Cytotoxicity of intracanal dressings on apical papilla cells differ upon activation with E. faecalis LTA.

OBJECTIVE: The aim of this study was to investigate the cytotoxic effects of modified triple antibiotic paste and an experimental composition using calcium hydroxide on lipoteichoic acid (LTA)-primed apical papilla cells (APC). MATERIAL AND METHODS: Human APC were tested for in vitro cytotoxicity of modified Triple Antibiotic Paste (mTAP - Ciprofloxacin, Metronidazole and Cefaclor at 1:1:1) and of a paste of Ciprofloxacin, Metronidazole and Calcium hydroxide (CMC - 1:1:2) and modified CMC (mCMC - 2:2:1) by using MTT assay. The substances were reconstituted in DMEM at 1,000 µg/mL and » serially diluted before being kept in contact with cells for 1, 3, 5 and 7 days. Further, cells were primed with 1 µg/mL of Enterococcus faecalis LTA for 7 days prior to the viability test with 1,000 µg/mL of each substance. Statistical analysis was performed using one-way analysis of variance (ANOVA) and two-way ANOVA respectively followed by Tukey's post-test. Significance levels were set at p<0.05. RESULTS: In the first assay, the higher cytotoxic rates were reached by mTAP for all experimental periods. CMC was found toxic for APC at 5 and 7 days, whereas mCMC did not affect the cell viability. Only CMC and mCMC were able to induce some cellular proliferation. In the second assay, when considering the condition with medium only, LTA-primed cells significantly proliferated in comparison to LTA-untreated ones. At this context, mTAP and CMC showed similar cytotoxicity than the observed for LTA-untreated cells, while mCMC was shown cytotoxic at 7 days only for LTA-primed APC. Comparing the medications, mTAP was more cytotoxic than CMC and mCMC. CONCLUSION: mTAP showed higher cytotoxicity than CMC and mCMC and the effect of topic antimicrobials might differ when tested against apical papilla cells under physiological or activated conditions.

Cytotoxicity of intracanal dressings on apical papilla cells differ upon activation with E. faecalis LTA

Abstract Objective The aim of this study was to investigate the cytotoxic effects of modified triple antibiotic paste and an experimental composition using calcium hydroxide on lipoteichoic acid (LTA)-primed apical papilla cells (APC). Material and Methods Human APC were tested for in vitro cytotoxicity of modified Triple Antibiotic Paste (mTAP - Ciprofloxacin, Metronidazole and Cefaclor at 1:1:1) and of a paste of Ciprofloxacin, Metronidazole and Calcium hydroxide (CMC - 1:1:2) and modified CMC (mCMC - 2:2:1) by using MTT assay. The substances were reconstituted in DMEM at 1,000 µg/mL and » serially diluted before being kept in contact with cells for 1, 3, 5 and 7 days. Further, cells were primed with 1 µg/mL of Enterococcus faecalis LTA for 7 days prior to the viability test with 1,000 µg/mL of each substance. Statistical analysis was performed using one-way analysis of variance (ANOVA) and two-way ANOVA respectively followed by Tukey's post-test. Significance levels were set at p<0.05. Results In the first assay, the higher cytotoxic rates were reached by mTAP for all experimental periods. CMC was found toxic for APC at 5 and 7 days, whereas mCMC did not affect the cell viability. Only CMC and mCMC were able to induce some cellular proliferation. In the second assay, when considering the condition with medium only, LTA-primed cells significantly proliferated in comparison to LTA-untreated ones. At this context, mTAP and CMC showed similar cytotoxicity than the observed for LTA-untreated cells, while mCMC was shown cytotoxic at 7 days only for LTA-primed APC. Comparing the medications, mTAP was more cytotoxic than CMC and mCMC. Conclusion mTAP showed higher cytotoxicity than CMC and mCMC and the effect of topic antimicrobials might differ when tested against apical papilla cells under physiological or activated conditions.

Direct effect of intracanal medicaments on survival of stem cells of the apical papilla.

