Pharmacokinetics of ticarcillin and clavulanic acid (timentin) in relation to renal function

Pharmacokinetic Drug-drug Interaction of Antibiotics Used in Sepsis Care in China

BACKGROUND

Many antibiotics have a high potential for interactions with drugs, as a perpetrator and/or victim, in critically ill patients, and particularly in sepsis patients.

METHODS

The aim of this review is to summarize the pharmacokinetic drug-drug interaction (DDI) of 45 antibiotics commonly used in sepsis care in China. Literature search was conducted to obtain human pharmacokinetics/ dispositions of the antibiotics, their interactions with drug-metabolizing enzymes or transporters, and their associated clinical drug interactions. Potential DDI is indicated by a DDI index ≥ 0.1 for inhibition or a treatedcell/ untreated-cell ratio of enzyme activity being ≥ 2 for induction.

RESULTS

The literature-mined information on human pharmacokinetics of the identified antibiotics and their potential drug interactions is summarized.

CONCLUSION

Antibiotic-perpetrated drug interactions, involving P450 enzyme inhibition, have been reported for four lipophilic antibacterials (ciprofloxacin, erythromycin, trimethoprim, and trimethoprim-sulfamethoxazole) and three antifungals (fluconazole, itraconazole, and voriconazole). In addition, seven hydrophilic antibacterials (ceftriaxone, cefamandole, piperacillin, penicillin G, amikacin, metronidazole, and linezolid) inhibit drug transporters in vitro. Despite no clinical PK drug interactions with the transporters, caution is advised in the use of these antibacterials. Eight hydrophilic antibiotics (all β-lactams; meropenem, cefotaxime, cefazolin, piperacillin, ticarcillin, penicillin G, ampicillin, and flucloxacillin), are potential victims of drug interactions due to transporter inhibition. Rifampin is reported to perpetrate drug interactions by inducing CYP3A or inhibiting OATP1B; it is also reported to be a victim of drug interactions, due to the dual inhibition of CYP3A4 and OATP1B by indinavir. In addition, three antifungals (caspofungin, itraconazole, and voriconazole) are reported to be victims of drug interactions because of P450 enzyme induction. Reports for other antibiotics acting as victims in drug interactions are scarce.

Pilot study of side effects and serum and urine concentrations of amoxicillin-clavulanic acid in azotemic and non-azotemic cats

OBJECTIVES

The aims of this study were to determine the side effect frequency and serum and urine drug concentrations of amoxicillin-clavulanic acid in cats with and without azotemic chronic kidney disease (azCKD).

METHODS

Owners whose cats had been prescribed amoxicillin-clavulanic acid completed a survey regarding the occurrence and type of side effects, and whether treatment was altered as a result. Cats were defined as azCKD (serum creatinine concentration >2.0 mg/dl, urine specific gravity [USG] <1.035 with a clinical diagnosis of chronic kidney disease) and without azCKD (serum creatinine concentration <2.0 mg/dl). Data were assessed with Fisher's exact test. Serum and urine samples were obtained from client-owned cats with azCKD (n = 6) and without azCKD (n = 6, serum creatinine concentration <1.8 mg/dl, USG >1.035) that were receiving amoxicillin-clavulanic acid. Amoxicillin and clavulanic acid were measured with liquid chromatography coupled to tandem mass spectrometry and compared between groups with a Mann-Whitney test. Correlation between serum creatinine and drug concentrations in urine and serum was determined using Spearman's rank test.

RESULTS

Sixty-one surveys were returned (11 azCKD cats and 50 without azCKD cats). No significant difference in the presence of side effects or type of side effects was seen between groups; however, significantly more azCKD cats had more than one side effect (P = 0.02). More owners of azCKD cats reported that an alteration in treatment plan was necessitated by side effects (55% vs 12%; P = 0.008). Urine amoxicillin was significantly lower in cats with azCKD (P = 0.01) and serum amoxicillin trended toward significance (P = 0.07). Serum amoxicillin concentration was positively correlated with serum creatinine (P = 0.02; r = 0.62) and urine amoxicillin concentration was negatively correlated with serum creatinine (P = 0.01; r = -0.65).

