Valsartan Loaded Solid Lipid Nanoparticles: Development, Characterization, and In vitro and Ex vivo Evaluation

Valsartan is an antihypertensive drug with poor oral bioavailability ranging from 10-35% because of poor solubility, dissolution and most importantly, extensive first pass hepatic metabolism. The present study deals with the development and characterization of Valsartan-loaded solid lipid nanoparticles (VSLNs) to enhance the solubility, bypass the first pass hepatic metabolism, and enhance the lymphatic absorption leading to improved bioavailability. VSLNs were developed using glyceryl behenate (Compritol 888 ATO®) as the lipid and Poloxamer 407 (Pluronic F 127) as the surfactant by the solvent injection method. VSLNs were characterized for mean particle Size (MPS), zeta potential, percentage drug entrapment (PDE), DSC Scans, XRD and TEM analysis. In vitro drug release studies were performed in 0.067 M phosphate buffer of pH 6.8 using dialysis diffusion bag method. Ex vivo drug release studies were also performed for both VSLNs and valsartan suspension in stomach and intestine. The optimized formulation of having the 80 mg lipid, 10 mg drug and 250 mg surfactant was found to have particle size distribution of 142.5 ± 1.859 nm, zeta potential of – 14.3 ± 0.384 mV, and 84.59 ± 0.328% drug entrapment. Based on these results, it is concluded that SLNs show promise for improving the oral bioavailability of valsartan. 

Review of sodium analysis proficiency test results

Proficiency testing results for sodium analysis in foods raised concerns over the proportion of laboratories achieving satisfactory z-scores. Test materials for sodium analysis include fruit juice, canned meat meal, tomato sauce, cheese and pasta meal, and snack food. Fruit juice and tomato sauce data sets are the most problematic in deriving the assigned value with sufficiently low uncertainty to provide evaluative z-scores. The standard deviation for proficiency is derived from Horwitz, with a lack of collaborative trial data for these matrices to provide other guidance. The status of accreditation for the method/matrix does not appear to influence the observed variation in results. Microwave digestion is much less commonly used than simple acid digestion. The choice of determination method appears to be entirely matrix dependent (whether flame atomic absorption spectroscopy, flame photometry or inductively coupled plasma spectroscopy). Results for juice matrix may be overestimated if flame photometry is used, due to either potassium interference or careless reporting where potassium is also determined.

Stepwise approaches for estimating the intakes of chemicals in food

Estimating intakes of chemicals in food requires residue data, giving the concentration of the chemical in food, and consumption data for foods which could contain the chemical. Residue data are often restricted to only a few foods and even then may not be representative of the foods of interest due to limitations in the sampling or analytical procedures. Obtaining reliable consumption data can also be complex. People normally eat a wide range of different foods, which may each contain a range of concentrations of the chemical of interest. Both sets of data can be combined using one of several approaches. This paper reviews the nature and relevance of the factors affecting the collection of these two data sets and the procedures available for combining them to estimate consumer exposure. Considerable expertise and judgment are necessary to obtain an estimate of exposure that is robust enough for risk management purposes.

Dynamic compatibility testing of DMP 840, an experimental antitumor agent

The purpose of this study is to evaluate the potential for DMP 840, a novel experimental antitumor agent, to precipitate during injection or dilution with infusion solutions. The influence of predilution of the drug solution before injection and addition of buffers to the drug vehicle were also investigated. The compatibility of normal saline solution, pH 7.4 phosphate buffers, and human plasma with DMP 840 was examined in vitro under both static conditions and dynamic flow. The combination of DMP 840 solutions with normal saline solution resulted in conversion of the drug to an insoluble dihydrochloride salt. Under conditions of dynamic flow, precipitation, accompanied by large changes in turbidity, occurred at relatively high concentrations of the drug in the injection solution. Dilution of the injection solution below 2 mg/mL or slow injection avoided precipitation. As was the case with the normal saline system, turbidity changes after injection into protein-phosphate buffer (PPB) were dependent on the initial concentration of DMP 840 solution as well as the rate of administration. In addition, the maximum injection rate at which complete miscibility occurred increased exponentially as the drug injection solution was made more dilute. Buffering the DMP 840 injection solution with acetate buffer improved the miscibility of DMP 840 with PPB, which indicated that the turbidity increases were most likely due to conversion of the drug to its insoluble free base form. The observed effects of the buffer on the turbidity response agreed qualitatively with predictions from a graphical approach that considers the effects of dilution and pH changes on drug solubility. Despite these observations, no evidence for the formation of a solid precipitate could be found after injection of the unbuffered drug solution into PPB. Further investigation indicated that the presence of albumin in the PPB prevented the formation of a solid phase during injection. Likewise, fresh human plasma, spiked with 1 and 2 mg/mL solutions of DMP 840, showed no evidence for the formation of a solid precipitate.

Klebsiella pneumoniae osteomyelitis in sickle cell anemia

A case of Klebsiella pneumoniae osteomyelitis in a patient with sickle cell anemia is reported. The literature is briefly reviewed. The case is presented because of the rarity of Klebsiella pneumonia osteomyelitis in sickle cell disease.