Pharmacokinetics and Safety of MP-376 (Levofloxacin Inhalation. Solution) in Cystic Fibrosis Subjects

Transcription

1 AAC Accepts, published online ahead of print on 28 March 2011 Antimicrob. Agents Chemother. doi: /aac Copyright 2011, American Society for Microbiology and/or the Listed Authors/Institutions. All Rights Reserved. Pharmacokinetics and Safety of MP-376 (Levofloxacin Inhalation Solution) in Cystic Fibrosis Subjects David E. Geller 1, Patrick A. Flume 2, David C. Griffith 3 *, Elizabeth Morgan 3, Dan White 3, Jeffery S. Loutit 3, and Michael N. Dudley 3 1 Nemours Children s Clinic, 496 S. Delaney Ave, Suite 406A, Orlando, FL USA 2 Medical University of South Carolina, 96 Jonathan Lucas St, 812-CSB, Charleston, SC USA; Mpex Pharmaceuticals, Sorrento Valley Rd., San Diego, CA USA * Corresponding author Phone: (408) Fax: (858) dgriffith@mpexpharma.com Running title: Pharmacokinetics and safety of MP-376 Page 1 of 13

2 Background. The pharmacokinetics and tolerability of nebulized MP-376 (levofloxacin inhalation solution; Aeroquin ) was determined in CF subjects Methods. Ten CF subjects received single 180 mg doses of two formulations of MP- 376, followed by a multiple dose phase of 240 mg QD for 7 days. Serum and expectorated sputum samples were assayed for levofloxacin content. Safety was evaluated following the single and multiple dose study phases Results. Nebulized MP-376 produced high concentrations of levofloxacin in sputum. The mean Cmax ranged between 2563 and 2932 mg/l for 180 mg doses of the 50 and 100 mg/ml formulations, respectively. After 7 days of dosing, the mean Cmax for the 240 mg dose was 4691 mg/l. Mean serum levofloxacin Cmax ranged from 0.95 and 1.28 for the 180 mg doses and was 1.71 for the 240 mg dose. MP-376 was welltolerated Conclusions. Nebulized MP-376 produces high sputum and low serum levofloxacin concentrations. Pharmacokinetics, safety, and tolerability were similar for 2 formulations. MP mg (100 mg/ml) is being advanced into late stage clinical development. 4 0 INTRODUCTION Patients with cystic fibrosis (CF) suffer from recurrent and chronic infections of the lower respiratory tract. Pseudomonas aeruginosa in particular has been implicated as a major risk factor for declining lung function and associated morbidity and mortality in CF patients (5). Aerosol delivery of an antibiotic directly to the lung increases the local concentration of the drug at the site of infection, thereby enhancing bacterial killing and Page 2 of 13

3 reducing the selection of resistance compared to systemic administration. Currently, tobramycin solution for inhalation (TOBI, Novartis Pharmaceuticals, East Hanover, NJ) and aztreonam lysine for inhalation (Cayston, Gilead Pharmaceuticals, Seattle, WA) are the two aerosol antibiotics approved in the United States for the management of CF patients with P. aeruginosa. For a number of reasons including decreased efficacy, drug intolerance, new emerging pathogens, and inconvenient dosing regimens, there is a need for alternative inhaled therapies to treat CF patients with pulmonary infections caused by P. aeruginosa and other bacteria Levofloxacin is a fluoroquinolone antibiotic with potent activity against key pathogens in CF patients, including P. aeruginosa. Unlike tobramycin, levofloxacin activity is not reduced in CF sputum (8). In addition levofloxacin has greater antimicrobial activity in biofilms produced by P. aeruginosa than tobramycin and aztreonam (8). Extensive in vitro and animal pharmacokinetic-pharmacodynamic studies as well as both retrospective and prospective clinical studies have established the clear link between the exposure to fluoroquinolones and clinical response (1). While not studied in patients with CF, studies with levofloxacin show that bacterial killing and clinical efficacy is linked to the plasma AUC:MIC ratio or Cmax:MIC ratio and that high peak concentrations relative to the MIC may reduce the selection of drug-resistant bacteria in vitro and in vivo (6,7). Aerosol administration of levofloxacin produces Cmax:MIC and AUC:MIC ratios in the airways that are substantially greater than those that can be obtained with parenteral or oral administration. High levofloxacin concentrations delivered to the lung may be active against even highly resistant organisms and may also reduce the selection of resistant bacteria (9). Page 3 of 13

