Hydroxystearic acid deposition and metabolism in rats fed hydrogenated castor oil

Particle Engineering of Innovative Nanoemulsion Designs to Modify the Accumulation in Female Sex Organs by Particle Size and Surface Charge

Particle engineering of nanosized drug delivery systems (DDS) can be used as a strategic tool to influence their pharmacokinetics after intravenous (i.v.) application by the targeted adaptation of their particle properties according to the needs at their site of action. This study aimed to investigate particle properties depending on patterns in the biodistribution profile to modify the accumulation in the female sex organs using tailor-made nanoemulsion designs and thereby to either increase therapeutic efficiency for ovarian dysfunctions and diseases or to decrease the side effects caused by unintended accumulation. Through the incorporation of the anionic phospholipid phosphatidylglycerol (PG) into the stabilizing macrogol 15 hydroxystearate (MHS) layer of the nanoemulsions droplets, it was possible to produce tailor-made nanoparticles with tunable particle size between 25 to 150 nm in diameter as well as tunable surface charges between −2 to nearly −30 mV zeta potential using a phase inversion-based process. Three chosen negatively surface-charged nanoemulsions of 50, 100, and 150 nm in diameter showed very low cellular toxicities on 3T3 and NHDF fibroblasts and merely interacted with the blood cells, but instead stayed inert in the plasma. In vivo and ex vivo fluorescence imaging of adult female mice i.v. injected with the negatively surface-charged nanoemulsions revealed a high accumulation depending on their particle size in the reticuloendothelial system (RES), being found in the liver and spleen with a mean portion of the average radiant efficiency (PARE) between 42–52%, or 8–10%, respectively. With increasing particle size, an accumulation in the heart was detected with a mean PARE up to 8%. These three negatively surface-charged nanoemulsions overcame the particle size-dependent accumulation in the female sex organs and accumulated equally with a small mean PARE of 5%, suitable to reduce the side effects caused by unintended accumulation while maintaining different biodistribution profiles. In contrast, previously investigated neutral surface-charged nanoemulsions accumulated with a mean PARE up to 10%, strongly dependent on their particle sizes, which is useful to improve the therapeutic efficacy for ovarian dysfunctions and diseases.

Amended Final Report on the Safety Assessment of Hydroxystearic Acid1

Hydroxystearic Acid is a fatty acid used as a surfactant–cleansing agent in cosmetic products. Initial review of available safety test data resulted in a finding that there were insufficient data to support the safety of Hydroxystearic Acid for use in cosmetic products. Data needed included concentration of use, chemical characterization, dermal reproductive and developmental toxicity, genotoxicity (and carcinogenicity data if the genotoxicity data were positive), and shin irritation data. Subsequent to that conclusion, new data were received. Use concentrations were reported as high as 10%. Small amounts of other fatty acids are commonly found in preparations of Hydroxystearic Acid. Genotoxicity was not found in bacterial or mammalian systems and only subcutaneous sarcomas at the site of injection were found in carcinogenicity studies. Dermal reproductive and developmental toxicity studies were negative. Skin irritation was produced by antiperspirant prototype formulations containing Hydroxystearic Acid under occluded or semioccluded patch test conditions. It was considered that such formulations under those exaggerated conditions can be irritating, but are generally not irritating in actual use. Because Hydroxystearic Acid and Stearic Acid are structurally similar, data from a previous safety assessment of Oleic Acid, Lauric Acid, Palmitic Acid, Myristic Acid, and Stearic Acid were summarized. On the basis of the animal and clinical data, it was concluded that Hydroxystearic Acid is safe as a cosmetic ingredient in the present practices of use.