INTRODUCTION: Regenerative endodontic procedures are an alternative treatment for immature teeth with necrotic pulps. Typically, intracanal medicaments such as triple antibiotic paste (TAP) or double antibiotic paste (DAP) and calcium hydroxide (Ca[OH](2)) are used for disinfection. However, their effect on human stem cells of the apical papilla (SCAPs) is unknown. We hypothesized that intracanal medicaments at high concentrations are toxic to SCAPs. To test this hypothesis, a cell culture assay was used. METHODS: Briefly, SCAPs were cultured and subjected to either no drug treatment or various concentrations including TAP, DAP, modified TAP (ciprofloxacin, metronidazole and cefaclor), Augmentin (Champs Pharmacy, San Antonio, TX), or Ca(OH)(2). Viable stem cells counts were obtained using an automated method of detecting trypan blue dye at 3 days after treatment. RESULTS: All 4 antibiotics significantly reduced SCAP survival in a concentration-dependent fashion. Interestingly, Ca(OH)(2) was conducive with SCAP survival at all concentrations. CONCLUSIONS: Collectively, our data show that high concentrations of antibiotics have a detrimental effect on SCAP survival, whereas lower concentrations as well as Ca(OH)(2) at all tested concentrations are conducive with SCAP survival and proliferation. These studies highlight the clinically important point that intracanal medicaments must be used at concentrations that are bactericidal while having minimal effects on stem cell viability.

Phase I study of multiple-dose cefprozil and comparison with cefaclor.

The objectives of this study were to assess the safety and tolerance of cefprozil, to characterize the pharmacokinetics of cefprozil after administration of multiple doses of the drug, and to compare these pharmacokinetic parameters with those obtained with cefaclor. The volunteers received 28 doses of 250, 500, or 1,000 mg of cefprozil or 500 mg of cefaclor every 8 h for 10 days. Serial blood samples and the total volume of urine voided by each individual were collected for pharmacokinetic evaluation on days 1, 5, and 10. Both cephalosporins were well tolerated after multiple oral dosing. The peak levels in plasma (Cmax) of cefprozil ranged from 5.7 to 18.3 micrograms/ml after oral administration of 250- to 1,000-mg doses. The regression analysis of Cmax on cefprozil dose showed a dose-linear response. The mean Cmax of cefaclor ranged from 15.2 to 16.7 micrograms/ml and did not change significantly on multiple dosing. The overall mean terminal half-life of cefprozil was 1.2 h and was invariant with respect to dose or duration of dosing. The area under the plasma-concentration-versus-time curve from 0 h to infinity (AUC0-infinity) of cefprozil increased in a dose-proportional manner with an increase in dose. The overall urinary recovery (61% of dose) and renal clearance values of cefprozil were generally invariant with respect to dose and duration of dosing. While cefprozil was apparently absorbed less rapidly and achieved lower Cmax values than cefaclor, the AUC0-infinity of cefprozil was nearly twofold greater than that of cefaclor. The half-life of cefprozil was also twofold longer than that observed for cefaclor. Although the urinary recovery of cefaclor (75% of dose) was significantly higher than that of cefprozil (61% of dose), the concentrations of cefprozil in urine remained significantly higher than those of cefaclor from 2 to 8 h postdosing. If the therapeutic concept is maintained that levels of beta-lactam antibiotics in plasma should exceed the MIC for the offending organisms over a period that approximates the dosing interval, then cefprozil would appear to be suitable for twice-daily administration, whereas cefaclor should probably be administered three or even four times a day.

[Effect of S6472 and cefaclor on bacterial flora in adult human feces].

