Linezolid Population Pharmacokinetics to Improve Dosing in Cardiosurgical Patients: Factoring a New Drug-Drug Interaction Pathway.

BACKGROUND: Linezolid-induced myelosuppression limits optimal therapy in cardiosurgical patients with deep-seated infections at current doses. METHODS: Adult patients who received a cardiac surgery intervention and linezolid for a documented or presumed serious gram-positive infection were evaluated. Therapeutic monitoring data, dosing, concomitant medications, and other pertinent laboratory data were collected retrospectively. A population pharmacokinetic model was constructed to identify covariates and test potential drug-drug interactions that may account for interpatient variability. Simulations from the final model identified doses that achieve a target therapeutic trough concentration of 2-8 mg/L. RESULTS: This study included 150 patients (79.3% male) with sepsis and hospital-acquired pneumonia in 71.7% as the primary indication. The population had a median (minimum-maximum) age, body weight, and estimated glomerular filtration rate (eGFR) of 66 (30-85) years, 76 (45-130) kg, and 46.8 (4.9-153.7) mL/minute, respectively. The standard linezolid dosage regimen achieved the therapeutic range in only 54.7% of patients. Lower-than-standard doses were necessary in the majority of patients (77%). A 2-compartment Michaelis-Menten clearance model with weight, kidney function, and the number of interacting drugs identified as covariates that best fit the concentration-time data was used. Cyclosporine had the greatest effect on lowering the maximum elimination rate (Vmax) of linezolid. Empiric linezolid doses of 300-450 mg every 12 hours based on eGFR and the number of interacting medications are suggested by this analysis. CONCLUSIONS: Lower empiric linezolid doses in cardiosurgical patients may avoid toxicities. Confirmatory studies are necessary to verify these potential drug interactions.

Hyposmia and Dysgeusia in COVID-19: Indication to Swab Test and Clue of CNS Involvement.

OBJECTIVE: To evaluate the prevalence of hyposmia and dysgeusia in patients with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection and their temporal relationship with the onset of other symptoms. METHODS: We performed a retrospective analysis of patients admitted during the month of March 2020 to the nonintensive COVID unit of Udine University Hospital on the basis of a positive swab test and/or of clinical-radiologic signs of SARS-CoV-2 infection. Patients were interviewed with a standardized questionnaire. Clinical and laboratory data were collected. Data were analyzed with descriptive statistics, and results expressed as point estimates and 95% confidence intervals (CIs). RESULTS: Of 141 patients admitted, 93 were interviewed. Hyposmia and dysgeusia were present in 58 cases (62.4%). In 22.4% of them, olfactory and gustatory impairment clearly preceded systemic symptoms. The presence of active smoking was very limited in both groups: 8.6% in hyposmic vs 2.9% in normosmic patients (odds ratio 3.2; 95% CI 0.3-28.6). Moreover, total leukocytes and neutrophils count were respectively 23% (effect estimate 1.23; 95% CI 1.06-1.42) and 29% (effect estimate 1.29; 95% CI 1.07-1.54) lower in the hyposmic cohort. No difference was found for other inflammatory biomarkers. CONCLUSIONS: Hyposmia and dysgeusia are common in SARS-CoV-2 infection and can precede systemic symptoms. They should be actively searched and prompt close monitoring and isolation until infection is confirmed or disproven. The lower number of total leukocytes and neutrophils in hyposmic patients might indicate an early-phase virus-induced cytopenia.