Effect of pluronic-F68 on the development of tumor metastasis

Safety Assessment of Poloxamers 101, 105, 108, 122, 123, 124, 181, 182, 183, 184, 185, 188, 212, 215, 217, 231, 234, 235, 237, 238, 282, 284, 288, 331, 333, 334, 335, 338, 401, 402, 403, and 407, Poloxamer 105 Benzoate, and Poloxamer 182 Dibenzoate as Used in Cosmetics

Poloxamers are polyoxyethlyene, polyoxypropylene block polymers. The impurities of commercial grade Poloxamer 188, as an example, include low-molecular-weight substances (aldehydes and both formic and acetic acids), as well as 1,4-dioxane and residual ethylene oxide and propylene oxide. Most Poloxamers function in cosmetics as surfactants, emulsifying agents, cleansing agents, and/or solubilizing agents, and are used in 141 cosmetic products at concentrations from 0.005% to 20%. Poloxamers injected intravenously in animals are rapidly excreted in the urine, with some accumulation in lung, liver, brain, and kidney tissue. In humans, the plasma concentration of Poloxamer 188 (given intravenously) reached a maximum at 1 h, then reached a steady state. Poloxamers generally were ineffective in wound healing, but were effective in reducing postsurgical adhesions in several test systems. Poloxamers can cause hypercholesterolemia and hypertriglyceridemia in animals, but overall, they are relatively nontoxic to animals, with LD50 values reported from 5 to 34.6 g/kg. Short-term intravenous doses up to 4 g/kg of Poloxamer 108 produced no change in body weights, but did result in diffuse hepatocellular vacuolization, renal tubular dilation in kidneys, and dose-dependent vacuolization of epithelial cells in the proximal convoluted tubules. A short-term inhalation toxicity study of Poloxamer 101 at 97 mg/m3 identified slight alveolitis after 2 weeks of exposure, which subsided in the 2-week postexposure observation period. A short-term dermal tox-icity study of Poloxamer 184 in rabbits at doses up to 1000 mg/kg produced slight erythema and slight intradermal inflammatory response on histological examination, but no dose-dependent body weight, hematology, blood chemistry, ororgan weight changes. A6-month feeding study in rats and dogs of Poloxamer 188 at exposures up to 5% in the diet produced no adverse effects. Likewise, Poloxamer 331 (tested up to 0.5 g/kg day-1), Poloxamer 235 (tested up to 1.0 g/kg day-1), and Poloxamer 338 (at 0.2 or 1.0 g/kg day-1) produced no adverse effects in dogs. Poloxamer 338 (at 5.0 g/kg day-1) produced slight transient diarrhea in dogs. Poloxamer 188 at levels up to 7.5% in diet given to rats in a 2-year feeding study produced diarrhea at 5% and 7.5% levels, a small decrease in growth at the 7.5% level, but no change in survival. Doses up to 0.5 mg/kg day-1 for 2 years using rats produced yellow discoloration of the serum, high serum alkaline phosphatase activity, and elevated serum glutamicpyruvic transaminase and glutamic-oxalacetic transaminase activities. Poloxamers are minimal ocular irritants, but are not dermal irritants or sensitizers in animals. Data on reproductive and developmental toxicity of Poloxamers were not found. An Ames test did not identify any mutagenic activity of Poloxamer 407, with or without metabolic activation. Several studies have suggested anti-carcinogenic effects of Poloxamers. Poloxamers appear to increase the sensitivity to anticancer drugs of multidrug-resistant cancer cells. In clinical testing, Poloxamer 188 increased the hydration of feces when used in combination with a bulk laxative treatment. Compared to controls, one study of angioplasty patients receiving Poloxamer 188 found a reduced myocardial infarct size and a reduced incidence of reinfarction, with no evidence of toxicity, but two other studies found no effect. Poloxamer 188 given to patients suffering from sickle cell disease had decreased pain and decreased hospitilization, compared to controls. Clinical tests of dermal irritation and sensitization were uniformly negative. The Cosmetic Ingredient Review (CIR) Expert Panel stressed that the cosmetic industry should continue to use the necessary purification procedures to keep the levels below established limits for ethylene oxide, propylene oxide, and 1,4-dioxane. The Panel did note the absence of reproductive and developmental toxicity data, but, based on molecular weight and solubility, there should be little skin penetration and any penetration of the skin should be slow. Also, the available data demonstrate that Poloxamers that are introduced into the body via routes other than dermal exposure have a rapid clearance from the body, suggesting that there would be no risk of reproductive and/or developmental toxicity. Overall, the available data do not suggest any concern about carcinogenesis. Although there are gaps in knowledge about product use, the overall information available on the types of products in which these ingredients are used, and at what concentration, indicates a pattern of use. Based on these safety test data and the information that the manufacturing process can be controlled to limit unwanted impurities, the Panel concluded that these Poloxamers are safe as used.

