A Method to Predict the Equilibrium Solubility of Drugs in Solid Polymers near Room Temperature Using Thermal Analysis

A method is presented for determining the equilibrium solubility of a drug in a solid polymer at or near room temperature, which represents a typical storage temperature. The method is based on a thermodynamic model to calculate the Gibbs energy change ΔG_SS associated with forming a binary drug–polymer solid solution from the unmixed polymer and solid drug. The model includes contributions from heat capacity differences between the solid solution and the corresponding unmixed components, breaking up of the solid drug structure, and drug–polymer mixing. Calculation of ΔG_SS from thermal analysis data is demonstrated, and it is shown that minima of plots of ΔG_SS versus the dissolved drug concentration represent the equilibrium drug solubility in the polymer. Solid solutions were produced for drug–polymer systems (griseofulvin, indomethacin, itraconazole; PVP K30, Eudragit L100, Eudragit E100) in drug weight fractions up to ～25%. At 25°C, it was seen that heat capacity effects were important in determining the drug solubility. It was concluded that drug solubilities in solid polymers can be determined using thermal analysis, and must include heat capacity effects when evaluated near room temperature.     

Ocular Disposition of the Hemiglutarate Ester Prodrug of ∆9-Tetrahydrocannabinol from Various Ophthalmic Formulations

Purpose

The overall goal of this project is to enhance ocular delivery of ?⁹-Tetrahydrocannabinol (THC) through the topical route.

Methods

Solubility, stability and in vitro transcorneal permeability of the relatively hydrophilic hemiglutarate ester derivative, THC-HG, was studied in the presence of surfactants. The solutions were characterized with respect to micelle size, zeta potential and solution viscosity. In vivo studies were carried out in New Zealand albino rabbits. A previously reported promising THC-HG ion-pair formulation was also studied in vivo.

Results

Aqueous solubility and stability and in vitro transcorneal permeability of THC-HG was enhanced significantly in the presence of surfactants. THC levels in the ocular tissues (except cornea) were found to be below detection limits from mineral oil, surfactant or emulsion based formulations containing THC. In contrast, micellar and ion pair based THC-HG formulations produced significantly higher total THC concentrations in the anterior ocular chamber.

Conclusion

In this study, although delivery of THC to the anterior chamber ocular tissues could be significantly increased through the prodrug and formulation approaches tested, further studies are needed to increase penetration to the back-of-the eye.     

Analytical strategy for the detection of ecdysterone and its metabolites in vivo in uPA(+/+)-SCID mice with humanized liver,human urine samples,and estimation of prevalence of its use in anti-doping samples

Ecdysteroids are of interest as potential sport performance enhancers, due to their anabolic effects. The current study aimed to analyze levels of the most abundant ecdysteroid, ecdysterone (20-hydroxyecdysone, 20-OHE) in easily available dietary supplements, and, outline an analytical strategy for its detection, and that, of its metabolites, (1) following administration of pure 20-OHE to uPA(+/+)-SCID mice with humanized liver, (2) in a human volunteer after ingestion of two supplements, one with a relatively low, and the other a high, concentration of 20-OHE, and, (3) to estimate the prevalence of use of 20-OHE in elite athletes (n = 1000). Of the 16 supplements tested, only five showed detectable levels of 20-OHE, with concentrations ranging from undetectable up to 2.3 mg per capsule. Urine of uPA(+/+)-SCID urine showed the presence of 20-OHE and its metabolite, 14 deoxy ecdysterone, within 24 hours (hr) of ingestion. In humans, both the parent and the metabolite were detectable within 2 to 5 hr of ingestion, with the metabolite being detectable for longer than the parent. After ingestion of a low dose supplement, the parent and metabolite were detectable for 70 and 48 hr, while following the higher dose it was 96 and 48 hr, respectively. Analysis of urines from athletes (n = 1000) confirmed four positives for 20-OHE, suggesting a prevalence of use of 0.4%. Prevalence of its use by elite athletes was relatively low, however, this needs to be confirmed in other populations, and with other related ecdysteroids.     

Sexuality in the nursing home,part 2: Managing abnormal behavior-legal and ethical issues

Everyone, regardless of age, needs love, touch, companionship, and intimacy. The 1.6 million elderly in the 20,000 U.S. nursing homes are not an exception. The literature indicates that nursing home residents continue to have an interest in sexual activity regardless of age. Sexuality, however, is frequently overlooked by physicians and staff working with nursing home residents. Many staff members have only a vague understanding of the sexual needs of the elderly. This results in a perception of residents' sexual interests as behavioral problems rather than expressions of need for love and intimacy. Inappropriate sexual behaviors in the nursing home can create an intense burden for nursing home staff. This article discusses ways to dealing with inappropriate sexual behaviors in long-term care settings and the ethical issues involved.     

Identification and characterization of the VAX2 p.Leu139Arg variant: possible involvement of VAX2 in cone dystrophy

Objective: This study was undertaken with the objective to investigate the potential involvement of VAX2 in retinal degeneration.

