Analysis of polymerized impurities in mezlocillin sodium and sulbenicillin sodium using two chromatographic separation mechanisms coupled to tandem mass spectrometry.

To effectively control the polymerized impurities in mezlocillin sodium and sulbenicillin sodium, a HPSEC method with TSK-gel G2000SWxl column and a RP-HPLC method with C18 analytical column were established to replace the classical gel filtration chromatography with Sephadex G-10 gel as stationary phase. By studying the chromatographic behavior of polymerized impurities in both methods with different chromatographic separation mechanisms, the polymerized impurities in mezlocillin sodium and sulbenicillin sodium were separated and detected effectively. The column switching two-dimension liquid chromatography ion trap/time-of-flight mass spectrometry was applied to characterize the structures of polymerized impurities eluted from the HPSEC method and RP-HPLC method for both drugs. The structures of the polymerized impurities in mezlocillin sodium and sulbenicillin sodium were deduced based on the MSn data. The results showed that the polymerized impurities detected by HPSEC method and RP-HPLC method were completely different. Therefore, two methods should be used meanwhile to control the polymerized impurities in mezlocillin sodium and sulbenicillin sodium.

MexXY RND pump of Pseudomonas aeruginosa PA7 effluxes bi-anionic ß-lactams carbenicillin and sulbenicillin when it partners with the outer membrane factor OprA but not with OprM.

Antibiotic resistance in Pseudomonas aeruginosa is a serious concern in healthcare systems. Among the determinants of antibiotic resistance in P. aeruginosa, efflux pumps belonging to the resistance-nodulation-division (RND) family confer resistance to a broad range of antibacterial compounds. The MexXY efflux system is widely overexpressed in P. aeruginosa isolates from cystic fibrosis (CF) patients. MexXY can form functional complexes with two different outer membrane factors (OMFs), OprA and OprM. In this study, using state-of-the-art genetic tools, the substrate specificities of MexXY-OprA and MexXY-OprM complexes were determined. Our results show, for the first time, that the substrate profile of the MexXY system from P. aeruginosa PA7 can vary depending on which OM factor (OprM or OprA) it complexes with. While both MexXY-OprA and MexXY-OprM complexes are capable of effluxing aminoglycosides, the bi-anionic ß-lactam molecules carbenicillin and sulbenicillin were found to only be the substrate of MexXY-OprA. Our study therefore shows that by partnering with different OMF proteins MexY can expand its substrate profile.

Modified Penicillin Molecule with Carbapenem-Like Stereochemistry Specifically Inhibits Class C ß-Lactamases.

Bacterial ß-lactamases readily inactivate most penicillins and cephalosporins by hydrolyzing and "opening" their signature ß-lactam ring. In contrast, carbapenems resist hydrolysis by many serine-based class A, C, and D ß-lactamases due to their unique stereochemical features. To improve the resistance profile of penicillins, we synthesized a modified penicillin molecule, MPC-1, by "grafting" carbapenem-like stereochemistry onto the penicillin core. Chemical modifications include the trans conformation of hydrogen atoms at C-5 and C-6 instead of cis, and a 6-α hydroxyethyl moiety to replace the original 6-ß aminoacyl group. MPC-1 selectively inhibits class C ß-lactamases, such as P99, by forming a nonhydrolyzable acyl adduct, and its inhibitory potency is ∼2 to 5 times higher than that for clinically used ß-lactamase inhibitors clavulanate and sulbactam. The crystal structure of MPC-1 forming the acyl adduct with P99 reveals a novel binding mode for MPC-1 that resembles carbapenem bound in the active site of class A ß-lactamases. Furthermore, in this novel binding mode, the carboxyl group of MPC-1 blocks the deacylation reaction by occluding the critical catalytic water molecule and renders the acyl adduct nonhydrolyzable. Our results suggest that by incorporating carbapenem-like stereochemistry, the current collection of over 100 penicillins and cephalosporins can be modified into candidate compounds for development of novel ß-lactamase inhibitors.

Asymmetric synthesis of allylic sulfonic acids: enantio- and regioselective iridium-catalyzed allylations of Na2SO3.

