Increases in discontinuous rib cartilage and fused carpal bone in rat fetuses exposed to the teratogens, busulfan, acetazolamide, vitamin A, and ketoconazole.

Skeletal changes induced by treatment of pregnant rats with four potent teratogens, busulfan, acetazolamide, vitamin A palmitate, and ketoconazole, were evaluated using Alizarin Red S and Alcian Blue double-staining to investigate the relationship between drug-induced skeletal malformations and cartilaginous changes in the fetuses. Pregnant rats (N = 8/group) were treated once or twice between gestation days (GDs) 10 to 13 with busulfan at doses of 3, 10, or 30 mg/kg; acetazolamide at 200, 400, or 800 mg/kg; vitamin A palmitate at 100,000, 300,000, or 1,000,000 IU/kg; or ketoconazole at doses of 10, 30, or 100 mg/kg. Uterine evaluations and fetal external and skeletal examinations were conducted on GD 20. Marked skeletal abnormalities in ribs and hand/forelimb bones such as absent/ short/bent ribs, fused rib cartilage, absent/fused forepaw phalanx, and misshapen carpal bones were induced at the mid- and high-doses of busulfan and acetazolamide and at the high-dose of vitamin A palmitate and ketoconazole. Increased incidences of discontinuous rib cartilage (DRC) and fused carpal bone (FCB) were observed from the low- or mid-dose in the busulfan and acetazolamide groups, and incidences of FCB were increased from the mid-dose in the vitamin A palmitate and ketoconazole groups. Therefore, DRC and FCB were detected at lower doses than those at which ribs and hand/forelimb malformations were observed in the four potent teratogens.

Drug-specific immune responses induced by immunization with drugs in guinea pigs and mice.

In order to develop a system for evaluating the allergenicity of drugs in clinical use, we tested drugs for the ability to induce drug-specific immune responses in guinea pigs and mice. Test drugs were benzylpenicillin, procainamide, hydralazine, isoniazid, alpha-methyldopa, D-penicillamine, captopril, sulfamethoxazole and 2,4-dinitrochlorobenzene (DNCB), which are known to induce allergic responses in man including hypersensitivity reactions and drug-induced auto-immune responses. Guinea pigs were immunized with an emulsion of complete Freund's adjuvant (CFA) and 25 mg of each drug. Mice were immunized with an emulsion of CFA and 2 mg of each drug or a mixture of aluminum hydroxide gel and 2 mg of each drug. In order to examine drug-specific immune responses, we employed detection of antibodies by enzyme-linked immunosorbent assay (ELISA) and passive cutaneous anaphylaxis tests, active systemic anaphylaxis (ASA) tests and delayed type hypersensitivity (DTH) tests. In guinea pigs, drug-specific antibodies were detected following immunization with benzylpenicillin, procainamide, hydralazine, isoniazid, captopril, sulfamethoxazole or DNCB. Some of these drugs were also positive in DTH tests and/or ASA tests. In mice, however, only DNCB gave positive results. Therefore, our system involving immunization of guinea pigs with CFA emulsion of a drug and detection of drug-specific immune responses is considered to be an effective test method for evaluating drug allergenicity.