Changes in serum levels of quinolones in rats under the influence of experimental trauma

Penetration of moxifloxacin into rat mandibular bone and soft tissue

OBJECTIVE

Based on its in vitro activity and spectrum of activity, the new 8-methoxyquinolone antibiotic moxifloxacin (MXF) seems suited for the antibiotic therapy of odontogenic infections. Penetration into the relevant tissue is another prerequisite for clinical efficacy. For this reason, the levels of MXF in plasma, soft tissue, and mandibular bone were determined in an animal model with Wistar rats.

MATERIAL AND METHODS

Samples of 49 rats were analyzed. Tissue samples were homogenized and proteins were precipitated. The pharmacokinetic evaluation was conducted based on non-compartmental analysis.

RESULTS

The concentration-time courses of tissues show a more plateau-shaped curve compared to plasma. Calculated AUC (area under the curve) ratios tissue:plasma were M. masseter:plasma = 2.64 and mandibles:plasma = 1.13.

CONCLUSIONS

Administration of antibiotics is considered an important part of therapy during and/or after surgical procedures in the maxillofacial area. Because of the good penetration into bone and muscle tissues demonstrated in Wistar rats, MXF might be an option for clinical application in this indication.

Age-dependent effects on redox status, oxidative stress, mitochondrial activity and toxicity induced by fluoroquinolones on primary cultures of rabbit tendon cells

The age-related difference in fluoroquinolone-induced tendon toxicity was investigated. In vitro tendon cells from juvenile and young adult rabbits, respectively, were incubated with quinolone (nalidixic acid, NA) or fluoroquinolone (ofloxacin, OFX or pefloxacin, PEF) at 0.01 microM to 1 mM for 72 h. Redox status, glutathione (GSH), reactive oxygen species (ROS), and mitochondrial activity were assessed using intracellular fluorescent probes. Fluorescence signal was detected on living adherent tenocytes in microplates using cold-light cytofluorometry. Tendon toxicity differed significantly between the two cell groups and the difference was greatest with highest dose (1 mM). For 72 h, significant (p < 0.001) differences between immature and young adult primary tenocytes were observed for redox status decrease, GSH decrease, and ROS production increase. Mitochondrial activity remained unaltered in immature tenocytes. We confirm two groups of intrinsic tendon toxicity (OFX/NA vs. PEF) associated to oxidative stress (GSH decrease). Our in vitro experimental model confirms the clinical observations of age dependent tenotoxicity. First group (NA, OFX) showed greater intrinsic tenotoxicity for young adult than immature tenocytes, second group (PEF) was highly toxic for immature and young adult cells. The three quinolones do not altered mitochondrial activity in immature tenocytes whereas alteration was observed in young adult tenocytes.

Adjuvant arthritis-induced changes on ampicillin binding in serum and tissues under the influence of non-steroidal anti-inflammatory drugs in rats

Adjuvant arthritis, as a model for investigating rheumatoid arthritis (RA), is characterized by reduced plasma albumin levels and interferes with drug binding in the plasma and tissues (liver and bone). Ampicillin interacts with non-steroidal anti-inflammatory drugs (NSAIDs) due to the acidic pk(a). The aim of this study was to investigate in vitro the concentrations of ampicillin in the serum, femur, mandible and liver proteins following the co-administration of ketoprofen, flurbiprofen, ibuprofen, oxyphenbutazone and ASA in adjuvant arthritis versus healthy control rats. Ampicillin binding was found to be reduced in the serum of arthritic rats, and ampicillin binding to serum proteins was also reduced under the influence of NSAIDs in the control animals. Differences in ampicillin binding were observed in the various tissues due to the effect of adjuvant arthritis as well as that due to the co-administration of NSAIDs. In conclusion, this in vitro study may provide a plausible explanation for the ampicillin-NSAIDs interaction and such a finding may be of therapeutic significance in the treatment of painful arthritic disease such as RA.

Alterations in cefalosporin levels in the serum and mandible of hyperlipaedemic rats after co-administration of ibuprofen

Several interactions between antibiotics and non-steroidal anti-inflammatory drugs (NSAIDs) have been described in the literature, and it has been reported that hyperlipidaemia induces significant changes in cefalosporin levels. The aim of this study was to determine the changes in the levels of several cefalosporins in the serum and mandible after ibuprofen co-administration in hyperlipaedemic rats. One hundred and forty male Wistar rats were used and divided in 4 groups (A-D), each of which was further divided into 5 subgroups (1-5), either with placebo or with various treatment regimes. The co-administration of NSAIDs led to increased cefalosporin levels in both control and hyperlipidaemic animals. Hyperlipidaemia was also found to augment cefalosporin levels. These observed increases might be due to the displacement of the cephalosporins from their binding sites in serum albumin and tissue proteins in the presence of ibuprofen. NSAIDs showed a greater binding affinity for tissue proteins compared to the cephalosporins, and probably play an antagonistic role in protein binding, resulting in higher concentrations of antibiotics.

Effect of various stress models on lidocaine pharmacokinetic properties in the mandible after masseter injection

PURPOSE

The aim of this study was to investigate the role of stress (trauma, cold swimming, and adjuvant rheumatoid arthritis) on lidocaine concentrations as well as lidocaine's protein binding in the mandible.

MATERIALS AND METHODS

Forty male Wistar rats were used. The animals were divided into four groups. Group A served as control. Group B underwent mandible osteotomy. Group C was submitted to cold swimming stress. Group D was subjected to experimental arthritis. Additionally, all the groups received 5 doses of lidocaine, 1 dose of lidocaine (3 mg/kg) intramuscularly every 2 hours. Two hours after the last dose, the animals were killed. Lidocaine concentrations were estimated in plasma. Furthermore, the mandible was isolated, and both lidocaine concentrations and lidocaine protein binding were assessed.

RESULTS

In groups under stress, lidocaine concentrations in serum showed a marked elevation. In addition, these animals demonstrated a significant decrease in the percent of lidocaine binding in the mandible.

CONCLUSIONS

Stress can modify local anesthetics pharmacokinetic properties, resulting in alterations both in their concentration in serum and their protein binding in mandibular bone.

Stress-induced lidocaine modification in serum and tissues

The aim of this study is to examine the influence of acute (trauma) and chronic (cold swimming and adjuvant rheumatoid arthritis) stress on lidocaine concentrations in plasma. Forty male Wistar rats were used. The animals were divided into four groups. Group A served as control. Group B underwent mandible osteotomy. Group C was submitted to swimming stress in cold water 4 degrees C for ten minutes daily for 15 minutes, while group D underwent experimental arthritis with Freud's adjuvant. All groups received lidocaine i.m (2.5 mg/kg). Blood samples were collected and FFA (free fatty acid), unbound-lidocaine, albumin and a1-acid glycoprotein concentrations were estimated. Furthermore, the adrenals, heart and liver were isolated. The adrenals' relative weight (adrenal weight/body weight) was assessed, while lidocaine concentrations in the heart and the liver incubation medium were measured by intertechnic a-counter. Lidocaine and FFA levels in serum as well as the adrenal weights demonstrated a significant elevation in stress-groups as compared to the control group. Furthermore, in the stress-groups, lidocaine concentrations in heart tissue were significantly increased, whereas in the liver they were significantly reduced as compared to the control group. Our results indicate that stress can alter lidocaine levels in plasma and tissues, suggesting that stress should be considered an important factor when determining the dosage of lidocaine in clinical application.