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Comparison of piperacillin alone versus piperacillin plus tobramycin for treatment of respiratory infections in children with cystic fibrosis.

Seventeen patients with cystic fibrosis (CF) and pulmonary exacerbations were randomly assigned to two treatment groups: piperacillin 600 mg/kg/day (P), and piperacillin 600 mg/kg/day plus tobramycin (PT), in order to determine the safety and pharmacokinetics of high-dose piperacillin and whether piperacillin alone was effective for the treatment of Pseudomonas infections. The mean half-life of piperacillin was 0.54 hours, with a peak concentration of 232 micrograms/ml. No differences between P and PT groups were noted in clinical assessment, as judged by Shwachman scores, pulmonary function testing, or weight gain. However, during the course of treatment, quantitative sputum cultures decreased by greater than 10(2) colony-forming units in only 5 out of 19 Pseudomonas isolates from the P group, compared with 12 of 19 isolates from the PT group (P less than 0.03, Chi-square). Although emergence of resistance was not seen, one isolate had an increase in minimum inhibitory concentration from 8 to 128 micrograms/ml. There were no serious adverse reactions to piperacillin; only one patient developed fever possibly related to piperacillin. Therapy with high-dose piperacillin was safe in children with CF. Treatment with piperacillin alone was less effective than combination therapy with gentamicin for reduction in titer of Pseudomonas in sputum. However, the role of antimicrobial agents in the treatment of CF remains undefined. A double-blind placebo-controlled trial is indicated.

Child

Comparative synergistic activity of netilmicin-piperacillin versus gentamicin-piperacillin.

The synergistic action of the combination netilmicin-piperacillin in comparison to gentamicin-piperacillin was studied in 206 clinical isolates of staphylococci, enterococci, Enterobacteriaceae and Pseudomonas aeruginosa by means of the checkerboard technique. Overall, netilmicin-piperacillin acted synergistically against 31% and gentamicin-piperacillin against 14% of the 206 strains. In particular, synergism was more frequently observed with netilmicin-piperacillin against Escherichia coli, Citrobacter spp., indole-positive Proteus spp. and Pseudomonas aeruginosa. Synergy was uncommon with either combination against enterococci, Staphylococcus epidermidis and Serratia spp. Only partial synergy or indifference was seen with both combinations against Klebsiella spp. The interaction of netilmicin would appear to be superior to that of gentamicin in combination with piperacillin.

Bacteria

Beta-lactam antibiotic therapy in febrile granulocytopenic patients. A randomized trial comparing cefoperazone plus piperacillin, ceftazidime plus piperacillin, and imipenem alone.

OBJECTIVE: To compare the efficacy, toxicity, and cost-effectiveness of double beta-lactam therapy with monotherapy. DESIGN: A randomized, controlled trial. PATIENTS: Febrile, granulocytopenic patients (429). INTERVENTIONS: Patients were randomly assigned to receive iv cefoperazone (3 g every 12 hours) plus piperacillin (75 mg/kg body weight every 6 hours), ceftazidime (2 g every 8 hours) plus piperacillin (75 mg/kg every 6 hours), or imipenem alone (1.0 g or 0.5 g every 6 hours). Patients also received prophylactic vitamin K. MEASUREMENTS: Clinical improvement, eradication of the infecting organism, and toxicity in 403 evaluable patients with one or more infections. MAIN RESULTS: Cefoperazone and ceftazidime, when given in combination with piperacillin, were equally effective (response rates of 75% (104 of 138 patients) and 74% (101 of 137 patients), respectively). Monotherapy with imipenem had a response rate of 82% (111 of 136 patients) and was as effective as double beta-lactam therapy. Overall antibiotic-related toxicity was minimal, although seizures were associated with high doses of imipenem. Seizures occurred in 3 of 29 patients (10.3%) who were receiving 4 g/d of imipenem, in 3 of 136 patients (2.2%) who were receiving cefoperazone plus piperacillin, in 0 of the 132 patients who were receiving ceftazidime plus piperacillin, and in 1 of 106 patients (0.9%) who were receiving 2 g/d of imipenem (P less than 0.005). The 2-g daily dose of imipenem was as effective as the 4-g daily dose. Diarrhea was more frequent in patients receiving cefoperazone, whereas nausea occurred more often with imipenem. No antibiotic-related hemorrhage or nephrotoxicity was observed. Superinfections caused by beta-lactam-resistant, gram-negative bacilli were uncommon but occurred more frequently with double beta-lactam therapy than with imipenem monotherapy (11 of 268 patients compared with 1 of 135 patients; P = 0.06). Xanthomonas maltophilia superinfections occurred only in patients receiving imipenem (3 of 135 patients compared with 0 of 268 patients; P = 0.03). Imipenem monotherapy was the least expensive therapy. CONCLUSIONS: Cefoperazone and ceftazidime were equally effective when used in combination antibiotic therapy with piperacillin. Twice-daily cefoperazone is less expensive than ceftazidime given three times daily. Monotherapy with imipenem, at a daily dose of 2 g, is as efficacious as double beta-lactam therapy and costs less than combination therapy.

