Ceftaroline fosamil for treatment of communityacquired pneumonia: findings from FOCUS 1 and 2 and potential role in therapy

Cephalosporins have been widely used over the last few decades (often as first-line antibiotic therapy) for numerous infections, owing primarily to their broad spectrum of microbiologic activity and favorable safety profile. Current Infectious Diseases Society of America guidelines identify a third-generation cephalosporin in combination with a macrolide antibiotic as an option for treatment of hospitalized adult patients with community-acquired pneumonia (CAP) outside the intensive care unit setting. Although ceftriaxone is a frequently used agent for CAP, increasing incidence of multidrug-resistant Streptococcus pneumoniae and concerns regarding poor outcomes associated with ineffective therapy have prompted the search for a well-tolerated treatment alternative that is effective against bacteria that can cause CAP. Ceftaroline fosamil, the prodrug of ceftaroline, is a new extended-spectrum cephalosporin that exhibits time-dependant bactericidal activity against numerous Gram-negative and Gram-positive organisms, including methicillin-resistant Staphylococcus aureus and penicillin-resistant S. pneumoniae. Notable exceptions include Pseudomonas spp. and Gram-negative organisms that produce extended-spectrum β-lactamases or carbapenemases. Two large Phase III clinical trials (FOCUS 1 and 2) reported that ceftaroline fosamil was well tolerated, with a clinical cure rate of CAP that was noninferior to that with ceftriaxone in nonintensive care unit adult inpatients with moderately severe (Pneumonia Outcomes Research Team score of III or IV) community-acquired pneumonia.     

β-Lactam allergenic determinants: fine structural recognition of a cross-reacting determinant on benzylpenicillin and cephalothin

BACKGROUND: An appreciation of the structural heterogeneity of allergenic determinants on penicillins and cephalosporins reveals the importance of side-chain groups and their involvement in many allergies to beta-lactam drugs. Although allergenic cross-reactions between penicillins and cephalosporins are known to occur, the precise molecular bases of such recognitions and cross-sensitivities have rarely been studied and identified. OBJECTIVES: The unexpected finding of a high incidence of positive IgE antibody reactions with both benzylpenicillin and cephalothin prompted serological and immunochemical studies to identify the chemical basis of antibody recognition of these drugs from the two different families of beta-lactam antibiotics. METHODS: Adsorption studies were employed to identify whether or not a single population of antibodies was involved in the recognition of benzylpenicillin and cephalothin. Identification of the fine structural features recognized by IgE antibodies was investigated by quantitative hapten inhibition studies employing carefully selected beta-lactam drugs, analogues and some other structurally related chemicals. RESULTS: Adsorption studies with penicilloic acid-solid phase clearly established that a single population of cross-reacting antibodies recognized both benzylpenicillin and cephalothin. Quantitative inhibition findings, especially with phenylacetic acid and 2-thiopheneacetic acid and with cephaloridine and cefoxitin, which have the same (2-thienyl)methyl side-chain as cephalothin, implicated the methylene group as the focus of the allergenic determinant recognized on benzylpenicillin and cephalothin. In addition to the methylene group, recognition graded into neighbouring structures including the amide group and extended weakly to the beta-lactam ring. CONCLUSIONS: Results confirmed that structural features as small as a methylene group may be allergenically important. In the present case, this group, making up only part of the different side-chains on benzylpenicillin and cephalothin, together with neighbouring structures extending toward the beta-lactam ring, accounted for the cross-reactivity seen between structures that, at first sight, appear to be not closely related. Such subtle, small, common structural features are likely to be immunologically recognized and implicated in allergic reactions to other drugs, including beta-lactam antibiotics.     

The bioavailability of cefpodoxime proxetil tablets relative to an oral solution

The bioavailability of cefpodoxime proxetil tablets relative to an oral solution of cefpodoxime proxetil in a sucrose/alcohol/citric acid vehicle was studied in 11 healthy volunteers in a randomized, crossover study. Fasted subjects took one cefpodoxime proxetil 100 mg tablet or 50 mL of a 2 mg mL^?1 cefpodoxime proxetil oral solution on two separate occasions. In a third study period, all subjects took a 100 mg dose of the oral solution with a high-fat meal to investigate the effect of food on cefpodoxime proxetil absorption from the oral solution. Serial blood samples were obtained over a 24h period, and urine was collected for 48h after dosing. Cefpodoxime concentrations in plasma and in urine were determined using HPLC methods. The bioavailability of cefpodoxime proxetil tablets relative to the oral solution was 82%, as determined from AUC ratios. There was no difference in the rate of cefpodoxime absorption between dosage forms. Food had no effect on the extent of drug absorption from the oral solution but did result in delayed absorption. These results suggest that complete dissolution of cefpodoxime proxetil is critical for optimal bioavailability.     

