Efficacy and pharmacodynamics of teicoplanin given daily during the first 3 days and then on alternate days for methicillin-resistant Staphylococcus aureus infections

Structure-based design, synthesis, and A-site rRNA cocrystal complexes of functionally novel aminoglycoside antibiotics: C2" ether analogues of paromomycin

A series of 2"-O-substituted ether analogues of paromomycin were prepared based on new site-selective functionalizations. X-ray cocrystal complexes of several such analogues revealed a new mode of binding in the A-site rRNA, whereby rings I and II adopted the familiar orientation and position previously observed with paromomycin, but rings III and IV were oriented differently. With few exceptions, all of the new analogues showed potent inhibitory activity equal or better than paromomycin against a sensitive strain of S. aureus. Single digit microM MIC values were obtained against E. coli, with some of the ether appendages containing polar or basic end groups. Two analogues showed excellent survival rate in a mouse septicemia protection assay. Preliminary histopathological analysis of the kidney showed no overt signs of toxicity, while controls with neomycin and kanamycin were toxic at lower doses.

Recommended initial loading dose of teicoplanin, established by therapeutic drug monitoring, and outcome in terms of optimal trough level

Teicoplanin has a long serum half-life, and therefore it takes time to reach a steady-state concentration. An initial loading procedure has been recommended for teicoplanin to enable prompt reaching of the optimal serum trough level (10-15 microg/ml). However, the dose of teicoplanin that should be administered to patients with varying renal function levels remains inconclusive. In this study, we monitored the serum concentrations of teicoplanin in patients with methicillin-resistant Staphylococcus aureus (MRSA) pneumonia and compared different teicoplanin serum concentrations and their clinical efficacy, investigating the significance of the mean dose administered during the initial 3 days. The study included 48 patients with MRSA pneumonia. The peak and trough concentrations of teicoplanin were determined utilizing a fluorescence polarization immunoassay and a two-compartment Bayesian population model. Teicoplanin was given at a loading dose of 400 or 800 mg on the first day, followed by maintenance doses of 200 or 400 mg. The mean initial dose (MID) over the first 3 days was calculated as: (loading dose + dose on 2nd day + dose on 3rd day)/3. Patients with an MID of 266.7 mg or less (400 mg for loading, 200 mg over the 2nd and 3rd days) did not have a trough level that exceeded 10 microg/ml at the point before the injection on the 4th day. Even in patients with hemodialysis (HD), an MID of 266.7 mg was not enough to provide a trough level of 10 microg/ml. Patients with an MID than 533.3 mg had significantly elevated trough levels, showing better outcomes. A multiple regression formula for predicting trough level before the fourth day of administration is given as: 0.034 + 0.030 x (MID; mg) - 0.057 x creatinine clearance (Ccr; ml/min). These findings suggest that 800 mg as an initial dose, followed by 400 mg maintenance doses over the following 2 days, makes it possible to safely attain an optimal trough level, even in the patients with HD.

Glycodiversification for the Optimization of the Kanamycin Class Aminoglycosides

In an effort to optimize the antibacterial activity of kanamycin class aminoglycoside antibiotics, we have accomplished the synthesis and antibacterial assay of new kanamycin B analogues. A rationale-based glycodiversification strategy was employed. The activity of the lead is comparable to that of commercially available kanamycin. These new members, however, were found to be inactive against aminoglycoside resistant bacteria. Molecular modeling was used to provide the explanation. Thus, a new strategy for structural modifications of kanamycin class aminoglycosides is suggested.

A peptide nucleic acid-neamine conjugate that targets and cleaves HIV-1 TAR RNA inhibits viral replication

The neamine part of the aminoglycoside antibiotic neomycin B was conjugated to a 16 mer peptide nucleic acid (PNA) targeting HIV-1 TAR RNA. Attachment of the neamine core allows cellular uptake of the PNA and results in potent inhibition of HIV-1 replication. The polycationic neamine moiety imparts greater solubility to the PNA and also confers a unique RNA cleavage property to the conjugate which is specific to its target site and functional at physiological concentrations of Mg(2+). These properties suggest a potential therapeutic application for this class of compounds.

