Roberto Rule

Pharmacokinetics and penetration into tissue fluid of ceftizoxime in normal and hyperthermic sheep

The pharmacokinetics of ceftizoxime was studied in six sheep before and after inducing hyperthermia using Escherichia coli endotoxin. Sheep implanted subcutaneously with cages of non-reactive material for collecting tissue cage fluid (TCF) were used to conduct two trials. In Trial 1 animals with normal basal temperature (normal sheep (NS)) were given intravenous (i.v.) and intramuscular (i.m.) monodoses of ceftizoxime (20mg/kg BW) at 1 week interval. One and 5 weeks later (Trial 2) each sheep were injected 1µg/kg BW of endotoxin to produce hyperthermia (hyperthermic sheep (HS)) previously to i.v. administration (HSi.v.) and i.m. (HSi.m.) of ceftizoxime (20mg/kg BW), respectively. Serum and TCF samples were collected over 6h post-administration. Ceftizoxime concentrations in serum and TCF were determined by a microbiological assay. The concentrations in serum and TCF of ceftizoxime were analyzed through compartmental and non-compartmental models.Rectal temperature were significantly incremented in all animals during Trial 2. The half-time and constant of elimination in serum of ceftizoxime in NSi.v. (t(1/2)=1.1+/-0.4h; lambda(z)=0.7+/-0.2h(-1)) were statistically different those observed in HSi.v. (t(1/2)=1.4+/-0.4h; lambda(z)=0.5+/-0.2h(-1)). The constants of distribution in NSi.v. and HSIV were 5.1+/-4.6 and 4.1+/-3.4h(-1), respectively. The time to reach the maximum concentrations in TCF was latter (p<0.05) in NS (t(max)=2.3+/-0.7h) than in HS (t(max)=1.3+/-0.6 h). After i.m. administration in NS the absorption half-life (0.12+/-0.19h) was latter (p<0.05) than in HS (0.06+/-0.007h) with greater areas under the curve (AUC in NS=65.4+/-20.8 and AUC in HS=34.7+/-7.5 (µg/ml) h). The maximum value of concentration in serum (C(max)) and AUC in TCF were greater (p<0.05) in NS (C(max)=46.1+/-10.6µg/ml and AUC=84.4+/-17.4 (µg/ml) h) as compared to same HS (C(max)=27.0+/-12.9µg/ml and AUC=47.9+/-3.9 (µg/ml) h). The concentrations of ceftizoxime in TCF after i.v. and i.m. in NS and HS were elevated during a 6h period after administration. The bioavailability of ceftizoxime in NS (101.6+/-59.9%) and HS (87.4+/-63.3%) was suitable for its use by the i.m. route.

Evaluation of cefepime kinetic variables and milk production volume in goats

Avaliaram-se as variaveis cineticas da cefepime e a producao de leite de cabras apos a administracao parenteral (intravenosa e intramuscular) de cefepime, com e sem reacao inflamatoria na regiao implantada. Dez cabras em lactacao, implantadas com caixas de material sem reacao imunologica para colher o fluido de tecido (FT) foram usadas em dois experimentos. No primeiro a aplicacao de cefepime foi feita na primeira semana apos a implantacao e no segundo na oitava semana. Na primeira semana apos a implantacao observou-se elevacao dos niveis de proteina no fluido do tecido apos uma simples dose de 20mg/kg de cefepime via endovenosa ou intramuscular. Amostras do sangue e do leite foram obtidas e as variaveis cineticas foram avaliadas.

Unión de los antibióticos tilosina, tilmicosina y oxitetraciclina a proteínas presentes en abejas, larvas y productos de la colmena de Apis mellifera L

American Foulbrood (AFB) caused by the spore-forming bacterium Paenibacillus larvae is the most serious disease of bacterial origin affecting larvae and pupae of honeybees. Antibiotics are used in many countries for the control of AFB in high incidence areas, but their misuse may lead to antibiotic resistance of bacterial strains and honey contamination. The objective of the present work was to determine, through a biological method, the protein binding of tylosin, tilmicosin and oxytetracycline to worker jelly; honey; pollen; adult bees and larvae in order to propose their kinetic routes. The sensitivity limit of the technique used was 0.05 μg/ml for tylosin and tilmicosin and 0.01 μg/ml for oxytetracycline, respectively. The method had intra and inter-assay correlation coefficients over 0.90, respectively and a coefficient variation of intra-and inter-assay for all antibiotics and processed samples under 5%. Tylosin and oxytetracycline presented lower percentages of protein binding in tissues and hive products (average 15%) in relation to those observed for tilmicosin (29%). In conclusion, tylosin is useful for AFB control in honey bee colonies due to its chemical characteristics, antimicrobial activity and levels of protein binding in bees, larvae, and beehive products.