Usefulness of liposomes carrying losefamate for CT opacification of liver and spleen.

Losefamate, a hepatobiliary contrast agent, was encapsulated into liposomes to increase its ability to opacify the liver and spleen on computed tomographic (CT) images. Multilamellar lipid vesicles (lecithin, cholesterol, and stearylamine, in 4:1:1 molar ratio) containing iosefamate in their aqueous phase were prepared. Seven dogs received intravenous injections of 100-300 mg I/kg in one of three forms: encapsulated, unencapsulated, or a mixture of the two in equal parts. Animals that received the opaque vesicles had marked opacification of their livers, bile ducts, gallbladders, spleens (maximum 106 H enhancement), and gastrointestinal tracts. Spleen CT values (an indicator of encapsulated material uptake) were always higher in these dogs than in the animals receiving equivalent amounts of unencapsulated iosefamate alone. At the high-dose level, liver uptake of the encapsulated materials was also greater. Liposome-encapsulated hepatobiliary contrast agents are effective liver and spleen opacifiers for CT imaging in the dog.

Biodistribution study of Ethiodized Oil Emulsion 13 for computed tomography of the liver and spleen.

Biodistribution studies were conducted with a new intravenous lipoid contrast material currently undergoing clinical trials in four hospitals. The contrast material selectively opacifies the liver and spleen for computed tomographic examination. The experiments were performed on rats with 125I-labeled ethiodized oil emulsion. The study showed that the liver accumulates nearly 80% of the injected iodine within 15 min of the injection and retains a high concentration over 3 h. The second highest concentration was found in the spleen. More than 99% of the iodine is eliminated from the liver and spleen within 48 h, primarily through the kidneys.

Ioglucomide: a new nonionic myelographic agent. Preclinical studies.

Ioglucomide, a new iodinated nonionic contrast medium directed primarily toward myelographic use, was subjected to an extensive toxicological examination in animals. In the majority of studies, ioglucomide was compared directly with metrizamide. In some respects, including freedom from production of arachnoiditis, ioglucomide and metrizamide were comparable. However, acute toxicity after intravenous injection or instillation into cerebrospinal fluid was significantly less for ioglucomide. Also, in contrast to metrizamide, ioglucomide produced no evidence of any type of convulsive activity after subarachnoid administration. The improved safety of ioglucomide could not be related to osmolality; therefore, the importance of osmolality for nonionic myelographic agent safety is questioned.

synthesis and biological testing of nonionic iodinated x-ray contrast media.

A series of nonionic x-ray contrast media containing novel linkages between the triiodobenzene and polyhydroxy moieties have been prepared and screened against established criteria. Of the coupler groups examined (amide including dipeptide, carbamate, ureido, and ester), amide showed the greatest overall utility in terms of safety, solubility, stability, and ease of synthesis. Acute toxicity, solubility and stability data are summarized for each series. In the CNS, certain compounds were well tolerated and some were devoid of any excitatory effects. Intrathecal tissue irritant effects were also unremarkable. Most agents exhibited relatively high osmolalities, raising questions as to the influence of this factor on the safety of myelographic agents. Intravascularly, nonionic media appear also to offer advantages over classical ionic media. However, nonionic media can exert positive inotropic effects and exhibit high viscosity at higher iodine concentrations. Nevertheless, overall results continue to demonstrate the radiographic potential of nonionic contrast media.