Amikacin Pharmacokinetics/Pharmacodynamics in a Novel Hollow-Fiber Mycobacterium abscessus Disease Model

The treatment of pulmonary Mycobacterium abscessus disease is associated with very high failure rates and easily acquired drug resistance. Amikacin is the key drug in treatment regimens, but the optimal doses are unknown. No good preclinical model exists to perform formal pharmacokinetics/pharmacodynamics experiments to determine these optimal doses. We developed a hollow-fiber system model of M. abscessus disease and studied amikacin exposure effects and dose scheduling. We mimicked amikacin human pulmonary pharmacokinetics. Both amikacin microbial kill and acquired drug resistance were linked to the peak concentration-to-MIC ratios; the peak/MIC ratio associated with 80% of maximal kill (EC₈₀) was 3.20. However, on the day of the most extensive microbial kill, the bacillary burden did not fall below the starting inoculum. We performed Monte Carlo simulations of 10,000 patients with pulmonary M. abscessus infection and examined the probability that patients treated with one of 6 doses from 750 mg to 4,000 mg would achieve or exceed the EC₈₀. We also examined these doses for the ability to achieve a cumulative area under the concentration-time curve of 82,232 mg · h/liter × days, which is associated with ototoxicity. The standard amikacin doses of 750 to 1,500 mg a day achieved the EC₈₀ in ≤21% of the patients, while a dose of 4 g/day achieved this in 70% of the patients but at the cost of high rates of ototoxicity within a month or two. The susceptibility breakpoint was an MIC of 8 to 16 mg/liter. Thus, amikacin, as currently dosed, has limited efficacy against M. abscessus. It is urgent that different antibiotics be tested using our preclinical model and new regimens developed.     

Effects of Age on the Pharmacokinetics and Pharmacodynamics of Cardiovascular Drugs: Application of Concentration-Effect Modeling. 3. Trimazosin

The effects of age on the disposition and hemodynamic responses to the selective post-synaptic alpha(1) adrenoceptor antagonist trimazosin were examined in an integrated manner using a combined pharmacokinetic--pharmacodynamic (PKPD) modeling approach. Thirty subjects were studied to represent, as far as was possible an age continuum. Single doses of trimazosin (100 mg) and placebo were administered intravenously and blood was withdrawn and heart rate and blood pressure were measured at frequent intervals up to 10 h post dose. Based on regression analysis there was a statistically significant decline in the clearance of trimazosin with increasing age. In addition, based on the ratio of the AUC values for the major metabolite and parent drug, there was evidence of a decline in the relative clearance of matabolite with increasing age. Trimazosin when compared with placebo produced significant changes in blood pressure and heart rate that were statistically greater in elderly subjects. PKPD modeling revealed that both trimazosin and its metabolite 1-hydroxy trimazosin contributed significantly to the hemodynamic profile of the drug but the blood pressure responsiveness to both parent drug and metabolite were unaffected by age. Thus the greater response in the elderly subjects could be attributed to the decline in drug clearance with age.     

Comparison of Plasma Protein Binding of Basic Drugs in Black and White Individuals

Interethnic difference in drug disposition is an important contributing factor to interindividual variation in drug response. Since interethnic differences in the protein binding of drugs may contribute to variation in drug disposition between ethnic groups, we conducted a study in 10 black Americans (A) and mean (plus minusSE) age 26 plus minus 6 years and weight 80 plus minus 9 kg matched against 10 white Americans (C) with a mean age of 28 plus minus 6 years and weight 81 plus minus 9 kg, all within 10% of ideal body weight. Serum alpha-1-acid glycoprotein (AGP) and albumin concentrations were measured using the auramine-O and bromcresol green methods, respectively. Verapamil, propranolol, lidocaine, disopyramide and diazepam binding in plasma were measured with the equilibrium-dialysis method, involving the determination of free and unbound drug concentrations. The unbound fraction of diazepam (A = 1.1 plus minus 0.1%; C = 1.1 plus minus 0.1%), verapamil (A = 9.5 plus minus 0.8%; C = 9.8 plus minus 0.4%), propranolol (A = 14.2 plus minus 1.0%; C = 12.6 plus minus 0.7%), lidocaine (A = 28.5 plus minus 2.1%; C = 25.7 plus minus 1.1%) and diphenhydramine (A = 42.9 plus minus 10.2; C = 30.4 plus minus 7.01%) showed no significant ethnic differences (unpaired t-test). Disopyramide measured at 7 different concentrations (1.0--20.0 &mgr;g/ml) was similar in both groups, as were the plasma concentrations of AGP (A = 100 plus minus 20 mg 100 ml; C = 120 plus minus 20 mg 100 ml) and albumin (A = 4.3 plus minus 0.1 g 100 ml; C = 4.5 plus minus 0.1 g 100 ml). It is therefore concluded that there are no interethnic differences in the protein binding of basic drugs between black Americans and white Americans and that it is not a major contributing factor to any possible interethnic variation in the disposition of responsiveness of these drugs.     

