The penetration of amoxycillin/clavulanic acid into peritoneal fluid

Pharmacokinetics of amoxicillin/clavulanic acid combination after intravenous and oral administration in goats

The intravenous and oral pharmacokinetics of an amoxicillin and clavulanic acid combination (20 mg/kg of sodium amoxicillin and 5 mg/kg of potassium clavulanate) were studied in six goats. After intravenous administration the pharmacokinetics of both drugs could be described by an open two-compartment model. Amoxicillin had a greater distribution volume (0.19 +/- 0.01 l/kg) than clavulanic acid (0.15 +/- 0.01 l/kg), whereas the distribution and elimination constants were higher for the latter, which was eliminated more quickly than amoxicillin. After oral administration of both drugs their pharmacokinetic behaviour was best described by an open one-compartment model with first-order absorption. Elimination half-lives were twice as long after oral (2.15 +/- 0.20 h and 1.94 +/- 0.16 h for amoxicillin and clavulanic acid respectively) than after intravenous administration (1.20 +/- 0.16 h and 0.86 +/- 0.09, respectively). An apparent 'flip-flop' situation was evident in this study. Bioavailability was 27% for amoxicillin and 50% for clavulanic acid.

Comparison of concentrations of two doses of clavulanic acid (200 and 400 milligrams) administered with amoxicillin (2,000 milligrams) in tissues of patients undergoing colorectal surgery

The concentrations of clavulanic acid and amoxicillin were determined in sera and different abdominal tissues of 17 patients who underwent elective colorectal surgery. Patients were randomly allocated to two groups. At the time of induction of anesthesia, patients in group 1 were given 200 mg of clavulanic acid with 2,000 mg of amoxicillin and patients in group 2 received 400 mg of clavulanic acid with 2,000 mg of amoxicillin. In both groups, the initial dose was administered again after 2 h. Blood samples were collected to determine peak and trough antibiotic levels. Serial blood samples were also collected at predetermined periods (opening and closure of the abdominal cavity and surgical anastomosis). Abdominal wall fat, epiploic fat, and colonic wall tissue samples were collected simultaneously. Antibiotic concentrations were determined by high-performance liquid chromatography. Increasing the dose of clavulanic acid to 400 mg resulted in significantly higher peak and trough levels in serum (P < 0.03). Following the injection of 400 mg, mean concentrations of clavulanic acid in the fatty tissues were significantly increased at the time of opening (P < 0.02). The concentrations of clavulanic acid and amoxicillin in fatty tissues were 17 to 52% and 12 to 23% of the levels in sera, respectively. In the colonic wall, the concentrations of clavulanic acid and amoxicillin were 52 to 63% and 49 and 27% of the levels in sera, respectively. In sera, clavulanic acid given at a dose of 200 or 400 mg reached or exceeded the concentrations found to be effective in vitro to reduce the MICs of amoxicillin from the resistant to the susceptible category for 90% of the potential pathogens. In most of the tissues investigated, increased the dose of clavulanic acid to 400 mg resulted in a significantly higher number of samples with concentrations found to be effective in vitro (72 versus 11%; P < 0.05). In conclusion, increasing the dose of clavulanic acid to 400 mg resulted in higher levels in sera and improved penetration into the abdominal tissues in patients undergoing colorectal surgery.

Inhibitory and bactericidal activity of selected beta-lactam agents alone and in combination with beta-lactamase inhibitors compared with that of cefoxitin and metronidazole against cefoxitin-susceptible and cefoxitin-resistant isolates of the Bacteroides fragilis group