Adolescent

In vitro activity and stability against novel beta-lactamases of investigational beta-lactams (cefepime, cefpirome, flomoxef, SCE2787 and piperacillin plus tazobactam) in comparison with established compounds (cefotaxime, latamoxef and piperacillin).

The therapeutic perspectives of flomoxef, SCE 2787, cefpirome, cefepime, latamoxef, cefotaxime and of piperacillin plus tazobactam were comparatively evaluated by their in vitro activity against 1119 clinical isolates of 83 bacterial species. Escherichia coli, Klebsiella spp. Enterobacter sakazakii, Proteus spp. and Shigella spp. were about equally susceptible to the cephalosporins (MIC90: 0.06 to 0.5 mg/l), while the MIC90 for piperacillin plus tazobactam was between 2 and 16 mg/l. Enterobacter cloacae, Enterobacter aerogenes and Serratia spp. were most susceptible to SCE 2787, cefpirome and cefepime (MIC90: 0.06 to 2 mg/l) followed by latamoxef, cefotaxime, flomoxef and piperacillin plus tazobactam. For Citrobacter spp., Providencia spp. and Yersinia enterocolitica MIC90 were between 0.06 and 0.5 mg/l. Flomoxef was between 2 to 4 log2 less active against these species but more active than piperacillin plus tazobactam (MIC90: 2 and 8 mg/l). Morganella morganii and Hafnia alvei were most susceptible to cefepime, cefpirome and latamoxef (MIC90: 0.13 to 0.5 mg/l) while cefotaxime (MIC90: 8 mg/l) and piperacillin plus tazobactam (MIC90: 8 and greater than 64 mg/l) were the least active compounds. SCE 2787, cefepime and cefpirome were the most potent beta-lactams against the majority of the 13 species of non-fermentative bacilli (NFB) investigated (MIC90: 0.5 to 16 mg/l). The oxacephems were the least active compounds against NFB. Cefepime was the most active of the compounds included against Pseudomonas aeruginosa (MIC90: 16 mg/l). Haemophilus spp., Neisseria gonorrhoeae and Bordetella pertussis were most susceptible to cefotaxime (MIC90: 0.03 to 0.06 mg/l). Latamoxef had the lowest activity of all compounds against gram-positive cocci. Flomoxef was the most active compound against penicillinase producing Staphylococcus aureus and about equally active as the other betalactams against methicillin susceptible staphylococci of other staphylococcal species.(ABSTRACT TRUNCATED AT 250 WORDS)

Anti-Bacterial Agents

Comparative in-vitro activity of piperacillin and piperacillin plus tazobactam towards beta-lactamase producing clinical isolates.