Effect of Food on the Pharmacokinetics and Pharmacodynamics of Torsemide

The effect of food on the bioavailability, pharmacokinetics, and pharmacodynamics of oral torsemide was examined in a group of 14 healthy male volunteers. Administration of torsemide with a standard high-fat, high-carbohydrate breakfast resulted in a decrease in absorption rate (fed: C(max) 988 plus minus 269 ng ml(minus sign1), T(max) 1.50 plus minus 0.64 h; fasting: C(max) 1466 plus minus 202 ng ml(minus sign1), T(max) 0.89 plus minus 0.37 h) but no change in the extent of absorption (fed: AUC 3424 plus minus 841 h ng ml(minus sign1); fasting: AUC 3357 plus minus 859 h ng ml(minus sign1)) or the amount of drug excreted unchanged (fed: % dose 23.5 plus minus 4.3; fasting: % dose 23.7 plus minus 6.2). Elimination half-life and renal clearance were unchanged. These minor alterations in the pharmacokinetics of the drug were not reflected by a change in either the pharmacodynamic relationship between urinary sodium and drug excretion rates or the cumulative amount of electrolytes and urine excreted. The diuretic effect of torsemide will be consistent regardless of drug administration relative to food intake.     

The Effects of Age on the Pharmacokinetics and Pharmacodynamics of Cardiovascular Drugs: Application of Concentration-Effect Modeling. 1. Tolmesoxide

The effects of age on the disposition and hemodynamic responses to the direct acting vasodilator tolmesoxide were examined in an integrated manner using a combined pharmacokinetic--pharmacodynamic (PKPD) modeling approach. Thirty subjects were studied to represent, as far as was possible, an age continuum. Single doses of tolmesoxide (100 mg) and placebo were administered intravenously and blood was withdrawn and heart rate and blood pressure were measured at frequent intervals up to 10 h post dose. No significant effects of age on the disposition of tolmesoxide and its sulfone metabolite were apparent. Tolmesoxide when compared with placebo produced significant changes in blood pressure and heart rate but PKPD modeling failed to demonstrate any significant effects of age on the blood pressure response to tolmesoxide.     

The Effects of Age on the Pharmacokinetics and Pharmacodynamics of Cardiovascular Drugs: Application of Concentration-Effect Modeling. 2. Acebutolol

The effects of age on the disposition and hemodynamic responses to the selective beta(1) adrenoceptor antagonist were examined in an integrated manner using a combined pharmacokinetic--pharmacodynamic (PKPD) modeling approach. Thirty subjects were studied to represent, as far as was possible an age continuum. Single doses of acebutolol (20 mg) and placebo were administered intravenously and blood was withdrawn and heart rate and blood pressure were measured at frequent intervals up to 10 h post dose. No significant effects of age on the disposition of acebutolol and its major acetylated metabolite were apparent. Acebutolol when compared with placebo produced significant changes in blood pressure and heart rate and application of PKPD modeling demonstrated a significant negative correlation between blood pressure responsiveness to acebutolol and age.     

The Pharmacokinetics and Pharmacodynamics of Methylprednisolone in Chronic Renal Failure

Methylprednisolone (MP) pharmacokinetics and its directly suppressive effects on cortisol secretion, circulating T-cells, and basophils in blood were compared in six chronic renal failure (CRF) subjects and six healthy controls after an IV administration of MP 0.6 mg kg(minus sign1) as the sodium succinate ester. The CRF subjects were studied between hemodialysis treatments. The total clearance of methylprednisolone sodium succinate (the prodrug) was reduced by 40% in CRF; however, the pharmacokinetics of methylprednisolone remained unchanged. Methylprednisolone clearance was approximately 280 ml h(minus sign1) kg(minus sign1) and volume of distribution was about 1.1 L kg(minus sign1). Physiological pharmacodynamic models were applied for the immediate effects of MP, based on the premise that receptor binding is followed by rapid suppression of the secretion of cortisol and recirculation of basophils, T-helper cells, and T-suppressor cells, which persist until inhibitory concentrations (IC(50)) of methylprednisolone disappear. The difference in IC(50) for each pharmacodynamic parameter was not statistically significant, suggesting no difference in the responsiveness of these factors to methylprednisolone in CRF. As the pharmacokinetics of other corticosteroids are altered in CRF, the lack of pharmacokinetic and pharmacodynamic changes of methylprednisolone may engender a therapeutic advantage for this corticosteroid in CRF.     

