Determination of cidofovir in human plasma after low dose drug administration using high-performance liquid chromatography-tandem mass spectrometry

Analytical Methods for Determination of Antiviral Drugs in Different Matrices: Recent Advances and Trends

Viruses are the main pathogenic substances that cause severe diseases in humans and other living things. They are among the most common microorganisms, and consequently, antiviral drugs have emerged to prevent and treat viral infections. Antiviral drugs are an essential drug group considering their prescription and consumption rates for different diseases and indications. Therefore, it is crucial to develop accurate and precise analytical methods to detect antiviral drugs in various matrices. Chromatographic techniques are used frequently for the quantification purpose since they allow simultaneous determination of antivirals. Electrochemical methods have also gained importance since the analysis can be performed quickly without the need for pretreatment. Spectrophotometric and spectrofluorimetric methods are used because they are simple, inexpensive, and less time-consuming methods. The purpose of this review is to present an overview of the analysis of currently used antiviral drugs from 2010 to 2021. Since studies on antiviral drugs are numerous, selected publications were reviewed in this article. The analysis of antiviral drugs was divided into three main groups: chromatographic, spectrometric, and electrochemical methods which were applied to different matrices, including pharmaceutical, biological, and environmental samples.

Tandem mass spectrometry of small-molecule antiviral drugs: 3. antiviral agents against herpes, influenza and other viral infections

For the treatment of various viral infections, antiviral drugs may be used. Liquid chromatography-mass spectrometry (LC-MS) with tandem mass spectrometry (MS-MS) operated in selected-reaction monitoring (SRM) mode is the method of choice in quantitative bioanalysis of drugs, e.g., to establish bioavailability, to study pharmacokinetics, and later on possibly for therapeutic drug monitoring. In this study, the fragmentation in MS-MS of small-molecule antiviral drugs against herpes and influenza viruses is reviewed. In this way, insight is gained on the identity of the product ions used in SRM. Fragmentation schemes of antiviral agents are also relevant in the identification of drug metabolites or (forced) degradation products. As information of the fragmentation of antiviral drugs in MS-MS and the identity of the product ions is very much scattered in the scientific literature, it was decided to collect this information and to review it. In this third study, attention is paid to small-molecule antiviral agents used against herpes and influenza virus infections. In addition, some attention is paid to broad-spectrum antiviral agents, that are investigated with respect to their efficacy in challenging virus infections of this century, e.g., involving Ebola, Zika and corona viruses, like SARS-CoV-2, which is causing a world-wide pandemic at this very moment. The review provides fragmentation schemes of ca. 35 antiviral agents. The identity of the product ions used in SRM, i.e., elemental composition and exact-m/z, is tabulated, and more detailed fragmentation schemes are provided.

Model of population pharmacokinetics of cidofovir in immunocompromised children with cytomegalovirus and adenovirus infection

Objectives

To describe cidofovir pharmacokinetics and assess the link between concentration and safety/efficacy in children.

Patients and methods

An observational study was conducted in 13 immunocompromised children receiving cidofovir for adenovirus and/or cytomegalovirus infection. A population pharmacokinetic model was built and AUC0-24 was derived for each patient. Virological success was defined as a decrease of the viraemia by ≥1 log10 copies/mL within 15 days of cidofovir initiation. The association between AUC0-24 and virological success was assessed using a Wilcoxon test. An AUC0-24 cut-off value was determined using a Fisher's exact test.

Results

Overall, 86 blood samples were analysed. A two-compartment model with first-order absorption and elimination best described the cidofovir data. Virological success (VS) was reached in 6/8 children with adenovirus viraemia and in 1/4 children with cytomegalovirus viraemia. Patients with VS displayed a non-significant higher median AUC0-24 compared with patients with virological failure: 48.6 (range 8.9-72.6) versus 19.1 (6.9-22.7) mg·h/L. Adenovirus-viraemic patients with an AUC0-24 value below 19.1 mg·h/L had a higher probability of treatment failure (P = 0.03). Aviraemic children with stool and/or nasopharyngeal adenovirus carriage cleared the viral carriage within a month of cidofovir initiation. During treatment, 1/13 children developed a tubulopathy but none of them had an increase in creatininaemia.

