Clinical pharmacology of extended-spectrum penicillins in infants and children

Compared with previously available penicillins, piperacillin, azlocillin, and mezlocillin have increased activity in vitro against gram-negative bacilli. After intravenous administration of conventional doses (50 to 100 mg/kg) in children, peak concentrations of these drugs are approximately 70 to 350 micrograms/ml. For piperacillin, azlocillin, and mezlocillin, the half-lives during the beta elimination phase (t 1/2 beta) are approximately 0.5 to 0.75, 0.8 to 1.7, and 0.8 to 1.0 hours, respectively. In patients receiving the higher dosage, particularly of azlocillin, the t 1/2 beta may be prolonged by approximately 20%. A total daily dosage of 300 mg/kg or 9 gm/m2 given in four to six divided dosages should produce peak concentrations of approximately 150 micrograms/ml, and concentrations greater than 16 micrograms/ml for at least 2 hours after each administration. Lower daily dosages are needed in neonates, but precise dosage recommendations cannot be made at this time. Only approximately 60% of piperacillin and approximately 45% of azlocillin are eliminated unchanged in the urine; thus only modest dosage reductions are needed in patients with decreased renal function. In children, adverse effects have been infrequent.

Adverse reactions to piperacillin in adults with cystic fibrosis

Nine adult patients with cystic fibrosis, nearly a quarter of the 38 patients with this disease who were treated with piperacillin (59 courses in all) during 1981-3 at the Brompton Hospital, developed a swinging pyrexia after a mean of 13.5 days' treatment with this antibiotic. The fever resolved shortly after the piperacillin treatment was stopped, as did the widespread rashes in the two patients who developed them. Three of four patients who had probable reactions to azlocillin may have been sensitised by piperacillin. As piperacillin does not appear to be any more effective than other antipseudomonal penicillins in cystic fibrosis, it is no longer used at the hospital for treating bronchopulmonary exacerbations in such patients.

Neutropenia associated with mezlocillin and piperacillin

Neutropenia associated with beta-lactam antibiotics has been widely reported since the first case was described in 1946. Cross-reactivity between beta-lactam antibiotics for this phenomenon rarely has been reported. This case describes the development of neutropenia after a course of mezlocillin, resolution upon discontinuation, and recurrence promptly after initiation of piperacillin, with resolution subsequent to discontinuation. Clinical practitioners should be aware that this adverse drug reaction has been associated with the newer beta-lactam antibiotics and that cross-reactivity may occur between these antibiotics.

Piperacillin. A review of its antibacterial activity, pharmacokinetic properties and therapeutic use

Piperacillin is one of the new generation of semisynthetic penicillins which can be administered intravenously or intramuscularly. It has a broad spectrum of activity against Gram-positive and Gram-negative aerobic and anaerobic bacteria. Although piperacillin has shown greater activity against beta-lactamase-producing organisms than the other penicillins, it is hydrolysed by the plasmid-mediated beta-lactamases (TEM-1). Activity against Pseudomonas aeruginosa is better than that of ticarcillin, carbenicillin and mezlocillin. Although only limited controlled studies have been reported, in those which have been conducted and in a larger number of open studies piperacillin was effective in the treatment of complicated urinary tract infections and lower respiratory tract infections, particularly pneumonia, caused by Gram-negative bacilli. Favourable clinical results have been obtained in patients with infections caused by mixed aerobic/anaerobic organisms (such as intra-abdominal infections) but the relatively average in vitro activity of piperacillin against Bacteroides fragilis may not indicate its usage in situations where this organism is the suspected or proven pathogen. Piperacillin in combination with an aminoglycoside or a 'third generation' cephalosporin gave encouraging results in the treatment of infections in immunocompromised patients, whilst its penetration into the diseased central nervous system and lack of toxicity indicate a potential value in the treatment of neonatal Gram-negative bacillary meningitis, particularly where the causative organism is Pseudomonas aeruginosa. Whether piperacillin alone is appropriate therapy for conditions usually treated with aminoglycosides (other than pseudomonal infections) needs additional clarification, but if established as equally effective in such conditions it has the advantages of its apparent lack of serious adverse effects and freedom from the need to undertake plasma concentration monitoring. These advantages would not, however, apply when considering one of the new (third generation) cephalosporins as alternative therapy in non-pseudomonal infections. Generally, however, it is still considered necessary to treat serious and complicated infections with combination therapy, either a cephalosporin, or in cases of resistance to P. aeruginosa an aminoglycoside.

