In vitro activities of LY163892, cefaclor, and cefuroxime

Uveitis attack and drug reaction due to cefuroxime axetil

Antibiotics are natural or synthetic substances that are used to control bacterial infections because antibiotics are by definition only effective against bacteria. A 30-year-old female came to our emergency clinic complaining rubor in both eyes, especially in the left eye, with swelling, rubor and pain in ears, and eruption in lips extremities. In her anamnesis, it has been determined that she did not have any medical disease that requires regular utilization of drugs. After the patient received cefuroxime axetil for acute tonsillitis, she observed eruptions in lip extremities on the 3rd day, but she did not care about it. On the 5th day, rubor in both eyes and, especially in the left eye, have been developed, and complaints such as unable to look toward light and pain have started together with swelling, rubor, and pain in both ears. She came to our clinic because she was very much worried about the situation. In this study, we aimed to discuss a drug reaction characterized by face and ear skin observations, due to uveitis after the use of antibiotics including cefuroxime axetil for acute tonsillitis.

Oral cephalosporins: current perspectives

Oral cephalosporins had been, for years, a small group of compounds belonging to the first or second-generation cephalosporins, with a limited antimicrobial spectrum. New oral first-generation cephalosporins include cefprozil and loracarbef, similar to cefadroxil and cefaclor, respectively, with activity similar to cefaclor but with pharmacokinetic improvements. Second-generation oral cephalosporins are esters of already available cephalosporins, and third-generation oral cephalosporins include a number of drugs whose activity is similar to available parenteral drugs, showing pharmacokinetic advantages and, some of them, better resistance to hydrolysis mediated by extended wide-spectrum beta-lactamases. They may be a good alternative against mild to moderate ENT infections, UTIs, STDs, lower respiratory tract and skin and soft tissue infections, mainly in the outpatient setting.

Cefaclor: a contemporary look at susceptibility of key pathogens from around the globe

The orally administered cephalosporin antibiotic, cefaclor, has been available for clinical use in many countries since 1979. Because widespread antibiotic use is often cited as a factor in the emergence of bacterial resistance to antibiotics, we sought to determine the degrees of resistance to cefaclor expressed by key pathogens recently isolated in 10 countries widely distributed around the world. Using the E-test, minimal inhibitory concentrations (MIC) were determined for cefaclor and several comparator antibiotics against approximately 700 fresh clinical isolates of each of six bacterial species. The results demonstrated that > 90% of Haemophilus influenzae (beta-lactamase producing and non-producing), Haemophilus parainfluenzae (beta-lactamase producing and non-producing), Moraxella catarrhalis (> 90% beta-lactamase producing), and methicillin-susceptible Staphylococcus aureus, and 85% of Escherichia coli were susceptible to cefaclor at the NCCLS interpretive breakpoints. MIC distributions showed that there has been no change in the activity of cefaclor against penicillin-susceptible strains of Streptococcus pneumoniae since 1977.

A national collaborative study of the in vitro activity of oral cephalosporins and loracarbef (LY 163892). Australian Group for the Study of Antimicrobial Resistance (AGAR)

A national collaborative study involving the laboratories of 17 Australian hospitals examined the in vitro activity of loracarbef, cefaclor, cephalexin, amoxycillin and amoxycillin/clavulanate against 2661 recently isolated common bacterial pathogens. Loracarbef was the most active agent against Escherichia coli (MIC90 = 1 mg/l) and had activity comparable to other agents against Klebsiella pneumoniae and Proteus mirabilis. Like the oral cephalosporins, it had no activity against species of Enterobacter and Serratia. beta-lactamase-producing Staphylococcus aureus and Haemophilus influenzae were moderately sensitive to loracarbef (MIC90 = 8 mg/l for both species). Streptococcus pneumoniae was moderately sensitive to loracarbef (MIC90 = 2 mg/l) but strains which were insensitive to penicillin were often highly resistant.

Cefuroxime axetil. A review of its antibacterial activity, pharmacokinetic properties and therapeutic efficacy

Cefuroxime axetil is an oral cephalosporin which is rapidly hydrolysed to the active parent compound, cefuroxime. Cefuroxime has a broad spectrum of in vitro antibacterial activity which encompasses methicillin-sensitive staphylococci and the common respiratory pathogens Streptococcus pneumoniae, Haemophilus influenzae, Moraxella (Branhamella) catarrhalis and group A beta-haemolytic streptococci. Cefuroxime has broad spectrum activity against the beta-lactamase positive respiratory pathogens H. influenzae and M. catarrhalis; it is also active against penicillin-susceptible and -intermediate strains of S. pneumoniae. In clinical trials, cefuroxime axetil (administered twice daily) has been evaluated in the treatment of upper and lower respiratory tract infections and has demonstrated similar efficacy to established antibacterial agents, including amoxicillin/clavulanic acid and cefaclor. Five days' treatment with cefuroxime axetil was recently shown to be as effective as 10 days' treatment with either cefuroxime axetil or amoxicillin/clavulanic acid in patients with acute otitis media or acute bronchitis. Cefuroxime axetil was at least as effective as phenoxymethylpenicillin (penicillin V) in the treatment of patients with group A beta-haemolytic streptococcal tonsillopharyngitis. A number of studies have evaluated the efficacy of cefuroxime axetil as the oral component of intravenous to oral sequential therapy in hospitalised patients with lower respiratory tract infection. In each study patients received parenteral cefuroxime for approximately 2 days followed by cefuroxime axetil for 5 to 10 days. In comparative studies, cefuroxime sequential therapy was as effective as amoxicillin/ clavulanic acid sequential therapy and full courses of parenteral cefuroxime, cefotiam or cefoperazone. Adults with urinary tract infections and skin infections were also effectively treated with cefuroxime axetil, as were adults and adolescents with early stage lyme disease. Cefuroxime axetil is associated with a low incidence of adverse events, with gastrointestinal disturbances being the most frequently observed. Thus, cefuroxime axetil is an effective and convenient treatment for a wide range of infections and may be considered a therapeutic option when empirical treatment of community-acquired infections is required. Moreover, given the promising results of several intravenous/oral sequential treatment studies, cefuroxime axetil may also become established as an oral component of sequential treatment regimens.