An enantioselective allylation reaction of allylic carbonates with sodium sulfite (Na2 SO3 ) catalyzed by Ir complex was accomplished, providing allylic sulfonic acids in good to excellent yields with a high level of enantio- and regioselectivities. (R)-2-Phenyl-2-sulfoacetic acid, a key intermediate for the synthesis of Cefsulodin and Sulbenicillin, was synthesized as well.

[Antibiotic ophthalmic solutions evaluated by pharmacokinetic parameters of maximum concentration in the aqueous].

PURPOSE: In order to determine whether the one-component method for calculating drug concentration in the aqueous(AQCmax) is useful for selecting an appropriate ophthalmic solution, 6 general purpose antimicrobial ophthalmic solutions already on the market were investigated. METHODS: The drugs examined were levofloxacin (LVFX), chloramphenicol(CP), erythromycin lactobionate(EM), micronomicin sulfate(MCR), cefmenoxime hydrochloride(CMX) and disodium sufobenzyl penicillin(SBPC). Fifty microliters of each solutions was instilled into the cul-de-sac of New Zealand White rabbit eyes 3 times at 15-minute intervals. The drug concentrations in(the anterior sac aqueous,: this is wrong) the aqueous humor 10, 30, 60, 120 and 240 minutes after the final instillation were examined by high performance liquid chromatography(HPLC) and/or bioassay. The AQCmax was calculated using the one-compartment method. RESULTS: The calculated AQCmax was 2.5 micrograms/ml (HPLC method) and 2.28 micrograms/ml (Bioassay Method) for LVFX, 2.17 micrograms/ml for CP, and 0.45 microgram/ml for EM. The AQCmax for CMX, MCR and SBPC could not be calculated by the one-compartment method. CONCLUSION: The AQCmax of LVFX was higher than that of the 2 other general purpose antimicrobial ophthalmic solutions. The AQCmax of these drugs might be a useful parameter for selecting an appropriate ophthalmic solution for the treatment of infected eyes.

Stereoselective binding and degradation of sulbenicillin in the presence of human serum albumin.

Binding of sulbenicillin (SBPC) isomers to human serum albumin (HSA) was stereoselective. There were at least two classes of binding sites on HSA for SBPC isomers. At the stereoselective high affinity site, binding was in favor of R-SBPC, the binding constant of R-SBPC being approximately 2.3-fold greater than that of S-SBPC. By using site marker ligands, it was revealed that the stereoselective site was Site I (warfarin binding site). Affinity for the low affinity (nonstereoselective) site was similar for the diastereomers, approximately 7--30-fold lower than for the stereoselective site. R-SBPC and S-SBPC appeared to displace each other competitively at both binding sites. On the other hand, R-SBPC was degraded much faster than S-SBPC in the presence of HSA, with a degradation rate constant approximately 7-fold greater for R-SBPC than for S-SBPC. The degradation of R-SBPC was inhibited in the presence of warfarin and dependent on the concentration of R-SBPC bound to Site I. The results demonstrate that Site I is responsible for the stereoselective degradation.

Stereoselective disposition of sulbenicillin in humans.

Stereoselective disposition of sulbenicillin (SBPC) epimers in healthy human volunteers was studied in order to clarify the differences in pharmacokinetic behavior between the epimers. Stereospecific high-performance liquid chromatography was used for the determination of SBPC epimers. Plasma protein binding was measured in vitro with an ultrafiltration method. The binding was stereoselective, with the unbound fraction (fu) of the R-epimer being approximately 1.3-fold greater than that of the S-epimer. SBPC was administered intravenously to human volunteers, and concentrations of SBPC in plasma and urinary excretion rates were measured. Renal clearance (CLR) for the unbound drug (approximately 400 ml/min) was greater than the glomerular filtration rate (GFR) (approximately 109 ml/min) for both epimers, suggesting that both epimers are secreted at the renal tubules. Renal tubular secretion appeared to be greater for the S-epimer. When probenecid was coadministered, the CLR values of both epimers were significantly reduced and were approximately equal to the GFR values. CLR was greater for the S-epimer (37.5 and 49.8 ml/min for R-SBPC and S-SBPC, respectively), which was simply due to the greater fu of the S-epimer in plasma. In contrast, total body clearance was greater for the R-epimer (67.8 and 56.3 ml/min for R-SBPC and S-SBPC, respectively) because of the stereoselective degradation of the R-epimer in plasma. It was revealed that stereoselective degradation in the body had significant influence on the disposition of SBPC epimers.