The authors evaluated the in-vitro antibacterial activity of piperacillin alone and of piperacillin combined with tazobactam, a new beta-lactamase inhibitor, on 398 clinical isolates, both Gram-positive and Gram-negative. The piperacillin/tazobactam combination was evaluated in the fixed ratio 8:1. The vast majority of the microorganisms tested had reduced susceptibility to piperacillin (minimum inhibitory concentration (MIC) range 0.12- greater than 256 mg/l) due to beta-lactamase production. The following results were obtained: against Haemophilus influenzae, tazobactam was effective in reducing the MICs of piperacillin by 512 fold. The activity of piperacillin/tazobactam was lower against Pseudomonas sp., while some activity was demonstrated against some strains of Klebsiella. Good activity was seen not only against methicillin-susceptible (MS) staphylococci but also against some methicillin-resistant (MR) strains. In the latter, the combination of piperacillin/tazobactam was active only if the strains showed beta-lactamase production. These findings are interesting above all in regard to the synergistic effect demonstrated against MR beta-lactamase producing staphylococci and the Klebsiella-Enterobacter-Serratia (KES) group.

Drug Synergism

Piperacillin plus amikacin vs. piperacillin plus amikacin plus teicoplanin for empirical treatment of febrile episodes in neutropenic patients receiving quinolone prophylaxis.

A prospective, randomized trial was initiated to evaluate the efficacy of two antibiotic regimens, differing in the agent included with activity against gram-positive bacteria, for the empirical treatment of febrile episodes in neutropenic patients with hematologic malignancies (group 1, piperacillin plus amikacin; group 2, piperacillin plus amikacin plus teicoplanin). After 72 hours of therapy, patients in group 1 who were still febrile were administered teicoplanin and those in group 2 were administered amphotericin B. A total of 158 evaluable episodes were observed within 8 months. The success rate was 50.6% in group 1 and 60% in group 2. The response rate among patients who did not respond to the original regimen increased to 86.7% with the addition of teicoplanin (group 1) and to 90% with the addition of amphotericin B (group 2). There were 86 unexplained febrile episodes and 56 documented episodes of bacteremia (34 caused by gram-positive organisms). Our results indicate that teicoplanin is safe, well tolerated, and effective for the treatment of documented episodes of gram-positive bacteremia and as an empirical agent. The inclusion of teicoplanin in the initial empirical regimen appears unnecessary if a combination of antibiotics active against gram-positive organisms is used, unless infections are due to oxacillin-resistant staphylococci.

4-Quinolones

[Medical treatment of pelvic inflammatory disease. A clinical study on the therapeutic effectiveness of piperacillin + erythromycin and of piperacillin + clindamycin + gentamycin].

The aim of the present clinical study was to evaluate the therapeutic effectiveness of two different antibiotic combinations (piperacillin + erythromycin and piperacillin + clindamycin + gentamycin) in the medical treatment of patients with pelvic inflammatory disease, respectively at the II and III stage. The findings confirm the therapeutic value and the low toxicity of both pharmacological regimens.

Clindamycin

Pharmacokinetic studies on the concomitant administration of piperacillin and cefazolin, and piperacillin and cefoperazone in rabbits.