Effectiveness of short-course therapy (5 days) with cefuroxime axetil in treatment of secondary bacterial infections of acute bronchitis

Five hundred thirty-seven patients were enrolled in two independent, investigator-blinded, multicenter, randomized clinical trials comparing the clinical and bacteriologic efficacies and the safety of 5- or 10-day treatment with cefuroxime axetil with those of 10-day treatment with amoxicillin-clavulanate in the treatment of secondary bacterial infections of acute bronchitis. Patients received either 5 or 10 days of treatment (n = 177 in each group) with cefuroxime axetil at 250 mg twice daily or 10 days of treatment (n = 183) with amoxicillin-clavulanate at 500 mg three times daily. Patients in the cefuroxime axetil (5 days) group received placebo on days 6 to 10. Bacteriologic assessments were based on sputum specimen cultures obtained preceding and, when possible, following treatment. Organisms were isolated from the pretreatment sputum specimens of 242 of 537 (45%) patients, with the primary pathogens being Haemophilus influenzae, Haemophilus parainfluenzae, Moraxella catarrhalis, Streptococcus pneumoniae, and Staphylococcus aureus (28, 25, 13, 9, and 8% of isolates, respectively). Pathogens were eradicated or presumed to be eradicated in 87% (52 of 60), 91% (53 of 58), and 86% (60 of 70) of bacteriologically evaluable patients treated with cefuroxime axetil (5 days), cefuroxime axetil (10 days), and amoxicillin-clavulanate, respectively. A satisfactory clinical outcome (cure or improvement) was achieved in 82% (107 of 130), 86% (117 of 136), and 83% (130 of 157) of the clinically evaluable patients treated with cefuroxime axetil (5 days), cefuroxime axetil (10 days), and amoxicillin-clavulanate, respectively. Treatment with amoxicillin-clavulanate was associated with a significantly higher incidence of drug-related adverse events than was treatment with cefuroxime axetil for either 5 or 10 days (P = 0.001), primarily reflecting a higher incidence of drug-related gastrointestinal adverse events (37 versus 19 and 15%, respectively; P < 0.001), particularly diarrhea and nausea. These results indicate that treatment with cefuroxime axetil at 250 mg twice daily for 5 days is as effective as treatment for 10 days with either the same dose of cefuroxime axetil or amoxicillin-clavulanate at 500 mg three times daily in patients with acute bronchitis. In addition, treatment with cefuroxime axetil for either 5 or 10 days is associated with significantly fewer gastrointestinal adverse events, particularly diarrhea and nausea, than is 10-day treatment with amoxicillin-clavulanate.

Bone and wound fluid concentrations of cephalosporins. Oral cefadroxil and parenteral cefuroxime compared in 52 patients with a trochanteric fracture

We performed a prospective and randomized study in 52 patients to compare the concentrations in cancellous bone and wound fluid of antibiotics, given orally (cefadroxil) or intravenously (cefuroxime) as prophylaxis in trochanteric fracture surgery. Oral cefadroxil resulted in adequate antibiotic levels in 22 of 26 patients in wound fluid and cancellous bone, while parenteral cefuroxime resulted in sufficient antibiotic levels in all 26 patients. The concentrations in bone varied greatly between the subjects.

Prophylaxis with oral cefadroxil versus intravenous cefuroxime in trochanteric fracture surgery. A clinical multicentre study

A prospective, randomized study was performed in 559 patients to compare two doses of oral cefadroxil with three doses of intravenous cefuorxime as antibiotic prophylaxis in intra- and subtrochanteric hip fracture surgery. Antibiotic concentrations in the wound fluid were determined at the start and at the end of the operation. The first dose of cefadroxil was given about 2 h before surgery and cefuroxime about 30 min before operation. In 226/242 (93%) patients randomized to oral cefadroxil, the concentration in the wound during surgery was on average 15 micrograms/ml, i.e., well above the minimum inhibitory concentration (MIC-90) for Staphylococcus aureus. In the cefuroxime group, antibiotic levels in the wound exceeded the MIC-90 for S. aureus in 204/210 (97%) of the patients at the start and/or at the end of surgery. All patients were followed up for 4 months. One deep and five superficial infections occurred in the cefuroxime group and no deep but one superficial infection in the cefadroxil group (P = 0.07). S. aureus was cultured in three of the infected cases while cultures were negative in four patients. Four of the seven infected patients had adequate levels of antibiotic in the wound during surgery, and in three patients no antibiotic assay was performed. The infected patients did not differ in age, sex, operation time, bleeding or any other basic variable compared with patients who healed without complications. Two doses of cefadroxil seems to be practical and as effective as intravenously administered cefuroxime as antibiotic prophylaxis in trochanteric hip fracture surgery.