CONCLUSIONS AND RELEVANCE

The data suggest that cats with azCKD have altered pharmacokinetics of amoxicillin, which may contribute to an increased incidence of multiple side effects.

Continuous-infusion beta-lactam antibiotics during continuous venovenous hemofiltration for the treatment of resistant gram-negative bacteria

OBJECTIVE

To describe the rationale, principles, and dosage calculations for continuous-infusion beta-lactam antibiotics to treat multidrug-resistant bacteria in patients undergoing continuous venovenous hemofiltration (CVVH).

DATA SOURCES

A MEDLINE search (1968-November 2008) of the English-language literature was performed using the terms continuous infusion and Pseudomonas or Acinetobacter; hemofiltration or CVVH or hemodiafiltration or CVVHDF or continuous renal replacement therapy or pharmacokinetics; and terms describing different beta-lactam antibiotics.

STUDY SELECTION AND DATA EXTRACTION

In vitro, in vivo, and human studies were evaluated that used continuous-infusion beta-lactam antibiotics to treat Pseudomonas aeruginosa and Acinetobacter baumannii infections. Studies were reviewed that described the pharmacokinetics of beta-lactam antibiotics during CVVH as well as other modalities of continuous renal replacement therapy.

DATA SYNTHESIS

Continuous infusion of beta-lactam antibiotics, maintaining drug concentrations 4-5 times higher than the minimum inhibitory concentration, is a promising approach for managing infections caused by P. aeruginosa and A. baumannii. Safe yet effective continuous infusion therapy is made difficult by the occurrence of acute renal failure and the need for renal replacement therapy. Case series and pharmacokinetic properties indicate that several beta-lactam antimicrobials that have been studied for continuous infusion, such as cefepime, ceftazidime, piperacillin, ticarcillin, clavulanic acid, and tazobactam, are significantly cleared by hemofiltration. Methodology and formulas are provided that allow practitioners to calculate dosage regimens and reach target drug concentrations for continuous beta-lactam antibiotic infusions during CVVH based on a literature review, pharmacokinetic principles, and our experience at the National Institutes of Health Clinical Center.

CONCLUSIONS

Continuous infusion of beta-lactam antibiotics may be a useful treatment strategy for multidrug-resistant gram-negative infections in the intensive care unit. Well-established pharmacokinetic and pharmacodynamic principles can be used to safely reach and maintain steady-state target concentrations of beta-lactam antibiotics in critical illness complicated by acute renal failure requiring CVVH.

Differences in antimicrobial drug exposure in patients with various degrees of renal function based on recommendations from dosing references

STUDY OBJECTIVE

To calculate and compare 24-hour area under the unbound drug concentration-time curves (AUC(0-24)) of antimicrobials with dosing recommendations from six commonly used dosing references.

INTERVENTION

Unbound plasma concentration-time profiles of 13 antimicrobial agents (4 penicillins, 3 cephalosporins, 2 carbapenems, aztreonam, 3 fluoroquinolones) were simulated at steady state using a one-compartment open model for a 70-kg adult based on pharmacokinetic parameters obtained from peer-reviewed literature. Simulations were performed at five levels of creatinine clearance (Cl(cr)).

MEASUREMENTS AND MAIN RESULTS

Differences in AUC(0-24) for each antimicrobial agent were noted among the six references at each level of Cl(cr) as well as within references across the range of Cl(cr). In addition, up to 16-fold and 3-fold ranges in AUC(0-24) values were observed for beta-lactams and fluoroquinolones, respectively, in one reference based on dosing recommendations at a single level of Cl(cr) (due to more than one dose and/or dosing interval).

CONCLUSION

Clinicians should be aware of differences among common references when selecting dosages of antimicrobial agents, especially for patients with moderate-to-severe renal impairment.

Rational prescribing of extended-spectrum penicillin beta-lactamase inhibitor combinations: focus on ticarcillin/clavulanic acid

OBJECTIVE

To provide an overview of the clinical pharmacokinetics and pharmacodynamics of ticarcillin/clavulanic acid and to reassess traditional dosage recommendations based on contemporary pharmacokinetic and pharmacodynamic principles.