Methods: A cohort of macular and cone dystrophy patients (n = 70) was screened for variant identification. Polymerase chain reaction (PCR) products were purified using ExoSAP-IT. Direct sequencing of PCR products was performed using BigDye 3.1 on the ABI 3730 DNA Analyzer and analyzed using DNASTAR software tool. Search for known variant was performed using the following platforms: 1000 Genomes Project, Ensembl, UCSC, ExAc, and dbSNP. The VAX2 mutants were generated using the GeneArt® Site-Directed Mutagenesis kit. In vitro analysis was performed in hTERTRPE-1 (RPE-1) cell line. Cells were photographed using a Zeiss AXIOVERT S100 microscope. Images were analyzed using Photoshop CS4 software.

Results: Here, we report the identification of a heterozygous non-synonymous variant (c.416T>G; p.Leu139Arg) in one cone dystrophy proband. Functional characterization of this variant in vitro revealed an aberrant phenotype seen as protein mislocalization to cytoplasm/nucleus and aggregates undergoing degradation or forming aggresomes. The cellular phenotype suggests protein loss-of-function. Analysis of the VAX2 p.Leu139Met, a variant present in the normal population, showed a phenotype similar to the wild-type, further supporting the hypothesis for the Leucine 139 to Arginine change to be damaging.

Conclusions: This study raises the interesting possibility for evaluating VAX2 as a candidate gene for cone dystrophy.     

Histidine-rich glycoprotein inhibits the antiproliferative effect of heparin on smooth muscle cells

Histidine-rich glycoprotein (HRGP), an alpha-glycoprotein in human plasma that is also present in platelets and macrophages, binds heparin with high affinity and neutralizes its anticoagulant activity. We now report that HRGP specifically inhibits the antiproliferative effect of heparin on arterial smooth muscle cells while other heparinoid-binding proteins do not influence mitogenesis. The multicellular inflammatory response to endothelial injury characterized, in part, by the influx of platelets and macrophages, may be associated with HRGP release into the arterial microenvironment. This release of HRGP may allow smooth muscle cell proliferation and atherogenesis by inhibiting the action of endothelial cell-derived heparinoid substances.     

Herpes simplex virus infection in human arterial cells. Implications in arteriosclerosis.

Herpesviruses have been implicated as etiologic factors in the pathogenesis of human arteriosclerosis. We have examined the pathobiological effects of human herpes simplex virus (HSV-1) infection in influencing lipid accumulation and metabolism in human and bovine arterial smooth muscle cells (SMC). Significantly greater amounts of saturated cholesteryl esters (CE) and triacylglycerols (TG) accumulate in HSV-1-infected human and bovine arterial SMC than uninfected cells. This CE accumulation results, in part, from decreased CE hydrolysis. Furthermore, arachidonate-stimulated, HSV-1-infected arterial SMC have a reduced capacity to produce prostacyclin (an agonist of intracellular CE hydrolytic activity) than uninfected, stimulated SMC. It appears that HSV-1 may induce lipid accumulation in arterial SMC similar, in part, to the lipid accumulation observed in vivo during human atherogenesis. Thus, herpesviruses may contribute to lipid accumulation, which is a characteristic feature of atherosclerosis.     

Functional interplay between gelatinases and hyperalgesia in endotoxin-induced localized inflammatory pain

The role of ECM-degrading proteinases in normal developmental processes and in pathological conditions is extensively studied. However, few reports describe the role ECM-degrading proteinases play in modulating hyperalgesia. The goal of this study is to describe the regulation of gelatinases during endotoxin mediated local inflammation, induced by intra plantar endotoxin (ET; 1.25 microg/50 microl) injection in Balb/c mice, and to correlate that with hyperalgesia. ET injections induced hyperalgesia, as determined by hot plate and paw pressure tests, which peaked by 24 h and recovered by 48 h post-injection. Contralateral paw of ET injected mice and saline injected paws in control mice elicited no hyperalgesia. Zymography showed that ET and saline injected paws elicited increased gelatinase activity by 9 h after injection. However, only the former maintained high levels of expression of a 90 kD gelatinase up to at least 96 h post ET injection, while in the latter gelatinase expression was down regulated by 24 h. Interestingly, the 90-kD gelatinase was upregulated in the contralateral paw of the ET-injected mice beyond 48 h post injection. Saline injection in that paw, during a time when gelatinases are upregulated, induced hyperalgesia. Intraperitoneal injection of either ZnCl(2) (100 microM), thymulin (5 microg/100 microl), or morphine (2 mg/kg/100 microl) reversed the ET-induced hyperalgesia and suppressed gelatinase activity. Furthermore, intraperitoneal injection of MPI, an ECM-degrading proteinase inhibitor, reversed ET induced hyperalgesia. Taken together, the above suggests that a functional interplay exists between gelatinase upregulation triggered by ET injections and hyperalgesia. The exact mechanism underlying such correlation remains to be determined.