Isolation and structure elucidation of a novel product of the acidic degradation of cefaclor

The acidic aqueous degradation of cefaclor, an orally administered cephalosporin antibiotic, has been investigated. The most prominent peak in the high-performance liquid chromatography profile of a degraded solution of cefaclor was isolated by preparative high-performance liquid chromatography. Mechanistically, the formation of this degradent from cefaclor involves a condensation of two cefaclor degradation products in which both products have undergone contraction from a six-membered cephem ring to a five-membered thiazole ring, presumably via a common episulfonium ion intermediate.

Loracarbef. A review of its antimicrobial activity, pharmacokinetic properties and therapeutic efficacy

Loracarbef is an orally administered member of a new synthetic class of beta-lactam antibiotics, the carbacephems, which is characterised by enhanced chemical stability. At low concentrations (< 2 mg/L) in vitro, it inhibits Streptococcus pneumoniae, S. pyogenes, beta-haemolytic streptococci groups B, C and G. Proteus mirabilis and Moraxella catarrhalis, including beta-lactamase-producing strains. At therapeutic plasma concentrations it is also active in vitro against most strains of Staphylococcus aureus, S. saprophyticus, Escherichia coli and beta-lactamase-positive and -negative strains of Haemophilus influenzae. Like other beta-lactams, loracarbef is inactive against methicillin-resistant strains of S. aureus. When administered at dosages of 200 to 400 mg twice daily, the clinical and bacteriological efficacy of loracarbef is comparable with that of amoxicillin and amoxicillin/clavulanic acid in patients with upper or lower respiratory tract infections, and comparable with that of cefaclor in treating infections of the lower respiratory tract, skin and skin structures and urinary tract. Loracarbef and phenoxymethylpenicillin (penicillin V) were equally effective in treating streptococcal pharyngitis and tonsillitis. Loracarbef is generally well tolerated by all age groups and causes less diarrhoea than amoxicillin/clavulanic acid. It is administered twice daily. It offers a suitable alternative to other orally administered antibiotics for the treatment of mild to moderate infections caused by susceptible organisms.

Loracarbef: a new orally administered carbacephem antibiotic

OBJECTIVE

To discuss the in vitro activity, pharmacokinetics, clinical efficacy, adverse effects, and relative merits of loracarbef, a new orally administered carbacephem antibiotic.

DATA SOURCES

Pertinent literature was identified by a review of selected journals and a MEDLINE search. Additional information was provided by the manufacturer of loracarbef.

STUDY SELECTION

All studies that have evaluated the clinical efficacy of loracarbef were included. In vitro studies were included if they used similar methodologies. Additional information was incorporated regarding the chemistry, pharmacokinetics, and adverse effects of loracarbef.

DATA SYNTHESIS

Loracarbef has antibacterial activity against most community-acquired respiratory tract, skin and skin structure, and urinary tract pathogens. The drug is well absorbed after oral administration and plasma concentrations achieved in patients are greater than the in vitro minimum inhibitory concentrations for most of the above bacteria. Although the majority of the clinical studies with loracarbef have methodologic deficiencies, loracarbef therapy has demonstrated similar efficacy in the treatment of upper respiratory tract (except otitis media), lower respiratory tract, skin and skin-structure, and urinary tract infections compared with accepted antibiotics. Potential advantages of the new carbacephem may be improved patient compliance with its less frequent dosing schedule (once or twice a day, depending on the infection), and a low incidence of adverse effects.

CONCLUSIONS

Preliminary data indicate that loracarbef may be an alternative agent for the treatment of a variety of community-acquired infections. Additional clinical experience and rigorously controlled comparative clinical trials are necessary to enable practitioners to fully define the therapeutic role of loracarbef.

Molecular basis of the efficacy of cefaclor against Haemophilus influenzae

Cefaclor sustained its inhibitory activity against a beta-lactamase-producing strain of Haemophilus influenzae. Although a relatively high permeability coefficient was calculated for ampicillin compared with that calculated for cefaclor, the resulting periplasmic concentration of cefaclor was 5.7 times that of ampicillin. The efficacy of cefaclor may be due to its higher beta-lactamase resistance, which allows it to achieve a greater periplasmic concentration and adequate binding to crucial penicillin-binding proteins.