The inhibitory activity of five beta-lactam agents, alone and in combination with a beta-lactamase inhibitor, was compared with that of cefoxitin and metronidazole against 300 beta-lactamase producing Bacteroides fragilis group isolates. Each of the beta-lactamase inhibitors significantly potentiated the activity of the respective beta-lactam. In the presence of clavulanate, the MIC90 (minimum inhibitory concentration) values of amoxicillin and ticarcillin were reduced 64-fold and 32-fold, respectively. Similarly, sulbactam enhanced the activity of ampicillin and cefoperazone 16-fold and 8-fold, respectively, whereas tazobactam potentiated the activity of piperacillin 16-fold. Few strains were resistant to the beta-lactam-beta-lactamase inhibitor combinations and were comprised of strains of B. fragilis, B. thetaiotamicron, and B. distasonis. Of the strains, 7% were resistant to cefoxitin, and none to metronidazole. Using time-kill kinetic studies, the bactericidal activity of the various beta-lactam agents, with and without beta-lactamase inhibitors, was determined and compared with that of cefoxitin and metronidazole against cefoxitin-susceptible and cefoxitin-resistant isolates of the B. fragilis group. Overall, metronidazole was the most bactericidal agent with all isolates being killed with less than or equal to 4 micrograms/ml at 24 hr. Ampicillin-sulbactam was the next most bactericidal agent with all isolates being killed with less than or equal to 16/8 micrograms/ml of ampicillin-sulbactam at 24 hr. Amoxicillin-clavulanate and cefoperazone-sulbactam had bactericidal activity similar to that of ampicillin-sulbactam. Piperacillin-tazobactam and ticarcillin-clavulanate were bactericidal at higher concentrations with all isolates killed with 64 micrograms/ml of piperacillin and 128 micrograms/ml of ticarcillin combined with their respective beta-lactamase inhibitors. None of the beta-lactam agents alone was able to kill more than 19 of the 26 isolates. We conclude that beta-lactam agents combined with beta-lactamase inhibitors have both inhibitory and bactericidal activity against cefoxitin-resistant members of the B. fragilis group provided that the concentrations achieved for these combinations are at the upper limits for maximum recommended dosing. Although isolates of the B. fragilis group have been reported to produce unusual beta-lactamases that are refractory to beta-lactamase inhibitors, none of the cefoxitin-resistant isolates tested in this study were resistant to the beta-lactam-beta-lactamase inhibitor combinations.

A randomised prospective controlled study of ciprofloxacin with metronidazole versus amoxicillin/clavulanic acid with metronidazole in the treatment of intra-abdominal infection

A prospective randomised study was undertaken in 80 patients to assess the combined regimen of ciprofloxacin with metronidazole against amoxicillin/clavulanic acid with metronidazole as treatment for established intra-abdominal infection. Treatment was for five days. Seventy-eight patients were clinically evaluable (38 patients on ciprofloxacin with metronidazole and 40 patients on amoxicillin/clavulanic acid with metronidazole). The overall clinical success rate in the treatment of intra-abdominal infections was 96% for the ciprofloxacin with metronidazole group, and 90% for the amoxicillin/clavulanic acid with metronidazole group. Over half of all patients were able to change from intravenous to oral antibiotic administration within the study period. One patient receiving ciprofloxacin with metronidazole developed pruritus near the injection site.

Pharmacokinetics and tissue distribution of amoxicillin plus clavulanic acid after oral administration in man

Augmentin (875 amoxicillin and 125 mg potassium clavulanate) was administered orally to patients with chronic bronchitis. Concentrations of amoxicillin and clavulanic acid were measured in serum, sputum and urine. Peak serum levels for amoxicillin of 11.23 +/- 2.61 micrograms/ml were observed at 2 hours and for clavulanic acid of 2.55 +/- 0.54 micrograms/ml at 1 hour. After 9 hours, 50% of the amoxicillin and 39% of the clavulanic acid had been renally excreted. The peak sputum concentration of amoxicillin was 1.31 +/- 0.42 micrograms/ml at 4 hours and of clavulanate was 0.79 +/- 0.23 micrograms/ml at 2 hours. Patients awaiting surgery received an oral dose of augmentin as above. Samples of lung, tonsil, middle ear mucosa and prostate were obtained and tissue concentrations of both compounds measured. Peak levels of amoxicillin ranged from 0.87 micrograms/g (tonsil) to 2.56 micrograms/g (lung) and of clavulanic acid from 0.20 micrograms/g (prostate) to 0.56 micrograms/g (lung) between 3 and 4 hours after dosing.

