Comparative activity of BRL 25.000 with amoxycillin against resistant clinical isolates

A review of the microbiology of amoxycillin/clavulanic acid over the 15 year period 1978-1993

A review of the published literature over the period 1978-1993 was undertaken to assess any changes in the prevalence of beta-lactamase-producing bacterial pathogens and also any changes in the susceptibility in these pathogens to amoxycillin/clavulanate. The review has involved the examination of over 1500 publications. The review shows that in general there has been an increase in the frequency of beta-lactamase-producing pathogens resistant to ampicillin and amoxycillin but there is no evidence for any significant increase in resistance to amoxycillin/clavulanate over the period of the review.

Antibiotic combinations: should they be tested?

When antibiotic combinations are used to provide a broader spectrum of antimicrobial activity or in an attempt to prevent the emergence of resistant organisms, it is rarely necessary or practical to perform tests of drug interactions in vitro. In vitro testing of combinations may be useful when combinations are used in an attempt to attain synergistic interactions. In some cases, screening methods can be used as substitutes for formal synergy testing. This paper examines the mechanisms of antibiotic interaction leading to synergism or antagonism, surveys attempts to correlate in vitro observations with efficacy in animal models, and reviews clinical data providing evidence for or against a useful role of synergistic antibiotic interactions in the treatment of human infections.

Tissue and serum concentrations of amoxycillin and clavulanic acid in patients having reconstructive vascular surgery

Fifteen patients received amoxycillin/clavulanic acid combination intravenously at anaesthetic induction as part of a three-dose schedule of antibiotic prophylaxis for vascular surgery. After 30 min, the mean serum concentration of amoxycillin was 39.9 mg/l and clavulanic acid was 9.3 mg/l. Mean amoxycillin tissue concentrations in fat, 5.1 mg/l; vein, 7.5 mg/l; and artery, 4.8 mg/l, were lower than serum values. Mean clavulanic acid concentrations were: fat, 0.7 mg/l; vein, 1.2 mg/l; and artery, 1.6 mg/l. At the end of surgery, the serum amoxycillin level was always greater than 6 mg/l and clavulanic acid greater than 2 mg/l, which were both still within the therapeutic range. Concentrations in fat had declined by the end of the surgery ranging from 0.76 to 5.2 mg/l for amoxycillin and from 0.03 to 0.6 mg/l for clavulanic acid, there being almost none detected in four cases. Serum and tissue concentrations of both compounds 30 min after injection were sufficient to inhibit the growth of 97% of pathogenic organisms recovered from the skin of 135 vascular surgical patients. In a few cases tissue levels of the compounds were below inhibitory concentrations for coliforms and anaerobes at the time of skin closure, although they were still effective against most Gram-positive organisms. Amoxycillin/clavulanic acid combination is suitable antibiotic prophylaxis for vascular surgery.

Amoxicillin-potassium clavulanate: a novel beta-lactamase inhibitor

Potassium clavulanate is a novel beta-lactamase inhibitor, which, in combination, expands the spectrum of amoxicillin to include many amoxicillin-resistant organisms. Potassium clavulanate is excreted 30-50 percent unchanged renally and its plasma time-course parallels that of amoxicillin. Several studies suggest that an increased incidence of gastrointestinal side effects may occur with this combination. In the current oral formulation, its greatest utility may be in pediatric infections due to beta-lactamase-producing Haemophilus influenzae and B. cattarhalis. In adults, the combination has not been adequately studied against other effective antibiotics.

Comparative study of amoxicillin-clavulanic acid and cephalexin in the treatment of bacteriuria during pregnancy

A comparative clinical trial of amoxicillin-clavulanic acid and cephalexin was carried out in 80 women with bacteriuria of pregnancy. Treatment was randomly allocated and consisted of either one tablet of amoxicillin plus clavulanic acid (250 and 125 mg, respectively) three times daily or cephalexin (250 mg) three times daily for 7 days. Overall bacteriological cure rates at 2 weeks were 77% in the amoxicillin-clavulanic acid group and 74% in the cephalexin group. At 6 weeks the respective rates were 76 and 60%. Twenty-five episodes of infection were with ampicillin-resistant strains; cure rates were 82% (2 weeks) and 80% (6 weeks) in the amoxicillin-clavulanic acid group and 85 and 64%, respectively, in the cephalexin group. Differences in cure rates were not statistically significant. No significant difference in the rate of side effects was found. In particular, no toxicity to the fetus was seen which could be ascribed to either drug. Amoxicillin-clavulanic acid would appear to be a safe and effective treatment for bacteriuria of pregnancy.

