Pharmacokinetics of Telavancin in Adult Patients with Cystic Fibrosis during Acute Pulmonary Exacerbation.

Adults with cystic fibrosis (CF) frequently harbor Staphylococcus aureus, which is increasingly antibiotic resistant. Telavancin is a once-daily rapidly bactericidal antibiotic active against methicillin-, linezolid-, and ceftaroline-resistant S. aureus Because CF patients experience alterations in pharmacokinetics, the optimal dose of telavancin in this population is unknown. Adult CF patients (n = 18) admitted for exacerbations received 3 doses of telavancin 7.5 mg/kg of body weight (first 6 patients) or 10 mg/kg (final 12 patients) every 24 h (q24h). Population pharmacokinetic models with and without covariates were fitted using the nonparametric adaptive grid algorithm in Pmetrics. The final model was used to perform 5,000-patient Monte Carlo simulations for multiple telavancin doses. The best fit was a 2-compartment model describing the volume of distribution of the central compartment (Vc ) as a multiple of total body weight (TBW) and the volume of distribution of the central compartment scaled to total body weight (Vθ) normalized by the median observed value (Vc = Vθ × TBW/52.1) and total body clearance (CL) as a linear function of creatinine clearance (CRCL) (CL = CLNR + CLθ × CRCL), where CLNR represents nonrenal clearance and CLθ represents the slope term on CRCL to estimate renal clearance. The mean population parameters were as follows: Vθ, 4.92 ± 0.76 liters · kg-1; CLNR, 0.59 ± 0.30 liters · h-1; CLθ, 5.97 × 10-3 ± 1.24 × 10-3; Vp (volume of the peripheral compartment), 3.77 ± 1.41 liters; Q (intercompartmental clearance), 4.08 ± 2.17 liters · h-1 The free area under the concentration-time curve (fAUC) values for 7.5 and 10 mg/kg were 30 ± 4.6 and 52 ± 12 mg · h/liter, respectively. Doses of 7.5 mg/kg and 10 mg/kg achieved 76.5% and 100% probability of target attainment (PTA) at a fAUC/MIC threshold of >215, respectively, for MIC of ≤0.12 mg/liter. The probabilities of reaching the acute kidney injury (AKI) threshold AUC (763 mg · h · liter-1) for these doses were 0% and 0.96%, respectively. No serious adverse events occurred. Telavancin 10 mg/kg yielded optimal PTA and minimal risk of AKI, suggesting that this FDA-approved dose is appropriate to treat acute pulmonary exacerbations in CF adults. (The clinical trial discussed in this study has been registered at ClinicalTrials.gov under identifier NCT03172793.).

High-dose Cholecalciferol Supplementation in Adults with Cystic Fibrosis.

INTRODUCTION: Despite the availability of consensus guidelines for the treatment of vitamin D deficiency, prospective trials are lacking to examine alternative dosing strategies for adult patients with cystic fibrosis (CF) who do not meet therapeutic goals with standard regimens. OBJECTIVES: The primary objective of this study was to determine the efficacy of high-dose cholecalciferol supplementation in increasing serum vitamin D (25-OHD) levels in adult patients with CF. METHODS: Patients were eligible for inclusion if they were 18 years or older, had baseline 25-OHD levels lower than 30 ng/ml, and were diagnosed with CF and pancreatic insufficiency. Patients were given a single dose of cholecalciferol 300,000 or 500,000 IU based on baseline 25-OHD levels. Response was defined by 25-OHD and ionized calcium levels at 3 months. At 6 months, responders received a second dose of the same strength, and nonresponders were given a weekly supplement of cholecalciferol 50,000 IU in addition to cholecalciferol 500,000 IU. A second 25-OHD level was obtained at 9 months. RESULTS: Of the 46 patients enrolled, 32 patients (70%) completed the study. Baseline levels of 25-OHD significantly increased over time in the per protocol population at 3 and 9 months. A total of 16 patients (50%) were considered nonresponders and required weekly supplementation. CONCLUSION: A protocol using high-dose cholecalciferol or high-dose plus weekly cholecalciferol is safe and effective in treating adult patients with CF and pancreatic insufficiency.