4 MP-376 is a novel solution formulation of levofloxacin for aerosol administration, being developed for the management of CF patients with chronic infections due to Pseudomonas aeruginosa. Pharmacokinetic studies in animals show that the formulation promotes retention of active drug in the lung which results in enhanced efficacy in animal models of infection compared to other aerosol or systemic formulations of levofloxacin (11). MP-376 is a preservative free, ph 5 7 and mosm (slightly hyperosmotic) solution that has been optimized for administration using a customized, investigational, high-efficiency PARI eflow nebulizer for rapid delivery using single or twice daily dosage regimens. The purpose of this study was to evaluate and compare the safety, tolerability, pharmacokinetic profile of two formulations of MP- 376 (50 and 100 mg/ml) at two dose levels in CF subjects, in order to facilitate the design of further clinical trials of MP MATERIALS AND METHODS Subjects. Entry criteria for this study included age 16 years or greater with a diagnosis of CF, baseline forced expiratory volume in 1 second (FEV 1 ) 40% predicted value, clinically stable with a stable medication regimen, no use of an investigational agent within 4 weeks before the first study visit, and no aerosol or systemic antibiotics within 7 days before the first visit (other than maintenance oral azithromycin). The Institutional Review Board at each site approved the study and all patients or their guardians provided written informed consent. Page 4 of 13

5 Study Design. This was a multi-center, randomized, single-blind, crossover study of two concentrations of MP-376 (50 mg/ml and 100 mg/ml; 180 mg dose) administered via inhalation using a customized, investigational, PARI eflow nebulizer, followed by 7 days of daily treatment with a 240 mg (100 mg/ml) dose. After completing the screening procedures, qualified patients were randomized to one of the treatment sequences as shown in Table 1. Subjects received, in an order specified by a randomization schedule, a single 180 mg dose of one formulation in Period 1 of the study, followed by a 7-day wash-out period and a single 180 mg dose of the other formulation in Period 2. On the days when pharmacokinetic samples were obtained, patients rinsed their mouths and swallowed 15 ml of Maalox (400 mg magnesium hydroxide, 400 mg aluminum hydroxide) 5 minutes prior to and 5 minutes after dosing in order in order to minimize oral absorption of any swallowed levofloxacin. This was done so that serum levofloxacin levels would better reflect the intrapulmonary deposition and absorption from the airways. After an additional 7-day wash-out period, the third and final period of the trial consisted of seven consecutive days of once-daily 240 mg dosing using the 100 mg/ml formulation Blood samples were collected before dosing, at the end of the inhalation (1 to 8 minutes) and at (10 minutes), 0.25 (15 minutes), 0.5 (30 minutes), 1, 2, 4, 8, and 24 hours after the start of dosing in periods 1 and 2 and after the last dose in period 3. Sputum samples were collected before dosing and at 0.25, 0.5, 1, 2, 4, 8, and 24 hours after dosing Analytical Methods. The concentrations of levofloxacin in serum and in the sputum were determined using validated high performance liquid chromatograph (HPLC) Page 5 of 13

6 method using fluorescence detection (Anapharm, Québec, Canada). Briefly, levofloxacin and an internal standard (difloxacin) were extracted from 0.1 ml aliquot of human serum or sputum using dichloromethane / isopropyl alcohol (90/10) using a liquid-liquid extraction. The extracted samples were injected into a liquid chromatograph equipped with a Zorbax SB C8, 4.6 x 150 mm, 5 m column. The mobile phase was a mixture of deionized water / acetonitrile (75/25), potassium dihydrogen orthophosphate 7.5 mm, ph Standard curves were obtained using a weighted (1/y 2 ) least squares linear regression analysis of the peak area ratios (levofloxacin / internal standard) versus the nominal concentration of the standard curve. Two standard curves were prepared, one for serum and one for sputum. Sample concentrations were determined by interpolation from the standard curve. The serum standard curve was linear from ng/ml, with a between- and within-day precision of < 8.0 %. The sputum standard curve was linear from ,000 ng/ml, with a between- and within-day precision of < 4.0% Pharmacokinetic Methods. All pharmacokinetic parameters were calculated using non-compartmental analysis. The maximum plasma concentration (Cmax) and time to Cmax (Tmax) were identified directly from the data. The elimination rate constant, z, was calculated as the negative of the slope of the terminal log-linear segment of the plasma concentration-time curve. The range of data used for calculation in each subject and treatment was determined by visual inspection of a semi-logarithmic plot of concentration vs. time. Pharmacokinetic parameters were calculated using SAS for Windows Version Page 6 of 13

