Crystal nephropathy and amoxicillin: insights from international spontaneous reporting systems

Amoxicillin Blood Concentration in High-Dose Intravenous Discontinuous Amoxicillin: Look Beyond Numbers. Max-Amox Study

PURPOSE

High doses of amoxicillin are recommended to treat severe infections such as endocarditis. Amoxicillin causes dose-dependent toxicities, in particular crystal nephropathy. Toxicity could be avoided by monitoring of amoxicillin trough plasma concentrations (ATPC). However, the relevance of ATPC testing in routine medical practice remains poorly studied.

METHODS

We conducted a prospective clinical trial in adults treated with high doses of discontinuous intravenous amoxicillin in a French university hospital. The primary outcome was the distribution of ATPCs over three days during the first week of treatment. Urine tests for amoxicillin crystalluria (AC), pH, and density were also performed.

FINDINGS

Seventy patients were included. Overall intra-class correlation (ICC) was 0.35 IC95% [0.21; 0.53] with the following pairwise concordances: D1-D4 (n= 55) 0.23 IC95% [-0.02; 0.47], D1-D7 (n= 47) 0.41 IC95% [0.19; 0.63], and D4-D7 (n= 50) 0.17 IC95% [-0.10; 0.43]. Inter-individual variability was also significant, with coefficients of variation being 0.87 at D1, 1.20 at D4, and 1.35 at D7. AC occurred in 32 patients (47.8%). Risk of AC increased when pH was below or equal to 6 (P = 0.002). ATPCs were higher in patients with AC and/or acute kidney injury.

IMPLICATIONS

Variability in ATPC was high and ATPC cannot be considered as the only monitoring tool to adjust amoxicillin dosage. High ATPC, low urinary pH, and presence of AC can alert physicians to a potential iatrogenic effect and lead to the decision to hydrate the patient, alkalinize urine and decrease the dosage of amoxicillin.

Amoxicillin crystalluria and amoxicillin-induced crystal nephropathy: a narrative review

Amoxicillin crystalluria (AC) refers to the precipitation of amoxicillin in the urine as amoxicillin trihydrate crystals. Amoxicillin-induced crystal nephropathy (AICN) refers to the obstruction of kidney tubules by amoxicillin trihydrate crystals, resulting in acute kidney injury. Usually considered rare and not serious, AC and AICN would be more frequent in patients receiving high-dose i.v. amoxicillin (≥150 mg/kg per day) than previously reported. AC prevalence ranges from 24% to 41%. AICN prevalence remains unclear. AC is generally asymptomatic, but sudden macroscopic hematuria with cloudy urine suggests the diagnosis. AC is diagnosed by detecting amoxicillin trihydrate crystals in urine. AC is a risk factor for acute kidney injury. Diagnosing AICN is more challenging in the absence of noninvasive diagnostic tools. It is suspected in high-dose i.v. amoxicillin-treated patients who develop acute kidney injury and AC, and after excluding other causes of acute kidney injury (mainly sepsis and acute interstitial nephritis). When testing for AC is unavailable, the presence of demonstrated (high blood amoxicillin levels and low urinary pH) or suspected (rapid i.v. amoxicillin administration and hypovolemia) risk factors for AC suggests its diagnosis. AICN management includes discontinuation/reduction of amoxicillin doses and volume resuscitation to improve tubular flow and urine output and decrease amoxicillin supersaturation. Patients generally recover normal kidney function rapidly after stopping amoxicillin, but renal replacement therapy is required in 10%-40% of patients. No deaths have been directly attributed to AICN. Future studies are needed to assess the exact prevalence of AC/AICN and to define optimal therapeutic options.

Pharmacovigilance Strategies to Address Resistance to Antibiotics and Inappropriate Use-A Narrative Review

The spread of antimicrobial resistance (AMR) is a global challenge. Close and continuous surveillance for quick detection of AMR can be difficult, especially in remote places. This narrative review focuses on the contributions of pharmacovigilance (PV) as an auxiliary tool for identifying and monitoring the ineffectiveness, resistance, and inappropriate use of antibiotics (ABs). The terms "drug ineffective", "therapeutic failure", "drug resistance", "pathogen resistance", and "multidrug resistance" were found in PV databases and dictionaries, denoting ineffectiveness. These terms cover a range of problems that should be better investigated because they are useful in warning about possible causes of AMR. "Medication errors", especially those related to dose and indication, and "Off-label use" are highlighted in the literature, suggesting inappropriate use of ABs. Hence, the included studies show that the terms of interest related to AMR and use are not only present but frequent in PV surveillance programs. This review illustrates the feasibility of using PV as a complementary tool for antimicrobial stewardship activities, especially in scenarios where other resources are scarce.

Incidence, associated factors, and effect on renal function of amoxicillin crystalluria in patients receiving high doses of intravenous amoxicillin (The CRISTAMOX Study): A cohort study

BACKGROUND

Amoxicillin crystalluria (AC), potentially responsible for acute kidney injury (AKI), is reported more and more frequently in patients treated with high doses of intravenous amoxicillin (HDIVA). The main objective of this study was to evaluate AC incidence in these patients. The secondary objectives were to identify factors associated with AC and to evaluate its impact on the risk of AKI.

METHODS

This multicentre, observational, cohort study was conducted between Mar 18, 2014 and Aug 16, 2019 in Dijon, Nancy, and Reims University Hospitals as well as Châlon-sur-Saône, Charleville-Mézières, and Troyes general hospitals in France. Adult patients (≥18 years) treated with HDIVA and having been tested for AC at least once during treatment were included. Clinical, biological, and therapeutic characteristics of the patients were collected. A univariable mixed logistic regression model assessed the factors associated with AC. A multivariable Cox model with AC as a time-dependent variable assessed the prognostic factors for AKI. ClinicalTrials.gov number: NCT02853292.

FINDINGS

Of the 112 included patients, 27 (24.1%, 95% CI [16.2-32.0]) developed at least one episode of AC within a mean of 5.1 days. The factors associated with its occurrence were the concomitant use of angiotensin converting enzyme (ACE) inhibitors (OR=4.6, 95% CI [2.2-9.3], p<0.0001) and the decrease of urinary pH (OR=2.1 for one pH point decrease, 95% CI [1.2-3.7], p=0.009). 20 patients (17.9%) presented with AKI, within a mean time of 10.9 days. The main factor associated with the occurrence of AKI was the occurrence of AC (aHR=7.4, 95% CI [2.5-22.2], p=0.0003).

INTERPRETATION

AC occurred in a quarter of patients treated with HDIVA and was highly prognostic of AKI.

FUNDING

None.