The pharmacokinetics of each drug on the concomitant administration of piperacillin (PIPC) and cefazolin (CEZ) or cefoperazone (CPZ) were studied in rabbits. When rabbits received the consecutive drip infusion administration of CEZ (0.71 mg/kg/minute) and PIPC (1.38 mg/kg/minute) and likewise of CPZ (0.72 mg/kg/minute) and PIPC (1.54 mg/kg/minute) for 1 hour, respectively, the serum half-lives of CEZ and CPZ were respectively prolonged about 1.8 and 1.6 times during drip infusion of PIPC than administered alone. However, when the sequence of administration were reversed, the serum levels of PIPC were not affected by the consecutive drip infusion administration of CEZ and CPZ. To study these findings in detail, the single intravenous dose of 20 mg/kg of CEZ and CPZ were administered under drip infusion of PIPC (2.65-2.93 mg/kg/minute). The serum half-lives of CEZ and CPZ were also prolonged about 5.4 and 1.9 times, respectively, whereas urinary excretion of CEZ, and urinary and biliary excretion of CPZ were reduced by PIPC. Moreover, when the single intravenous dose of 20 mg/kg of PIPC were administered under drip infusion administration of CEZ (0.96-2.60 2.60 mg/kg/minute), the pharmacokinetics of PIPC was not affected by the presence of CEZ. However, under drip infusion administration of CPZ (2.60-2.70 mg/kg/minute), the PIPC serum half-life was prolonged about 1.4 times, and biliary excretion of PIPC was reduced but urinary excretion was not. From the results of renal clearance experiments, tubular secretion appeared to be the predominant mechanism of renal elimination for these three drugs. These results indicate that PIPC influences the pharmacokinetics of both drugs by the competitively inhibiting tubular secretion in CEZ, and tubular secretion and hepatic transport system in CPZ. Therefore, in this respect PIPC seems to have probenecid-like action.

Animals

Pharmacokinetics and tissue penetration of tazobactam and piperacillin in patients undergoing colorectal surgery.

The pharmacokinetics of tazobactam and piperacillin in plasma and different tissues after a 30-min intravenous infusion of 4 g of piperacillin and 0.5 g of tazobactam were investigated in 18 patients who underwent elective colorectal surgery. Serial blood samples were collected for up to 6 h after the initiation of the infusion. The types of tissue collected were fatty tissue, muscle, skin, appendix, and intestinal mucosa (proximal and distal). On the basis of concentrations in plasma, the following pharmacokinetic parameter values were obtained (values are means +/- standard deviations): maximum concentration of drug in serum, tazobactam, 27.9 +/- 7.67 micrograms/ml; piperacillin, 259 +/- 81.8 micrograms/ml; time to maximum concentration of drug in serum, tazobactam, 0.51 +/- 0.03 h; piperacillin, 0.51 +/- 0.03 h; area under the concentration-time curve, tazobactam, 47.6 +/- 13.3 micrograms.h/ml; piperacillin, 361 +/- 80.3 micrograms.h/ml; clearance, tazobactam, 188 +/- 52.3 ml/min; piperacillin, 194 +/- 42.9 ml/min; half-life, tazobactam, 1.42 +/- 0.32 h; piperacillin, 1.27 +/- 0.24 h; apparent volume of distribution, tazobactam, 0.31 +/- 0.07 liter/kg of body weight; piperacillin, 0.29 +/- 0.06 liter/kg; volume of distribution at steady state, tazobactam, 0.28 +/- 0.04 liter/kg; piperacillin, 0.25 +/- 0.05 liter/kg. The concentrations of tazobactam and piperacillin in fatty tissue and muscle tissue were 10 to 13 and 18 to 30% of the levels in plasma, respectively. In skin, the concentrations of piperacillin were 60 to 95% of the levels in plasma, whereas the concentrations of tazobactam in plasma were 49 to 93% of the levels in skin tissue. The mean concentration of tazobactam in the investigated gastrointestinal tissues (appendix, proximal and distal mucosa) exceeded levels in plasma after 1 h, while piperacillin showed a mean penetration into these tissues of 43 and 53%. The mechanisms that can be used to explain the extent of penetration of piperacillin and tazobactam are discussed. Simple diffusion may take place in fatty and muscle tissue, while penetration into skin and gastrointestinal tissue is governed by more complex mechanisms which lead to differences in penetration between piperacillin and tazobactam. For all tissues investigated (except fatty tissue), the time course of the concentrations of both compounds was similar, with a peak in concentration at between 1 and 2 h after the start of infusion followed by a decline of concentrations that were almost parallel to the curves of the drug concentrations in plasma. In plasma and in all investigated tissues, piperacillin as well as tazobactam reached or exceeded the concentrations found to be effective in vitro.