Conclusions

Cidofovir appears safe and reasonably well tolerated and seemed to have efficacy in a subset of patients with adenovirus/cytomegalovirus infection. Therapeutic drug monitoring may be useful in children receiving cidofovir and, in the case of adenovirus infection, targeting an AUC0-24 above 19.1 mg·h/L could be associated with higher probability of virological success.

Pharmacokinetics and safety of intravenous cidofovir for life-threatening viral infections in pediatric hematopoietic stem cell transplant recipients

Children undergoing hematopoietic stem cell transplantation (HSCT) are at risk for life-threatening viral infections. Cidofovir is often used as a first-line agent for adenovirus infections, despite the absence of randomized controlled trials with HSCT patients, and as a second-line agent for resistant herpesvirus infections. The frequency and severity of adverse effects, particularly nephrotoxicity, in pediatric HSCT recipients are unclear, and pharmacokinetics (PK) of cidofovir in children have not previously been reported. This study was an open-label, nonrandomized, single-dose pilot study to determine the safety and PK of cidofovir in pediatric HSCT recipients with symptomatic adenovirus, nucleoside-resistant cytomegalovirus (CMV) or herpes simplex virus (HSV), and/or human papovavirus infections. Subsequent dosing and frequency were determined by clinical response and side effects, as assessed by the treating physician. Blood and urine samples were obtained from patients for PK studies and assessment of toxicity and virologic response. Twelve patients were enrolled (median age, 9 years; 33.5 days posttransplantation). Four of seven patients with adenovirus infection were successfully treated and eventually cleared their infections. Four of twelve patients died of disseminated viral disease and multiorgan failure. Two of twelve patients had evidence of acute kidney injury after the first dose, and one of these patients developed chronic kidney disease; two other patients developed late nephrotoxicity. The mean drug half-life was 9.5 h. There was no correlation between nephrotoxicity and plasma maximum concentration, clearance, or half-life. PK were similar to those reported for adults, although the drug half-life was significantly longer than that for adults. Cidofovir was well tolerated in the majority of patients. However, effective therapeutic strategies are urgently needed to support patients until immune reconstitution is achieved.

Pharmacokinetics of low-dose cidofovir in kidney transplant recipients with BK virus infection

BACKGROUND

BK virus (BKV) infection in kidney transplant recipients is associated with progressive graft dysfunction and graft loss. Cidofovir, an antiviral agent with known nephrotoxicity, has been used in low doses to treat BKV infections. However, the systemic exposure and disposition of the low-dose cidofovir regimen are not known in kidney transplant recipients.

METHODS

We investigated the pharmacokinetics (PK) of low-dose cidofovir (0.24 - 0.62 mg/kg) both without and with oral probenecid in 9 transplant patients with persistent BK viremia without nephropathy in a crossover design.

RESULTS

The mean estimated glomerular filtration rate (eGFR) of the study participants was 46.2 mL/min/1.73 m(2) (range: 17-75 mL/min/1.73 m(2) ). The contribution of active renal secretion to cidofovir total body clearance was assessed by evaluating the effect of probenecid on cidofovir PK. Maximum cidofovir plasma concentrations, which averaged approximately 1 μg/mL, were significantly below the 36 μg/mL 50% effective concentration in vitro for cidofovir against BKV. The plasma concentration of cidofovir declined with an overall disposition half-life of 5.1 ± 3.5 and 5.3 ± 2.9 h in the absence and in the presence of probenecid, respectively (P > 0.05).

CONCLUSIONS

Cidofovir clearance and eGFR were linearly related irrespective of probenecid administration (r(2) = 0.8 without probenecid; r(2) = 0.7 with probenecid). This relationship allows for the prediction of systemic cidofovir exposure in individual patients and may be utilized to evaluate exposure-response relationships to optimize the cidofovir dosing regimen for BKV infection.