Pre-formulation Study of Salicylidine-cephalexin-Zn(II) dihydrate, a New Derivative of Cefalexin.

BACKGROUND: Salicylidine-cefalexin-Zn(II)·2H2O, a new derivative of cefalexin, has been reported to possess enhanced anti-microbial activity and lower toxicity than cefalexin. It is, therefore, desirable to carry out a pre-formulation study to determine its pharmaceutical properties which will be useful in conversion of the new molecule into various dosage forms. METHODS: The compound was synthesized by the previously reported method and characterized by elemental, Fourier-transform infrared and electronic spectral analyses. Crystallinity was determined by powder x-ray diffraction. Particle size distribution was determined by a laser-based sizer. Other properties including flow, density and compaction strength were determined by use of appropriate standard methods. The compound was also evaluated as a prodrug through dissolution study by the USP method. RESULTS: It was found that the new derivative is an amorphous powder with different bulk density, porosity, compressibility, plasticity and flow properties as compared to cefalexin. The amorphous character of the new compound suggests that it will have better bioavailability. The dissolution study indicated that this compound is hydrolyzed to produce cefalexin in water in a sustained manner, thus it will act as a prodrug in vivo. The release data fitted well into Highuchi model. CONCLUSION: Various pharmaceutical properties essentially required for formulation of salicylidine-cefalexin-Zn(II)·2H2O into dosage forms were determined. This study has shown that the new drug would behave as a prodrug for cefalexin with better bioavailability.

Characterization of the transport system for beta-lactam antibiotics and dipeptides in rat renal brush-border membrane vesicles by photoaffinity labeling.

The uptake of the alpha-aminocephalosporin cephalexin into brush-border membrane vesicles from rat renal cortex was independent on an inward H+-gradient in contrast to the intestinal transport system. The transport system could be irreversibly inhibited by photoaffinity labeling. Two binding polypeptides for beta-lactam antibiotics and dipeptides with apparent molecular weights 130,000 and 95,000 were identified by photoaffinity labeling with [3H]benzylpenicillin and N-(4-azido[3,5-3H]benzoyl) derivatives of cephalexin and glycyl-L-proline. The uptake of cephalexin and the labeling of the respective binding proteins was inhibited by beta-lactam antibiotics and dipeptides as with intestinal brush-border membranes. These data indicate that the transport systems for beta-lactam antibiotics and dipeptides in the brush-border membrane from rat kidney and small intestine are similar but not identical.

Blinded comparison of cefuroxime to cefaclor for lower respiratory tract infections.

Cefuroxime axetil was compared with cefaclor for the therapy for lower respiratory tract infections. Sixty-one patients were randomized to receive the following drug dosages: (1) cefuroxime axetil, 250 mg orally every 12 hours (21 patients); (2) cefuroxime axetil, 500 mg orally every 12 hours (21 patients); and (3) cefaclor, 500 mg orally every eight hours (19 patients). Of these 61 patients, 80% were male, with a mean age of 59.5 years; 56% had acute pneumonia, and the remainder had an acute bronchitis. Causative pathogens included typical respiratory tract pathogens. Overall, 23 of 27 patients with bronchitis were clinically cured at the end of therapy. Thirty-one of 34 pneumonias were clinically cured or improved at the end of therapy; the three pneumonia treatment failures occurred in the lower dose cefuroxime (n = 2) and cefaclor (n = 1) treatment groups. Overall, bacteriologic cure occurred in 86% of patients treated with 500 mg of cefuroxime axetil compared with 60% of cefaclor-treated patients. Adverse clinical effects were uncommon. From this study, it was concluded that cefuroxime given every 12 hours is at least as clinically efficacious as cefaclor; it is a new oral cephalosporin with pharmacologic and bacterial spectrum advantages over many older agents.

Single-dose cefaclor therapy of urinary tract infection. Evaluation of antibody-coated bacteria test and C-reactive protein assay as predictors of cure.