Adipose Tissue

[Piperacillin-amikacin combinations: killing curves].

Bactericidal activity as a function of time of piperacillin (PIP) and amikacin (AKN) alone and in combination was evaluated by killing curves technique on 23 clinical isolates: E. coli (6), K. pneumoniae (5), E. cloacae (6) and P. aeruginosa (6), for which the minimal inhibitory concentrations ranges of piperacillin were 0.25 to 64 mg/l and of amikacin 1 to 8 mg/l. For each species, the strains were chosen according to the most frequent phenotypes: beta-lactams susceptible, penicillinase (Pase), cephalosporinase (Case) and Pase + Case producers. Killing curves were carried out with the following concentrations (mg/l): piperacillin (2, 16, 64); amikacin (4, 8, 16); piperacillin (2) + amikacin (4); piperacillin (16) + amikacin (8); piperacillin (64) + amikacin (16). Antibiotic concentrations corresponded to pharmacokinetics and/or to critical values of piperacillin and amikacin. Bactericidal activity was defined as a 4 log 10 decrease in CFU/ml between 2 and 24 hours. When piperacillin (64) was combined with amikacin (16), the bactericidal effects were nearly the same as those with amikacin alone. But piperacillin (16) + amikacin (8) combination had bactericidal effect for the majority of strains (21/23) and it prevented for some of them the bacterial regrowth observed with amikacin alone at the same concentration. A bactericidal activity without regrowth (until the 24th hour) was obtained for 9 strains; 2 susceptible E. coli, 3 K. pneumoniae (chromosomal Pase producer) and 4 cefotaxime susceptible E. cloacae, with low dose combination piperacillin (2) + amikacin (4). Finally, only combinations piperacillin (64) + amikacin (16) or piperacillin (16) + amikacin (8) had bactericidal activity on 2 Ticarcillin-resistant P. aeruginosa, the two antibiotics being separatedly bacteriostatic.(ABSTRACT TRUNCATED AT 250 WORDS)

Amikacin

Piperacillin, a new penicillin active against many bacteria resistant to other penicillins.

The in vitro activity of piperacillin, a new semisynthetic piperazine penicillin derivative, was evaluated against 626 clinical isolates and compared with the activity of other beta-lactam antibiotics. At a concentration of 0.1 microgram/ml, piperacillin inhibited all streptococci except enterococci. Non-beta-lactamase-producing staphylococci were inhibited by 1.6 microgram or less per ml. Both beta-lactamase- and non-beta-lactamase-producing Haemophilus were inhibited by 0.1 microgram/ml. Piperacillin inhibited non-beta-lactamase-producing Escherichia coli, Salmonella, and Shigella at a concentration of 6.3 micrograms/ml, but 20% of strains of these species containing type III beta-lactamase were not inhibited by 100 micrograms/ml. Piperacillin at 25 micrograms/ml, inhibited 83% of Citrobacter, 58% of Klebsiella, 88% of Enterobacter, and 50% of indole-positive Proteus, Acinetobacter, and Providencia. At 25 micrograms/ml, piperacillin inhibited 95% of Pseudomonas aeruginosa and 78% of Bacteroides fragilis. The minimal inhibitory concentration of piperacillin against Pseudomonas was affected by increasing the inoculum size and by pH. Minimum bactericidal concentrations against Pseudomonas and Serratia often were eightfold greater than the minimum inhibitory concentrations. Piperacillin was equal in activity to ampicillin against enterococci. It was more active than carbenicillin against E. coli, Klebsiella, Enterobacter, and Bacteroides. It was the most active penicillin against Pseudomonas and inhibited many strains of Pseudomonas for which the MICs of carbenicillin were above 200 micrograms/ml. Piperacillin was hydrolyzed by many different beta-lactamases. Synergistic activity of piperacillin was demonstrated when it was combined with amikacin, gentamicin, and cefazolin against P. aeruginosa and members of the Enterobacteriaceae. No antagonism was observed when piperacillin was combined with aminoglycosides; however, antagonism was observed rarely against E. coli when piperacillin was combined with cefazolin.

