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The investigated polymers, poly(sebacic acid-co-ricinoleic acid) containing > or =70% ricinoleic acid, may be injected via a 22 gauge needle and become gel upon contact with aqueous medium, both in vitro and in vivo. Various properties of the polymers including viscosity, thermal analysis, and in vivo behavior, before and after exposure to aqueous medium, were determined. These polymers were observed using scanning electron microscopy (SEM) at dry and wet states. It was found that the viscosity and melting temperature of P(SA:RA) increased after exposure to buffer. The viscosity at 37 degrees C of P(SA:RA)3:7 had the highest increase: from 4200 cP before to 8940 cP after exposure to buffer; in the case of P(SA:RA)25:75 before exposure to buffer the viscosity was 1150 cP while after it raised to 3200 cP. The viscosity of P(SA:RA)2:8 also increased from 400 cP before exposure to buffer to 1000 cP after. On the other hand polymer without sebacic acid, (poly(ricinoleic acid)), did not show gelation properties. Thermal analysis also showed an increase in the melting point of the polymers exposed to the aqueous medium during the first 24 h of incubation. Images obtained by SEM showed formation of a three-dimensional network in polymers exposed to buffers. When injected into animals, P(SA:RA) forms a solid implant in the injection site already at 8 h postinjection.

Male Fischer-344 rats administered a single intraperitoneal dose of perfluoro-n-octanoic acid (PFOA) or perfluoro-n-decanoic acid (PFDA) display a similar "wasting toxicity" characteristic of perfluorocarboxylic acids, with marked differences in temporal expression. Food/water consumption and urine output were monitored daily in PFOA-treated, PFDA-treated, and control rats. Fluorine-19 nuclear magnetic resonance (NMR) spectroscopy was used to monitor these fluorocarbons and possible fluoro metabolites in vivo, and to correlate differences in elimination with differences in effective toxicity. The data reveal a prolonged hypophagic response to PFDA and a more acute but transient response associated with PFOA treatment. PFOA causes a greater decline in food consumption than PFDA within the first 24 h postdose. PFOA-treated rats also show a ca. 2.5-fold increase in urine output on day 1, with only a slight increase in water consumption. In contrast to PFDA, PFOA-treated rats recover from hypophagia within 8 days. Fluorine-19 NMR spectra of various bodily fluids and liver in vivo display resonances of the parent PFOA or PFDA compounds and do not reveal any evidence of metabolism. Inorganic fluoride from dietary sources is detected in urine from both exposed and control rats. Differences in the route of excretion of PFOA vs PFDA are apparent from the spectral signal-to-noise ratio. The data suggest that PFOA is more readily excreted in the urine while PFDA is preferentially carried in bile. These apparent differences in elimination may account for their observed differences in effective toxicity. The acute transient toxicity and higher LD50 associated with PFOA may result from its rapid renal clearance.(ABSTRACT TRUNCATED AT 250 WORDS)