Cefaclor into the millennium

Structure-Based Analysis of Cefaclor Pharmacokinetic Diversity According to Human Peptide Transporter-1 Genetic Polymorphism

Cefaclor is a substrate of human-peptide-transporter-1 (PEPT1), and the impact of inter-individual pharmacokinetic variation due to genetic polymorphisms of solute-carrier-family-15-member-1 (SLC15A1) has been a topic of great debate. The main objective of this study was to analyze and interpret cefaclor pharmacokinetic variations according to genetic polymorphisms in SLC15A1 exons 5 and 16. The previous cefaclor bioequivalence results were integrated with additional SLC15A1 exons 5 and 16 genotyping results. An analysis of the structure-based functional impact of SLC15A1 exons 5 and 16 genetic polymorphisms was recently performed using a PEPT1 molecular modeling approach. In cefaclor pharmacokinetic analysis results according to SLC15A1 exons 5 and 16 genetic polymorphisms, no significant differences were identified between genotype groups. Furthermore, in the population pharmacokinetic modeling, genetic polymorphisms in SLC15A1 exons 5 and 16 were not established as effective covariates. PEPT1 molecular modeling results also confirmed that SLC15A1 exons 5 and 16 genetic polymorphisms did not have a significant effect on substrate interaction with cefaclor and did not have a major effect in terms of structural stability. This was determined by comprehensively considering the insignificant change in energy values related to cefaclor docking due to point mutations in SLC15A1 exons 5 and 16, the structural change in conformations confirmed to be less than 0.05 Å, and the relative stabilization of molecular dynamic simulation energy values. As a result, molecular structure-based analysis recently suggested that SLC15A1 exons 5 and 16 genetic polymorphisms of PEPT1 were limited to being the main focus in interpreting the pharmacokinetic diversity of cefaclor.

Exploring the pharmacokinetics of second-generation cephalosporin, cefaclor: a systematic review in healthy and diseased populations

Cefaclor is a bactericidal antibiotic recommended for treating diverse types of infections. This review aims to comprehensively assess the pharmacokinetic (PK) data on cefaclor in humans.Google Scholar, PubMed, Cochrane Library, and EBSCO databases were systematically performed to identify all the relevant studies containing at least one reported PK parameter of cefaclor.Cefaclor shows the linear PK profile as the area under the plasma concentration-time curve from 0 to t (AUC0-t) and maximum plasma concentration (Cmax) increase in a dose-dependent manner. The AUC0-t of cefaclor in the rice diet was found to be higher than that of bread food, i.e. 19.9 ± 2.6 ug/ml.hr vs 15.4 ± 4 ug/ml.hr. The AUC in paediatrics during the fed state was significantly higher compared to that in adults. Patients with renal impairments showed a Cmax 2.2 times higher than that of normal subjects. A significant increase in Cmax was depicted among individuals following a vegetarian diet in comparison with the non-vegetarian diet. Moreover, cefaclor exhibits time-dependent killing above the minimum inhibitory concentration (MIC < 2 ug), favouring its use in treating infections caused by specific pathogens.This systematic review summarises all the reported PK parameters of cefaclor in healthy and diseased subjects in the literature. This data can help practitioners in adjusting cefaclor doses among different diseases and populations to avoid drug interactions and adverse effects.

A Synthetic Dual Drug Sideromycin Induces Gram-Negative Bacteria To Commit Suicide with a Gram-Positive Antibiotic

Many antibiotics lack activity against Gram-negative bacteria because they cannot permeate the outer membrane or suffer from efflux and, in the case of β-lactams, are degraded by β-lactamases. Herein, we describe the synthesis and studies of a dual drug conjugate (1) of a siderophore linked to a cephalosporin with an attached oxazolidinone. The cephalosporin component of 1 is rapidly hydrolyzed by purified ADC-1 β-lactamase to release the oxazolidinone. Conjugate 1 is active against clinical isolates of Acinetobacter baumannii as well as strains producing large amounts of ADC-1 β-lactamase. Overall, the results are consistent with siderophore-mediated active uptake, inherent activity of the delivered dual drug, and in the presence of β-lactamases, intracellular release of the oxazolidinone upon cleavage of the cephalosporin to allow the freed oxazolidinone to inactivate its target. The ultimate result demonstrates that Gram-positive oxazolidinone antibiotics can be made to be effective against Gram-negative bacteria by β-lactamase triggered release.