Chemical Phenomena

Piperacillin, tazobactam, and gentamicin alone or combined in an endocarditis model of infection by a TEM-3-producing strain of Klebsiella pneumoniae or its susceptible variant.

The efficacy of tazobactam, a beta-lactamase inhibitor, in combination with piperacillin, was studied in vitro and in rabbit experimental endocarditis due to a Klebsiella pneumoniae strain (KpR) producing an extended-spectrum beta-lactamase, TEM-3, or its nonproducing variant (KpS). In vitro, piperacillin was active against KpS (MIC = 4 micrograms/ml, MBC = 8 micrograms/ml with 10(7)-CFU/ml inoculum) but not against KpR (MIC = MBC = 256 micrograms/ml). Tazobactam (1 microgram/ml) restored the activity of piperacillin against KpR (MIC = 2 micrograms/ml, MBC = 4 micrograms/ml). Gentamicin was active against both strains (MIC = 0.25 and 0.5 micrograms/ml for KpS and KpR, respectively). The piperacillin-tazobactam-gentamicin combination was synergistic in vitro. The piperacillin/tazobactam ratio in plasma and in vegetations was always lower than the 4/1 injected dose ratio. In vivo, piperacillin (300 mg/kg of body weight four times a day [QID]) was active against KpS but not against KpR. Tazobactam (75 mg/kg QID) was able to restore the in vivo effect of piperacillin (300 mg/kg QID) against KpR (-3.0 log10 CFU/g of vegetation versus that of controls). Gentamicin (4 mg/kg twice a day [BID]) was active against both strains. Compared with controls, the combination of gentamicin plus piperacillin against KpS (-5.6 log10 CFU/g of vegetation), and the gentamicin-piperacillin-tazobactam combination against KpR (-4.4 log10 CFU/g of vegetation) achieved the greatest decrease in bacterial counts in vegetations and were the only regimens that significantly increased the proportion of sterile vegetations. It is concluded that (i) tazobactam was able to restore the effect of piperacillin against a TEM-3 extended-spectrum Beta-lactamase-producing strain of K. pneumoniae, both in vitro and in a severe experimental infection with high inoculum, when used in a 4/1 piperacillin/tazobactam dose ratio; (ii) gentamicin alone was effective because of the high peak/MBC ratio in plasma; (iii) piperacillin-tazobactam-gentamicin, probably because of the effect of gentamicin in reducing bacterial inoculum in vivo, as stressed by the results obtained by piperacillin-gentamicin against KpS, may be the most effective regimen against KpR.

Animals

Timentin versus piperacillin in the therapy of serious urinary tract infections.

In a comparative study, 47 patients received Timentin, a combination of ticarcillin plus clavulanic acid, or piperacillin to treat serious urinary tract infections. Thirty-nine infections in 38 patients were clinically evaluable (21 in the Timentin-treated group and 18 in the piperacillin-treated group). These included pyelonephritis (10 in the Timentin-treated group and five in the piperacillin-treated group), bladder infections with sepsis (11 in the Timentin-treated group and 11 in the piperacillin-treated group) and bladder infections without fever (two in the piperacillin-treated group). The addition of clavulanic acid to ticarcillin greatly enhanced the susceptibility of five of the 28 evaluable pathogens in the Timentin-treated group (two Escherichia coli isolates, two Staphylococcus aureus isolates, and one Klebsiella pneumoniae isolate). The minimal inhibitory concentrations at which 50 and 90 percent of the bacterial growth was inhibited were 4 and 64 micrograms/ml, respectively, for Timentin, and 4 and 32 micrograms/ml, respectively, for piperacillin. All evaluable patients had a satisfactory symptomatic response at the end of the trial. Of 28 evaluable pathogens treated with Timentin, 18 were eradicated up through the one-week post-therapy evaluation period; of 27 evaluable pathogens treated with piperacillin, 18 were eradicated up through the same time period. Eradicated pathogens included E. coli (six of 13 in the Timentin-treated group and six of 11 in the piperacillin-treated group), other Enterobacteriaceae (three of three in the Timentin-treated group and eight of 10 in the piperacillin-treated group), Pseudomonas aeruginosa (two of four in the piperacillin-treated group), enterococcus (two of three in the Timentin-treated group and two of two in the piperacillin-treated group), staphylococcal species (four of five in the Timentin-treated group), and other organisms (three of four in the Timentin-treated group). Resistance did not develop in any of the persisting pathogens. Adverse effects thought possibly to be related to the study drugs were minimal and included rash in one Timentin-treated patient and diarrhea in another.

