Objective:Antimicrobial agents in combination with anti-inflammatory drugs have been usually prescribed in both Medicine and Dentistry. However, few scientific reports support this clinical practice. The aim of this study was to evaluate the effect of betamethasone and diclofenac sodium on serum and tissue concentration of amoxicillin in rats.Methods:Four polyurethane sponges were implanted in the back skin of 48 rats. After seven days the animals were divided into 6 groups (n=8). Group 1: amoxicillin (25 mg/kg); G2: diclofenac sodium (2.5 mg/kg); G3: betamethasone (0.1 mg/kg); G4: diclofenac sodium and amoxicillin; G5: betamethasone and amoxicillin; and G6: 0.9% sodium chloride solution (1.0 mL - control group). All drugs were administered in a single dose. After 90 minutes, the granulomatous tissues of each animal were surgically removed and weighed. Blood was collected from cervical plexus, centrifuged and 10μL of serum was placed on paper discs. In order to estimate amoxicillin concentration, serum and granulomatous tissues were separately submitted to microbiological assay, which used 108cfu/mL of Staphylococcus aureus ATCC 25923 (penicillin-susceptible strain). After incubation (18 hours, 37°C) the inhibition zones were measured and compared to a regression curve.Results:No inhibition zones were observed for groups 2, 3 and 6. Tissue and serum concentrations of both G1 (4.14μg/g and 2.06μg/mL, respectively) and G5 (3.87μg/g and 1.70μg/mL, respectively) showed statistically significant differences (Kruskal-Wallis, p<0.05) in comparison to G4 (1.45μg/g and 0.41μg/mL, respectively). G1 and G5 did not differ significantly (p>0.05).Conclusion:Considering single doses, betamethasone did not interfere with amoxicillin levels but diclofenac sodium reduced both tissue and serum levels of amoxicillin in rats.

-It was studied the influence of the antimitotic drug 5 -fluorouracil (5-FU), administered to pregnant rats, on dental germ formation of newborn rats. A total of 125 female aged 90-100 days and 15 male adult rats (Rattus rattus norvaegicus, albinus, Wistar) were used. The drug was injected intraperitoneally in single doses to females at the 9 th , 10 th , 11 th , 12 th and 13 th days of pregnancy. The animals were divided in four groups according to the doses administered: 10, 20, 30 and 40 mg/kg. Results show that the drug induced no toxicity to mothers, other than loss of body weight with higher doses (30-40 mg/kg), but caused in the fetuses dental germ anomalies and body external malformations. The proportion of such anomalies were, besides dose dependent, influenced by the day of pregnancy when the drug was administered to the mothers: there was a greater sensitivity at the 9 th day and a lesser one at the 10 th day. Higher doses (30-40 mg/kg) caused frequently embryonic death or fetal uterine reabsorption. Agenesia of the dental germ was frequently found.Key Words: antimitotic drugs; 5-fluorouracil; dental germ; fetal malformation.RESUMO -Foi estudada a influência da droga antimitótica 5-fluoruracil (5-FU), administrada a ratas prenhes sobre a formação do germe dental de ratos recém nascidos. Foram utilizadas 125 fêmeas com 90-100 dias de idade e 15 machos adultos (Rattus rattus norvaegicus, albinus, Wistar). A droga foi injetada por via intraperitoneal a ratas grávidas, em doses únicas, aos 9 º , 10 º , 11 º , 12 º ou 13 º dias de gestação. Os animais foram divididos em quatro subgrupos de acordo com a dose administrada: 10, 20, 30 e 40 mg/kg. Os resultados mostraram que nessas doses, o 5-FU não teve efeito tóxico nas ratas prenhes, alem de perda de peso com doses mais elevadas (30-40 mg/kg), enquanto causou anomalias dentais nos embriões, bem como malformações externas. A proporção de tais anomalias foi, alem de dose dependente, influenciada pelo dia de gestação no qual antimitótico foi administrado às mães: foi observada maior sensibilidade ao 9 º dia e menor ao 10 º dia. Doses mais elevadas (30-40 mg/kg) causaram freqüentemente morte do embrião e reabsorção fetal. Agenesia do germe dentário foi freqüentemente observada.Palavras-Chave: drogas antimitóticas; 5-fluorouracil; germe dentário; malformações fetais.