Pharmacokinetics of loracarbef and interaction with acetylcysteine

A study was conducted to evaluate the pharmacokinetics of loracarbef, a new synthetic oral carbacephem antibiotic, following administration of 400 mg in normal male volunteers. The influence of food and possible interaction with acetylcysteine, a commonly used mucolytic agent, was also studied. Twelve healthy volunteers participated in the study and randomly received an oral dose of 400 mg loracarbef in the fasting state, 400 mg loracarbef following a standard breakfast or 400 mg loracarbef together with 200 mg acetylcysteine in granular form. Serum and urine concentrations were determined over 24 h by means of a bioassay. Loracarbef was well tolerated. Four volunteers complained of mild, transient headache. The substance was well absorbed with a mean peak level of 19.21 +/- 3.94 mg/l in the fasting state; it was primarily excreted in active form via the kidneys (urine recovery/24 h: 86-92%). The elimination half-life ranged from 70.3 to 102.0 min. Acetylcysteine had no effect on the absorption of loracarbef. The intake together with food delayed the absorption time, but had no influence on the bioavailability.

Loracarbef versus penicillin V in the treatment of streptococcal pharyngitis and tonsillitis

Ten-day, double-blind, randomized, parallel treatment regimens of loracarbef (200 mg capsule twice daily or 15 mg/kg/day oral suspension in two divided doses up to a maximum of 375 mg/day; n = 169) and penicillin V (250 mg capsule four times daily or 20 mg/kg/day suspension in four divided doses up to a maximum of 500 mg/day; n = 175) were compared in the treatment of group A beta-haemolytic streptococcal (GABHS) pharyngitis and tonsillitis. Post-therapy clinical responses were similar for evaluable patients in both treatment groups: 97.4% of the loracarbef group (101/115 patients cured and 11/115 improved) and 96.0% of the penicillin group (101/124 patients cured and 18/124 improved). A statistically significant difference in the pathogen elimination rate was noted between treatment groups: post-therapy throat cultures were negative for GABHS in 94.8% (109/115) of loracarbef-treated patients compared with 87.1% (108/124) of penicillin-treated patients (p = 0.040). Loracarbef and penicillin V were comparable in terms of safety. Headache and nausea/vomiting were the most common events reported during therapy (nausea/vomiting were slightly less common in the loracarbef group). Three patients in each group were discontinued from the study due to drug-related adverse events; one due to rash in the loracarbef group and one due to rash and one due to vomiting in the penicillin group. These data support the conclusion that loracarbef twice daily is more effective in eradicating GABHS than penicillin V four times daily, and the two drugs are comparable in safety and clinical efficacy in the treatment of GABHS pharyngitis and tonsillitis.

The carbacephems: a new beta-lactam antibiotic class

The carbacephems are a new class of beta-lactam antibiotics that are similar in structure to the cephalosporins. Carbacephems differ from cephalosporins, however, in the substitution of a sulfur atom in the dihydrothiazine ring with a methylene group to form a tetrahydropyridine ring. The result of this structural difference is the carbacephem class. Carbacephems have remarkable chemical stability that allows for structural manipulation in a manner that could not be done previously with the cephalosporin ring system. Potent broad-spectrum antibiotics result from the incorporation at the 3 position of substituents that include quaternary pyridinium or imidazole, sulfones, and heterocyclic thiazole structures. Because of the chemical stability of the carbacephems, these highly electronegative side chains can be added to the 3 or 3' position of the tetrahydropyridine ring system. Increasing the electronegativity of these side chains can increase the microbiologic activity of the compounds. In addition, utilizing the side chains that have traditionally conferred good oral absorption on the cephalosporins offers the possibility of a new series of broad-spectrum oral antibiotics. Loracarbef is the first carbacephem to undergo clinical development, and other experimental carbacephems are being produced with the aim of developing potent oral antibiotics that can be used against pathogens that cause infections commonly found in the outpatient setting.

Loracarbef (LY163892) in the treatment of acute exacerbations of chronic bronchitis: results of U.S. and European comparative clinical trials

Two controlled clinical trials compared loracarbef (LY163892 with amoxicillin/clavulanate or amoxicillin in the treatment of acute exacerbations of chronic bronchitis. Collectively, of 1,057 patients enrolled, 390 qualified for analysis: group 1 comprised 200 patients treated with loracarbef (400 mg twice daily); group 2, 120 patients treated with amoxicillin/clavulanate (500 mg three times daily); and group 3, 70 patients treated with amoxicillin (500 mg three times daily). Symptomatic and bacteriologic outcomes were assessed at post-therapy (within 72 hours of therapy completion), and at late-posttherapy (10-14 days after therapy completion). These evaluations were combined to provide an "overall" evaluation that accounted for all unfavorable outcomes occurring at either the posttherapy or late-posttherapy visit. At the posttherapy evaluation, 93.0% of group 1 patients, 95.0% of group 2 patients, and 88.6% of group 3 patients demonstrated favorable clinical outcomes (cure or improvement). "Overall" favorable clinical outcomes were achieved in 88.0% of group 1 patients, 90.0% of group 2 patients, and 81.4% of group 3 patients. Bacteriologic results from the two studies could not be merged due to marked differences in how posttherapy bacteriologic results were assessed. The clinical significance of positive posttherapy sputum cultures was doubtful: 90% of patients with a positive sputum culture at the posttherapy visit who returned for the late-posttherapy visit had successful clinical outcomes documented at the late-posttherapy evaluation. Loracarbef was associated with a lower incidence of diarrhea and a higher incidence of headache as compared with amoxicillin/clavulanate. These results suggest that 400 mg loracarbef twice daily for 7 days is effective and safe in the treatment of acute exacerbations of chronic bronchitis.