Adult

Comparative in vitro and in vivo activities of piperacillin combined with the beta-lactamase inhibitors tazobactam, clavulanic acid, and sulbactam.

Tazobactam (YTR-830H), a novel beta-lactamase inhibitor, was compared with clavulanic acid and sulbactam for enhancement of the activity of piperacillin against beta-lactamase-producing, piperacillin-resistant clinical isolates. Piperacillin MICs were determined in media containing a fixed concentration of 2 or 4 micrograms of the inhibitors per ml. The higher concentration was generally more effective. Tazobactam was superior to sulbactam in enhancing the spectrum and potency of piperacillin. Although the calvulanic acid combination was more potent, tazobactam was effective for a similar spectrum of resistant gram-negative clinical isolates containing beta-lactamase. MICs were reduced to the susceptible range for Escherichia coli, Klebsiella pneumoniae, Proteus spp., Salmonella spp., and Shigella spp. Combinations with tazobactam and sulbactam, but not clavulanic acid, were effective against Morganella spp. Some antagonism of the activity of piperacillin was observed with clavulanic acid but not with tazobactam or sulbactam. The inhibitors were similarly effective with piperacillin against beta-lactamase-positive Staphylococcus spp. and the Bacteroides fragilis group. Piperacillin-tazobactam was more effective against a broader spectrum of gram-negative enteric bacteria than ticarcillin plus clavulanic acid was. Combinations with tazobactam or clavulanic acid had a broader spectrum of activity than combinations with sulbactam against bacteria that produce characterized plasmid-mediated enzymes of clinical significance. In particular, piperacillin with tazobactam or clavulanic acid, but not with sulbactam, inhibited TEM-1, TEM-2, and SHV-1 enzymes. In vitro activity was reflected in vivo. Tazobactam and clavulanic acid were superior to sulbactam in enhancing the therapeutic efficacy of piperacillin in mice infected with beta-lactamase-positive E. coli, K. pneumoniae, Proteus mirabilis, and Staphylococcus aureus. Only combinations with tazobactam and sulbactam were effective against the Morganella infection. Tazobactam has a good potential for enhancing the clinical efficacy of piperacillin.

Animals

Piperacillin sodium: antibacterial spectrum, pharmacokinetics, clinical efficacy, and adverse reactions.

Piperacillin sodium is a beta lactam antibiotic with a broad range of antibacterial activity that includes gram-negative bacilli, gram-positive cocci (except penicillinase-producing S. aureus) and anaerobic pathogens such as Clostridium difficile, and Bacteroides fragilis. Piperacillin inhibits many of the members of the Enterobacteriaceae, including Klebsiella sp and Pseudomonas, at lower concentrations than required for carbenicillin and ticarcillin. Piperacillin sodium is administered by intramuscular and intravenous injection and is widely distributed throughout body fluids and tissues. Like other newer penicillins, piperacillin is excreted by both renal and biliary mechanisms. The primary route of elimination is by glomerular filtration, which results in high urinary concentrations of the unchanged compound. Piperacillin has been approved for patients with serious infection caused by susceptible strains of specific organisms in intra-abdominal, urinary tract, gynecologic, lower respiratory tract, skin and skin structure, bone and joint, and gonococcal infections and septicemia. As with other penicillins, piperacillin has a low frequency of toxicity. The usual dose of piperacillin in adults with serious infections with normal renal function is 3-4 g every 4-6 hr as a 20-30 min infusion, with a maximum dose of 24 g per day. It is stable in most large volume parenteral solutions. Less serious infectins (requiring smaller dosages) may be treated by intramuscular injection; however, no more than 2 g should be given at any one injection site. Overall, piperacillin has a greater degree of activity than other penicillins. Evidence from prospective studies indicates that piperacillin is a highly effective agent for the treatment of patients with infections caused by susceptible organisms.