The role of the kidney in the elimination of cephapirin in man

A pharmacokinetic model was developed to describe the absorption, distribution, metabolism, and excretion of cephapirin and its major metabolite, desacetylcephapirin, following intravenous and intramuscular administration of cephapirin in healthy adult subjects. The model involved a two-compartment open model for cephapirin in plasma and extravascular tissues and included metabolism of cephapirin to desacetylcephapirin in both the plasma compartment and the kidney. Renal metabolism of cephapirin was followed by excretion of the desacetylcephapirin into the urine. Clearance calculations and digital computer simulation supported these features of the model.     

Prevalence of colonisation with third-generation cephalosporin-resistant Enterobacteriaceae in ICU patients of Heidelberg University Hospitals

The aim of this study was to assess colonisation and transmission of third-generation cephalosporin-resistant Enterobacteriaceae (CRE) from patients in 16 intensive care units. A prospective, repetitive point prevalence survey was performed over 6 months, involving samples from 1851 patients. CRE were isolated from 186 (10%) patients, with Enterobacter spp. being the most common. Mean point prevalence rates were significantly higher for paediatric wards (22.5%) compared to surgical (8.1%) and medical (5.5%) units. All CRE isolates were typed by pulsed-field gel electrophoresis. Non-outbreak nosocomial transmission rates of these pathogens were calculated as 12.8% for paediatric patients, compared to 6.8% for adult patients, which may reflect differences in sensitivity to overgrowth with resistant bacteria and contact with health care workers.     

头孢菌素C发酵添加侧链的研究

如在头孢菌素C(简称CPC)的发酵培养基中,添加硫脲、头孢孟多侧链,1-甲基-5-巯基四唑等含硫化合物,发酵过程中在CPC累积的同时,可生成CPC 3位取代衍生物,其效价约占头孢菌素总效价的20～26%,且不影响CPC的产量和提取收率。这些副产物综合利用,有一定的经济意义。     

Population pharmacokinetics of ceftriaxone in critically ill septic patients: a reappraisal

AIMS

To investigate the population pharmacokinetics of ceftriaxone in critically ill patients suffering from sepsis, severe sepsis or septic shock.

METHODS

Blood samples were collected at preselected times in 54 adult patients suffering from sepsis, severe sepsis or septic shock in order to determine ceftriaxone concentrations using high-performance liquid chromatography-ultraviolet detection. The pharmacokinetics of ceftriaxone were assessed on two separate occasions for each patient: on the second day of ceftriaxone therapy and 48 h after catecholamine withdrawal in patients with septic shock, or on the fifth day in patients with sepsis. The population pharmacokinetics of ceftriaxone were studied using nonlinear mixed effects modelling.

RESULTS

The population estimates (interindividual variability; coefficient of variation) for ceftriaxone pharmacokinetics were: a clearance of 0.88 l h⁻¹ (49%), a mean half-life of 9.6 h (range 0.83–28.6 h) and a total volume of distribution of 19.5 l (range 6.48–35.2 l). The total volume of distribution was higher than that generally found in healthy individuals and increased with the severity of sepsis. However, the only covariate influencing the ceftriaxone pharmacokinetics was creatinine clearance. Dosage simulations showed that the risk of ceftriaxone concentrations dropping below the minimum inhibitory concentration threshold was low.

CONCLUSIONS

Despite the wide interpatient variability of ceftriaxone pharmacokinetic parameters, our results revealed that increasing the ceftriaxone dosage when treating critically ill patients is unnecessary. The risk of ceftriaxone concentrations dropping below the minimum inhibitory concentration threshold is limited to patients with high glomerular filtration rates or infections with high minimum inhibitory concentration pathogens (>1 mg l⁻¹).     

盐酸头孢他美酯的合成

盐酸头孢他美酯是一口服前体药,口服后在体内迅速水解为具有抗菌活性的头孢他美。本文报道了盐酸头孢他美酯的制备方法,其生产工艺简单,成本低廉:以3-去乙酰氧基-7-氨基头孢烷酸(7-ADCA)为起始物与活性酯反应,先制备头孢他美(酸),然后和特戊酸卤甲酯反应生成头孢他美酯,最后头孢他美酯成盐得盐酸头孢他美酯。     

头孢菌素C钠盐最佳制备工艺探讨

为了探讨制备头孢菌素 C 钠盐的最佳工艺,采用溶媒结晶法和喷雾干燥法分别制备头孢菌素 C 钠盐。结果是,溶媒结晶法制备的头孢菌素 C 钠盐含量和透光率均值分别为84.03%和95.90%,分别与喷雾干燥法比较,P<0.05。溶媒结晶法合格率为100%,而喷雾干燥法合格率仅为20%。结论溶媒结晶法制备头孢菌素 C 钠盐的方法优于喷雾干燥法。