Interferon regulatory factor-5 is genetically associated with systemic lupus erythematosus in African Americans.

Increased expression of interferon (IFN)-inducible genes is implicated in the pathogenesis of systemic lupus erythematosus (SLE). One transcription factor responsible for regulating IFN, interferon regulatory factor-5 (IRF5), has been associated with SLE in genetic studies of Asian, Caucasian and Hispanic populations. We genotyped up to seven polymorphic loci in or near IRF5 in a total of 4870 African-American and Caucasian subjects (1829 SLE sporadic cases and 3041 controls) from two independent studies. Population-based case-control comparisons were performed using the Pearson's chi(2)-test statistics and haplotypes were inferred using HaploView. We observed significant novel associations with the IRF5 variants rs2004640 and rs3807306 in African Americans and replicated previously reported associations in Caucasians. While we identified risk haplotypes, the majority of haplotypic effects were accounted for by one SNP (rs3807306) in conditional analyses. We conclude that genetic variants of IRF5 associate with SLE in multiple populations, providing evidence that IRF5 is likely to be a crucial component in SLE pathogenesis among multiple ethnic groups.

Ocular toxicity of vitreal pluronic polyol F-127.

To evaluate pluronic polyol F-127 (PF-127) as a vitreous substitute and an intraocular drug delivery system, a total vitrectomy was performed on 18 New Zealand rabbits (18 eyes). The vitreous was replaced with either PF-127 (9 eyes) or balanced salt solution (9 eyes). There was little difference clinically between the eyes containing PF-127 and the control eyes. Both groups showed mild postoperative inflammation, with no differences in intraocular pressures. Histopathologic findings for the control group showed no significant retinal alteration, and serial ERG findings were within normal limits. In contrast, the eyes containing PF-127 showed marked destruction of the retina by 2 weeks after surgery. The ERG amplitudes decreased dramatically to a flat tracing by 24 hours after surgery. Although it is attractive as a potential vitreous substitute, PF-127 is not safe for human use, at least at the concentration used.

Drug release studies on an oil-water emulsion based on a eutectic mixture of lidocaine and prilocaine as the dispersed phase.

The in vitro drug release properties of a topical anesthetic formulation known to be effective on intact skin, based on a 1:1 eutectic mixture of lidocaine and prilocaine emulsified in water, were investigated with a poly(dimethylsiloxane) membrane partition model. Aqueous solutions and solubilized systems of lidocaine and prilocaine in a 1:1 ratio by weight were also included in the study as well as the eutectic mixture itself. Two identical sets of samples were used, one of which was gelled with carbomer 934 P. Drug solubilities in the membrane, partition coefficients between membrane and water, and diffusion coefficients in the membrane and the formulations were determined. As in the case of an aqueous medium, lidocaine and prilocaine in combination had lower solubilities in the membrane than they did separately. However, in the aqueous phase or in the membrane, the diffusion coefficients were mutually independent. Carbomer 934P, when neutralized totally with sodium hydroxide, did not decrease the aqueous diffusivities of the local anesthetic bases. The major advantages of using the emulsion formulation based on a eutectic mixture rather than more conventional formulations are: (a) the local anesthetic bases are present in their permeable uncharged forms; (b) the use of a poor solvent, water, as the vehicle provides a saturated system at low concentrations; (c) lipophilic solvent is absent in the dispersed phase, the presence of which would decrease the effective distribution coefficients of the active substances between the skin and the formulation; (d) the droplets consist of dissolvable drug and act as reservoirs to obtain steady-state release; and (e) the fluid state of the excess drug provides a higher dissolution rate than from a solid state.

Phase distribution studies on an oil-water emulsion based on a eutectic mixture of lidocaine and prilocaine as the dispersed phase.

The distribution conditions in oil-water emulsions prepared by emulsifying a 1:1 eutectic mixture of lidocaine and prilocaine with a nonionic surfactant in water were studied by membrane and gel filtration methods. In this system, the local anesthetics are considered to be freely dissolved, surfactant solubilized, and emulsified in three separate phases. The dispersity of the oil phase was investigated by light microscopy and light-scatter spectroscopy. The majority of drops in the lidocaine-prilocaine emulsions were less than 1 micron in size. The concentration of freely dissolved drug in the aqueous phase of the emulsions was equal to the aqueous solubility of lidocaine-prilocaine in a 1:1 ratio. At constant lidocaine/prilocaine/surfactant ratio, increasing the total drug concentration in the emulsion resulted in an increase of the emulsified fraction of lidocaine-prilocaine, whereas the surfactant-solubilized fraction remained constant.

Dissolution dialysis studies of metronidazole-montmorillonite adsorbates.

In the context of the potential usefulness of clays in retarding the rate of release of adsorbed drugs, dissolution dialysis studies of the release of metronidazole from montmorillonite adsorbates have been conducted. The goal was to develop a means for improving local gastrointestinal therapy of amebiasis while concurrently maintaining efficacy in treating hepatic amebiasis. At acidic pH, the clay was in a flocculated state and the rate of drug release was inhibited. This effect was apparently due to slow diffusion of the drug throughout the clay flocculate. A physical admixture of montmorillonite and metronidazole was also effective in inhibiting the rate of release of metronidazole. Upon increasing the pH to 7, the clay particles progressively deflocculated and the rate of release increased significantly.

Investigation of the beta-cyclodextrin-hydrocortisone inclusion compound.

The formation of an inclusion compound by beta-cyclodextrin with hydrocortisone has been studied by proton magnetic resonance (1H-NMR) and phase solubility analysis. The magnitude of the chemical shifts of the interior and exterior beta-cyclodextrin protons in the presence of hydrocortisone indicated that hydrocortisone is included within the beta-cyclodextrin cavity and probably interacts with protons on the edge of the torus. The overall stoichiometry of the inclusion compound was not a single, simple relationship, but was unusual in that it was variable and apparently dependent on the relative amounts of hydrocortisone and beta-cyclodextrin in the system.