[Infective endocarditis associated with vertebral osteomyelitis: report of two cases].

A 42-year-old man and a 65-year-old woman with infective endocarditis suffered onset of severe back pain. Magnetic resonance imaging and technetium-99 m bone scanning demonstrated osteomyelitis in the lumbar spine which is an unusual complication of infective endocarditis. The man was treated by antibiotics and finally aortic valve replacement and laminectomy with bone grafting. The woman had small patent ductus arteriosus and developed aortic regurgitation, but was treated by antibiotics and corset application with good result. The possibility of osteomyelitis in the lumbar spine should be considered in a patient with endocarditis complaining of severe back pain. The appropriate antibiotic therapy over a prolonged period is recommended.

Application of topical lomefloxacin against experimental Pseudomonas endophthalmitis in rabbits.

Lomefloxacin is a new quinolone compound with a broad antibacterial spectrum and excellent penetration into the aqueous humor by topical application. Therefore, an experimental study was done to evaluate the efficacy of topical lomefloxacin against experimental endophthalmitis with Pseudomonas aeruginosa. Lomefloxacin eye drops were instilled six times a day onto infected rabbit eyes and gentamicin, sulbenicillin and saline were also tested comparatively in the same manner as lomefloxacin. Clinical observation for 1 week and counting viable pseudomonas cell numbers in the anterior chamber were done. Among all topical eye drops tested, lomefloxacin was shown to be most effective in lowering clinical scores and viable cell numbers in the anterior chamber. In conclusion, lomefloxacin is expected to be a useful ophthalmic solution in the treatment of pseudomonal endophthalmitis.

[Penetration of antibiotics into second degree burned skin in rabbits].

This study was designed to determine the concentration of antibiotics administered systemically in second degree burned skin in rabbits. I: Penetration of Sulfobenzyl-penicillin (SBPC) into Deep Dermal Burn (DDB). The concentration of SBPC was determined in the skin and serum of four groups. One group acted as control and the other three had DDB. The rabbits in each were administered 100 mg/kg of SBPC by 2 hour drip infusion. In burn groups SBPC was given on the 1st, 4th and 7th post burn day, respectively. In the control group, peak concentration in the serum and skin was obtained at the end of the drip administration decreasing quickly thereafter. In every burn group, SBPC was detected in the skin and peak concentration was obtained at the end of the drip administration. After drip infusion, the SBPC level in the skin remained longer in the burn groups than in the control group. In the first day burn group, SBPC could not be detected until 1 hour after the initiation of the drip, while in the other two burn groups, SBPC could be detected a little at 30 minutes. The SBPC skin to serum ratio at the end of the drip administration in each burn group was half the value of that in the control group. II: Penetration of Cefpiramide (CPM) into Superficial Dermal Burn (SDB). The concentration of CPM was determined in the skin and serum of five groups. One group acted as control and the other four had SDB. The rabbits in each group were administered 20 mg/kg of CPM intravenously by bolus injection. In burn groups CPM was given at 8, 16, 24 and 48 hours, respectively, after burn inducement. As in the control group, CPM was detected in the SDB at every stage after burn inducement. However, CPM remained in the burned skin longer than in the non-burned skin. In the 16-hour-after-burn-group the CPM level reached its peak at 30 minutes after injection, while in the other three burn groups, the maximum level was achieved at 15 minutes. The CPM concentration in the skin of each burn group was the same or higher than that of the control group. III: Antibiotics systemically administered were determined in second degree burned skin. However, the degree of penetration was different according to the degree of burn.(ABSTRACT TRUNCATED AT 400 WORDS)

Nontoxic concentration of antibiotics for intravitreal use--evaluated by human in-vitro ERG.

