Pharmacokinetics of reshaped MAb 425 in three animal species.

The murine monoclonal antibody (MAb) 425 (mMAb 425) directed against the human EGFR (epidermal growth factor receptor) was reshaped (rMAb 425) in order to improve its therapeutical potential in humans. The pharmacokinetic properties of [125I]-mMAb and [125I]-rMAb 425 were compared in three animal species. Whereas the clearance curves of both antibodies decreased biphasically in rats and nude mice bearing human mammary carcinoma, a monophasic decline was observed in Cynomolgus monkeys. Plasma elimination half-lives of murine and reshaped MAb 425 were similar, short in the monkey (26 h for mMAb 425 and 31 h for rMAb 425) and long in rats (240 h for mMAb 425 and 225 h for rMAb 425). In xenografted nude mice however, the half-life of mMAb 425 (203 h) was about twice as long as that of rMAb 425 (124 h). The half-lives of intact rMAb 425 in the three species obtained by ELISA differed at most by a factor of two from those obtained by radioactivity measurements. Biodistribution studies of [125I]-rMAb 425 revealed a tumor/blood ratio of 1.2 on d 1 and 5.1 on d 18, respectively. Fifty-four and thirty-eight percent of the radioactive dose were excreted with urine in nude mice (within 12 d) and rats (within 11 d), respectively. Specific localization of [125I]-rMAb 425 in human mammary carcinoma xenografted to nude mice was demonstrated.

Distribution of humanized MAb 425 (EMD 62,000) in rats and specific localization in tumor-bearing nude mice.

The murine MAb 425 (IgG2a) directed against human epidermal growth factor receptor is considered to have therapeutic potential in glioma patients. In order to circumvent immune response in clinical use, the MAb 425 was humanized by CDR-grafting (IgG1). We have studied the distribution of reshaped MAb 425 (EMD 62,000) in Wistar rats and the specific localization in female nude mice bearing human mamma carcinoma xenografts. The 125I-labelled MAb 425 was administered intravenously in a single dose (1 mg/kg) using unspecific human IgG1 antibody as control. The biodistribution was investigated both quantitatively and by whole-body autoradiography. The autoradiographs showed a selective uptake of radioactivity by the tumour tissue. 15 days after administration, radioactivity was bound exclusively to the tumour. Similar results were obtained with the murine monoclonal antibody. Quantitative studies exhibited a tumour-blood ratio of about 5. The study demonstrates that the humanized MAb 425 is selectively localized in human mamma carcinoma xenografted to athymic mice.

Dermal absorption of fluprednidene-21-acetate and miconazole from a new topical preparation in pigs.

The dermal absorption of fluprednidene-21-acetate (CAS 1255-35-2) and miconazole nitrate (CAS 22832-87-7) of a new combination cream (Decoderm tri) was studied in pigs after application of 0.5 g cream/kg body weight under occlusive dressing for 5 h. 3H-labelled fluprednidene-21-acetate and 14C-labelled miconazole nitrate were introduced into the base cream as single components or in combination. The three resulting creams were tested in groups of 3 pigs each. To obtain a basis for the assessment of the data after dermal application the two labelled drugs were also examined after intravenous injection. Based on the comparison of the AUC of the radioactive labels an absorption of 4.4% for fluprednidene-21-acetate was calculated when administered alone and 2.4% when administered in the combination cream. For miconazole a smaller absorbed fraction of the dermal dose of 0.5 and 0.8%, resp., was found. Since the differences between single and combined administration were not significant, it follows that there is no relevant reciprocal influence of the two compounds on their dermal absorption.

Pharmacokinetics and metabolism of bisoprolol-14C in three animal species and in humans.

The pharmacokinetic properties of bisoprolol-14C were studied in Wistar rats, beagle dogs, and Cynomolgus monkeys. Bisoprolol is well absorbed in these species; independent of the route of administration (i.v. or p.o.), 70-90% of the 14C-dose was recovered in urine. Faecal excretion was approximately 20% in rats and less than 10% in dogs and monkeys. Rats excreted approximately 10% of the dose in bile after i.v. as well as after oral administration. The plasma half-life of the unchanged drug was approximately 1 h in rats, 3 h in monkeys, and 5 h in dogs. The bioavailability was 40-50% in monkeys, approximately 80% in dogs, and 10% in rats. Studies in rats have shown that the drug is rapidly taken up by the tissues. After i.v. administration, high levels of radioactivity were found in lung, kidneys, liver, adrenals, spleen, pancreas, and salivary glands. After oral administration, the highest concentration occurred in the liver and kidneys. With the exception of plasma and liver, unchanged bisoprolol was the major radioactive constituent in all tissues studied. Both the blood-brain and placental barriers were penetrated, but only to a small degree. No accumulation of radioactivity in tissues was observed after repeated dosing (1 mg/kg/day). The metabolism of bisoprolol was studied in the same three animal species and in humans. The major metabolites are the products of O-dealkylation and subsequent oxidation to the corresponding carboxylic acids. The amount of bisoprolol excreted unchanged in the urine is 50-60% of the dose in humans, 30-40% in dogs, and approximately 10% in rats and monkeys.