Antibiotic therapy for urinary tract infections

Loracarbef, a member of the carbacephem class of beta-lactam antibiotics, was tested in randomized, double-blind, parallel studies for the treatment of uncomplicated urinary tract infections (UTIs). In one study conducted in the United States, a 7-day course of once-daily doses of loracarbef (200 mg) was compared with a 7-day course of multiple daily doses of cefaclor (250 mg three times a day). Analysis of data from a small, homogeneous patient population of 108 college-aged women showed that loracarbef produced clinical and bacteriologic responses similar to those produced by cefaclor. At 5-9 days posttherapy, bacteriologic cure was observed in 96% of patients in the loracarbef group and 90% of patients in the cefaclor group (p = 0.614); at 4-6 weeks post-therapy, the same cure rate (81%) was observed in both groups. Analysis of the larger (333 patients) and more heterogeneous study population containing several male and elderly female patients showed that loracarbef again produced responses similar to those produced by cefaclor, with no statistically significant differences seen between the groups at 5-9 days or at 4-6 weeks posttherapy. The adverse events reported by the loracarbef and cefaclor groups were also comparable in both the small and large patient populations analyzed. Similarly favorable results were seen when a 7-day regimen of loracarbef (200 mg once a day) was compared with a 7-day regimen of norfloxacin (400 mg twice a day) in a large European study of approximately 300 patients with uncomplicated cystitis. These studies demonstrate that the safety and efficacy of once-daily loracarbef are comparable to the safety and efficacy of multiple-dose/day therapy with other antimicrobial agents commonly used in the treatment of uncomplicated UTIs.

Loracarbef versus penicillin VK in the treatment of streptococcal pharyngitis and tonsillitis in an adult population

Loracarbef, a member of the carbacephem class of beta-lactam antibiotics, is a potent anti-bacterial agent. In a double-blind, randomized clinical trial to assess the efficacy and safety of loracarbef in the treatment of streptococcal pharyngitis and tonsillitis, 107 adult patients were treated with loracarbef (200 mg capsules twice a day or 15 mg/kg/day suspension) and 111 patients were treated with penicillin VK (250 mg capsules four times a day or 20 mg/kg/day suspension) for 10 days. In the loracarbef treatment group, 96.6% of the evaluable patients had a favorable clinical response 3-5 days after therapy, a result that compared favorably with the 93.9% response rate achieved in the penicillin group. The clinical failure/relapse rates were 3.4% for loracarbef-treated patients and 6.1% for patients receiving penicillin. Bacteriologic response data approximated the clinical results, with a successful response in 89.9% of the loracarbef-treated patients and 91.5% of the penicillin recipients. Two (1.9%) loracarbef-treated patients with rash and one (0.9%) penicillin-treated patient with diarrhea discontinued the study early because of these adverse events. The incidence of adverse events was comparable in the two treatment groups except for increased cough, which was reported by 3.7% of the loracarbef-treated patients and none of the penicillin recipients. These data support the conclusion that loracarbef is comparable to penicillin VK in the treatment of streptococcal pharyngitis and tonsillitis in adults.

Loracarbef (LY163892) versus cefaclor and norfloxacin in the treatment of uncomplicated pyelonephritis

Optimal therapy for pyelonephritis requires the immediate administration of an effective broad-spectrum antibiotic. Because conventional oral antibiotics such as the sulfonamides and the aminopenicillins are limited by the development of resistant bacteria associated with this common disease, the therapeutic effectiveness of a new oral carbacephem antibiotic was investigated. Two double-blind, randomized clinical trials of loracarbef (LY163892) were conducted. A total of 245 patients (greater than or equal to 18 years old) with uncomplicated pyelonephritis were enrolled in parallel studies. One study compared loracarbef with cefaclor; the other compared loracarbef with norfloxacin. In the combined patient population, 119 patients were treated with loracarbef (400 mg twice daily), 43 with cefaclor (500 mg three times daily), and 83 with norfloxacin (400 mg twice daily). All treatment regimens continued for greater than or equal to 14 days. A total of 68 patients in the loracarbef group, 25 in the cefaclor group, and 43 in the norfloxacin group qualified for efficacy analysis. Escherichia coli was the causative pathogen in 85.0% of these patients. Successful posttherapy clinical and bacteriologic responses were similar for all three study drugs: 94.1 and 86.8%, 96.0 and 80.0%, 97.7 and 88.4% for loracarbef, cefaclor, and norfloxacin, respectively. Late posttherapy clinical responses were 87.4, 83.3, and 91.7% for the loracarbef, cefaclor, and norfloxacin groups, respectively. Bacteriologic responses for the three groups were 79.6, 60.0, and 88.9%. The most frequent adverse effects (headache, diarrhea, and nausea) were experienced by three patients (2.5%) in the loracarbef group; headaches were noted in two (4.7%) cefaclor patients, diarrhea was noted in three (7.0%) patients in the cefaclor group, and nausea was noted in four (9.3%). Gastrointestinal events were noted in four patients (4.8%) in the norfloxacin group. The data demonstrate that loracarbef is comparable in efficacy and safety to both cefaclor and norfloxacin as oral therapy for uncomplicated pyelonephritis.