Bacteria

Therapeutic evaluation of piperacillin for acute pulmonary exacerbations in cystic fibrosis.

The efficacy and pharmacokinetics of piperacillin monotherapy were studied in 46 patients with cystic fibrosis. Two patients were dropped from the study within 24 hr of enrollment because of drug-associated nausea and vomiting. Initially fourteen older patients (greater than 12 years) receiving piperacillin 450 mg/kg/day underwent a preliminary evaluation. Based on the results, 30 younger patients (less than or equal to 12 years) randomized in a double-blind fashion received either 600 or 900 mg/kg/day of piperacillin in six divided doses. Pharmacokinetic parameter estimates for t1/2 Vdss, and Cl were similar for first dose and steady-state evaluations. In 27 patients, approximately 43% of the administered dose was recovered in the urine after 4 hr. Piperacillin CiR averaged 49% of the total Cl. No difference in overall clinical efficacy could be identified between 600 and 900 mg/kg/day of piperacillin using two different objective scoring systems. Although a reduction in sputum Pseudomonas colony counts was greater following the 900 mg/kg/day regimen, this appeared to be independent of clinical effect. In 14 patients (32%), a distinct adverse serum-sicknesslike reaction was observed. The incidence of this reaction appeared to increase as the dose of piperacillin increased. All signs and symptoms of this reaction resolved within 36 hr of discontinuing piperacillin administration but recurred immediately on rechallenge in four patients. All patients with the adverse reaction were subsequently treated with beta-lactam antibodies without ill effect. Overall, clinical improvement appeared to be independent of the piperacillin dose. Our data support the use of total daily piperacillin dosages not exceeding 600 mg/kg.

Adolescent

Protective effect of piperacillin against nephrotoxicity of cephaloridine and gentamicin in animals.

The protective effect of piperacillin against the nephrotoxicity of cephaloridine and gentamicin was examined in experimental animals. In rabbits, piperacillin was infused at a dose of 1 mg/kg (body weight) per min over 225 min and cephaloridine (300 mg/kg) was intravenously administered as a bolus 45 min after the start of a drip infusion. Blood urea nitrogen, serum creatinine, and N-acetyl-beta-D-glucosaminidase (NAG) in urine were measured as the renal toxicological parameters before and 24 h after cephaloridine dosing. Although the single administration of cephaloridine significantly elevated these parameters, the elevation was prevented by the concomitant administration of piperacillin. The protective effect of piperacillin was superior to those of cephalothin and fosfomycin. In rats, piperacillin (1,000 mg/kg) was intravenously administered and immediately followed by the intramuscular administration of gentamicin (100 mg/kg) every 24 h for 5 days. When piperacillin was concomitantly administered with gentamicin, the elevations of blood urea nitrogen, serum creatinine, and urinary NAG were significantly lower than when gentamicin was given alone. The concomitant administration of piperacillin resulted in a significant protective effect against the nephrotoxicity of cephaloridine in rabbits and of gentamicin in rats. Histopathological observation also supported the protective effect of piperacillin. The protective mechanism of piperacillin might be the inhibition of transport from the peritubular side to tubular cells for cephaloridine and from both the peritubular and luminal sides for gentamicin.

Animals