7 Safety Evaluation. Patients were seen a total of 9 times during the study; a screening visit, 2 visits around each of the single dose periods, 3 visits during the multiple dose period, and a follow up visit. AEs were collected at each visit. Safety was assessed by evaluating adverse events (AEs), and changes from baseline in physical examinations, vital signs, electrocardiograms, pulse oximetry results, spirometry, and laboratory test results RESULTS Ten CF subjects enrolled in the study and all subjects completed the study successfully. Patient characteristics were similar across the two treatment sequences and are shown in Table 2. The overall mean age was 32.4 years, 60% of the patients were female, all were Caucasian and there were no clinically relevant differences in medical history or screening physical examination findings. The average baseline percent predicted FEV 1 for all patients was 67.1%, with similar mean baseline FEV1 values in each treatment sequence Pharmacokinetics Serum. The mean serum levofloxacin concentrations for all three doses are shown in Figure 1. A comparison of the mean serum and sputum exposures are shown in Figure 2. After administration of 180 mg MP-376, the mean Cmax and AUC(0- inf) for the 100 mg/ml formulation were 35% and 22% higher than the corresponding values for the 50 mg/ml formulation, respectively (Table 3), but the differences were not statistically signficant. There was a 1.33-fold increase in the mean Cmax after administration of 240 mg versus 180 mg as the 100 mg/ml formulation, exactly proportional to the Page 7 of 13

8 increase in dose. There was a corresponding 1.71-fold increase in the mean AUC(0-inf) after the 240 mg dose versus the 180 mg dose Sputum. Sputum pharmacokinetic parameters are shown in Table 4. Inhalation of a 180 mg dose as either the 50 or 100 mg/ml formulation resulted in similar mean sputum levofloxacin Cmax and AUC (Table 4). After 7-days of 240 mg per day dosing with the 100 mg/ml formulation, increases in Cmax and AUC were both slightly higher than dose proportional (1.6-fold and 2.3-fold increase, respectively, versus a dose increase of 1.33-fold). The mean t½ was comparable for all three doses, ranging from 3.55 h to 4.58 h (Table 3) Safety. MP-376 was very well tolerated with both concentrations and doses. A total of 26 AEs were reported by 7 of the 10 patients during the study. The number of patients reporting an AE was similar across each treatment period (60%, 50%, and 40% for periods 1, 2, and 3, respectively). Adverse events that were reported in 2 or more patients are as follows: Dysgeusia was noted in 4/10 patients with the 180 mg single dose (50 mg/ml), 4/10 with the 180mg single dose (100 mg/ml), and 4/10 during the 240 mg multiple dose (100 mg/ml) period. Hemoptysis occurred in 1/10 patients with the 180mg single dose (50 mg/ml) and 1/10 patients with the 180mg single dose (100mg/ml). No patients experienced hemoptysis during the multiple dose period. Of the 26 AEs, 25 were mild and one was moderate. The moderate AE was back pain and was judged not to be related to study drug. Nineteen events in 4 patients were considered related to study drug (either possibly or probably). A similar AE profile, with respect to event, severity, and relationship, was observed across treatment periods. No patient experienced a serious adverse event and no patient discontinued the study due Page 8 of 13