The efficacy of single-dose (cefaclor, 2 g orally) and multidose (cefaclor, 250 mg orally three times a day for 10 days) antibiotic regimens in the therapy of acute uncomplicated urinary tract infections (UTI) in nonpregnant women were compared. The patient's clinical status and results of urine cultures were compared in retrospect with the results of the antibody-coated bacteria (ACB) test and C-reactive protein (CRP) test in order to determine if either test would predict the patient's response. Overall, 10 of 30 patients (33 percent) and 18 of 22 patients (81 percent) given single doses and multidoses, respectively, had negative urine cultures four weeks after completion of therapy. A negative urine culture at four weeks correlated with a negative ACB test utilizing the less inclusive criteria for negativity (less than 5 bacteria with fluorescence in 5 minutes of search) but not with a negative ACB test utilizing the more inclusive criteria (less than 10 percent bacteria with fluorescence) or with a negative CRP test. The cure rate in the ACB-negative single-dose group (7 of 9 patients) utilizing the less inclusive criteria for negativity was similar to the cure rate in the ACB-negative multidose group (8 of 10 patients). This study suggests that the ACB test, if properly standardized, might permit identification of a population of patients with UTI who would respond to single-dose cefaclor therapy.

Cephalosporin derivatives with 2- and 4-pyridone groups at carbon-3.

Two compounds, analogues of cephalexin with 2- and 4-pyridone groups at C-3, were prepared. Biological evaluation found the compounds to exhibit activity against Gram-positive and Gram-negative organisms in vitro and in vivo. The compounds were only active in vivo on subcutaneous administration.

Structure--activity relationships in cephalosporins prepared from penicillins. 2. Analogues of cephalexin substituted in the 3-methyl group.

A previously outlined general procedure for preparing various 3-substituted cephalosporins from the penicillin nucleus has been used, with modifications where required, to prepare a series of analogues of cephalexin with various substituents in the 3-methyl group. The 3-substituents most conducive to broad-spectrum antibacterial activity were 3-pyridylmethyl and m- or p-carboxybenzyl. The compounds were only poorly absorbed by the oral route in mice, but the 3-(carboxybenzyl) compounds gave more prolonged useful serum levels than the usual cephalosporins.

Synthesis and antibacterial activities of new (alpha-hydrazinobenzyl)cephalosporins.

Some (alpha-hydrazinobenzyl)cephalosporins, I (R = Me, CH2OAc, Cl) and II (R = Me, CH2OAc), structurally related (formula; see text) to cephalexin, cephaloglycin, and cefaclor have been prepared and evaluated in vitro for their antimicrobial activity. The synthesis involves the condensation of the chloride hydrochloride III (R = H or Me) with the 7-aminocephem derivatives IV. The hydrazino compound I (R = Cl), an analogue of cefaclor, resulted in being the most active compound of the series.

Evaluation of short-term antibiotic therapy in children with uncomplicated urinary tract infections.

This study was designed to determine whether serum C-reactive protein (CRP) concentrations could be used to identify children with uncomplicated lower urinary tract infection who would respond favorably to short-term antibiotic therapy. A one-day or ten-day regimen of cefadroxil (30 mg/kg/day in two divided doses) was assigned randomly to 80 children who had acute urinary tract infection and CRP concentrations less than 28 microgram/ml (CRP-negative group). Ten days of cefadroxil therapy was used to treat 44 children with urinary tract infection and CRP values greater than or equal to 28 microgram/ml (CRP-positive group). The clinical and laboratory characteristics of the children in the two CRP-negative therapy groups were similar to, but different from those of children with CRP-positive infections. Recurrent infections occurred significantly more often at four to five days after completion of therapy in CRP-negative children who received one day (44.4%) compared to ten days (20%) of cefadroxil therapy (P less than .05). When data from this study were combined with those from our previously published investigation of short-term antibiotic therapy in CRP-negative children, a significantly larger percentage of recurrences was documented immediately after one or four days of antibiotics (79%) compared to recurrences after the standard ten-day regimen (41%). Additionally, the total rate of recurrent infections for all children in both studies was significantly larger in those who received short-term therapy (48%) as opposed to conventional therapy (34%). These data indicate that short-term antibiotic therapy is less effective than the conventional ten-day regimen in children with CRP-negative urinary tract infection.

Comparative treatment trial of augmentin versus cefaclor for acute otitis media with effusion.