Particulate matter in four reconstituted cephalosporin injections.

The amount and size of particulate contamination in three commercially available cephalosporin injections and a new product, anophilized cephalothin sodium injection, were studied. Particles in reconstituted cephalothin sodium (commercially available and anophilized), cephapirin sodium, and cephradine injections were counted using two methods: (1) modified USP membrane-filtration technique and (2) Elzone computerized particle analyzer. The amount of particulate contamination in the ranges of 10-24 and greater than or equal to 25 microns was determined by both methods. In the 10-24-microns range, the cephalothin, cephapirin, and cephradine products had significantly greater particle counts than the anophilized cephalothin product. The greater than or equal to 25-microns particle counts showed that the cephapirin and cephradine products had particle counts greater than the anophilized cephalothin product, while total particle counts showed the same results as the 10-24-microns particle counts. A comparison of counting methods showed that the only significant difference between the number of particulates obtained using the modified USP and Elzone computer methods was with the cephalothin product. Anophilized cephalothin sodium injection has significantly fewer particles in the size ranges studied. No conclusion could be reached as to the more accurate method for counting particles.

Phase solubility analysis and PMR study of complexing behavior of dinoprostone with beta-cyclodextrin in water.

The mechanism of inclusion compound formation by dinoprostone (prostaglandin E2) with beta-cyclodextrin was studied by phase solubility analysis and PMR spectroscopy. As indicated by the linear increase of aqueous solubility of dinoprostone with beta-cyclodextrin concentration, some types of molecular interactions definitely exist between dinoprostone and the complexing ligands. The temperature dependence of a 1:1 complex formation constant yielded the following thermodynamic data at 20 degrees : deltaG degrees = -4.11 kcal/mole, deltaH degrees = 7.20 kcal/mole, and deltaS degrees = 10.5 e.u. Since water was the solvent system, these parameters appear to be largely determined by solvent reorganization through hydrogen bonding rather than solely by the binding of desolvated free dinoprostone and beta-cyclodextrin entities. PMR data indicate that dinoprostone is included within the cavity and also interacts with protons on the exterior of the beta-cyclodextrin molecule. A model consisting of a 1:1 complex, in which a dinoprostone molecule is partially included within the cavity and the remainder of the molecule extends around the edge of the opening of the cavity to the exterior of the beta-cyclodextrin molecule, is proposed as the most probable structure of this inclusion compound.

Tritiated naltrexone binding in plasma from several species and tissue distribution in mice.

The binding of 15,16,-3H-naltrexone in human, monkey, dog, guinea pig, rat, and mouse plasma was investigated over a range of concentrations, including predicted therapeutic levels. Studies using equilibrium dialysis at 37 degrees indicate that the extent of binding is independent of naltrexone concentration over the concentration range of 1-500 ng/ml for dog plasma and of 0.1-500 ng/ml for human, monkey, guinea pig, rat, and mouse plasma. The extent of naltrexone binding in plasma is similar in the six species studied, the range being from 20% bound in rat plasma to 26% in plasma from beagle and mongrel dogs. This relatively low extent of naltrexone binding in plasma is consistent with previous findings of a large apparent volume of distribution of this drug in the dog. To investigate further the distribution of tritiated naltrexone, the tissue levels of radioactivity in mice at 1, 5, and 15 min after intravenous administration of 8-3H-naltrexone were determined. Naltrexone was rapidly distributed from plasma to tissues, with less than 4% of the dose being present in plasma at 1 min after injection.

Metabolic reduction of naltrexone. I. Synthesis, separation and characterization of naloxone and naltrexone reduction products and qualitative assay of urine and bile following administration of naltrexone, alpha-naltrexol, or beta-naltrexol.

Reduction of naltrexone and naloxone with sodium borohydride gave a mixture (85:15) of the 6alpha- and 6beta-hydroxy epimers, alpha- and beta-naltrexol and alpha- and beta-naloxol, respectively. Each pair of epimers was separated by preparative thin-layer chromatography and the physical and spectral properties of each compound were determined. Previous assignments for the configuration of the epimers were verified. A semi-quantitative electron capture gas-liquid chromatographic method was devised for distinguishing either alpha- or beta-naltrexol in the presence of the other and in the presence of large amounts (at least 10-fold greater) of naltrexone. The method was used to determine the approximate weight ratio of beta-naltrexol to naltrexone present in enzymatically hydrolyzed urine samples. It was found that substantially greater quantities of beta-naltrexol and/or its conjugates were excreted in the urine of man, monkey, guinea pig and rabbit after administration of naltrexone, whereas very small quantities were excreted by the mouse, rat and dog. In contrast, just trace amounts of the 6alpha-hydroxy epimer, alpha-naltrexol, were detected in the urine of only 2 of the 7 species that had received naltrexone, i.e., monkey and guinea pig. After administration of 3H-15,16-naltrexone, 1 mg/kg, i.v. to the guinea pig, 25% of the radioactivity found following thin-layer chromatography of the extract of acid-hydrolyzed urine corresponded to beta-naltrexol. In gall bladder bile from the guinea pig, only conjugates of naltrexone and beta-naltrexol were found 2 hours after administration of naltrexone. Following administration of beta-naltrexol, 1 mg/kg, i.v. to guinea pigs only beta-naltrexol and/or its conjugates were detected in urine or bile. However, urine collected after administration of alpha-naltrexol, 1 mg/kg, i.v. to guinea pigs contained alpha-naltrexol and its conjugates, as well as a yet unidentified metabolite.