Pharmacokinetics of cefpiramide in volunteers with normal or impaired renal function

An Overview of the Protein Binding of Cephalosporins in Human Body Fluids: A Systematic Review

Introduction: Protein binding can diminish the pharmacological effect of beta-lactam antibiotics. Only the free fraction has an antibacterial effect. The aim of this systematic literature review was to give an overview of the current knowledge of protein binding of cephalosporins in human body fluids as well as to describe patient characteristics influencing the level of protein binding.

Method: A systematic literature search was performed in Embase, Medline ALL, Web of Science Core Collection and the Cochrane Central Register of Controlled Trials with the following search terms: “protein binding,” “beta-lactam antibiotic,” and “body fluid.” Only studies were included where protein binding was measured in humans in vivo.

Results: The majority of studies reporting protein binding were performed in serum or plasma. Other fluids included pericardial fluid, blister fluid, bronchial secretion, pleural exudate, wound exudate, cerebrospinal fluid, dialysate, and peritoneal fluid. Protein binding differs between diverse cephalosporins and between different patient categories. For cefazolin, ceftriaxone, cefpiramide, and cefonicid a non-linear pattern in protein binding in serum or plasma was described. Several patient characteristics were associated with low serum albumin concentrations and were found to have lower protein binding compared to healthy volunteers. This was for critically ill patients, dialysis patients, and patients undergoing cardiopulmonary bypass during surgery. While mean/median percentages of protein binding are lower in these patient groups, individual values may vary considerably. Age is not likely to influence protein binding by itself, however limited data suggest that lower protein binding in newborns. Obesity was not correlated with altered protein binding.

Discussion/Conclusion: Conclusions on protein binding in other body fluids than blood cannot be drawn due to the scarcity of data. In serum and plasma, there is a large variability in protein binding per cephalosporin and between different categories of patients. Several characteristics were identified which lead to a lower protein binding. The finding that some of the cephalosporins display a non-linear pattern of protein binding makes it even more difficult to predict the unbound concentrations in individual patients. Taken all these factors, it is recommended to measure unbound concentrations to optimize antibiotic exposure in individual patients.

Systematic Review Registration: PROSPERO, identifier (CRD42021252776).

Quantitation of plasma and biliary cefpiramide concentrations in human samples using high-performance liquid chromatography

Cefpiramide is frequently used to treat biliary infections. However, no bioanalytical method has been validated to quantitate cefpiramide in human samples, particularly in bile. Therefore, this study was conducted to develop a simple, selective and validated high-performance liquid chromatographic method to determine cefpiramide in human plasma and bile. A protein precipitation procedure was used to extract cefpiramide and cefoperazone (internal standard, IS) from 200 μl of plasma and bile. Utilizing a Capcell Pak C₁₈ column (4.6 × 250 mm), cefpiramide and IS were separated using the timed-gradient mobile phase consisting of 0.1 m sodium acetate (pH 5.2) and acetonitrile at a flow rate of 1 ml/min with photodiode array detector (wavelength set at 273 nm). The calibration curves showed linearity at concentrations ranging from 1 to 150 μg/ml in both plasma and bile (r²  > 0.999). The within- and between-run coefficients of variation (CVs) for plasma samples were 0.570-4.43 and 1.10-2.76%, respectively; for bile samples, the within- and between-day precision (CV) was 0.814-6.34 and 2.05-4.00%, respectively. Our newly developed bioanalytical method was successfully employed to quantify cefpiramide concentrations in both plasma and bile at multiple time points in patients with acute cholangitis.

Evaluation of a novel method to estimate absolute bioavailability of drugs from oral data

The goal of this investigation was to evaluate the performance of a novel method allowing estimation of absolute bioavailability from oral data only. In contrast to the traditional method, which compares areas under the drug concentration time curves after oral and intravenous administration in subjects with normal renal function, the novel method uses total and renal clearance values following oral administration from subjects with varying renal functions to estimate bioavailability. The novel method can also provide estimates for nonrenal clearance.Published data on total clearance and renal clearance of drugs obtained from subjects with variable renal functions were collected, the novel method applied, estimates of bioavailability and nonrenal clearance obtained and compared with reported estimates by the traditional methods. In addition computations were performed to assess various factors that could possibly affect the reliability of the novel method. The results indicated that the novel method provides accurate estimates for bioavailability of drugs meeting the prerequisites: linear kinetics, predominant renal excretion in normals, absence of metabolic polymorphism and independence of bioavailability and nonrenal clearance from renal function. The average (standard deviation) of the prediction error and bias of the bioavailability estimates by the novel method was 7.8 (6.0) and -1.4 (9.8)%, respectively. The estimates for nonrenal clearance by the novel method were less accurate. The computations confirmed that the estimates by the novel method are sensitive to renal-function dependent changes in nonrenal clearance and bioavailability and also depend on the extent of renal excretion of a drug. In conclusion, the novel method's main use is to diagnose absence or presence of changes in bioavailability and non-renal clearance of drugs in populations with varying renal function.