Pharmacokinetics and Pharmacodynamics of Levornidazole in Patients With Intra-abdominal AnaerobicInfection

Purpose

The pharmacokinetic (PK) and pharmacodynamic characteristics of levornidazole were studied in patients with intra-abdominal anaerobic infection to provide the rationale of new clinical dosing regimen of levornidazole.

Pharmacokinetics and Pharmacodynamics of Recombinant Human Insulin-Like Growth Factor

Recombinant human insulin-like growth factor (rhIGF-I) was evaluated in 18 healthy males to determine its effects on serum glucose, its relationship of total IGF levels to serum glucose response and dose proportionality when administered intravenously (IV) and subcutaneously (SQ). One group of six subjects received 60, 120, and 180 &mgr;g kg(minus sign1) IV over 8 h, 1 week apart, and three groups of four subjects received 60, 120, and 180 &mgr;g kg(minus sign1) IV over 8 h, and then 1 week later received 60, 120, and 90 &mgr;g kg(minus sign1) SQ of rhIGF-I, respectively. During each dosing period, placebo and then rhIGF-I was administered on two consecutive days. Intravenous and subcutaneous does of rhIGF-I demonstrated significant decreases in glucose levels as compared to placebo that did not correspond to peak total IGF levels. Sequential repeat administration of IV infusions of rhIGF-I in a single group of subjects demonstrated significant dose-dependent increases, whereas single administration of the doses in three groups of subjects failed to demonstrate dose dependency for either the IV or subcutaneous routes of administration. These findings suggest that saturation of the binding proteins and sites occurred at the lowest dose (60 &mgr;g kg(minus sign1)) evaluated.     

Pharmacokinetics and Pharmacodynamics of Clofazimine in a Mouse Model of Tuberculosis

The antileprosy drug clofazimine has shown potential for shortening tuberculosis treatment; however, the current dosing of the drug is not evidence based, and the optimal dosing is unknown. Our objective was to conduct a preclinical evaluation of the pharmacokinetics and pharmacodynamics of clofazimine in the mouse model of tuberculosis, with the goal of providing useful information on dosing for future studies. Pharmacokinetic parameters were evaluated in infected and uninfected BALB/c mice. Pharmacodynamic parameters were evaluated in Mycobacterium tuberculosis-infected mice that were treated for 12 weeks with one of six different clofazimine dosing regimens, i.e., doses of 6.25, 12.5, and 25 mg/kg of body weight/day and 3 regimens with loading doses. Clofazimine progressively accumulated in the lungs, livers, and spleens of the mice, reaching levels of greater than 50 μg/g in all tissues by 4 weeks of administration, while serum drug levels remained low at 1 to 2 μg/ml. Elimination of clofazimine was extremely slow, and the half-life was dependent on the duration of drug administration. Clofazimine exhibited dose-dependent tissue and serum concentrations. At any dose, clofazimine did not have bactericidal activity during the first 2 weeks of administration but subsequently demonstrated potent, dose-independent bactericidal activity. The antituberculosis activity of clofazimine was dependent on neither the dose administered nor the drug concentrations in the tissues, suggesting that much lower doses could be effectively used for tuberculosis treatment.     