Loracarbef (LY163892) versus cefaclor in the treatment of bacterial skin and skin-structure infections in an adult population

Loracarbef (LY163892), a member of the class of beta-lactam antibiotics known as carbacephems, is characterized by a high level of chemical stability and a broad spectrum of antibacterial activity that persists in the presence of beta-lactamase. The efficacy and safety of loracarbef, 200 mg (twice daily), and cefaclor, 250 mg (three times daily) (one patient received 178 mg of cefaclor suspension, three times daily), were compared in a randomized, double-blind, multicenter trial conducted in adults with skin and skin-structure infections due predominantly to Staphylococcus aureus. Examination within 72 hours after the completion of therapy indicated a favorable clinical response in 84 (93.3%) of the 90 loracarbef-treated patients evaluable for efficacy and in 79 (95.2%) of the 83 evaluable patients treated with cefaclor. Pathogens were eradicated in 83 (92.2%) of the patients in the loracarbef group and 74 (89.2%) of those in the cefaclor group. Only four adverse events--headache/migraine, diarrhea, abdominal pain, and nausea--occurred in greater than 2% of the total study population. The overall incidence of adverse events in the 201 loracarbef-treated and 192 cefaclor-treated patients evaluated for safety was 19.9% and 24.5%, respectively. Adverse events that required hospitalization or discontinuation of treatment occurred in four patients in the cefaclor group but in none of those treated with loracarbef. There were no statistically significant differences in the clinical or bacteriologic response or the incidence of side effects between the two treatment groups. These findings indicate that loracarbef given twice daily is comparable in safety and efficacy to cefaclor given three times daily in the treatment of adults with skin and skin-structure infections.

In vitro activity of loracarbef and effects of susceptibility test methods

Loracarbef is a new oral antimicrobial of the carbacephem class with in vitro activity against the common pathogens associated with skin infections, otitis media, sinusitis, bronchopulmonary infections, and urinary tract infections. A review of the literature shows the following ranges for 90% minimum inhibitory concentration (MIC90) values (microgram/mL) against the organisms that commonly cause these illnesses: Streptococcus pneumoniae, 0.25-2.0; Moraxella (Branhamella) catarrhalis (beta-lactamase positive), 0.5-8.0; M. catarrhalis (beta-lactamase negative), 0.12-0.25; Haemophilus influenzae (beta-lactamase positive), 0.5-16.0; H. influenzae (beta-lactamase negative), 0.25-8.0; Escherichia coli, 2.0-25; Klebsiella pneumoniae, 0.25-8.0; Proteus mirabilis, 1.0-8.0; Streptococcus pyogenes, less than or equal to 0.06-1.0; Staphylococcus aureus (beta-lactamase positive), 8.0; S. aureus (beta-lactamase negative), 1.0-2.0. The in vitro activity of loracarbef against these common outpatient pathogens is similar to that of other oral antimicrobials such as cefaclor, cefuroxime axetil, cefixime, amoxicillin/clavulanate, and trimethoprim/sulfamethoxazole. The results of in vitro susceptibility tests with any antimicrobial, including loracarbef, are somewhat dependent on the specific test method that is employed in the laboratory. This is particularly true with H. influenzae. Furthermore, the results of loracarbef susceptibility tests are of uncertain value in predicting therapeutic outcome.

Acute bacterial maxillary sinusitis: results of U.S. and European comparative therapy trials

Loracarbef, which is the first agent of the carbacephem class of beta-lactam antibiotics to be developed, provides good activity against a broad spectrum of bacteria. A single-blinded, randomized, parallel clinical trial in 10 centers in the United States compared the efficacy and safety of loracarbef with that of amoxicillin/clavulanate potassium in the treatment of acute bacterial maxillary sinusitis. A 7-10-day regimen of loracarbef (400 mg twice daily) was as effective as amoxicillin/clavulanate (500/125 mg three times a day) and resulted in somewhat fewer side effects. The results of a European trial in Sweden, Finland, and Iceland showed that loracarbef was clinically more effective than doxycycline in the treatment of acute bacterial maxillary sinusitis.