Experience with parenteral and sequential parenteral-oral amoxicillin/clavulanate (augmentin) in hospitalized patients

The efficacy and safety of sequential parenteral-oral Augmentin (amoxicillin plus clavulanic acid) therapy was evaluated in an open study with 249 adult patients in 18 Swiss hospitals. The patients were suffering from infections of the respiratory tract, skin and/or soft tissues, urinary tract, or female pelvic organs, and 36 had bacteraemia. One quarter of the patients treated were in a poor or critical condition. The overall bacteriological success rate was 94.1%. Augmentin achieved a satisfactory clinical response (cure or improvement) in 96.7% of the infections treated, with the following response rates for the five major categories of infection: respiratory tract infections 97.0%, urinary tract infections 97.8%, pelvic inflammatory disease 100%, septicaemia 91.4% and skin and soft tissue infections 95.7%. The observed adverse drug events include slight to moderate diarrhoea in 3.6% of the patients and skin reactions in 4.8%. It is concluded that Augmentin was an effective and safe treatment in this group of hospitalized patients.

Beta-lactamase inhibitors: another approach to overcoming antimicrobial resistance

Beta-lactamase inhibitors in combination with a beta-lactam antimicrobial agent provide another approach to the treatment of infections caused by many bacteria resistant to commonly used agents. Currently two fixed combinations are commercially available. One is the oral preparation of amoxicillin and potassium clavulanate (Augmentin). The other is for intravenous therapy and combines ticarcillin and potassium clavulanate (Timentin). In vitro studies confirm that the combination of a beta-lactamase inhibitor and a beta-lactam can increase the activity of the beta-lactam to such important pathogens as S aureus, Klebsiella, H influenzae, Bacteroides spp and other bacteria which produce plasmid-mediated beta-lactamase. Clinical efficacy studies have demonstrated potential usefulness of these combinations particularly for therapy of suspected or proven infections caused by mixed aerobic and anaerobic bacteria. The combination of amoxicillin or ticarcillin with clavulanic acid can be used to improve cost-effectiveness of antimicrobial therapy if they replace regimens that use multiple drugs or drugs with a relatively high incidence of adverse reactions.

Bactericidal effects of ticarcillin-clavulanic acid against beta-lactamase-producing bacteria in vivo

The comparative efficacies of ticarcillin and ticarcillin plus clavulanic acid have been determined in the mouse against experimental infections caused by ticarcillin-resistant bacteria. The infections studied comprised an intraperitoneal infection, local tissue infections, pyelonephritis, and pneumonia. Both ticarcillin and clavulanic acid penetrated readily to the sites of infection studied and at the doses employed were present at concentrations of the same order as those obtained in humans after the administration of ticarcillin-clavulanic acid formulations (Timentin; Beecham). At these concentrations, the ticarcillin-clavulanic acid combination caused significant bactericidal effects at the sites of infection against the ticarcillin-resistant strains of Bacteroides fragilis, Escherichia coli, Klebsiella pneumoniae, Pseudomonas aeruginosa, and Staphylococcus aureus investigated. The efficacy of ticarcillin plus clavulanic acid against the infections resistant to therapy with ticarcillin demonstrated the beta-lactamase-inhibitory activity of clavulanic acid in vivo.

Penetration of sulbactam-ampicillin and clavulanic acid-amoxicillin into the pelvic peritoneum

Sixteen patients were given single intravenous injections of ampicillin (0.5 g) with sulbactam (0.5 g), and 15 patients were given amoxicillin (1 g) with clavulanic acid (0.2 g) before elective laparoscopy. At 2 h after dosing, the concentrations of the four compounds in serum and in the peritoneal fluid from the Pouch of Douglas and the ratio of each combination reached levels shown to be effective for antimicrobial activity in vitro.

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.

Penetration of sulbactam and ampicillin into peritoneal fluid

Twenty-five patients undergoing elective intraabdominal surgery received either 1 or 2 g of ampicillin together with 1 g of sulbactam intravenously before surgery. The peritoneal levels of the agent were measured. Both compounds penetrated peritoneal fluid readily; the mean percentage of penetration by ampicillin was 92%; that of sulbactam was 96%. After 1 g of each agent, the peritoneal levels of sulbactam were 47% greater than those of ampicillin. Our results suggest that 2 g of ampicillin plus 1 g of sulbactam should provide peritoneal levels that would inhibit most susceptible beta-lactamase-producing pathogens encountered in intraabdominal sepsis.