9 to an AE. There were no clinically relevant changes in physical exam findings, vital signs, ECGs, pulse oximetry, spirometry, or laboratory results. Nebulization time. The mean delivery time for MP-376 was 5.5 minutes for the 180 mg dose (50 mg/ml), 3.0 minutes for the 180 mg dose (100 mg/ml), and 4.8 minutes for the 240 mg dose. DISCUSSION Both formulations of MP-376 tested produced very high sputum concentrations with low systemic exposure. The 180 and 240 mg doses using the 100 mg/ml formulation produced 24h serum AUCs of 9.05 and mg*hr/l, respectively. These measures of serum levofloxacin exposure from MP-376 are only 12-19% of the 24-hour serum AUC achieved in another study of CF patients dosed with 750 mg oral levofloxacin (24h AUC = 76.6 mg*hr/l).(3) Systemic absorption from the lung was very rapid, with serum Tmax occurring within 20 minutes of dose administration For CF patients who spend considerable time taking their prescribed daily inhaled medications, it is important to consider the treatment burden when developing new therapies. This pharmacokinetic study showed that the 100 mg/ml formulation of MP-376 produced serum and sputum levels of levofloxacin that were similar to the 50 mg/ml formulation and required less time for nebulization After 7 days of 240 mg daily dosing using the 100 mg/ml formulation, the serum and sputum exposures were approximately dose-proportional with the 180 mg dose with regard to Cmax, and seemed higher than dose-proportional with regard to AUC values. However, there was very high inter-subject variability, with standard deviations Page 9 of 13

10 approximating or exceeding the mean values, making it difficult to evaluate doseproportionality. This high degree of variability can be seen in most studies of aerosol drugs, and stems from factors including breathing patterns during drug inhalation (tidal volume, inspiratory flow, respiratory rate) and disease severity (degree and location of airway obstruction).(4) Sputum concentrations of inhaled antibiotics are frequently measured in clinical trials as a guide to ensure that they exceed the minimum inhibitory concentration of the bacteria. However, as a measure of deposited dose in the airways, sputum levels can be misleading, as the drug is not evenly distributed in the airways, and the exact source of sputum may differ between specimens, leading to more variability. (4) Aerosol dosing with MP-376 produced a mean sputum AUC of 4,500 mg/l and a mean sputum Cmax of 4,700 mg*hr/l after a 240 mg dose. Extensive in vitro and animal pharmacokinetic-pharmacodynamic studies as well as both retrospective and prospective clinical studies have established the clear link between the exposure to fluoroquinolones and antibacterial effects. Studies with levofloxacin show that bacterial killing and clinical efficacy are linked to the plasma drug area under the curve (AUC): minimum inhibitory concentration (MIC) ratio, or the Cmax:MIC ratio (6,7,10,12). Studies with levofloxacin also show that high levels of exposure relative to the MIC can reduce the selection of drug-resistant bacteria in vitro and in vivo (7,12). Based on an MIC 90 to P. aeruginosa of 16 mg/l for levofloxacin, aerosol administration of MP-376 resulted in a sputum AUC:MIC 90 ratio of 280 and a Cmax:MIC 90 of 290. These sputum exposures are greater than those that can be achieved with either parenteral or oral administration. Page 10 of 13

11 While sputum levofloxacin exposures were very high, serum exposures were only 10 16% of those previously reported with 750 mg oral dosing (Figure 2). (3) With lower systemic exposures, aerosol MP-376 should the safety and tolerability profile compared to either parenteral or oral administration of levofloxacin. Overall, this study demonstrated that aerosol administration of MP-376 was well tolerated and produced sputum levofloxacin exposures that should maximize bacterial killing while minimizing the development of resistance. Based on these data, the 100 mg/ml formulation of MP-376 was advanced into Phase 2 studies (2) REFERENCES 1. Ambrose PG, Bhavnani SM, Rubino CM, Louie A, Gumbo T, Forrest A, Drusano GL Pharmacokinetics-pharmacodynamics of antimicrobial therapy: it's not just for mice anymore. Clin Infect Dis.; 44: Conrad D, Flume P, Sindel L, Andrews S, Morgan E, Loutit J, Geller DE Phase 2b Study of Inhaled MP-376 (Aeroquin, Levofloxacin Inhalation Solution) in Stable Cystic Fibrosis (CF) Patients with Chronic Pseudomonas aeruginosa (PA) Lung Infection. Am J Respir Crit Care Med; 181:A Geller DE, Kesser KC, Surber M, Bostian K, Rock J, Griffith D, Dudley M Pharmacokinetics of oral levofloxacin (LVX) in stable adult CF subjects. Pediatr Pulmonol; Suppl 29; 328 Page 11 of 13

