Differential interactions of the β-lactam cloxacillin with human renal organic anion transporters (OATs)

Study on the impurity profiles of cloxacillin and flucloxacillin based on liquid chromatography tandem ion trap/time-of-flight mass spectrometry

RATIONALE

Cloxacillin and flucloxacillin are prone to degradation and polymerization in humid and hot environments, and their polymers have long been recognized to trigger allergic manifestations. A series of the degradation and polymerized impurities in cloxacillin and flucloxacillin were separated and characterized to ensure safe use of these drugs by the public.

METHODS

By studying the chromatographic behavior of the degradation impurities and polymerized impurities in reversed-phase high-performance liquid chromatography (RP-HPLC) gradient elution, the impurities in cloxacillin and flucloxacillin were effectively separated and eluted. RP-HPLC tandem ion trap/time-of-flight mass spectrometry (MS) was applied to characterize the structures of unknown impurities eluted from the RP-HPLC methods for cloxacillin and flucloxacillin. The mechanisms of formation of the impurities in cloxacillin and flucloxacillin were also investigated.

RESULTS

The structures of 10 unknown impurities in cloxacillin and 8 unknown impurities in flucloxacillin were elucidated based on the high-resolution MSn data at positive and negative modes, respectively. Six polymerized impurities were found and characterized, of which three were from the polymerization of cloxacillin and three were from the polymerization of flucloxacillin.

CONCLUSIONS

The study on the impurity profiles of cloxacillin and flucloxacillin provided a scientific basis for improving their production processes and quality control.

The Combination of Amoxicillin and 1,8-Cineole Improves the Bioavailability and the Therapeutic Effect of Amoxicillin in a Rabbit Model

In this study, the effectiveness of the combination therapy of 1,8-cineole with amoxicillin (AMX) and clavulanic acid (Clav) was investigated. For this, the pharmacokinetic behaviors of AMX in rabbits were studied after a single oral dose. The animals were divided randomly into two groups: the reference group (received AMX/Clav (50/12.5 mg/kg)) and the test group (received AMX/Clav/1,8-cineole (50/12.5/10 mg/kg)). Blood samples were collected prior to administration and after T1h, T2h, T3h, and T6h post-administration. Plasma concentrations of AMX were quantified using a validated HPLC method. The antibacterial activity of plasma and cerebrospinal fluid (CSF) of treated rabbits was tested against Escherichia coli ESBL-producing a strain by microdilution method. The obtained results showed significant differences in pharmacokinetic parameters between the two groups. The resulting AUC_0–6h and C_max mean values of the AMX reference group were 14.74 µg.h/mL and 3.49 µg/mL, respectively. However, those of the AMX test group were 22.30 µg.h/mL and 5.79 µg/mL, respectively. The results showed that the antibacterial activity of the plasma and CSF test group was significantly higher than that of the reference group. The effectiveness of this combination (Olipen: AMX/Clav/1,8-cineole) was demonstrated by increasing the level of the antibiotic and by improving the bioavailability.