Loracarbef (LY163892) versus amoxicillin-clavulanate in the treatment of bacterial acute otitis media with effusion

The efficacy and safety of loracarbef, a new beta-lactam antibiotic, was compared with that of amoxicillin-clavulanate potassium in the treatment of bacterial acute otitis media with effusion. A double-blind format was utilized to administer 10-day, randomized, parallel treatment regimens to patients who were between 6 months and 12 years of age. The most prevalent causative pathogens found in the two treatment groups were Streptococcus pneumoniae, Haemophilus influenzae, and Moraxella (Branhamella) catarrhalis. The percentages of favorable posttherapy clinical responses in evaluable patients were similar for both drugs: 87.3% (124/142) of the loracarbef group, compared with 91.5% (130/142) of the amoxicillin-clavulanate group, showed favorable responses within 72 hours after treatment. Ten to sixteen days after treatment, 68.1% of the loracarbef group, compared with 76.1% of the amoxicillin-clavulanate group, showed favorable responses. More patients in the amoxicillin-clavulanate group reported treatment-emergent events: 46.1% compared with 35.8% in the loracarbef group (p = 0.023). Diarrhea was the most frequently reported event, occurring in 13.3% of the loracarbef group and in 26.3% of the amoxicillin-clavulanate group (p less than 0.001). Vomiting was reported by 5.8% of the loracarbef group and 10.3% of the amoxicillin-clavulanate group (p = 0.072). Loracarbef is comparable in efficacy to amoxicillin-clavulanate in the treatment of bacterial acute otitis media with effusion and has a more desirable safety profile.

Comparison of loracarbef (LY163892) versus amoxicillin in the treatment of bronchopneumonia and lobar pneumonia

Loracarbef (LY163892), a carbacephem, is the first of a new class of beta-lactam compounds. A 14-day, double-blind, randomized, parallel treatment study compared loracarbef (400 mg b.i.d.; n = 169) and amoxicillin (500 mg t.i.d.; n = 167) in the treatment of lobar pneumonia and bronchopneumonia. Forty-four patients in the loracarbef group and 40 patients in the amoxicillin group were evaluable for efficacy analysis. Streptococcus pneumoniae and Haemophilus influenzae were isolated from pure or mixed cultures in 45.5% of the evaluable patients, with S. pneumoniae being isolated most frequently. Favourable clinical responses (cure or improvement) in the loracarbef-treated group (42/44; 95.5%) were similar to those in the amoxicillin-treated group (38/40; 95%). A favourable bacteriological response was observed for 36/44 (81.8%) loracarbef-treated patients compared with 28/40 (70%) amoxicillin-treated patients (p = 0.2). Adverse events were similar in both groups. Withdrawal of treatment was required in three patients in each group due to gastrointestinal events or rash/allergic exanthema. These data support the conclusion that loracarbef and amoxicillin have comparable efficacy and safety in the treatment of bronchopneumonia and lobar pneumonia caused by susceptible pathogens. However, loracarbef can be administered twice daily, offering the advantage of improved patient compliance. It is also active against beta-lactamase producing organisms.

Loracarbef (LY163892) vs Amoxicillin/Clavulanate in Bacterial Maxillary Sinusitis

Loracarbef (LY 163892), a β-lactam antibiotic (carbacephem), was compared with amoxicillin/ clavulanate potassium in a 10-day, single-blind, randomized parallel trial in the treatment of acute bacterial maxillary sinusitis. Based on posttherapy aspirate and culture, there was a 95.2% bacteriologic cure rate in patients receiving loracarbef (400 mg twice daily) and an 86.7% cure rate in patients receiving amoxicillin/clavulanate (500/125 mg three times daily) ( p = 0.359). Loracarbef was comparable in efficacy to amoxicillin/clavulanate with a more desirable safety profile.

Bactericidal titers of loracarbef (LY 163892) in serum and killing rates in volunteers receiving 400 versus 200 milligrams

In a randomized crossover trial, six volunteers received 200- and 400-mg doses of loracarbef (LY 163892), a new oral cephalosporin. Mean +/- standard error of the mean concentrations in serum obtained after 1.5 and 3 h were 13.2 +/- 2.8 and 4.3 +/- 0.7 mg/liter, respectively, after the 400-mg dose and 6.9 +/- 1.0 and 1.7 +/- 0.2 mg/liter, respectively, after the 200-mg dose. Bactericidal reciprocal titers measured against respiratory pathogens in serum suggested that loracarbef would be highly effective against Streptococcus pneumoniae and Streptococcus pyogenes (median titers, 8 to 128 at 1.5 h and less than 2 to 32 at 3 h) and beta-lactamase-negative Haemophilus influenzae (median titers, 4 at 1.5 h and 2 to 4 at 3 h). Other species (Branhamella catarrhalis, Streptococcus anginosus, Staphylococcus aureus) were associated with lower bactericidal titers. Killing curves performed against 12 strains demonstrated that the bioactivity of loracarbef (measured by the reduction in the area under the control growth curve) was significantly correlated with the concentration/MIC ratio, whereas the initial rate of killing was not, once the concentration was greater than the MIC. Our results suggest that administration of 400 mg of loracarbef every 8 h might be associated with more favorable pharmacodynamic parameters against target bacteria.

High-performance liquid chromatographic determination of loracarbef, a potential metabolite, cefaclor and cephalexin in human plasma, serum and urine

A high-performance liquid chromatographic (HPLC) method is reported for the determination of a new carbacephem antibiotic, loracarbef, a hydroxylated analogue, and two cephalosporins, cefaclor and cephalexin, in plasma, serum, and urine. The antibiotics are extracted from plasma by means of C18 solid-phase cartridges. Urine samples are diluted with water and directly injected on the HPLC system. The HPLC system utilizes a Supelcosil LC-18-DB (250 mm x 4.6 mm I.D.) reversed-phase column and ultraviolet detection at 265 nm. The limit of quantitation is 0.5 micrograms/ml for each compound. Excellent correlation of plasma concentrations is shown between results determined by HPLC and those obtained by microbiological agar-well diffusion assays. Stability studies of loracarbef in human plasma show the antibiotic to be stable for at least 24 h at room temperature and for at least twelve months at -20 degrees C.