S6472 is a mixture of cefaclor (CCL) granules with gastric-soluble coating and those with enteric-soluble coating at the ratio (in potency) of 4 to 6. With administration of this formulation, a prolonged blood level of CCL is obtained. S6472 and CCL were administered orally to 19 healthy male volunteers between 20 and 27 years of age (mean: 23 years) weighing between 51 and 80 kg (mean: 64.7 kg). Four subjects were given 2 capsules and 5 subjects were given 4 capsules each containing 187.5 mg of S6472, 30 minutes after breakfast and supper for 5 days. Five subjects were given 1 capsule and 5 subjects were given 2 capsules each containing 250 mg of CCL 30 minutes after breakfast, lunch and supper for 5 days. The number of fecal bacteria was examined 5 days before the start of administration, the day of the start of administration, 3 and 5 days after the start of administration, and 3, 5 and 10 days after the end of administration. Concentration of CCL in feces and susceptibility of isolated fecal bacteria (at the inoculum size of 10(6) cells/ml) to CCL were examined. Adverse reactions and the effects on laboratory test values were also checked. In 4 subjects receiving 375 mg of S6472 twice a day, the mean population of E. coli was 10(7)-10(9) cells/g feces on all days of observation. There was no effect on the population of Klebsiella sp., Citrobacter sp. Enterobacter sp. and other Enterobacteriaceae. The mean population of all Enterobacteriaceae was 10(8)-10(9) cells/g feces on all days of observation. The population of other Gram-negative bacilli did not show a consistent change, either. There was no effect on the population of Gram-positive bacteria such as Staphylococcus sp., Enterococcus, sp., Micrococcus sp., and of Candida sp. Among anaerobic bacteria, Bacteroides sp. showed the mean population of 10(10) cells/g feces on all days of examination. C. difficile was isolated from 2 subjects out of 4 at the level of 10(2)-10(3) cells/g feces 5 days after the start of administration and 3 days after the end of administration. However, there was no production of toxin in either of the 2 subjects. In another subject, C. difficile was isolated at 10(2)-10(4) cells/g feces with a toxin titre of 10(-3)-10(-4) 3 and 5 days after the start of administration and 10 days after the end of administration. The total population of anaerobic bacteria was 10(10)-10(11) cells/g feces on all days of examination.(ABSTRACT TRUNCATED AT 400 WORDS)

Synthesis and antibacterial activities of new (alpha-hydrazinobenzyl)cephalosporins.

Some (alpha-hydrazinobenzyl)cephalosporins, I (R = Me, CH2OAc, Cl) and II (R = Me, CH2OAc), structurally related (formula; see text) to cephalexin, cephaloglycin, and cefaclor have been prepared and evaluated in vitro for their antimicrobial activity. The synthesis involves the condensation of the chloride hydrochloride III (R = H or Me) with the 7-aminocephem derivatives IV. The hydrazino compound I (R = Cl), an analogue of cefaclor, resulted in being the most active compound of the series.

Effects of ureteral obstruction on the toxicity of cephalosporins in the rabbit kidney.

The nephrotoxicity of the cephalosporin antibiotics is closely related to their secretory transport into the proximal tubular cell at the antiluminal (blood) site. The present report describes the effects of transient ureteral obstruction, which increases intracellular concentrations of secreted organic anions, on the cortical uptake and the proximal tubular toxicity of several cephalosporins given in mildly toxic doses. Unilateral obstruction for 1-2 hr increased the cytotoxicity of cephaloglycin and cefaclor, both of which are rapidly secreted across the tubular cell, but not of cephaloridine, which undergoes minimal secretion. Bilateral obstruction significantly increased the toxicity of cefaclor, which is rapidly secreted, but not of cefazolin, which is slowly secreted. Finally, there was a further augmentation of the effects of obstruction on the toxicity of cefaclor by a minimally toxic pretreatment regimen of neomycin. Studies of cortical antibiotic concentrations support the conclusion that the effects on toxicity are largely the result of the increased intracellular accumulation that results from obstruction.

An evaluation of the toxicity of cefaclor in laboratory animals.

The toxicity of cefaclor, a new orally-administered cephalosporin, was evaluated in laboratory animals given single or multiple doses of the antibiotic. The acute toxicity data for cefaclor in mice, rats, dogs and monkeys were comparable to that previously reported for cephalexin. Rats were maintained on dietary mixtures of cefaclor which provided average daily doses of approximately 230 to 950 mg/kg for 28 days in subacute toxicity tests, and 160 to 675 mg/kg for 1 year in chronic toxicity tests. Treatment-related effects in the above studies were limited to soft stool excretion and caecal dilatation in the subacute test. Effects in dogs given daily oral doses of 50 to 200 mg/kg for 30 days were limited to a transient moderate fall in haemoglobin concentration in the two males at the highest dose. Soft stool excretion and occasional episodes of emesis were observed in dogs given cefaclor for 1 year at oral doses of 100 to 400 mg/kg/day. A reversible thrombocytopenia occurred in one animal at the highest dose. Analysis of various tissue fluids taken 2 hours after the last dose revealed that the concentration of cefaclor in the synovial fluid was approximatley one-half of that in serum. The results of these studies indicate that cefaclor has a low toxic potential in the species tested.