The fate of ingested glyceran esters of condensed castor oil fatty acids [polyglycerol polyricinoleate (PGPR)] in the rat

Samples of the emulsifier polyglycerol polyricinoleate (PGPR) were synthesized using the radiolabelled precursors [1-14C]glycerol ([14C]polyglycerol PGPR), [9,10-3H] or [12-3H]ricinoleic acid ([3H] PGPR) or [1-14C]stearic acid ([14C]stearyl PGPR). The absorption, tissue distribution, metabolism and excretion of these 14C- or tritium-labelled PGPR samples administered to rats was studied. The effects of intestinal and porcine pancreatic lipases on PGPR preparations were examined. Rats were dosed with [1-14C]glycerol, [14C]polyglycerol and ([14C]polyglycerol)PGPR by gavage and their urine. faeces and expired CO2 monitored for 14C. The results from the [1-14C]glycerol treated animals showed extensive metabolism of glycerol. For [14C]polyglycerols, the lower polyglycerols were preferentially absorbed from the intestine and were excreted unchanged in the urine while the higher polyglycerols were found in the faeces. After 4 days, 93% of the dose of polyglycerols was recovered, of which some 30% was found in the urine and 60% in the faeces. Traces of 14C activity were found in depot fat and liver. The excretory pattern and urinary metabolites from ([14C]polyglycerol) PGPR was very similar to that of [14C]polyglycerol. Analysis of urinary and faecal 14C material indicated that the PGPR polymer was digested to give free polyglycerol and polyricinoleic acid. PGPR was synthesised incorporating [1-14C]stearic into polyricinoleic acid which was then esterified with polyglycerol. The resulting [14C]PGPR or [1-14C] stearic acid in a dietary slurry was administered to groups of fed or starved rats by gavage. The results indicated complete digestion of PGPR and absorption of the fatty acids. The 14C-material absorbed was extensively laid down in depot fat and some metabolism to 14CO2 was demonstrated. The fate of the stearic acid was similar whether dosed alone or incorporated into the PGPR polymer. Samples of PGPR were synthesized containing 3H-labelled ricinoleic acid. The resulting [3H]PGPR was intubated into rats as a component of a dietary slurry. The results indicated that the polymer is extensively digested and 90% of the administered tritium is absorbed. The absorbed material was extensively metabolized within 24 hr so that large amounts of tritium were present in the aqueous phase of the tissues examined. After 24 hr, less than 5% of the administered material was present as lipid material, of which a large proportion was as non-hydroxy fatty acids. No traces of polymer material were found in the tissues examined. In vitro digestion of PGPR by porcine pancreatic lipase and rat intestinal fractions was demonstrated. The results indicate very extensive digestion of the PGPR polymer to polyglycerols and fatty acids. The fatty acids are metabolized extensively. The mono-, di- and triglycerols are extensively absorbed from the intestinal tract and rapidly excreted in the urine unchanged but the hexa-, penta- and higher polyglycerols are essentially not absorbed and excreted in the faeces unchanged.

Actions of ricinoleic acid and structurally related fatty acids on the gastrointestinal tract. II. Effects on water and electrolyte absorption in vitro

Ricinoleic acid, the active component of castor oil, and related fatty acids were studied to determine their relative inhibitory effects on water and electrolyte absorption using everted hamster jejunal and ileal segments. Differences were found between hydroxylated and nonhydroxylated congeners as well as between cis and trans geometric isomers. At a mucosal concentration of 2.0 mM, the unsaturated fatty acids had the following rank order of potency on inhibition of water absorption: ricionoleate greater than or equal to ricinelaidate- greater than equal to linoleate greater than oleate greater than linelaidate greater than elaidate. Ricinoleyl alcohol was effective at 2.0 mM but the methyl ester of ricinoleic acid was ineffective at this concentration. Among a series of saturated fatty acids including palmitate, stearate, a mixture of 9- and 10-hydroxystearate, and 12-hydroxystearate, only the last compound had any inhibitory effect on water absorption. The results define those portions of the ricinoleic acid molecule required for its effect on water and electrolyte absorption and suggest that classification of this cathartic as an "irritant" or "stimulant" should be re-evlauated.