甲磺酸帕珠沙星注射液在健康人体的药动学及药效学研究

目的:研究甲磺酸帕珠沙星注射液的药代动力学及药效学特点.方法:筛选健康受试者12名,单次及多次静滴甲磺酸帕珠沙星注射液,用反向高效液相色谱-紫外法测定血药浓度及尿药浓度,用DASver1.0软件拟合药代动力学参数.结果:甲磺酸帕珠沙星体内过程符合二室模型;单次给药后的药代动力学参数:Tmax为0.47±0.09 h,Cmax为13.71±1.81 mg/L,AUC0-t为24.60±4.15 mgh/L,T1/2为1.46±0.64 h.Q 12 h静滴帕珠沙星500 mg连续5日,第2、3、4、5日晨测得的谷浓度分别为0.13、0.16、0.17、0.14 mg/L,提示血药浓度已达稳态.末剂给药后的药代动力学参数:Tmax为0.48±0.10 h,Cmax为15.41±1.67 mg/L,AUC0-t为28.42±4.90 mg*h/L,T1/2为1.33±0.49 h,(Css)av为2.34±0.43 mg/L,DF为99.48±0.38%,以上参数与单次给药比较除Cmax外差异均无统计学意义,且累积系数小,说明本品多次给药无体内蓄积.女性和男性受试者主要药动学参数比较均无统计学意义.本品对临床大多数常见致病菌的AUC0～24 h/MIC＞ 100且Cmax/MIC＞8.受试者给药期间未出现严重不良反应.结论:500 mg Q 12 h静滴,在人体内可达到有效血药浓度,可作为临床应用的推荐方案.     

Intrapulmonary Pharmacokinetics and Pharmacodynamics of Micafungin in Adult Lung Transplant Patients

Invasive pulmonary aspergillosis is a life-threatening infection in lung transplant recipients; however, no studies of the pharmacokinetics and pharmacodynamics (PKPD) of echinocandins in transplanted lungs have been reported. We conducted a single-dose prospective study of the intrapulmonary and plasma PKPD of 150 mg of micafungin administered intravenously in 20 adult lung transplant recipients. Epithelial lining fluid (ELF) and alveolar cell (AC) samples were obtained via bronchoalveolar lavage performed 3, 5, 8, 18, or 24 h after initiation of infusion. Micafungin concentrations in plasma, ELF, and ACs were determined using high-pressure liquid chromatography. Noncompartmental methods, population analysis, and multiple-dose simulations were used to calculate PKPD parameters. C_max in plasma, ELF, and ACs was 4.93, 1.38, and 17.41 μg/ml, respectively. The elimination half-life in plasma was 12.1 h. Elevated concentrations in ELF and ACs were sustained during the 24-h sampling period, indicating prolonged compartmental half-lives. The mean micafungin concentration exceeded the MIC₉₀ of Aspergillus fumigatus (0.0156 μg/ml) in plasma (total and free), ELF, and ACs throughout the dosing interval. The area under the time-concentration curve from 0 to 24 h (AUC_0-24)/MIC₉₀ ratios in plasma, ELF, and ACs were 5,077, 923.1, and 13,340, respectively. Multiple-dose simulations demonstrated that ELF and AC concentrations of micafungin would continue to increase during 14 days of administration. We conclude that a single 150-mg intravenous dose of micafungin resulted in plasma, ELF, and AC concentrations that exceeded the MIC₉₀ of A. fumigatus for 24 h and that these concentrations would continue to increase during 14 days of administration, supporting its potential activity for prevention and early treatment of pulmonary aspergillosis.Postoperative invasive pulmonary aspergillosis is a frequent clinical problem among patients who have undergone lung transplantation (13, 23, 38-42). Strategies for management of invasive pulmonary aspergillosis in lung transplant recipients are not well defined. While voriconazole is indicated for the primary treatment of invasive aspergillosis, not all patients are able to tolerate this triazole, and drug interactions may be complicated. The role of echinocandins in treatment and prevention of invasive aspergillosis in lung transplant recipients is unknown. Although most lung transplant centers administer some form of antifungal prophylaxis, these regimens vary widely from center to center, and the optimal strategy for prophylaxis is unknown. Aerosolized amphotericin B, either alone or with systemically administered antifungal agents, may be used for prevention of invasive aspergillosis in lung transplant recipients (13).Micafungin, a member of the echinocandin class of antifungal agents, has in vitro as well as in vivo activities against Candida spp. and Aspergillus spp. in treatment of experimental disseminated candidiasis (3, 5, 6, 33-35) and invasive pulmonary aspergillosis (33). Micafungin is licensed for the treatment of patients with esophageal candidiasis and candidemia (5, 12, 15, 30, 32, 36, 49). Micafungin also is approved for prevention of candidemia in neutropenic hematopoietic stem cell transplant recipients (44). Micafungin has been studied alone or in combination with other antifungal agents for treatment of invasive aspergillosis in hematopoietic stem cell transplant recipients (22). Although studies of micafungin for treatment and prevention of invasive pulmonary aspergillosis in animal models and in patients have demonstrated activity against this serious infection (8, 26, 33, 45), little is known about its intrapulmonary pharmacokinetics in patients at risk for invasive aspergillosis (28). We therefore studied the simultaneous intrapulmonary and plasma pharmacokinetics and pharmacodynamics of micafungin in adult lung transplant recipients.     

