Assessment of micafungin loading dosage regimens against Candida spp. in ICU patients by Monte Carlo simulations

Association of doses based on body constitutional parameters with the efficacy of micafungin in candidemia

BACKGROUND

Invasive candidiasis is a life-threatening infection associated with high mortality, necessitating early and effective treatment. Micafungin, an echinocandin, is recommended as initial therapy for invasive candidiasis. However, the optimal micafungin dose relative to patients' body constitutional parameters (BCPs) remains unclear. This study aimed to evaluate the relationship between the dose of micafungin per BCPs (Dose/BCPs) and treatment outcomes.

METHODS

This two-center retrospective study included patients treated with micafungin who had confirmed positive blood cultures for Candida species between January 1, 2010, and December 31, 2020. We assessed the association between Dose/BCP and treatment success, as well as time to recovery following micafungin therapy.

RESULTS

Eighty-three patients were included in the analysis, with a median age of 78 years. The primary isolated Candida species were Candida albicans (n = 34), Candida parapsilosis (n = 19), and Candida glabrata (n = 16). The treatment success rate was 44.6 % and was significantly associated with age ≥75 years. Although no significant differences in Dose/BCP were observed between the success and failure groups, patients with a Dose/BSA ≥100 mg/m2 experienced a significantly shorter time to recovery with micafungin therapy.

CONCLUSION

Our study identified an association between Dose/BSA and the time to recovery with micafungin therapy. While some missing data, including APACHE-II scores, limit the robustness of the findings because of the retrospective design, dose adjustment to achieve Dose/BSA ≥100 mg/m2 may be beneficial in antifungal stewardship. This adjustment could reduce treatment duration with this broad-spectrum antifungal agent.

Factors influencing methotrexate pharmacokinetics highlight the need for individualized dose adjustment: a systematic review

PURPOSE

To develop a population pharmacokinetic (PPK) model for methotrexate (MTX) dosage for all ages, assess the association between concentration and clearance, and determine covariates affecting MTX disposition.

METHODS

We compared MTX PK profiles among neonates, children, and adults by performing a systematic literature search for published population MTX models and conducted a Monte Carlo-based meta-analysis. Subsequently, we evaluated study quality and covariates significantly affecting dosage regimens and compared LDMTX and HDMTX PK profiles.

RESULTS

Of the total 40 studies included, 34 were HDMTX, and six were LDMTX studies. For HDMTX, three studies involving neonates reported estimated apparent clearances (median, range) of 0.53 (0.27-0.77) L/kg/h; for 14 studies involving children, 0.23 (0.07-0.23) L/kg/h; and for 13 involving adults, 0.11 (0.03-0.22) L/kg/h. Neonates had a higher volume of distribution than children and adults. For LDMTX studies, apparent clearance was 0.085 (0.05-1.68) L/kg/h, and volume of distribution was 0.25 (0.018-0.47) L/kg, lower than those of HDMTX studies, with large between-subject variability. Bodyweight significantly influenced apparent clearance and volume of distribution, whereas renal function mainly influenced clearance. Mutations in certain genes reduced MTX clearance by 8-35.3%, whereas those in others increased it by 15-48%. Body surface area (BSA) significantly influenced apparent clearance with a median reduction of 51% when BSA increased in pediatric patients.

CONCLUSIONS

Methotrexate dosage regimens were primarily based on body surface area and renal function. Further studies are needed to evaluate MTX pharmacokinetics and pharmacodynamics in both children (especially infants) and adults.