The effects of penicillin G (PC-G) sodium, procaine PC-G, cloxacillin sodium (MCIPC), disodium sulbenicillin (SBPC), cefazolin sodium (CEZ), gentamicin sulfate (GM) and fosfomycin sodium (FOM) on the electroretinogram (ERG) of the human in-vitro eye-cup were studied. The oscillatory potentials (OPs) were selectively and greatly suppressed by 1.0 mM PC-G sodium. The OPs and c-wave were suppressed by 0.85 mM procaine PC-G. The b-wave and OPs were slightly suppressed by 1.0 mM MCIPC. The a-wave, b-wave, OPs and c-wave were not deteriorated by 1.0 mM SBPC. The OPs appeared to be selectively suppressed by 1.0 mM CEZ. The b-wave was suppressed and the peak latencies of the OPs were delayed by 184 micrograms/ml (approximately 0.4 mM) GM. The amplitudes of the a-wave and c-wave were slightly enhanced and their peak latencies were slightly delayed by 184 micrograms/ml GM. The a-wave, b-wave, OPs and c-wave were not deteriorated by 1.0 mM FOM. The results of the present study on the human retina were comparable to those on the albino rabbit retina in our previous studies.

Retinal toxicity of antibiotics: evaluation by electroretinogram.

Toxicity of an intravitreal injection of gentamicin sulfate, disodium sulbenicillin and cefazolin sodium on the retina was investigated by electroretinogram in albino and pigmented rabbits. Recordings were made before injection and 2 hours and 3, 7, 14, and 21 days after injection. Significant differences were found in the susceptibility of the electroretinogram components to various antibiotics as follows. Gentamicin 0.24 mg/0.1 ml irreversibly abolished all the components examined. Sulbenicillin 4.0, 8.0, or 12 mg/0.1 ml transiently suppressed the b-wave and the oscillatory potentials incrementally with increasing dose. Cefazolin 0.5, 2.0, or 5.0 mg/0.1 ml selectively reduced the oscillatory potentials, leaving the a- and b-waves almost unattenuated. The cefazolin-suppressed oscillatory potentials recovered within 14 days after injection. Judging from the most susceptible electroretinogram components to each antibiotic, we recommend intravitreal doses of these antibiotics for clinical use as follows: gentamicin 0.1 mg/0.1 ml, sulbenicillin 2 mg/0.1 ml, and cefazolin 0.25 mg/0.1 ml.

Effect of ursodeoxycholate on the biliary excretion of cefotiam and sulbenicillin in patients with percutaneous transhepatic biliary drainage.

The effects of ursodeoxycholate administration on the biliary excretion of the antibiotics cefotiam and sulbenicillin were studied in five patients with stable hepatic function receiving percutaneous transhepatic biliary drainage for obstructive jaundice. Cefotiam (I g) and sulbenicillin (2 g) were administered intravenously before and after ursodeoxycholate administration, and the maximum concentrations of the antibiotics in the bile and total amounts excreted in the bile during the 4 h after administration were determined. After ursodeoxycholate administration, both the maximum concentration of cefotiam in the bile and the amount excreted increased significantly. Ursodeoxycholate also increased the peak concentration and total excretion of sulbenicillin. For both cefotiam and sulbenicillin, the amount of antibiotic excreted in the bile during the 4 h after administration showed a significant correlation with the amount of bile acids excreted in the bile. This strongly suggests a common mechanism for the biliary excretion of these antibiotics and bile acids. Ursodeoxycholate administration is a benign way to increase both the concentration and the total amount of antibiotic excreted in the bile. Therefore, it may be useful in the treatment of serious biliary tract infections, especially in patients receiving biliary drainage.

Comparison between sulbenicillin and piperacillin levels in serum and in bronchial secretions--a pharmacokinetic study.

In order to assess pharmacokinetic differences between sulbenicillin (S) and piperacillin (P), two penicillin derivatives, 24 in-patients, 12 males and 12 females mean age 59.4 years, suffering from recurrent bronchial infections were enrolled. Patients were randomly allocated to S (12 patients) and to P (12 patients) and were given 2 g i.m. every 12 h of the awarded antibiotic, for a 7-day period. At the first and 7th day blood samples (0.25, 0.5, 1, 2, 4, 6, 8 and 12 h after dosing) as well as sputum samples (1, 2, 4, 8, 12 h after dosing) and urine samples (3, 6, 9 and 12 h after dosing) were collected, and the levels of S or P were determined by bacillus subtilis test. The pharmacokinetic analysis was performed by a standard program. On day 1 and 7 the mean peak serum concentration occurred at the first hour for S (39.9 +/- 5.2; 40.9 +/- 5.1 mcg/ml, respectively) and for P (32.2 +/- 5.4; 33.1 +/- 5.4 mcg/ml, respectively). Serum AUC0-12 and AUC0-00 (mg/l.h) levels of S were significantly higher (p less than 0.01 or less) than those of P on day 1 and 7. Similarly MRT (8 h) and Cmax (mg/l) where higher but only on day 7. Sputum AUC0-12 (mg/l.h) level of S was significantly higher (p less than 0.05) than that of P on day 1 and 7. In conclusion serum and sputum S appear to have a different pharmacokinetic profile in respect to P. However, when compared to the AUC, both drugs reach antibacterial levels.