Moxalactam plus piperacillin versus moxalactam plus amikacin in febrile granulocytopenic patients

In a prospective randomized trial, febrile granulocytopenic patients received either moxalactam plus piperacillin or moxalactam plus amikacin as initial empiric antimicrobial therapy. Most patients were also given prophylactic vitamin K. The overall response rates for the two regimens were similar (105 of 136, or 77 percent, for moxalactam plus piperacillin versus 107 of 136, or 79 percent, for moxalactam plus amikacin). For Pseudomonas aeruginosa infections, the response rate was better in patients receiving moxalactam plus amikacin (seven of nine versus one of five, p = 0.06); two patients treated with moxalactam plus piperacillin experienced relapse of P. aeruginosa bacteremia in association with the emergence of beta-lactam-resistant P. aeruginosa isolates. On the other hand, bacteremic enterococcal superinfections occurred in seven patients receiving moxalactam plus amikacin but in none given moxalactam plus piperacillin (p = 0.02). Serious side-effects were minimal with both regimens, and nephrotoxicity was less common in patients receiving moxalactam plus piperacillin (two of 136 versus six of 136, p = 0.28). There was no antibiotic-related hemorrhage. These results suggest that the overall efficacy and toxicity of moxalactam plus piperacillin and moxalactam plus amikacin are similar. Moxalactam/piperacillin therapy may be limited in certain patients by the emergence of beta-lactam-resistant P. aeruginosa, whereas enterococcal superinfections may complicate moxalactam/amikacin therapy.

Piperacillin levels in human tears and aqueous humor

Thirty patients scheduled to undergo elective intraocular surgery were each given 4 g of piperacillin intravenously. Specimens of serum, tears, and aqueous humor were collected from zero to nine hours after infusion and assayed for piperacillin content by high pressure liquid chromatography. In noninflamed eyes piperacillin sodium distributed into tears and aqueous humor in concentrations exceeding the minimum inhibitory concentration required for many gram-positive and gram-negative organisms. Higher levels of piperacillin were anticipated in patients with inflamed eyes who possessed an altered blood-aqueous barrier, and in patients receiving serial doses of this agent.

Ticarcillin-induced cystitis. Cross-reactivity with related penicillins

Two children had dysuria, sterile pyuria, and microscopic hematuria develop during treatment with ticarcillin disodium. With the exception of a predominance of pyuria over hematuria, the clinical course and laboratory findings in this disorder were similar to those observed in hemorrhagic cystitis, a potential complication of the use of several semisynthetic penicillins and penicillin G potassium. One patient had urinary abnormalities develop during two courses of ticarcillin therapy and subsequently after initiation of piperacillin sodium therapy. A second patient in whom hemorrhagic cystitis due to carbenicillin disodium developed experienced this related disorder four years later when first exposed to ticarcillin. Neither reduction of the dose nor substitution of one semisynthetic penicillin for another (piperacillin for ticarcillin, ticarcillin for carbenicillin) prevented recurrence of the disorder. The clinical importance of either form of cystitis induced by semisynthetic penicillins is uncertain, as is the risk for progression to interstitial nephritis.