Block copolymeric biotransport carriers as versatile vehicles for drug delivery

This review describes block co-polymer-based systems that are used in drug delivery. The main focus is on amphiphilic block co-polymers, the application of which modifies the pharmacological performance of various classes of drugs and is attracting more and more attention. The two main reasons for this are the high tendency of block co-polymer-based drug formulations to self-assemble and the flexibility of block co-polymer chemistry, which allows precise tailoring of the carrier to virtually any chemical entity. The combination of these and some other features makes it possible to adjust block co-polymer-based drug formulations to achieve the most beneficial balance in their biological interactions (biotransport), with systems that control drug removal from the body and those that are responsible for drug therapeutic activity. The following major aspects are considered: The role of physical properties of formulations in their pharmacological performance. The chemistry and physico-chemistry of block co-polymers and structure-function relationships in these systems. Examples describing the effects of biotransport systems on drug transport and activity in cells and some results on their in vivo applications with various drugs.

Structure and design of polymeric surfactant-based drug delivery systems

The review concentrates on the use of polymeric micelles as pharmaceutical carriers. Micellization of biologically active substances is a general phenomenon that increases the bioavailability of lipophilic drugs and nutrients. Currently used low-molecular-weight pharmaceutical surfactants have low toxicity and high solubilization power towards poorly soluble pharmaceuticals. However, micelles made of such surfactants usually have relatively high critical micelle concentration (CMC) and are unstable upon strong dilution (for example, with the blood volume upon intravenous administration). On the other hand, amphiphilic block co-polymers are also known to form spherical micelles in solution. These micelles have very high solubilization capacity and rather low CMC value that makes them very stable in vivo. Amphiphilic block co-polymers suitable for micelle preparation are described and various types of polymeric micelles are considered as well as mechanisms of their formation, factors influencing their stability and disintegration, their loading capacity towards various poorly soluble pharmaceuticals, and their therapeutic potential. The basic mechanisms underlying micelle longevity and steric protection in vivo are considered with a special emphasis on long circulating drug delivery systems. Advantages and disadvantages of micelles when compared with other drug delivery systems are considered. New polymer-lipid amphiphilic compounds such as diacyillipid-polyethylene glycol, are described and discussed. These compounds are very attractive from a practical point of view, since they easily micellize yielding extremely stable micelles with very high loading capacity. Micelle passive accumulation in the areas with leaky vasculature (tumors, infarct zones) is discussed as an important physiology-based mechanism of drug delivery into certain target zones. Targeted polymeric micelles prepared by using thermo- or pH-sensitive components or by attaching specific targeted moieties (such as antibodies) to their outer surface are described as well as their preparation and some in vivo properties. The fast growing field of diagnostic micelles is analyzed. Polymeric micelles are considered loaded with various agents for gamma, magnetic resonance, and computed tomography imaging. Their in vitro and in vivo properties are discussed and the results of the initial animal experiments are presented.

Cytotoxic effects of methionine alkyl esters and amides in normal and neoplastic cell lines

Homologous series of L-methionine alkyl ester hydrochlorides and tosylates were synthesized and evaluated for in vitro growth inhibitory activity in Meth A sarcoma. Cytotoxicity, as determined by [3H]thymidine incorporation, was found to be directly proportional to alkyl chain length and surface tension lowering activity. L-Methionine decyl and dodecyl ester hydrochlorides possessed optimum cytotoxic activity (IC50 = 29, 28 microM) which was not reversible by the addition of L-methionine. Surface tension of a 50 microM solution of the decyl and dodecyl ester hydrochlorides were 35.4 and 32.7 dyn/cm, respectively. The corresponding decyl and dodecyl ester tosylates and amide hydrochlorides were less active. The N-t-butoxycarbonyl analogues were essentially inactive, demonstrating the necessity of an unsubstituted and/or potentially cationic amino group. Methionine dependence characteristics and cytotoxicity were also determined for three human (IMR-90, LX-1, MCF7) and four additional murine (L1210, L5178Y, 3T3, SV-T2) cell lines. The human cell lines Meth A, LX-1, and SV-T2 were found to be methionine independent. The LX-1 tumor cell line and the SV-T2 transformed line exhibited two to four times more sensitivity to the cytotoxic and cytolytic properties of the decyl and dodecyl ester hydrochlorides than their normal counterparts. The dodecyl amide hydrochloride derivative demonstrated enhanced cytotoxic activity in vivo relative to the corresponding ester, possibly due to decreased metabolic hydrolysis.