Sulbenicillin: pharmacokinetics and penetration into bronchial secretion in elderly patients.

This study evaluates the pharmacokinetics of sulbenicillin (alpha-sulfobenzylpenicillin) in elderly subjects after single and multiple doses and the penetration into bronchial secretion in elderly patients with chronically superinfected bronchial pathology. Peak plasma levels were 53.34 micrograms/ml (group I); 55.80 and 57.82 micrograms/ml (group II) after 1 h. The half-life (t 1/2 beta) was 1.47 h (group I); 1.49 and 1.62 h (group II). Renal clearance was 6.68 l/h; 6.25 and 5.44 l/h; whereas the volume of distribution was 18.02 l; 17.84 and 17.21 l for groups I and II respectively. The mean percentage of the recovered active drug in urine over 12 h was 77.72% of dose. The mean peak reaching the bronchial secretion was 3.60 micrograms/ml at the 4th hour. The results of the multiple dose study indicated that there was no apparent change in the distribution or elimination kinetics of sulbenicillin after 2 g i.m. administration. Thus, the kinetics from the multiple dose study were in close agreement with those from the single dose study and no accumulation of sulbenicillin was observed. This study provided satisfactory results and confirmed the significant presence of sulbenicillin into bronchial secretions.

Electron microscopy of Pseudomonas aeruginosa treated with sulbenicillin and dibekacin.

A possible mechanism responsible for the combined effects of sulbenicillin and dibekacin on Pseudomonas aeruginosa IAM 1007 was investigated. The bactericidal activity of the above two drugs in combination was very strong. The regrowth of test strains after removal of the drugs was suppressed markedly, even when they were exposed to sulbenicillin plus dibekacin at a subinhibitory concentration of individual drugs. Sulbenicillin caused elongation of the bacterial cells. At the early stage of elongation, no demonstrable changes of ultrastructure of the cell wall were observed. At the late stage, lysis of the peptidoglycan layer occurred and spheroplast was formed. However, most of the outer membrane of the cell wall remained intact. Sulbenicillin acts upon the peptidoglycan layer, but not on the outer membrane. Thus it is difficult for sulbenicillin alone to cause cell lysis. On the other hand, dibekacin caused destruction of ribosomes and lysis of the outer membrane of the cell wall. Both sulbenicillin and dibekacin act on the cell wall, the former on the peptidoglycan layer (the inner membrane) and the latter on the outer membrane. The combined use of sulbenicillin and dibekacin caused elongation of bacilli and severe destruction of the inner and outer membranes of the cell wall. These morphological changes occurred even when the concentration of the individual drug was lower than its minimum inhibitory concentration (MIC). Furthermore, the cells elongated by sulbenicillin were ruptured easily when treated with dibekacin subsequently. The bacilli treated with dibekacin at a concentration lower than MIC and then treated with sulbenicillin at a concentration lower than MIC showed a marked elongation of the cells, which indicated that the effects of sulbenicillin was enhanced by dibekacin. These findings suggested strongly that sulbenicillin and dibekacin act on cell wall constituents and that their effects were complementary and synergistic.

Evaluation of the minimal bactericidal time (MBT) of sulbenicillin against multiresistant pathogens.

The in vitro antibacterial activity of sulbenicillin was evaluated against multiresistant strains isolated from in-patients and compared with that of carbenicillin and piperacillin. Sulbenicillin resulted in being as active as the other drugs against the strains tested, both at different pH, and at different bacterial inocula. In the time-kill tests sulbenicillin demonstrated bactericidal activity similar to that of piperacillin, and a higher killing rate when compared with that of carbenicillin.