Loracarbef versus cefaclor in the treatment of urinary tract infections in women

In a double-blind, prospective, randomized study, 108 college women with acute urinary tract infections were treated for 7 days with either loracarbef (LY163892) at 200 mg once daily (n = 53) or cefaclor at 250 mg three times daily (n = 55). The cure rates at 5 to 9 days after treatment in the loracarbef and cefaclor groups were 96 and 90%, respectively. Both loracarbef and cefaclor are safe, well tolerated, and effective in the treatment of urinary tract infections in women.

Effect of loracarbef on the normal oropharyngeal and intestinal microflora

20 healthy volunteers received loracarbef capsules 200 mg b.i.d. for 7 days. Saliva and stool specimens were taken before loracarbef administration and on the 2nd, 5th, and 7th day during the administration period, and again 2, 5 and 9 days after withdrawal of the antibiotic to study the effect of loracarbef on the normal microflora. The concentrations of loracarbef in serum, saliva and faeces were determined by an agar diffusion method. The mean serum peak concentration attained after 1 h was 6.8 mg/l and the saliva concentrations were in the range 0-0.9 mg/l. The loracarbef concentrations in faeces ranged from 0 to 0.9 mg/kg. The changes in the the oropharyngeal microflora were minor and only bacteroides rods were affected. In the intestinal aerobic microflora, the number of enterococci and streptococci slightly increased while staphylococci, micrococci, corynebacteria, bacillus and enterobacteria were not affected. The number of bifidobacteria and eubacteria in the anaerobic microflora decreased while no other bacterial groups were affected. One week after withdrawal of loracarbef, both the oropharyngeal and intestinal microflora had returned to normal. No new colonizing loracarbef resistant microorganisms were observed during the investigation period.

Comparative in vitro activities of several new fluoroquinolones and beta-lactam antimicrobial agents against community isolates of Streptococcus pneumoniae

The in vitro susceptibilities of 551 community isolates of Streptococcus pneumoniae from the Canadian province of Ontario to several new fluoroquinolones and beta-lactam antimicrobial agents were determined by a broth microdilution technique. Eight (1.5%) of these isolates were moderately susceptible (MICs, greater than or equal to 0.12 and less than or equal to 1.0 microgram/ml) to penicillin; none was resistant. Temafloxacin, ciprofloxacin, and ofloxacin (MICs for 90% of strains tested, between 1 and 2 micrograms/ml) were the most active fluoroquinolones tested, and BMY-28100 (MIC for 90% of strains tested, 0.25 microgram/ml) was the most active of the new beta-lactams tested.

Pharmacokinetics of LY163892 in infants and children

Two dosages (7.5 and 15 mg/kg of body weight) of LY163892 were given to infants and children, and five plasma specimens were collected for antibiotic assay during the ensuing 4 h. Peak concentrations of 12.6 and 18.7 micrograms/ml occurred at 45 min. The mean half-lives were 0.85 and 0.78 h, and the mean areas under the curve were 24.4 and 38.0 micrograms.h/ml.

Influence of storage and susceptibility test conditions on stability and activity of LY163892 and four other cephalosporins

A new carbacephem analog of cefaclor, LY163892, was examined along with four other cephalosporins for chemical stability and for antibacterial activity under a variety of susceptibility test conditions. LY163892 was found to be markedly more stable than cefaclor during storage at 4 and 35 degrees C in human serum, human urine, and various bacteriological media. Under these conditions, LY163892 demonstrated stability equal or superior to the stabilities of cephalexin, cephalothin, and cefuroxime. Broth and agar dilution susceptibility tests did not reveal significant differences in LY163892 activity in a variety of test media, although LY163892 MICs were somewhat higher in Mueller-Hinton chocolate agar or Trypticase soy broth (BBL Microbiology Systems, Cockeysville, Md.) than in other media. The activity of LY163892 against selected pathogens was only slightly influenced by the increased or decreased pH of the test medium, in a manner similar to that of the other cephalosporins tested. Thus, the carbacephem structure of LY163892 appears to represent a more stable cephalosporin than cefaclor, while retaining a similar antimicrobial spectrum.

In vitro activity and beta-lactamase stability of LY163892

Susceptibility testing of clinical isolates of several gram-negative and gram-positive species showed LY163892 to be more active than cefaclor and cephalexin. OXA-2, TEM-1, TEM-2, PSE-1, CEP-1, CARB-3 and SHV-1 beta-lactamases showed similar activity against LY163892 and cefaclor, whereas OXA-1 hydrolyzed the latter more rapidly. Organisms producing these beta-lactamases, but not TEM-2 and CEP-1, appeared to be more susceptible to LY163892 than cephalexin, although cephalexin proved to be more resistant to beta-lactamase activity. Strains producing TEM-2 and CEP-1 were resistant to LY163892, cefaclor and cephalexin.