Pharmacokinetics and Pharmacodynamics of Multiple-Dose Intravenous Nemonoxacin in Healthy Chinese Volunteers

This study evaluated the safety and pharmacokinetic/pharmacodynamic profiles of nemonoxacin in healthy Chinese volunteers following multiple-dose intravenous infusion once daily for 10 consecutive days. The study was composed of two stages. In the open-label stage, 500 mg or 750 mg of nemonoxacin (n = 12 each) was administered at an infusion rate of 5.56 mg/min. In the second stage, with a randomized double-blind placebo-controlled design, 500, 650, or 750 mg of nemonoxacin (n = 16 in each cohort; 12 subjects received the drug and the other 4 subjects received the placebo) was given at an infusion rate of 4.17 mg/min. The results showed that, in the first stage, the maximal nemonoxacin concentrations (mean ± SD) at steady state (C_{max_ss}) were 9.60 ± 1.84 and 11.04 ± 2.18 μg/ml in the 500-mg and 750-mg cohorts, respectively; the areas under the concentration-time curve at steady state (AUC_{0–24_ss}) were 44.03 ± 8.62 and 65.82 ± 10.78 μg · h/ml in the 500-mg and 750-mg cohorts, respectively. In the second stage, the nemonoxacin C_{max_ss} values were 7.13 ± 1.47, 8.17 ± 1.76, and 9.96 ± 2.23 μg/ml in the 500-mg, 650-mg, and 750-mg cohorts, respectively; the AUC_{0–24_ss} values were 40.46 ± 9.52, 54.17 ± 12.10, and 71.34 ± 17.79 μg · h/ml in the 500-mg, 650-mg, and 750-mg cohorts, respectively. No accumulation was found after the 10-day infusion with any regimen. The drug was well tolerated. A Monte Carlo simulation indicated that the cumulative fraction of response of any dosing regimen was nearly 100% against Streptococcus pneumoniae. The probability of target attainment of nemonoxacin therapy was >98% when the MIC of nemonoxacin against S. pneumoniae was ≤1 mg/liter. It is suggested that all of the studied intravenous nemonoxacin dosing regimens should have favorable clinical and microbiological efficacies in future clinical studies. (This study has been registered at ClinicalTrials.gov under registration no. {"type":"clinical-trial","attrs":{"text":"NCT01944774","term_id":"NCT01944774"}}NCT01944774.)     

Steady-State Intrapulmonary Pharmacokinetics and Pharmacodynamics of Posaconazole in Lung Transplant Recipients