Probiotics and prebiotics in the elderly

Probiotics (usually lactobacilli and bifidobacteria) and prebiotics (non-digestible oligosaccharides) have been shown to be useful in preventing certain disease conditions as well as possibly promoting specific aspects of health. In the present review, the evidence from clinical trials for benefits from probiotics and prebiotics to elderly populations is presented and discussed, specifically in respect of three common conditions found in the elderly. Both probiotics and prebiotics may be helpful in malnutrition, particularly in lactose intolerance and calcium absorption, and in constipation. Probiotics have been shown clearly to boost immunity in the elderly, but the clinical significance of this remains to be clarified. These results are encouraging, and further large scale studies seem justified to establish the place of probiotic and prebiotic supplements in elderly subjects.

Pharmacokinetic parameter prediction from drug structure using artificial neural networks

Simple methods for determining the human pharmacokinetics of known and unknown drug-like compounds is a much sought-after goal in the pharmaceutical industry. The current study made use of artificial neural networks (ANNs) for the prediction of clearances, fraction bound to plasma proteins, and volume of distribution of a series of structurally diverse compounds. A number of theoretical descriptors were generated from the drug structures and both automated and manual pruning were used to derive optimal subsets of descriptors for quantitative structure-pharmacokinetic relationship models. Models were trained on one set of compounds and validated with another. Absolute predicted ability was evaluated using a further independent test set of compounds. Correlations for test compounds ranged from 0.855 to 0.992. Predicted values agreed closely with experimental values for total clearance, renal clearance, and volume of distribution, while predictions for protein binding were encouraging. The combination of descriptor generation, ANNs, and the speed and success of this technique compared with conventional methods shows strong potential for use in pharmaceutical product development.

Multiple pharmacokinetic parameter prediction for a series of cephalosporins

The goal of quantitative structure-pharmacokinetic relationship analyses is to develop useful models that can predict one or more pharmacokinetic properties of a particular compound. In the present study, a multiple-output artificial neural network model was constructed to predict human half-life, renal and total body clearance, fraction excreted in urine, volume of distribution, and fraction bound to plasma proteins for a series of cephalosporins. Descriptors generated solely from drug structure were used as inputs for the model, and the six pharmacokinetic parameters were simultaneously predicted as outputs. The final 10 descriptor model contained sufficient information for successful predictions using both internal and external test compounds. Descriptors were found to contribute to individual pharmacokinetic parameters to differing extents, such that descriptor importance was independent of the relationships between pharmacokinetic parameters. This technique provides the advantage of simultaneous prediction of multiple parameters using information obtained by nonexperimental means, with the potential for use during the early stages of drug development.

Comparative efficacy and safety of 5-day cefaclor and 10-day amoxycillin treatment of group A streptococcal pharyngitis in children

A total of 384 children with group A beta-haemolytic streptococcal (GABHS) pharyngitis were randomized to receive either 40 mg/kg/day of cefaclor in two doses for 5 days (192 patients), or 40 mg/kg/day of amoxycillin in three doses for 10 days (192 patients). The signs and symptoms of pharyngitis were recorded and throat cultures were obtained at presentation and on days 6-7, 11-15, 16-20 and 28-35. Patient compliance was significantly higher in the children treated with cefaclor (100 vs. 95.1%; P = 0.003). At the end of follow-up, the percentage of clinical success was 91.4% for cefaclor and 91.9% for amoxycillin (P = 0.974); bacteriological success was obtained in 85.7 and 89.6% children (P = 0.348), respectively. Both treatments were well-tolerated with adverse event rates of 8.3% in the cefaclor group and 9.4% in the amoxcillin group (P = 0.857). Our study shows that five days' treatment with cefaclor is as effective and safe as the conventional 10-day course of amoxycillin in the treatment of GABHS pharyngitis, but compliance seems to be significantly greater.

Interrelationship between the pharmacokinetics and pharmacodynamics of cefaclor advanced formulation in patients with acute exacerbation of chronic bronchitis