Allergy to semisynthetic penicillins in cystic fibrosis

Allergic reactions to anti-Pseudomonal penicillin derivatives are an increasing problem in therapy of cystic fibrosis lung disease. We evaluated 15 patients, ages 12 to 37 years, with documented allergic reactions to carbenicillin, ticarcillin, or piperacillin. Intradermal skin test reactions were positive for benzylpenicillin in seven patients, penicilloyl-polylysine in one, and ticarcillin or piperacillin in eight, for a total of 11 of 11 tested. Results of radioallergosorbent testing to penicilloyl conjugates were positive in eight of 14 patients and equivocal in four others. Overall, skin tests or RAST results were positive in 13 of 15 patients. All patients were desensitized with a semisynthetic penicillin by continuous serial intravenous infusion of 10-fold dose increments, beginning with 10(-6) of the therapeutic dose. Desensitization was successful in 25 of 26 instances. After intravenously administered therapy, maintenance of desensitization with dicloxacillin orally was unsuccessful in four of six patients. We conclude that (1) allergy to semisynthetic penicillins in cystic fibrosis usually is IgE mediated; (2) such allergy can be evaluated by skin testing; (3) it can be safely and in most cases successfully treated by intravenous desensitization; and (4) allergic patients should be desensitized on each subsequent admission for intravenously administered therapy.

Comparative efficacy of piperacillin versus carbenicillin for complicated urinary tract infections

In this controlled, randomized clinical trial we compared piperacillin and carbenicillin in the treatment of complicated urinary tract infections. 24 patients received piperacillin 150 mg/kg/day for 7.2 +/- 2.75 days and 17 patients received carbenicillin 200 mg/kg/day for 7.5 +/- 2.90 days. Patients were evaluated for clinical and bacteriologic responses and tolerance to therapy. Although the clinical cure rate significantly favored carbenicillin treatment (p less than 0.01), the sum of the percentages of cases with clinical cure and clinical improvement were similar between groups: 91.6% for piperacillin and 88.2% for carbenicillin. The bacteriologic cure rates for piperacillin and carbenicillin patients (54.1 and 47.0%, respectively) were not significantly different (p greater than 0.05). The low cure rates in our study were probably the result of uncorrected/uncorrectable genitourinary tract abnormalities. Superinfections developed in 12.5 and 17.6% of piperacillin and carbenicillin patients, respectively, and were due to Klebsiella pneumonia, Proteus mirabilis, Citrobacter diversus, and Pseudomonas aeruginosa. Overall, side effects were mild, reversible, and did not require discontinuation of treatment. However, carbenicillin caused elevations in liver enzymes more frequently than piperacillin (p less than 0.05). Based on our data, we recommend reserving piperacillin monotherapy for patients who are poor candidates for aminoglycosides, or are on severe sodium restriction, and have serious complicated urinary tract infections due to susceptible organisms. We do not recommend piperacillin alone for empiric treatment of complicated urinary tract infections.

Prospective randomized trial of piperacillin monotherapy versus carboxypenicillin-aminoglycoside combination regimens in the empirical treatment of serious bacterial infections

Piperacillin as a single agent was compared in a prospective randomized trial with carboxypenicillin-aminoglycoside combinations in empirical therapy of serious bacterial infections. The difference in the clinical response rates with piperacillin (77% of 26 infection episodes) and combination therapy (75% of 24 infection episodes) were not statistically significant. Fewer adverse effects occurred in the piperacillin-treated group (42%) than in the combination-treated group (71%) (P = 0.0399 by Fisher's exact test), although neither nephrotoxicity nor hypokalemia alone was significantly less frequent in patients receiving piperacillin. However, the emergence of resistant organisms during therapy was more frequent among patients receiving piperacillin alone (42% of patients) than among patients receiving combination therapy (17% of patients) (P = 0.465 by Fisher's exact test). Moreover, emergence of resistance accounted for 5 of 9 patients with treatment failure, superinfection, or both when piperacillin was used as a single agent, compared with 2 of 10 similar patients in the combination group (P = 0.1299 by Fisher's exact test). The use of piperacillin as a single agent in the treatment of serious bacterial infections is not advocated, and the addition of an aminoglycoside to prevent emergence of resistance during empirical therapy of such infections is strongly recommended.