Pharmacokinetics of cefodizime in volunteers with normal or impaired renal function

The pharmacokinetics of single, 1- or 2-g intravenous doses of cefodizime were studied in subjects with normal, impaired renal function or requiring chronic hemodialysis. Drug concentrations were measured using high-performance liquid chromatography. Forty-five subjects (20 with creatinine clearance of > or = 90 mL/min, 15 with creatine clearances between 5 and 89 mL/min, and 10 requiring chronic hemodialysis) were studied. The concentration-time curve of cefodizime was best represented by an open two-compartment model. The elimination half-lives in subjects with normal (Group 1) and impaired renal function (Group 2) or requiring chronic hemodialysis (Group 3) were 4.14 +/- 1.55, 5.10 +/- 2.24, and 10.1 +/- 6.01 hours, respectively (Group 3 versus 1 or 2, P < .05; Group 1 versus 2, P > .05). The total body (serum) clearances in the same groups were 3 +/- 0.52, 2.22 +/- 0.61, and 0.99 +/- 0.33 L/hour, respectively (Group 1 versus 2 or 3, P < .05; Group 2 versus 3, P < .05). Although renal function has an effect on the pharmacokinetics of cefodizime, its effect on the elimination half life is marginal in subjects with creatinine clearance of more than 25 mL/min. In individuals with more severe renal impairment or those requiring chronic hemodialysis, dosage adjustment would be required.

Cefpiramide kinetics and plasma protein binding in cholestasis

Cefpiramide is a new parenteral cephalosporin mainly excreted in the bile. Eight patients with cholestasis and 11 healthy subjects received a single 1 g i.v. dose. Cefpiramide concentrations in plasma and urine were measured by h.p.l.c. and plasma binding was determined by ultrafiltration. Total clearance of cefpiramide (mean +/- s.d.) was 15.5 +/- 7.1 ml min-1 in patients and 25.6 +/- 4.6 ml min-1 in healthy subjects. As a result, the terminal elimination half-life was longer in patients (12.0 +/- 2.9 h vs 5.3 +/- 0.9 h). Owing to impaired biliary elimination of cefpiramide in cholestasis, the urinary recovery of unchanged drug in patients was about five times greater than in healthy subjects (85.1 +/- 10.3% vs 16.2 +/- 3.9%). Plasma binding was significantly lower in cholestasis (fu = 0.23 +/- 0.13 vs 0.02 +/- 0.004 in healthy subjects). Accordingly, the dosage regimen of cefpiramide should be modified in patients with cholestasis.

Considerations in dosage selection for third generation cephalosporins

Pharmacokinetic parameters of third generation cephalosporins vary widely, requiring different dosage regimens and adjustment methods for each agent. Although their antibacterial spectrum favours their usage in infections caused by aerobic Gram-negative organisms, due to their limited post-antibiotic effect against these organisms, dosage regimens should ensure that free drug concentrations at the site of infection remain above the minimum inhibitory concentration for as much of the dosage interval as possible in patients with normal host defence mechanisms and for the entire dosage interval in immunocompromised patients. Altered protein binding encountered in various disease states can affect both microbiological and pharmacokinetic properties especially for drugs with high protein binding. Since the concentrations at the site of action are often different from those in serum, a higher or lower range of dosages needs to be selected depending on the target site. Decreased renal function affects the elimination of most third generation cephalosporins, whereas the presence of hepatic disease does not generally necessitate dosage adjustment. Because of the complex age-related physiological changes in paediatric and elderly patients, dosage should be adjusted on the basis of the reported pharmacokinetic data in these populations. The usual recommended dose may or may not be optimal in a given condition depending on the complex interactions between pharmacokinetic, microbiological and other host factors.

The effect of renal failure on hepatic drug clearance

It is known that loss of renal function decreases the hepatic clearance of some drugs, but the mechanisms by which this occurs are unclear. Knowledge of which drugs display reduced hepatic metabolism may be important for appropriate dosing of these drugs in uremic patients. Although no firm conclusions can be made regarding common pharmacokinetic and metabolic characteristics of drugs that display decreased hepatic metabolism in renal failure, certain observations deserve consideration. It appears that drugs metabolized by oxidation, conjugation, or both may be predisposed to decreased hepatic clearance in renal failure. Drugs that undergo oxidation by the P-450IID6 isozyme may be more likely to exhibit inhibition whereas those metabolized by the P-450IIIA4 isozyme may be spared. Future studies designed to clarify the mechanisms of decreased hepatic clearance in renal failure should take into account the multiplicity of P-450 enzymes for drugs that are oxidatively metabolized. The phenomenon of reduced hepatic drug clearance in uremia should be considered when evaluating the influence of renal failure on drug disposition.

Pharmacokinetics of newer drugs in patients with renal impairment (Part I)

Many drugs are eliminated via the renal route and the usual dose must be modified in patients with severe renal impairment. This review is an attempt to supply physicians with the more recent data on pharmacokinetic studies of new drugs administered in uraemic patients. The review is in 2 parts: the first indicates the results of studies on the pharmacokinetics of antibiotic agents, antifungal, antiviral and antiulcer drugs, and nonsteroidal anti-inflammatory drugs. Special mention is made of epoetin (recombinant human erythropoietin). It was not possible to give all the information collected from the recent literature: since mild renal failure has little effect on the fate of a drug, pharmacokinetic data obtained in patients with a creatinine clearance (CLCR) of more than 50 ml/min has been omitted. Both the text and tables give recommendations for treating patients with moderate renal insufficiency (CLCR of about 50 ml/min), more severe renal impairment (CLCR between 10 and 50 ml/min) and end-stage renal failure with a very low creatinine clearance (below 10 ml/min). It was not possible to give uniform recommendations (i.e. reducing the dose while maintaining the same interval, or giving the same dose and prolonging the interval). This article follows the recommendations of the authors, which may vary for drugs in similar classes.