DATA SOURCES

Published ticarcillin and clavulanic acid pharmacokinetic data derived from infants and children combined with data obtained from a rigorous, dose-escalation study performed in 12 healthy adults. Pharmacodynamic correlates were derived from published in vitro susceptibility data for the combination drug ticarcillin/clavulanic acid.

DATA SYNTHESIS

Limited differences were observed in the pharmacokinetic disposition profiles between ticarcillin and clavulanic acid and relative to subject age. Integration of these data with defined pathogen minimum inhibitory concentrations underscores the appropriateness of an extended dosing interval (e.g., q8h to q12h) for many infections and demonstrates the probable therapeutic interchangeability of the following three intravenous dosing regimens: 3.1 g every 6 hours, 75 mg/kg every 8 hours, and 100 mg/kg every 12 hours of a 30:1 ticarcillin/clavulanic acid combination.

CONCLUSIONS

Integration of pharmacokinetic and pharmacodynamic data is an appropriate means to assess/reassess dosing recommendations for antimicrobial agents. Initial ticarcillin/clavulanic acid dose recommendations did not account for known dynamic interactions for this combination antibiotic. Pharmacokinetic data in infants, children, and adults support a less frequent dosing interval (q8h to q12h) for the treatment of infections arising outside the central nervous system.

Antimicrobial agents for the dermatologist. I. Beta-lactam antibiotics and related compounds

We review the newer antimicrobial agents that are being employed by dermatologists with increased frequency as well as some of the more commonly used older agents. Particular emphasis is based on selection factors such as causative pathogens and their resistance profiles, routes of administration, toxicity, drug interactions, and dosing requirements. Emphasis in this review is on the newer classes of antimicrobials such as third- and fourth-generation cephalosporins; beta-lactam, beta-lactamase inhibitor combination agents; monobactams; carbapenems; macrolides; and fluoroquinolones. Dermatologic indications and treatment alternatives are highlighted; this will expand the practicing clinician's therapeutic armamentarium and enable him/her to make rational decisions concerning treatment approaches to infectious disease problems encountered in daily practice.

Pharmacokinetic-based ticarcillin/clavulanic acid dose recommendations for infants and children

The pharmacokinetic characteristics of ticarcillin and clavulanic acid were determined after the first dose (n = 22) and again under steady-state conditions (n = 16) in a group of infants and children. Study subjects ranged in age from 1 month to 9.3 years; all but 3 study patients were 6 months of age or older. Each patient received 50 mg of ticarcillin and 1.7 mg of clavulanic acid (30:1 ratio) per kg of body weight given intravenously every 4 hours. Elimination half-life, steady-state volume of distribution, and body clearance averaged 1.1 hours, 0.22 L/kg, and 2.7 mL/min/kg, respectively, for ticarcillin, and 0.9 hours, 0.4 L/kg, and 6.2 mL/min/kg, respectively, for clavulanic acid. A total of 71% of the ticarcillin and 50% of the clavulanic acid dose were excreted unchanged in the urine over the 4-hour sampling period. Corresponding renal clearances averaged 2.1 and 3.2 mL/min/kg for ticarcillin and clavulanic acid, respectively. No differences were observed between first dose and steady-state evaluations in the pharmacokinetic behavior of either agent. In contrast, the pharmacokinetic behavior of clavulanic acid was significantly different from that observed for ticarcillin. These pharmacokinetic data combined with known in vitro susceptibilities of important clinical pathogens support a dose of 80 mg of ticarcillin and 2.7 mg/kg clavulanic acid per kg body weight given as a fixed dose combination every 8 hours for the treatment of most systemic infections that occur outside the central nervous system.