Amoxicillin and potassium clavulanate: an antibiotic combination. Mechanism of action, pharmacokinetics, antimicrobial spectrum, clinical efficacy and adverse effects

The combination of amoxicillin and potassium clavulanate will soon be marketed in 2:1 and 4:1 fixed ratio dosage forms. In vitro and in vivo evidence suggests that clavulanic acid, a potent inhibitor of many bacterial beta-lactamase enzymes, will increase the spectrum of amoxicillin to include, at achievable serum concentrations, Haemophilus influenzae, H. ducreyi, Neisseria gonorrhoeae, Staphylococcus aureus and Branhamella catarralis and, at achievable urine levels, many beta-lactamase-producing strains of E. coli, Klebsiella, Proteus and Citrobacter. Both amoxicillin and clavulanic are well absorbed after oral administration, reach peak serum levels in 40-120 min and have similar half-lives of 45 to 90 min. This combination will be suitable for the treatment of complicated urinary tract infections, otitis media, sinusitis and respiratory tract infections. However, precise recommendations for its use will need to await further clinical trials that compare amoxicillin/clavulanate to alternative therapies.

Double-blind comparative study of two dosage regimens of cefaclor and amoxicillin-clavulanic acid in the outpatient treatment of soft tissue infections

A total of 88 patients were enrolled in a double-blind comparison of cefaclor and amoxicillin-clavulanic acid for the outpatient treatment of soft tissue infections (abscesses, cellulitis, and impetigo). In 84 clinically evaluable patients, high cure rates were obtained for all treatment groups (64 to 85%). Patients who received amoxicillin-clavulanic acid had a much higher incidence of gastrointestinal side effects than did patients who received cefaclor (34 versus 3%, P less than 0.005). However, only five patients with gastrointestinal reactions to amoxicillin-clavulanic acid had symptoms severe enough to warrant halting the completion of antibiotic therapy.

Antibacterial activity and kill kinetics of amoxicillin-clavulanic acid combinations against Escherichia coli and Klebsiella aerogenes

Combinations of amoxicillin and clavulanic acid were tested against 11 Escherichia coli strains and five Klebsiella aerogenes strains. Apart from one E. coli, the strains were highly resistant to amoxicillin due to beta-lactamase production. Synergy was demonstrated in all strains by agar dilution. Synergy was detected against the beta-lactamase-producing strains under simulated in vivo conditions with constantly decreasing concentrations simulating in vivo pharmacokinetics. The correlation between antibacterial activity determined by minimum inhibitory concentrations and bacterial kill kinetics in the in vivo simulation model was acceptable. A higher bacterial kill rate was observed when the antibiotic dosage was increased beyond the minimum concentration where an antibacterial effect was seen; this was not demonstrable by traditional agar dilution tests. In combination, a greater relative amount of amoxicillin compared to clavulanic acid allows a reduction in the total amount of antimicrobial agents with the same degree of antibacterial activity.

Pharmacokinetics of amoxicillin and clavulanic acid administered alone and in combination

The pharmacokinetics of amoxicillin and clavulanic acid, administered alone and in combination, were studied in six male and six female normal human volunteers. Each ingested 500 mg of amoxicillin or 125 mg of clavulanic acid or the above agents in combination in randomized sequences. The results indicate that most of the parameters tested for either substance are essentially independent of the presence of the other one.

Amoxycillin/clavulanic acid: a review of its antibacterial activity, pharmacokinetics and therapeutic use

Clavulanic acid is a beta-lactamase inhibitor produced from Streptomyces clavuligerus, which when combined with certain beta-lactam antibiotics extends their activity against bacteria which owe their resistance to the production of beta-lacatamases. In combination with amoxycillin it extends the antibacterial activity of amoxycillin to include beta-lactamase-producing strains, which are otherwise resistant, as well as amoxycillin-resistant species such as Bacteroides fragilis. The addition of clavulanic acid to amoxycillin occasionally extends (but does not decrease) the susceptibility of amoxycillin-sensitive bacteria. Clavulanic acid is adequately absorbed after oral administration and its basic pharmacokinetic characteristics are similar to those of amoxycillin. Preliminary therapeutic trials suggest that amoxycillin plus clavulanic acid is effective in urinary tract infections caused by amoxycillin-resistant organisms and in lower respiratory tract infections unresponsive to previous routine antibiotic therapy, in hospitalised patients. It is generally well tolerated; nausea, vomiting, diarrhoea and skin rash being the most frequently reported adverse effects.