A total of 150 children with acute otitis media were randomly allocated to treatment with amoxicillin-potassium clavulanate (Augmentin) or with cefaclor. Each drug was given in a daily dosage of approximately 40 mg/kg in three divided doses for ten days. Tympanocentesis done before treatment yielded specimens that contained pneumococcus or Haemophilus sp or both in 67% of specimens. Viridans group streptococci were isolated from 10% of specimens and Branhamella catarrhalis from 6%. Patients were scheduled for follow-up examinations at midtreatment, end of therapy, and at 30, 60, and 90 days. Of the 150 children, 130 were evaluable. Five of 60 patients (8%) treated with cefaclor were considered therapeutic failures because of persistent purulent drainage and isolation of the original pathogen or suprainfection. There were no failures among patients treated with Augmentin (P = .019). Rates of relapse, recurrent acute otitis media with effusion, and persistent middle ear effusion were comparable in the two groups of patients. Diaper rash, or loose stools, or both were significantly more common in children treated with Augmentin (34%) than in those taking cefaclor (12%), but in no case was it necessary to discontinue medication because of these mild side effects (P = .002). Cefaclor therapy was discontinued in one patient because of severe abdominal pain and vomiting. In this study, treatment with Augmentin was superior to treatment with cefaclor in the acute phase of acute otitis media with effusion, but Augmentin produced more adverse effects. The rates of persistent middle ear effusion and recurrent acute otitis media with effusion were comparable with the two regimens.

Nasopharyngeal carriage of Haemophilus influenzae type b: attempted eradication by cefaclor or rifampin.

The efficacy of cefaclor and rifampin in eradicating Haemophilus influenzae type b (HITB) from the nasopharynx of day care center and household contacts of children with HITB meningitis was evaluated. In 38/50 children treated with cefaclor, the carrier state persisted, a failure rate of 76%. Although cefaclor failed to eradicate HITB from many carriers, an appreciable reduction in the intensity of colonization following treatment was noticed. When rifampin was used in 17 children who had failed to respond to cefaclor, persistence of the carrier state with HITB was found in only two children, a failure rate of only 12%. During the study, two episodes of invasive HITB disease were documented to be acquired from sources other than the index cases or from children who were screened, which suggested the need to reevaluate the usually recommended strategy to screen for carriage and to treat only the immediate contacts 6 years of age and younger. Furthermore, the most appropriate agent for eradicating nasopharyngeal carriage of HITB awaits additional studies.

Cefadroxil compared with cefaclor in the treatment of streptococcal pneumonia in adults.

103 young male Black African gold-miners with pneumococcal pneumonia confirmed by culture or serology were randomly assigned to receive the long acting oral cephalosporin cefadroxil 1 g every 12 hours or cefaclor 500 mg every 8 hours for 10 days. Clinical cures were obtained in 94% of the group who received cefadroxil and in 94% of the cefaclor group. Similarly, the causative organism S. pneumoniae was eradicated in 98% and 96% of patients who received cefadroxil and cefaclor, respectively. Minimal side effects occurred in both groups, although 1 patient withdrew from therapy with cefaclor because of severe diarrhoea. Thus, cefadroxil and cefaclor both displayed effective antimicrobial activity with low toxicity in the treatment of pneumococcal pneumonia.

The effects of cephem antibiotics and related compounds on the aldehyde dehydrogenase in rat liver mitochondria.

The effects of cephem antibiotics and their related compounds on aldehyde dehydrogenase obtained from rat liver mitochondria were studied. A pH of 8.8 and reaction temperature 24 degrees were the conditions for measurement of enzyme activity. The apparent Michaelis constant Km values for NAD, acetaldehyde and propionaldehyde were 3.8 X 10(-5) M, 4.0 X 10(-5) M and 2.5 X 10(-5) M, respectively. Cefamandole, cefoperazone and cefmetazole, having a 1-methyl-5-thiotetrazol group at position 3 of the cephem ring, caused a relatively potent inhibition of aldehyde dehydrogenase. Cefmetazole and cefoperazone also showed a significant inhibition on highly purified yeast aldehyde dehydrogenase; the extent of inhibition on yeast enzyme was almost the same as that on rat mitochondrial aldehyde dehydrogenase. The decrease in enzyme activity effected by 1-methyl-1H-tetrazol-5-thiol (MTT) was greater than those of 1H-tetrazol (TZ), 1H-tetrazol-5-thiol and 1-(2-dimethylaminoethyl)-1H-tetrazol-5-thiol, but was, of course, less than that of disulfiram. Cefamandole, cefmetazole and MTT showed competitive inhibition with NAD, while TZ was uncompetitive inhibitor with respect to both NAD and acetaldehyde. Enzyme inhibition caused by disulfiram, cefmetazole and MTT increased time-dependently and the addition of 2-mercaptoethanol into the medium effectively and completely restored enzyme inhibition. These results suggest that thiol group at position 5 of 1H-tetrazol ring is responsible for the type of inhibition with NAD, and methyl group at position 1 of 1H-tetrazol ring is important to exhibit a potent inhibition on aldehyde dehydrogenase.