This prospective study evaluated the plasma and intrapulmonary pharmacokinetics and pharmacodynamics (PKPD) of posaconazole (POS) in lung transplant recipients. Twenty adult lung transplant patients were instructed to take a 400-mg POS oral suspension twice daily (BID) with a high-fat meal for a total of 14 doses. Pulmonary epithelial lining fluid (ELF) and alveolar cell (AC) samples were obtained via bronchoalveolar lavage, and blood samples were collected at the approximate time of bronchoscopy. POS concentrations were assayed using liquid chromatography with tandem mass spectrometry. The maximum concentrations (C_max) (mean ± standard deviation [SD]) in plasma, ELF, and AC were 1.3 ± 0.4, 1.3 ± 1.7, and 55.4 ± 44.0 μg/ml. POS concentrations in plasma, ELF, and AC did not decrease significantly, indicating slow elimination after multiple dosing. Mean concentrations of POS in plasma, ELF, and AC were above the MIC₉₀ (0.5 μg/ml) for Aspergillus species over the 12-h dosing interval and for 24 h following the last dose. Area under the concentration-time curve from 0 to 12 h (AUC_0-12)/MIC₉₀ ratios in plasma, ELF, and AC were 21.98, 22.42, and 1,060. We concluded that a dose of 400 mg BID resulted in sustained plasma, ELF, and AC concentrations above the MIC₉₀ for Aspergillus spp. during the dosing interval. Confirmation of the therapeutic value of these observations requires further investigation. The intrapulmonary PKPD of POS may be favorable for treatment or prevention of aspergillosis, although further research on the relevant PKPD parameters and the effect of POS protein binding is required.Posaconazole (POS) is a new antifungal agent with activity against Aspergillus, Cryptococcus, Candida, Histoplasma, and Blastomyces spp. and others (9, 15, 17, 19, 27). POS is approved for prophylaxis of invasive aspergillosis and candidiasis in immunocompromised patients and for the treatment of refractory oropharyngeal candidiasis. Recent reports suggest that it may also be effective in the treatment of refractory invasive aspergillosis (16, 26), zygomycosis (23), and other fungal infections (3, 18).The oral bioavailability of POS is increased by ingestion of a high-fat meal and by the use of divided dosing (8, 10). There are no clinically or kinetically important metabolites of POS. POS has a high apparent volume of distribution, 1,774 liters, and a prolonged half-life, 35 h, at steady state (G. Krishna and A. Sansone-Parsons, presented at the 41st American Society of Health System Pharmacists Midyear Clinical Meeting and Exhibition, Anaheim, CA, 3 to 7 December 2006). Its pharmacokinetics (PK) are unaffected by age, gender, or race/ethnicity (21), and dose correction is not required for patients with impaired renal function (7); 66.3% of an oral POS dose is excreted unchanged in feces (12). Protein binding in human plasma is >98%. We recently reported on the intrapulmonary pharmacokinetics and pharmacodynamics (PKPD) of POS in healthy subjects (5). Maximum concentration of drug in serum (C_max) values were 2.08, 1.86, and 87.7 μg/ml, and area under the concentration-time curve from 0 to 12 h (AUC_0-12) values were 21.9, 18.3, and 715 μg·h/ml in plasma, pulmonary epithelial lining fluid (ELF), and alveolar cells (AC), respectively. POS concentrations did not decline significantly over 24 h in any compartment. The purpose of this study was to determine the intrapulmonary PKPD of POS in lung transplant recipients.     

Pharmacokinetics and Pharmacodynamics of Once-daily Prolonged-release Tacrolimus in Liver Transplant Recipients

PurposeLimited published data are available regarding the pharmacokinetic (PK) and pharmacodynamic (PD) variables of prolonged-release tacrolimus (PRT) after liver transplantations. The goal of this study was to compare the PK and PD profiles of PRT in early and stable liver transplant recipients by developing a population PK model of PRT and investigating the profile of calcineurin activity (CNA) in the peripheral blood mononuclear cells.MethodsA conversion from BID immediate-release tacrolimus (IRT) to once-daily PRT based on a one-to-one daily dose was performed at day 7 (D7) and D90 posttransplantation in groups A (n = 12) and B (n = 12), respectively. Extensive PK samplings, including whole-blood tacrolimus (TAC) concentration, and CNA assessments were performed at D14 and D104 in groups A and B, respectively. TAC concentration–time data (N = 221) were analyzed by using nonlinear mixed effects modeling.FindingsA 2-compartment model with linear elimination and a delayed first-order absorption characterized by 2 transit compartments best described the PK data. Model-predicted dose-normalized (6.0 mg/d) area under the TAC concentration–time curve over the dosing interval in groups A and B was similar (geometric mean, 235.6 ng/mL · h [95% CI, 139.6–598.7] vs 224.6 ng/mL · h [95% CI, 117.6–421.5], respectively; P = 0.94). Area under the CNA versus time curve over the dosing interval did not differ between groups (4897 [3437] and 4079 [1008] pmol/min/10⁶ cells; P = 0.50). In group A, trough CNA at D14 posttransplantation was statistically higher than that measured just before the switch to PRT (ie, D7 posttransplantation) (198 [92] vs 124 [72] pmol/min/10⁶cells, n = 8; P = 0.048); no statistical difference in TAC concentration was observed (P = 0.11). In group B, no statistical difference between D90 and D104 was observed in either trough CNA (149 [78] vs 172 [82] pmol/min/10⁶ cells, n = 6; P = 0.18) or TAC (P = 0.17) concentration. No graft rejection was observed in either of the groups.ImplicationsThis study suggests that one-to-one dosage conversion to once-daily PRT during the early posttransplantation period could result in significant CNA variations but without causing graft rejection. Further investigations in larger cohorts are warranted to confirm these results. ClinicalTrials.gov identifier: NCT02105155.