Cefaclor advanced formulation (cefaclor AF) is an extended-release form of the oral cephalosporin cefaclor. When cefaclor AF 750 mg twice-daily and cefaclor immediate release 500 mg three-times-a-day are compared there is a skew to the right of the pharmacokinetic profile and higher levels are achieved. Based on this pharmacokinetic finding, we examined the relationship between the bacterial susceptibility to cefaclor (MIC), the achieved cefaclor AF serum and sputum concentrations, and in vivo eradication of the bacteria in 36 patients with acute exacerbations of chronic bronchitis. The mean peak concentrations in serum and sputum 5 h after administration were 8.6 microg/ml (95% CI: 8.1 microg/ml - 9.1 microg/ml) and 1.5 microg/ml (95% CI: 1.4 microg/ml - 1.7 microg/ml), respectively. Cefaclor was always detectable 8 h after administration. At post therapy, treatment was successful in 31 (86.1%) patients. Cefaclor concentrations in serum persisted above the MIC for more than 40% of dosing interval in 31 subjects, and those in sputum in 24 patients. Treatment was successful in all subjects with percent of time above the MIC in serum of >40%, whereas the time that levels in sputum stayed above the MIC was not the pharmacodynamic parameter that correlated best with therapeutic efficacy for cefaclor. Our data demonstrate that when cefaclor AF is dosed twice-daily, the in vivo pharmacodynamic susceptibility breakpoint is 8 microg/ml. The good activity and pharmacokinetics of cefaclor AF provide serum concentrations higher than the MIC of Haemophilus influenzae, Streptococcus pneumoniae, and Moraxella catarrhalis for more than 40% of the validated dosing interval. Therefore, it might be considered for first choice treatment of acute exacerbations of chronic bronchitis.

Novel oral cephalosporins

The therapeutic use of oral cephalosporins to treat infectious diseases continues to challenge clinicians; many attempts have been made over recent years to improve the efficacy and spectrum of these anti-infectives. Many oral cephalosporins are in development and include cefdinir, cefprozil, cefetamet pivoxil, cefcapene pivoxil, cefcanel daloxate hydrochloride in Phase II trials, S-1090 in Phase III trials and the novel compounds E1100, E1101 and BRL-57347. Differences between these drugs are sometimes subtle and the improvement over existing compounds modest, although recent cephalosporins have shown greater activity against Gram-negative bacterial infections. A better knowledge of the pharmacodynamic and pharmacokinetic interrelationships of existing oral cephalosporins is demanded for a more rational use of these compounds and to avoid the subsequent development of resistance. Perhaps with such an approach, the perceived need for new cephalosporins will diminish.

Antibiotics in neonatal infections: a review

The bacteria most commonly responsible for early-onset (materno-fetal) infections in neonates are group B streptococci, enterococci, Enterobacteriaceae and Listeria monocytogenes. Coagulase-negative staphylococci, particularly Staphylococcus epidermidis, are the main pathogens in late-onset (nosocomial) infections, especially in high-risk patients such as those with very low birthweight, umbilical or central venous catheters or undergoing prolonged ventilation. The primary objective of the paediatrician is to identity all potential cases of bacterial disease quickly and begin antibacterial treatment immediately after the appropriate cultures have been obtained. Combination therapy is recommended for initial empirical treatment in the neonate. In early-onset infections, an effective first-line empirical therapy is ampicillin plus an aminoglycoside (duration of treatment 10 days). An alternative is ampicillin plus a third-generation cephalosporin such as cefotaxime, a combination particularly useful in neonatal meningitis (mean duration of treatment 14 to 21 days), in patients at risk of nephrotoxicity and/or when therapeutic monitoring of aminoglycosides is not possible. Another potential substitute for the aminoglycoside is aztreonam. Triple combination therapy (such as amoxicillin plus cefotaxime and an aminoglycoside) could also be used for the first 2 to 3 days of life, followed by dual therapy after the microbiological results. In late-onset infections the combination oxacillin plus an aminoglycoside is widely recommended. However, vancomycin plus ceftazidime (+/- an aminoglycoside for the first 2 to 3 days) may be a better choice. Teicoplanin may be a substitute for vancomycin. However, the initial approach should always be modified by knowledge of the local bacterial epidemiology. After the microbiological results, treatment should be switched to narrower spectrum agents if a specific organism has been identified, and should be discontinued if cultures are negative and the neonate is in good clinical condition. Penicillins and third-generation cephalosporins are generally well tolerated in neonates. There is controversy regarding whether therapeutic drug monitoring of aminoglycosides will decrease toxicity (particularly renal damage) in neonates, and on the efficacy and safety of a single daily dose versus multiple daily doses of these drugs. Toxic effects caused by vancomycin are uncommon, but debate still exists over the need for therapeutic drug monitoring of this agent. When antibacterials are used in neonates, accurate determination of dosage is required, particularly for compounds with a low therapeutic index and in patients with renal failure. Very low birthweight infants are also particularly prone to antibacterial-induced toxicity.