Bactericidal activity of moxifloxacin compared to grepafloxacin and clarithromycin against Streptococcus pneumoniae and Streptococcus pyogenes investigated using an in vitro pharmacodynamic model

Moxifloxacin in the treatment of skin and skin structure infections

Moxifloxacin is a recent addition to the fluoroquinolone class, differing from ciprofloxacin and other older agents in having much better in vitro activity against Gram-positive aerobes while retaining potent activity against Gram-negative aerobes. It is also active against the pathogens of human and animal bite wounds and those species of atypical mycobacteria associated with dermatologic infections. Its activity against anaerobes is quite variable. Moxifloxacin penetrates well into inflammatory blister fluid and muscle and subcutaneous adipose tissues. Moxifloxacin should thus be a reasonable option for the treatment of skin and skin structure infections (SSSIs). In 3 randomized controlled trials (RCTs), oral moxifloxacin was as effective as cephalexin in the treatment of uncomplicated SSSIs in adults while in 2 RCTs, intravenous/oral moxifloxacin was as effective as intravenous/oral β-lactam/β-lactamase inhibitor therapy in the treatment of complicated SSSIs in adults. Moxifloxacin does not inhibit cytochrome P450 enzymes and thus interact with warfarin or methylxanthines. However, multivalent cations can reduce its oral bioavailability substantially. Dosage adjustment is not required in the presence of renal or hepatic impairment. The clinical relevance of its electrophysiologic effects (QT_c prolongation) remains unresolved.

Treating diabetic foot infections with sequential intravenous to oral moxifloxacin compared with piperacillin–tazobactam/amoxicillin–clavulanate

OBJECTIVES

Complicated skin and skin structure infections (cSSSIs), including diabetic foot infections (DFIs), are often polymicrobial, requiring combination or broad-spectrum therapy. Moxifloxacin, a broad-spectrum fluoroquinolone, is approved for cSSSI and can be administered by either intravenous (iv) or oral routes. To assess the efficacy of moxifloxacin for treating DFIs, we analysed a subset of patients with these infections who were enrolled in a prospective, double-blind study that compared the efficacy of moxifloxacin with piperacillin-tazobactam and amoxicillin-clavulanate.

METHODS

Patients>or=18 years of age with a DFI requiring initial iv therapy were randomized to either moxifloxacin (400 mg/day) or piperacillin-tazobactam (3.0/0.375 g every 6 h) for at least 3 days followed by moxifloxacin (400 mg/day orally) or amoxicillin-clavulanate (800 mg every 12 h orally), if appropriate, for 7-14 days. DFI was usually defined as any foot infection plus a history of diabetes. Our primary efficacy outcome was the clinical response of the infection at test-of-cure (TOC), 10-42 days post-therapy.

RESULTS

Among 617 patients enrolled in the original study, 78 with DFIs were evaluable for treatment efficacy. Clinical cure rates at TOC were similar for moxifloxacin and piperacillin-tazobactam/amoxicillin-clavulanate (68% versus 61%) for patients with investigator-defined infection (P=0.54). Overall pathogen eradication rates in the microbiologically-valid population were 69% versus 66% for moxifloxacin and comparator, respectively (P=1.00).

CONCLUSIONS

Intravenous+/-oral moxifloxacin was as effective as iv piperacillin-tazobactam+/-amoxicillin-clavulanate in treating moderate-to-severe DFIs. Moxifloxacin may have potential as a monotherapy regimen for DFIs.

Moxifloxacin: a review of its use in the management of bacterial infections

Moxifloxacin (Avelox) is a fluoroquinolone antibacterial with a methoxy group in the C-8 position and a bulky C-7 side chain. Moxifloxacin is approved for use in the treatment of acute exacerbations of chronic bronchitis (AECB), community-acquired pneumonia (CAP), acute bacterial sinusitis and uncomplicated skin and skin structure infections (approved indications may differ between countries). Moxifloxacin has a broad spectrum of antibacterial activity, including activity against penicillin-resistant Streptococcus pneumoniae. It achieves good tissue penetration and has a convenient once-daily administration schedule, as well as being available in both intravenous and oral formulations in some markets. Moxifloxacin has good efficacy in the treatment of patients with AECB, CAP, acute bacterial sinusitis and uncomplicated skin and skin structure infections, and is generally well tolerated. Thus, moxifloxacin is an important option in the treatment of bacterial infections.

Evaluation of T-3811ME (BMS-284756), a new des-F(6)-quinolone, for treatment of meningitis caused by penicillin-resistant Streptococcus pneumoniae in rabbits

T-3811ME (BMS-284756) is a new des-F(6)-quinolone with high levels of activity against gram-positive bacteria, including penicillin-resistant Streptococcus pneumoniae (PRSP) strains. T-3811, the free base of T-3811ME, exhibited potent activity against 28 clinical strains of PRSP isolated clinically (MIC at which 90% of the isolates tested are inhibited, 0.0625 microg/ml). After the intravenous dosing of T-3811ME (20 mg/kg of body weight as T-3811) in rabbits with meningitis caused by PRSP, the area under the concentration-time curve (AUC) of T-3811 in cerebrospinal fluid (CSF) was 5.79 microg. h/ml and was 4.5-fold higher than that of T-3811in the CSF of rabbits without meningitis. In addition, the AUC/MIC for T-3811ME (20 mg/kg as T-3811) in CSF was 185, which was 4.3-fold higher than that for ceftriaxone (administered intravenously at 100 mg/kg). After the administration of any dose of T-3811ME (5, 10, and 20 mg/kg as T-3811), the viable cell counts in CSF decreased in a dose-dependent manner. In particular, after dosing of 20 mg/kg (as T-3811), the viable cell counts in CSF were significantly less than those in the nontreated group (P < 0.01). By histopathological evaluation, 6 h after the administration of T-3811ME (20 mg/kg as T-3811), the thickening of the cerebral meninx and the infiltration of neutrophils into the cerebral meninx were less severe in the treated group than in the nontreated group. T-3811ME (BMS-284756) may be expected to be evaluated for the management of meningitis caused by highly penicillin-resistant pneumococci.

Developments in PK/PD: optimising efficacy and prevention of resistance. A critical review of PK/PD in in vitro models

In vitro pharmacokinetic models are excellent tools with which to study an antibacterial's pharmacodynamics (pD), being flexible, adaptable, low cost, and correlating well with animal and human systems. They can be used to perform simple descriptive studies on antibacterial effect, determine the dominant pD factor and its magnitude for antibacterial effect, and finally be used to assess the effect of dosing on emergence of resistance. A wide range of model designs are used and some standardisation maybe of value in the near future, however it is clear that in vitro models in conjunction with animal studies and human trials offer an excellent way of studying drug dosing to optimise outcomes.