Clinical pharmacokinetics of antibiotics in patients with impaired renal function

Many antibiotics are eliminated renally and dosage adjustments are commonly made in patients with renal insufficiency. This is a critical review of antibiotic pharmacokinetics in patients with various degrees of renal function. Detailed information regarding pharmacokinetic alterations with specific antibiotics or antibiotic classes has been compiled and tabulated. From pharmacokinetic evidence, recommendations for dosage adjustments of antibiotics are supplied. The criteria used for assigning rating levels to specific pharmacokinetic articles as well as the grading system for dosage adjustments are outlined. In addition, a basic review of pharmacokinetic alterations in renal failure and factors affecting the removal of drugs by haemodialysis is included.

Pharmacokinetics of amoxycillin and clavulanic acid in haemodialysis patients following intravenous administration of Augmentin

1. Serum concentrations of amoxycillin and clavulanic acid were measured in patients with end-stage renal disease (ESRD) following intravenous administration of 1.2 g Augmentin. Augmentin was administered on a non-dialysis day and 2 h prior to a 4 h dialysis session. 2. The mean values of total serum clearance, mean residence time, volume of distribution at steady state, and terminal half-life for amoxycillin on the non-dialysis day were 14.4 ml min-1, 19.2 h, 14.9 l and 13.6 h, respectively. 3. The mean values of dialysis clearance, total serum clearance during dialysis, fractional drug removal during haemodialysis and half-life during dialysis for amoxycillin were 77.1 ml min-1, 91.5 ml min-1, 0.64 and 2.30 h, respectively. 4. The mean values of total serum clearance, mean residence time, volume of distribution at steady state, and terminal half-life for clavulanic acid on the non-dialysis day were 43.6 ml min-1, 4.4 h, 11.0 l and 3.05 h, respectively. 5. The mean values of dialysis clearance, total serum clearance during dialysis, fractional drug removal during haemodialysis and half-life during dialysis for clavulanic acid were 92.8 ml min-1, 136 ml min-1, 0.65 and 1.19 h, respectively. 6. The total serum clearance on the non-dialysis day, which represents non-renal clearance, was lower than that in normal subjects for both amoxycillin and clavulanic acid. These data would suggest some degree of hepatic impairment in patients with ESRD.(ABSTRACT TRUNCATED AT 250 WORDS)

Clinical pharmacokinetics of enzyme inhibitors in antimicrobial chemotherapy

The effectiveness of some antimicrobial agents can be enhanced by using them in combination; such combinations are termed synergistic. Where one compound potentiates the effect of a second drug they may be coformulated. Inhibition of the bacterial degradation of an active antimicrobial is the basis of clavulanate and sulbactam-potentiated penicillin combinations, and inhibition of degradative pathways in the host is the rationale behind imipenem/cilastatin therapy. Trimethoprim/sulphonamide combinations depend on the maintenance of an effective ratio for synergistic action. In order to achieve potentiation the coformulated drugs should have similar pharmacokinetics. Trimethoprim was originally matched with sulphamethoxazole, since these two drugs have similar elimination half-lives, but the significantly poorer penetration of sulphonamides, their greater non-renal clearance, the emergence of resistance, and the adverse reactions attributable to them argue against the rationale that underlies their coformulation. Time-dependent inhibition of bacterial beta-lactamases by clavulanic acid and sulbactam has extended the use of penicillins which are highly susceptible to beta-lactamase inactivation. The beta-lactamase inhibitors must penetrate to the same extent as the penicillin used with them, and be present long enough to effect inhibition; thus, rapid penetration, similar or slower elimination and equivalent volume of distribution are necessary. These requirements are met for amoxycillin/clavulanic acid, ticarcillin/clavulanic acid and ampicillin/sulbactam combinations. Clavulanic acid is absorbed orally and is given with amoxycillin. However, since sulbactam is labile by this route, the combination of sulbactam with ampicillin to form the prodrug sultamicillin has been necessary to enable an oral form to be developed. Imipenem is metabolised by renal brush-border dehydropeptidases, and may cause proximal tubular necrosis. Cilastatin was designed to inhibit this metabolism, which it effectively does, thereby both potentiating the effect of imipenem and avoiding toxicity. Appropriate matching of the kinetics of coformulated drugs is intended to maximise potentiation and minimise the risk of emergent resistance. The kinetics of the above combinations are discussed in the light of these requirements and the effects of age and disease.