Historical control data on developmental toxicity studies in rodents.

Historical control data on rodent developmental toxicity studies, performed between 1994 and 2010, were obtained from 19 laboratories in Japan, including 10 pharmaceutical and chemical companies and nine contract research organizations. Rats, mice, and hamsters were used for developmental toxicity studies. Data included maternal reproductive findings at terminal cesarean sections and fetal findings including the spontaneous incidences of external, visceral, and skeletal anomalies. No noticeable differences were observed in maternal reproductive data between laboratories. Inter-laboratory variations in the incidences of fetuses with anomalies appeared to be due to differences in the selection of observation parameters, observation criteria, classification of the findings, and terminology of fetal alterations. Historical control data are useful for the appropriate interpretation of experimental results and evaluation of the effects of chemical on reproductive and developmental toxicities.

Teratology study of amide derivatives of branched aliphatic carboxylic acids with 4-aminobenzensulfonamide in NMRI mice.

BACKGROUND: Valproic acid (VPA), widely used to treat epilepsy, bipolar disorders, and migraine prophylaxis, is known to cause neural tube and skeletal defects in humans and animals. Aminobenzensulfonamide derivatives of VPA with branched aliphatic carboxylic acids, namely 2-methyl-N-(4-sulfamoyl-phenyl)-pentanamide (MSP), 2-ethyl-N-(4-sulfamoyl-phenyl)-butyramide (ESB), 2-ethyl-4-methyl-N-(4-sulfamoyl-phenyl)-pentanamide (EMSP), and 2-ethyl-N-(4-sulfamoyl-benzyl)-butyramide (ESBB), have shown more potent anticonvulsant activity than VPA in preclinical testing. Here, we investigated the teratogenic effects of these analogous compounds of VPA in NMRI mice. METHODS: Pregnant NMRI mice were given a single subcutaneous injection of either VPA at 1.8 or 3.6 mmol/kg, or MSP, ESB, EMSP, or ESBB at 1.8, 3.6, or 4.8 mmol/kg on gestation day (GD) 8. Cesarean section was performed on GD 18, and the live fetuses were examined for external and skeletal malformations. RESULTS: Compared with VPA, which induced neural tube defects (NTDs) in fetuses at 1.8 and 3.6 mmol/kg, the analog derivatives induced no NTDs at dose levels up to 4.8 mmol/kg (except for a single case of exencephaly at 4.8 mmol/kg MSP). Skeletal examination showed several abnormalities mainly at the axial skeletal level with VPA at 1.8 mmol/kg. Fused vertebrae and/or fused ribs were also observed with MSP, ESB, EMSP, and ESBB, they were less severe and seen at a lower incidence that those induced by VPA at the same dose level. CONCLUSIONS: In addition to exerting more potent preclinical antiepileptic activity, teratology comparison indicates that aminobenzensulfonamide analogs are generally more weakly teratogenic than VPA.

Historical control data on prenatal developmental toxicity studies in rabbits.

Historical control data on rabbit prenatal developmental toxicity studies, performed between 1994-2010, were obtained from 20 laboratories, including 11 pharmaceutical and chemical companies and nine contract laboratories, in Japan. In this paper, data were incorporated from a laboratory if the information was based on 10 studies or more. Japanese White rabbits and New Zealand White rabbits were used for prenatal developmental toxicity studies. The data included maternal reproductive findings at terminal cesarean sections and fetal findings including spontaneous incidences of morphological alterations. No noticeable differences between strains or laboratories were observed in the maternal reproductive and fetal developmental data. The inter-laboratory variations in the incidences of fetal external, visceral, and skeletal alterations seem to be due to differences in the selection of observation parameters, observation criteria, and classification of the findings, and terminology of fetal alterations.

Anticonvulsant profile and teratogenic evaluation of potent new analogues of a valproic acid urea derivative in NMRI mice.

BACKGROUND: Valproic acid (VPA) is used to treat epilepsy and bipolar disorders, as well as for migraine prophylaxis. However, its clinical use is limited by two life-threatening side effects: hepatotoxicity and teratogenicity. To develop a more potent and safer second-generation VPA drug, the urea derivatives of four VPA analogs (2-ethyl-3-methylpentanoyl urea, 2-ethylhexanoyl urea, 2-ethyl-4-methylpentanoyl urea, and 2-methylbutanoyl urea) were synthesized. METHODS: Four CNS-active analogs of a VPA urea derivative testedthe anticonvulsant activity in the maximal electroshock seizure test (MES) and subcutaneous metrazol seizure threshold test (scMet). Teratogenic effects of these compounds were evaluated in NMRI mice susceptible to VPA-induced teratogenicity by comparison with VPA. RESULTS: All four VPA analogs showed superior anticonvulsant activity over VPA. Compared with VPA, which induced neural tube defects (NTDs) in fetuses at 1.8 and 3.6 mmol/kg, the analog derivatives induced no NTDs at any concentration up to 4.8 mmol/kg (except for a single abnormality at 3.6 mmol/kg with 2-ethyl-3-methylpentanoyl urea). Skeletal examination also revealed that the acylurea derivatives induced vertebral and rib abnormalities in fetuses markedly less frequently than VPA. Our results confirmed that the analogue derivatives are significantly less teratogenic than VPA in NMRI mice. CONCLUSIONS: The CNS-active VPA analogs containing a urea moiety, which have better anticonvulsant potency and lack teratogenicity, are good potential candidates as second-generation VPA antiepileptic drugs.