Cost effectiveness in the choice of antibiotics for the initial treatment of otitis media in children: a decision analysis approach.

If the initial use of amoxicillin fails to cure otitis media, a family will be burdened with medical costs for a second medication, additional office visit fees and time lost from employment. For some families the initial choice of a more expensive but more effective antibiotic may be more cost effective. Using a decision analysis approach we compared the cost effectiveness of amoxicillin and cefaclor. As the amoxicillin efficacy rate decreases or as parental salaries are increased, the cost-effective advantage moves towards cefaclor. With the decision analysis method described, a practitioner can use costs and efficacy rates relevant to his or her practice to determine the most cost-effective initial antibiotic for a child with otitis media.

Cefaclor treatment of upper and lower respiratory tract infections caused by Moraxella catarrhalis.

A retrospective analysis of data from 18 clinical studies was performed to examine the effectiveness and safety of cefaclor in the treatment of upper and lower respiratory tract infections caused by Moraxella catarrhalis (previously called Branhamella catarrhalis). Eighty-six percent of 56 evaluable patients had improvement in their symptoms of infections following therapy with cefaclor. There were no serious or life-threatening adverse drug experiences reported by any patient. Cefaclor appears to be an appropriate antibiotic for the safe and effective treatment of respiratory tract infections caused by M. catarrhalis.

Five vs. ten days of therapy for acute otitis media.

In a double blind study 175 patients with acute otitis media were randomized into 2 treatment groups: 10 days of therapy with cefaclor or 5 days of therapy followed by 5 days of placebo. The dosage of cefaclor was 40 mg/kg/day administered orally in equally divided doses at 12-hour intervals. Tympanocentesis before treatment yielded specimens that contained Streptococcus pneumoniae or Haemophilus influenzae or both in 55% of specimens. Branhamella catarrhalis was isolated from 21% of specimens. Culture of material from the ear canal of patients with spontaneous perforation of the tympanic membrane of less than 24 hours duration yielded pneumococci or H. influenzae or both in 38% of specimens and staphylococci in 31%. Patients were scheduled for follow-up examinations at 5 or 6, 10, 30, 60 and 90 days. Of the 175 children 151 were evaluable at 10 days. There were 123 patients with both tympanic membranes intact at the time of diagnosis. There were 6 (10%) treatment failures of therapy in the 59 patients assigned to 5 days of therapy and 4 (6%) failures and 1 (2%) early relapse in the 64 assigned to 10 days of therapy (difference not significant). There were 28 evaluable patients with spontaneous perforation. There were 8 (53%) failures in the 15 children assigned to 5 days of therapy and only 1 (8%) failure in the 13 children assigned to receive 10 days of therapy (P = 0.016, Fisher exact test). Rates of reinfection and persistent middle ear effusion at 10, 30, 60 and 90 days follow-up were not significant different in patients assigned to 5 to 10 days of therapy. In patients with acute otitis media with intact tympanic membranes we have not been able to show any advantage of the standard duration of 10 days of therapy over a shortened course of 5 days. A 5-day course of antibiotic therapy does not appear to be sufficient for children with acute otitis media and spontaneous purulent drainage.

Amoxicillin-clavulanate potassium compared with cefaclor for acute otitis media in infants and children.

One hundred thirty-three infants and children with documented acute otitis media (OM) were randomized to receive the oral suspension of either amoxicillin-clavulanate potassium or cefaclor. Beta-lactamase-producing bacteria were found in 10.9 and 14.5% of subjects treated with amoxicillin-clavulanate potassium and cefaclor, respectively. Subjects were reexamined at 5, 10, 30, 60 and 90 days after the initiation of therapy and whenever signs/symptoms of acute otitis media recurred. All but two children had resolution of otalgia/otorrhea during the initial treatment period. The drug groups were not significantly different in the percentage of evaluable subjects with otitis media with effusion at each scheduled follow-up visit. Recurrence of acute OM/otorrhea [corrected] developed in a similar percentage of subjects in both treatment categories. Both subjects with and those without middle ear effusion at 10 days had approximately a 50% recurrence rate of subsequent middle ear disease. Adverse side effects/complaints, which occurred in significantly more children treated with amoxicillin-clavulanate potassium, were generally mild and primarily gastrointestinal.

