Preclinical safety studies with Temofel, a new choleretic compound.

Temofel (2,5-dimethyl-alpha-ethyl-benzhydrol) is a choleretic compound. Safety studies required for Phase I and II clinical trials were performed. No oestrogenic, antioestrogenic, androgenic or antiandrogenic effect was induced in infantile rats treated with 100 and 200 mg/kg. No CNS effects were induced by 50 mg/kg in mice. No haemodynamic or respiratory changes were induced in dogs by 300 mg/kg. In a 28-day oral toxicity study with 40, 80, 160, 320, 640 and 1280 mg/kg doses on Lati: CFY (SD) rats died at the 2 highest doses (640 and 1280 mg/kg). Large necrotic foci in the liver were found at the highest dose 1280 mg/kg. In rats treated with 320 mg/kg and higher doses, hepatic hyperplasia, renal tubular hyperplasia and protein retention in the renal cortex were observed. Testicular atrophy, damaged spermiogenesis, spermiohistogenesis and regulative Leydig-cell hyperplasia were induced by 640 and 1280 mg/kg. In a 28-day study on Velz: BEAGLE dogs with daily doses of 40, 120 and 360 mg/kg sporadically increased SAP activity occurred at the high dose. In a 6-month study rats were fed 400, 2000 and 10000 ppm Temofel. Growth was retarded in the medium and high dose group, no sperm could be seen in the urinary sediment of the high dose group. Testicular atrophy, complete lack of spermiogenesis, spermiohistogenesis occurred in this group. In contrast to the administration of 1280 mg/kg for 28 days by gavage, no hepatic or renal changes were induced by 10000 ppm consumed for 6 months. A 6-month canine study with 40, 120 and 360 mg/kg doses revealed sporadic SAP increase at the high dose.(ABSTRACT TRUNCATED AT 250 WORDS)

Analysis of cataract and keratotic damage induced by 4-diethylaminoethoxy-alpha-ethyl-benzhydrol (RGH-6201) in rats.

RGH-6201 (4-diethylaminoethoxy-alpha-ethyl-benzhydrol) in the first dose-range finding study on rats produced severe, irreversible ophthalmic damage. The underlying mechanism was studied in a series of experiments with daily doses of 50, 100 and 200 mg/kg in rats by gavage. Lenticular damage appeared as a moderate nuclear degeneration during Week 4 of treatment with 50 mg/kg RGH-6201. This could be detected in the isolated eye and in histological examination but not by ophthalmoscopy. Keratitis and iridocyclitis developed about the 2nd week of treatment followed by epithelial proliferation in the lens under the anterior capsule in the higher dose groups. Nuclear and total cataract developed from the 2nd week on in the 200 mg/kg group and from the 3rd week on in the 100 mg/kg group. Further gross pathological changes in the high dose group were characterized by marked hairloss, desquamation in the cardiac region of the stomach and diarrhoea. It has to be emphasized that fine lenticular changes were unrelated to keratitis and iridocyclitis. Since other benzhydrol derivatives such as 2,5-dimethyl-alpha-ethylbenzhydrol and 3-trifluoro-methyl-alpha-ethyl-benzhydrol do not induce similar changes, the diethyl-amino-ethoxy group was assumed to be the toxic part of the molecule. Intravenous studies with equimolar doses of diethyl-aminoethanol revealed no similar symptoms.

Preclinical toxicity studies with two thymopoietin-like peptides.

Differentiation of T-lymphocytes is regulated by thymopoietin, a 49 amino acid polypeptide chain. The site of immunological activity is in the 32-36 (Arg-Lys-Asp-Val-Tyr) fragment. This pentapeptide can be reduced to a tetrapeptide (RGH-0206: Arg-Lys-Asp-Val) and further to a tripeptide (RGH-0205: Arg-Lys-Asp) which still retains immunological activity. To prepare Phase I and II clinical trials preclinical toxicity studies were duly performed. Mice, rats and dogs tolerated a single 1000 mg/kg dose i.v. without any symptom. In a 14-day i.v. test on Lati:Han:WISTAR rats daily doses of 10,25, 62.5, 150, 400 and 1000 mg/kg of either test compound were tolerated without symptom or damage. In a 28-day i.v. toxicity test on Wobe:BEAGLE dogs given daily doses of 6, 20 and 60 mg/kg of either test compound, no adverse reaction occurred. The low toxicity of both RGH-0205 and RGH-0206 are probably attributable to their short half-life, as half-life of the pentapeptide fraction is less than 30 sec in humans. It was concluded that the planned clinical dose of 1 mg/kg i.v. was safe for both peptides for short-term administration.

Summary of safety tests with pipecurium bromide, a new neuromuscular blocking agent.

Acute toxicity studies with 2 beta,16 beta-bis(4'-dimethyl-1'-piperazino)-3 alpha,17 beta-diacetoxy-5 alpha-androstane dibromide (pipecurium bromide, RGH-1106, Arduan), a new neuromuscular blocking agent, revealed an order of sensitivity as follows: rabbits greater than mice greater than rats. Subchronic toxicity was tested on conscious dogs by 20 daily doses of 150 microgram/kg i.v. corresponding to 4-fold the planned clinical dose followed by daily intubation and artificial ventilation until recovery of spontaneous respiration. Dosage was limited by prolonged paralysis time requiring artificial ventilation. Apart from daily stress of paralysis preceding intubation no irreversible toxic changes were detected by laboratory and morphological tests. ECG changes were restricted to paralysis time, they were characterized by transitory arrhythmia and variation of the ST-segment. In additional studies on conscious and unconscious dogs no lethal ECG changes could be induced with cumulative dose totalling 10 mg/kg i.v. Short-term in vivo and in vitro mutagen tests did not reveal either mutagenic and clastogenic effects or increase of chromosomal aberrations. Intravenous local tolerance in rats was satisfactory.

Summary of safety tests of ethyl apovincaminate.

Subchronic toxicity test (4-week p.o. on rats with 25 and 100 mg/kg; 3-month i.p. with 5 and 25 mg/kg; 3-month i.v. with 2 and 5 mg/kg daily doses on dogs) and chronic toxicity tests (6-month p.o. on rats with 25, 50 and 100 mg/kg and on dogs with 5 and 25 mg/kg daily doses) were performed with ethyl apovincaminate (RGH-4405, Cavinton), a cerebral vasodilatory compound, to study adverse effects in adult age. Reproduction tests (male and female fertility test on rats p.o. with 10 and 50 mg/kg; teratogenicity test in midpregnancy on rats p.o. with 12.5, 25, 50 mg/kg, 15, 50, 150 mg/kg, and 15, 45, 135 mg/kg daily doses, i.v. with 3.13, 6.25 and 12.5 mg/kg daily doses; on rabbits p.o. with 6, 12 and 18 mg/kg daily doses; peri- and postnatal studies in late pregnancy on rats p.o. with 15, 45 and 135 mg/kg i.v. with 4.13, 6.25, and 12.5 mg/kg daily doses) were carried out to study harmful effects in various early phases of life. Local tolerance was studied after i.m. and i.v. application. It was concluded that the planned 3 X 5 or 3 X 10 mg daily oral dose, 1 X 10 mg i.v. dose of Cavinton were safe for human application in adult age. Although the compound proved not to be teratogenic, it is not recommended for administration to pregnant women because of liability of increased sensitivity in pregnancy. Therapy of women in fertile age should be interrupted in case of pregnancy.