Combination therapy with polymyxin B-immobilized fibre haemoperfusion and teicoplanin for sepsis due to methicillin-resistant Staphylococcus aureus

The aim of the present study was to determine whether treatment with polymyxin B-immobilized fibre (PMX-F) haemoperfusion, teicoplanin, or both in combination is effective in patients with methicillin-resistant Staphylococcus aureus (MRSA) sepsis. Sixty patients with MRSA sepsis were randomly assigned to one of four treatments: (A) PMX-F treatment (N=15), (B) teicoplanin treatment (N=15), (C) PMX-F and teicoplanin in combination (N=20) and (D) conventional therapy (N=10). PMX-F treatment was repeated twice. Teicoplanin was administered by intravenous injection. Plasma endotoxin levels were determined by endospecy test. Plasma endotoxin levels were reduced in groups A and C (P<0.05). Survival rates were 53, 47, 90, and 20% in groups A, B, C and D, respectively (group C versus group A, P<0.05; group C versus group B, P<0.01; group C versus group D,P <0.001). The mean duration of stay was 44, 42, 28 and 56 days in groups A, B, C and D, respectively. Our data suggest that combination therapy with PMX-F and teicoplanin is effective for sepsis caused by MRSA.

Clinical pharmacokinetics of teicoplanin

The glycopeptide antibacterial teicoplanin has become increasingly popular in the last decade with the rise in infections related to methicillin-resistant Staphylococcus aureus. Teicoplanin has 6 major and 4 minor components. It is predominantly (90%) bound to plasma proteins. Of the several methods available to measure concentrations in serum, fluorescence polarisation immunoassay has high reliability and specificity. Teicoplanin is not absorbed orally, but intravenous and intramuscular administration are well tolerated. Teicoplanin is eliminated predominantly by the kidneys and only 2 to 3% of an intravenously administered dose is metabolised. Total clearance is 11 ml/h/kg. Steady state is reached only slowly, 93% after 14 days of repeated administration. Elimination is triexponential, with half-lives of 0.4 to 1.0, 9.7 to 15.4 and 83 to 168 hours. Volumes of distribution are 0.07 to 0.11 (initial phase), 1.3 to 1.5 (distribution phase) and 0.9 to 1.6 (steady state) L/kg. A standard dosage regimen of 6 mg/kg every 12 hours for 3 doses, then daily, will produce therapeutic serum concentrations of > or = 10 mg/L in most patients. Higher dosages may be required in certain patients, for example intravenous drug abusers or those with burns, because of unpredictable clearance. Concentrations in bone reach 7 mg/L at 12 hours after a dose of teicoplanin 6 mg/kg, but reach only 3.5 mg/L in the cartilage. Doses of 10 mg/kg are necessary to achieve adequate bone concentrations. There is little penetration into cerebrospinal fluid or the aqueous or vitreous humour. In fat, concentrations may be subtherapeutic (0.5 to 5 mg/L) after a dose of 400mg. A single prophylactic dose of 12 mg/kg is sufficient to maintain therapeutic concentrations during cardiopulmonary bypass or burns surgery. High loading doses reduce the delay to attaining therapeutic concentrations. Premature neonates require a loading dose of 15 mg/kg and a maintenance dosage of 8 mg/kg daily to ensure therapeutic serum concentrations. Children need loading with 10 mg/kg every 12 hours for 3 doses followed by maintenance with 10 mg/kg/day. Clearance is reduced predictably in renal failure, and dosage adjustments can be based on the ratio of impaired clearance to normal clearance. In patients on haemodialysis, 3 loading doses of 6 mg/kg at 12-hour intervals followed by maintenance doses every 72 hours produced trough plasma concentrations of 8 mg/L in most patients at 48 hours. The monitoring of serum concentrations is not necessary to avoid toxicity, but can be helpful in certain patient groups to ensure therapeutic concentrations are present, especially in those not responding to treatment.