micafungin and Obesity

Obesity is a worldwide epidemic associated with multiple comorbidities that increase the risk of hospitalization. Very little pharmacokinetic data are available for antifungal agents in obesity, as this population is often excluded from drug development studies and these agents are less commonly used than other antimicrobials. Systemic antifungal therapy for invasive candidiasis continues to have a high failure rate, and dose optimization in obesity provides an opportunity for improvement. Based on currently available data, some antifungals should be dosed based on total body weight (i.e. fluconazole), while others should not be adjusted for increased body weight (i.e. posaconazole). More studies are needed to determine if and when dosing changes are needed for many of the antifungal agents. Therefore, drug therapy regimens should be individually evaluated for dose optimization due to body weight.

Topics: Amphotericin B; Antifungal Agents; Candidiasis, Invasive; Caspofungin; Echinocandins; Fluconazole; Humans; Lipopeptides; Micafungin; Mycoses; Nitriles; Obesity; Pyridines; Triazoles

Echinocandins belong to the class of antifungal agents. Currently, three echinocandin drugs are licensed for intravenous treatment of invasive fungal infections: anidulafungin, caspofungin and micafungin. While their antifungal activity overlaps, there are substantial differences in pharmacokinetics (PK). Numerous factors may account for variability in PK of echinocandins including age (pediatrics vs adults), body surface area and body composition (normal weight vs obesity), disease status (e.g., critically ill and burn patients) and organ dysfunction (kidney and liver impairment). Subsequent effects of altered exposure might impact efficacy and safety. Knowledge of PK behavior is crucial in optimal clinical utilization of echinocandin in a specific patient or patient population. This review provides up-to-date information on PK data of anidulafungin, caspofungin and micafungin in special patient populations. Patient populations addressed are neonates, children and adolescents, obese patients, patients with hepatic or renal impairment, critically ill patients (including burn patients) and patients with hematological diseases.

Topics: Adolescent; Adult; Anidulafungin; Antifungal Agents; Candida; Caspofungin; Child; Critical Illness; Drug Interactions; Echinocandins; Hematologic Diseases; Humans; Infant, Newborn; Kidney; Lipopeptides; Liver; Micafungin; Microbial Sensitivity Tests; Obesity

The majority of Americans are overweight, and the incidence of obesity continues to increase. This trend predisposes people to a number of deleterious consequences, including the metabolic syndrome and other conditions that lead to a greater number of hospital admissions. Invasive candidiasis is an important nosocomial infection that results from these admissions. Echinocandins such as micafungin are indicated for treatment. We have previously demonstrated that overweight patients exhibit higher micafungin systemic clearance (SCL) than leaner patients. We hypothesized that obese and extremely obese people would show even higher SCL than merely overweight patients. To test this, we performed a prospective study of 36 adult volunteers randomized to receive a single dose of either 100 mg or 300 mg of micafungin whose body mass index fell within one of the following categories: <25, 25 to 40, and >40 kg/m(2). The male-to-female ratio was 1:1. The minimum weight was 43 kg, the median 97 kg, and the maximum weight 155 kg. A two-compartment model was examined using the maximum likelihood solution via the expectation-maximization algorithm. Men had a higher median SCL of 1.53 liters/h versus 1.29 liters/h (P = 0.01) in the Mann-Whitney U-test. The typical SCL was 1.04 liters/h but increased by a factor of (weight/66)(0.75) as weight increased above 66 kg. Thus, the relationship between micafungin SCL and weight in adults is best described by fractal-geometry-based laws. Furthermore, micafungin SCL continues to increase as weight increases, with no obvious plateau. This leads to a requirement for strategies to determine individualized dosing levels for obese and extremely obese patients.

Topics: Adult; Antifungal Agents; Body Mass Index; Body Weight; Echinocandins; Female; Humans; Lipopeptides; Male; Micafungin; Middle Aged; Obesity; Overweight; Young Adult

The rising pandemic of obesity means an increasing number of obese patients who require antimicrobial therapy for serious infections. Micafungin is an echinocandin drug frequently used as therapy or prophylaxis for fungal infections, predominantly with Candida species. In order to maximize the efficacy of micafungin in obese patients, the dose that corresponds to optimal exposure for each obese individual needs to be identified.. We performed a prospective study in 16 obese and 8 normal-weight healthy subjects with a weight ranging from 61.5-184 kg (ClinicalTrials.gov Identifier: NCT03102658). A population pharmacokinetic model was developed and used to simulate several dosing regimens to evaluate the PTA for relevant MICs to define the optimal dose using the pharmacokinetic/pharmacodynamic target of an AUC/MIC ratio above 5000.. Total body weight was found to be most predictive for CL and V. Simulations showed that a 100 mg dose results in a PTA of >90% in patients weighing ≤125 kg infected with a Candida species having an MIC of 0.016 mg/L. The maintenance dose should be increased to 200 mg in patients >125 kg infected with a Candida species with an MIC of 0.016 mg/L. For an MIC of 0.032 mg/L, a 300 mg maintenance dose is recommended above 125 kg weight. Furthermore, we demonstrate that patients can benefit from a loading dose (i.e. twice the maintenance dose).. We present easy-to-use dose recommendations for obese patients, based on both weight and target MIC, that result in adequate exposure in patients with body weight up to 190 kg.

Topics: Adolescent; Adult; Antifungal Agents; Biostatistics; Candida; Female; Healthy Volunteers; Humans; Male; Micafungin; Microbial Sensitivity Tests; Middle Aged; Obesity; Plasma; Prospective Studies; Young Adult

There are 2.1 billion people worldwide who are overweight or obese. However, most current doses of drugs were derived for normal weight patients. For several drugs, the relationship between clearance and patient weight follows fractal geometry rules. Clearance directly determines the area under the concentration time curve (AUC) after i.v. infusion. For micafungin, AUC-to-minimum inhibitory concentration (AUC/MIC) ratios have a close deterministic relationship with efficacy in candidiasis; an AUC/MIC ≥3,000 is associated with 98% efficacy. We performed computer-aided clinical trial simulations of 100,000 patients with candidiasis to identify the lowest micafungin dose able to achieve AUC/MIC ≥3,000 in patients weighing up to 200 kg. We used the cumulative fraction of response to derive the formula "Dose (mg) = patient weight + 42" for use by the clinician at the bedside to individualize micafungin doses for overweight and obese patients. This paradigm for dose individualization could be used to optimize efficacy for many classes of anti-infective agents in obese patients.

Topics: Antifungal Agents; Candidiasis; Clinical Trials as Topic; Computer Simulation; Drug Dosage Calculations; Echinocandins; Fractals; Humans; Lipopeptides; Micafungin; Obesity; Overweight; Patient-Specific Modeling