Comparative efficacies of erythromycin-sulfisoxazole and cefaclor in acute otitis media: a double blind randomized trial.

A prospective double blind trial compared the fixed combination of erythromycin-sulfisoxazole (E/S) with cefaclor in the treatment of acute otitis media. One hundred nineteen children in six centers across Canada were studied. Diagnostic tympanocentesis of 134 ears yielded 135 bacterial isolates: Streptococcus pneumoniae (42%); Haemophilus influenzae (21%); Branhamella catarrhalis (10%); Streptococcus pyogenes (5%); and other bacteria (22%). Seventy-seven percent of strains of B. catarrhalis and 14% of strains of H. influenzae were beta-lactamase producers. E/S exhibited greater in vitro activity against H. influenzae and B. catarrhalis. Twenty-three patients had bacteriologically sterile middle ear fluid. The overall clinical outcome at Days 10 and 31 was identical in both treatment groups. Otoscopic findings improved more rapidly in the E/S group than in the cefaclor group at 10 and 31 days (P less than or equal to 0.04). In cases where pre-treatment middle ear fluid was negative on routine bacterial culture, complete cure at 10 days was observed in 75% of patients treated with E/S but only in 14% of those treated with cefaclor (P = 0.02). Side effects were infrequent and comparable between the test drugs. E/S is at least as effective as cefaclor in the management of acute otitis media and may be superior, particularly for cases not yielding bacteria on routine culture.

Cefaclor levels in human aqueous humor.

In an attempt to investigate penetration of cefaclor into human aqueous humor, we administered 500-mg and 1-g doses of cefaclor to 39 patients about to undergo cataract extraction. Average aqueous humor levels of 0.27, 0.27, and 0.17 microgram/mL were achieved at 1, 2, and 4 hours, respectively, after the 500-mg oral dose. After 1 g orally, we found average aqueous humor levels of 0.61, 0.64, 0.72, 0.4, and 0.31 microgram/mL at 1, 2, 3, 4, and 5 hours, respectively. Therapeutic levels in primary aqueous humor were consistently achieved against Streptococcus pneumoniae and St pyogenes, group A.

Reliability of cefaclor, cefazolin, cefamandole, and cephalothin disks to predict susceptibility of Enterobacteriaceae, Staphylococcus species, and Haemophilus influenzae.

Interpretive zone-size standards currently used for cephalothin and cefamandole disk tests also may be applied to tests with disks containing 30 micrograms of cefaclor or cefazolin. Against 627 representative isolates, susceptibility to cefaclor and cefazolin could be predicted by testing cephalothin. However, cefazolin is more active than cephalothin against isolates of Escherichia coli with a TEM beta-lactamase plasmid. The expanded spectrum of cefamandole continues to necessitate separate testing. Against methicillin-resistant staphylococci, cefaclor disks were more reliable than cephalothin or cefamandole, but false-susceptible results were seen with all four disks. For testing Haemophilus influenzae, the cefazolin disks were not reliable; cephalothin or cefaclor disks could predict susceptibility to either drug.

Prospective randomized study comparing the efficacy and safety of ciprofloxacin with cefaclor in the treatment of patients with purulent bronchitis.

We compared safety and efficacy of ciprofloxacin and cefaclor in the treatment of patients with purulent bronchitis. Fifty-five patients were randomized prospectively to receive ciprofloxacin with a dose of 500 mg orally twice daily or cefaclor 250 mg over 8 hr for 5 days or longer. Patient groups did not differ with respect to age, duration of illness, severity of infection, or number of other concomitant disease states. A significantly larger number of patients in the ciprofloxacin group had poor health status (39.3% vs 7.4% for the ciprofloxacin and cefaclor groups, respectively, p = 0.02). The response to therapy did not differ between groups. Infection was completely resolved in 71.4% vs 66.7% and markedly improved in 7.1% and 11.1% for the ciprofloxacin and cefaclor groups, respectively. The response to therapy and adverse reaction rate did not differ between groups. Seven patients treated with ciprofloxacin and five patients treated with cefaclor developed adverse reactions. We conclude that ciprofloxacin is a useful agent for the treatment of purulent bronchitis.