhibitors (puromycin, bestatin, bacitracin, actinonin and thiomersal) were used as model compounds and the mechanisms of ciliary inhibition were investigated by probing the involvement of arachidonic acid metabolism, guanylate cyclase (cGMP), protein kinase C (PKC) and adenosinetriphosphate (ATP) inhibition. Bestatin concentration-dependently reduced CBF by inhibiting arachidonic acid metabolism, cGMP, PKC and endogenous ATP consumption. Thiomersal and DMSO used for dissolving actinonin reduced CBF (P<0.05) via a non-specific mechanism. Bacitracin (8 mM) and puromycin (135 mM) had no effect on CBF after acute exposure (15-30 min) (P>0.05), but significantly reduced the CBF by approximately 15.0% following daily 15-min exposure for 1 week. This study shows that (i) sequential monolayer-suspension culture system is a valid model to screen both acute and subacute effects of drug excipients on CBF; and (ii) bacitracin, puromycin and actinonin are more cilio-compatible than bestatin and thiomersal and as such are more potentially useful nasal absorption enhancer from ciliotoxicity perspective.

Characterization of methacrylated inulin hydrogels designed for colon targeting: in vitro release of BSA.

PURPOSE: To characterize methacrylated inulin hydrogels with respect to their release properties. METHODS: Proteins (bovine serum albumin or lysozyme) were used as model drugs and were loaded during or after hydrogel formation. Parameters such as the drug loading method, the molecular weight of the proteins, the initial drug loading concentration, the hydrogel feed composition, degree of substitution, and size of the hydrogel were investigated by determining the release of the model proteins from the hydrogels in a phosphate buffer solution. The biodegradable properties were investigated by studying the release of bovine serum albumin in a solution of inulinase. RESULTS: In vitro protein release from methacrylated hydrogels was influenced by factors such as the drug loading procedure and the molecular weight and loading concentration of the proteins. The feed composition and degree of substitution of inulin seem to be crucial in controlling both the extent and the rate of release. Protein release was clearly enhanced in the presence of inulinase, indicating the biodegradable properties of methacrylated inulin hydrogels. CONCLUSIONS: Several hydrogels show interesting properties with respect to the development of a colon-specific drug delivery system.

Development of a lag time coating for drug-layered fish feed pellets.

The purpose of this work was to develop a release-delaying coat for drug-layered fish pellets, in order to prevent a premature release of the drug in the tank water but allowing a rapid release after uptake by the fish. Blank pellets were prepared in a rotary processor and drug layered in a Wurster coater with bovine serum albumin or riboflavin using hydroxypropyl methyl cellulose (HPMC) as a binder. On the drug-loaded pellets, different mixtures of ethyl cellulose (EC) and HPMC were applied as the release-delaying coat. The aim was to obtain less than 10% drug release during the first 10 min followed by a fast release after the "lag" period, resulting in a sigmoidal release profile. In order to prevent coat bursts it was necessary to increase the amount of plasticizer from 20 to 40% triethylcitrate. To have a complete coat around the pellets, the thickness of the coat (amount EC) was important up to a certain level. The EC/HPMC ratio had a decisive influence on optimizing the permeability of the coating and realizing a sigmoidal release profile. The release rate was studied as a function of several formulation variables and physicochemical parameters (salinity, pH, and temperature) of the dissolution medium as the coating system is intended for different fish species. Salinity of the water proved to be important as well as the temperature. The developed system seems to be promising for a lot of ichthyologic applications, although it has to be evaluated for each intended drug, keeping in mind the properties of the particles to be coated, the fish species, and the environment.

Nasal absorption enhancement strategies for therapeutic peptides: an in vitro study using cultured human nasal epithelium.

This study examined the potential usefulness of cultured human nasal epithelium as a model to investigate nasal absorption enhancement strategies for therapeutic peptides. The transport of leucine enkephalin (Leu-Enk) in the presence of bestatin and puromycin, respectively and various combinations of these protease inhibitors with absorption enhancers capable of inhibiting proteases or protecting peptides against protease degradation (glycocholate, dimethyl-beta-cyclodextrin (DM beta CD)) was studied. Epithelial membrane perturbation, protein leakage, bestatin/puromycin absorption and rebound aminopeptidase activity were used as toxicological end-points. The combination of puromycin with glycocholate or DM beta CD resulted in a higher absorption enhancement of Leu-Enk (9-14%) than when the absorption enhancers were combined with bestatin (1-3%) or when the inhibitors were used alone (2-4%). The higher absorption enhancement resulting from the combination of protease inhibitors with absorption enhancers caused a significant reduction of epithelial resistance and increased sodium fluorescein transport. Although only puromycin permeated the human nasal epithelium, both protease inhibitors induced a significant rebound aminopeptidase activity (25-61%), which can be associated with protein leakage (21-46%). This study highlighted (i) the potential usefulness of cultured human nasal epithelium as a model to study nasal absorption enhancement of therapeutic peptides; (ii) further studies using in vivo nasal models are required to ascertain whether the membrane perturbation and cytotoxicity observed with various combinations of the protease inhibitors and absorption enhancers really raise safety concerns.

Polysaccharides as excipients for colon-specific coatings. Permeability and swelling properties of casted films.

Oligosaccharides such as inulin (In) and polysaccharides such as galactomannans, combined with polymethacrylates on isolated films for film coatings, were obtained from aqueous-based solvents and investigated as potential vehicles for colonic drug delivery. These compositions, which are susceptible to fermentation by colonic microflora, constitute promising excipients for the development of new colon-specific therapeutic systems. The characteristics of several compositions have been demonstrated in permeability and swelling studies on isolated films composed of a polymethacrylate associated with In or galactomannans of mesquite seed gum (MSG). Results reported prove a dependency of the properties of mixed films on the polymethacrylate-polysaccharide concentration ratio and on the composition of the dissolution media. An increase in permeability through the mixed films was observed in a simulated colonic environment for the following compositions: Eudragit RS30D-MSG 70:30 w/w; Eudragit RS30D-In 90:10 w/w; Eudragit RS30D-In 76:24 w/w.