Dermal absorption and metabolism of the antipsoriatic drug dithranol triacetate.

Percutaneous absorption, excretion kinetics, and metabolism of dithranol triacetate (2) have been investigated in Wistar rats. By the use of two differently labelled molecules--3H in the anthracene nucleus and 14C in the acetoxy groups of 2, resp.--the fate of the different parts of the dithranol triacetate molecule could be followed. After injection, large amounts of 2 are cleaved under the influence of enzymes into acetate and dithranol. These deacetylated metabolites lose half their 3H label with formation of 3H2O. In urine, 1,8-diacetoxy-9-anthrone, 1-acetoxy-8-hydroxy-9-anthrone, 1,8-dihydroxy-9,10-anthraquinone and its diacetate were found as metabolites. After dermal application, unchanged 2 is practically not absorbed at all. Arylesterases which, according to in vitro studies, are present in or on the skin, hydrolyse dithranol triacetate to give free dithranol. Up to 33% of the latter are absorbed from under an occlusive dressing. Dithranol triacetate, therefore, shows pro-drug characteristics for the treatment of psoriasis.

Sucralfate: pharmacokinetics, metabolism and selective binding to experimental gastric and duodenal ulcers in animals.

Pharmacokinetics, metabolism, and binding capability of a basic aluminium salt of sucrose octasulphate (sucralfate, Ulcogant) to ulcer lesions were investigated in Wistar rat, Beagle dog, Rhesus, and Cynomolgus monkey with 14C-labelled material. After i.v. injection in rats the 14C-radioactivity has a very short serum half-life of 1 h and is excreted almost completely by the kidneys. After oral administration only a very small portion of the dose is detectable in serum which is eliminated rapidly from the intravascular space. From the renal excretion data it is concluded that sucralfate is absorbed from the gastrointestinal tract of rat, Beagle dog, and Rhesus monkey only from 1% to 5% of the dose. The radioactive constituents in plasma, urine, and feces of rat and Cynomolgus monkey were analysed by HPLC. Both after i.v. and p.o. administration only unchanged substance could be detected. A possible binding of 14C-sucralfate to the ulcerated mucosa of stomach and duodenum was investigated in rats by histoautoradiography. The ulcers were induced by acetic acid. A selective accumulation of 14C-sucralfate in the area of the stomach ulcer could be demonstrated as long as 8 h after single p.o. administration. In the duodenum the autoradiographs showed a specific binding of 14C-sucralfate to the ulcerated mucosa at 1, 2, and 4 h after administration. Neither pretreatment with an H2-receptor antagonist nor simultaneous administration of an antacid influenced the binding of 14C-sucralfate. These results suggest that the mode of action of sucralfate is the formation of a protective layer which stops harmful agents like gastric juice and bile from further damaging the ulcerous lesions, thus ensuring an uninterrupted healing process. The very small extent of absorption and the rapid excretion from the organism minimize the risk of a systemic burden.

Preparation and progestational activity of 6-cyano-16-methylene-17 -hydroxy-4,6-pregnadiene-3,20-dione 17-acetate and related compounds.

PIP: The synthesis of of 6-formyl-6-dehydro-16-methylene-17alpha-acetoxyprogesterone (3) and of 6-cyano-6-dehydro-16-methylene-17alpha-acetoxyprogesterone (4) is reported. The preparation of (3) was carried out by converting 3-ethoxy-16-methylene-17alpha-YDROXY-3,5PREGNADIEN-20-ONE 17-acetate (5) by the Vilsmeier reaction to 3-ethoxy-6-formyl-16-methylene-17alpha-hydroxy-3,5-pregnadien-20-one 17-acetate (6). On treatment with dichlorodicyanobenzoquinone (DDQ) in 95% aqueous acetone (6) afforded the desired (3) in 45% yield. The 6-cyano derivative (4) was prepared by reacting (6) with hydroxylamine to give 3-ethoxy-6-oximinomethyl-16-methylene-17alpha-hydroxy-3, 5-pregnadien-20-one 17-acetate; this compound on treatment with DDQ in 95% aqueous acetone gave 6-oximinomethyl-16-methylene-17alpha-hydroxy-4, 6-pregnadien-3,20-dione 17-acetate (9) in 68% yield. Reaction of (9) with phosphorus oxychloride in pyridine afforded the desired 6-cyano dienone (4) in 70% yield. Progestational activity of (3) was the same as that of progesterone, while that of (4) was 5.8 as great.^ieng