12 Geller DE The science of aerosol delivery in Cystic Fibrosis. Pediatr Pulmonol; 43(9, suppl A):S5-S Gibson RL, Burns JL, Ramsey BW Pathophysiology and Management of Pulmonary Infections in Cystic Fibrosis. Am. J. Respir. Crit. Care Med; 168: Griffith DC, Corcoran E, Lofland D, Lee A, Cho D, Lomovskaya O, Dudley MN Pharmacodynamics of Levofloxacin Against Pseudomonas aeruginosa with Reduced Susceptibility Due to Different Efflux Pumps: Do elevated MICs Always Predict Reduced In Vivo Efficacy? Antimicrob Agents Chemother.; 50: Jumbe N, Louie A, Leary R, et al Application of a Mathematical Model to Prevent In Vivo Amplification of Antibiotic-Resistant Bacterial Populations During Therapy. J. Clin. Invest.; 112: King P, Lomovskaya O, Griffith DC, Burns JL, Dudley MN In vitro pharmacodynamics of levofloxacin and other aerosolized antibiotics under multiple conditions relevant to chronic pulmonary infection in cystic fibrosis. Antimicrob. Agents Chemother. ; 54(1): King P, Senekeo-Effenberger K, Nolan T, Lomovskaya O, Dudley MN, Griffith DC In vitro PK-PD of levofloxacin (LVX): A new dosing paradigm for aerosolized antibiotics. Abstr. 48th Intersci. Conf. Antimicrob. Agents Chemother., abstr. A Preston S, Drusano G, Berman AL, et al Pharmacodynamics of Levofloxacin: A New Paradigm for Early Clinical Trials. JAMA.; 279: Sabet M, Miller CE, Nolan TG, Senekeo-Effenberger K, Dudley MN, Griffith DC Efficacy of aerosol MP-376 (levofloxacin inhalation solution) in mouse lung Page 12 of 13

13 infection models due to Pseudomonas aeruginosa. Antimicrob. Agents Chemother.; 53(9): Tam VH, Louie A, Deziel MR, Weiguo L, Leary R, Drusano GL Bacterialpopulation responses to drug-selective pressure: examination of garenoxacin's effect on Pseudomonas aeruginosa. J Infect Dis.; 192:420-8 Page 13 of 13

14 TABLES Table 1: Study Design Sequence 180 mg Dose 240 mg Dose Sequence Period 1 Period 2 Period 3 A 50 mg/ml 100 mg/ml 100 mg/ml B 100 mg/ml 50 mg/ml 100 mg/ml Table 2: Demographic characteristics of CF Subjects in this Study Treatment Sequence A Treatment Sequence B Total N Age (years) Mean (SD) 33.6 (16.4) 31.2 ( 9.7) 32.4 (12.8) Median Min, Max 16, 60 19, 46 16, 60 Sex M 2 (40.0%) 2 (40.0%) 4 (40.0%) F 3 (60.0%) 3 (60.0%) 6 (60.0%) FVC Absolute (L) Mean (SD) 3.2 (1.2) 3.4 (0.5) 3.3 (0.9) % predicted Mean (SD) 81.8 (10.4) 83.8 (18.7) 82.8 (14.3) FEV 1 Absolute (L) Mean (SD) 2.2 (1.1) 2.4 (0.3) 2.3 (0.8) % predicted Mean (SD) 64.4 (10.9) 69.8 (20.4) 67.1 (15.7) Weight (kg) Mean (SD) 73.8 (29.6) 68.5 (25.8) 71.1 (26.4)

15 Table 3: Summary of serum pharmacokinetic parameters for levofloxacin after administration of single 180 mg doses as a 50 or 100 mg/ml inhalation solution and after administration of 240 mg as a 100 mg/ml inhalation solution to patients with CF. Parameter* 180 mg Dose 240 mg Dose*** 50 mg/ml 100 mg/ml 100 mg/ml Cmax (mg/l) 0.95 ± ± ± 0.62 Tmax (h)** AUC (0-24) (h*mg/l) 7.07 ± ± ± 9.97 AUC (0-inf) (h*mg/l) 8.06 ± ± ± T1/2 (h) 6.40 ± ± ± 2.89 * Mean ± standard deviation ** Tmax is reported as the median *** PK parameters assessed after dosing on Day 7 Table 4: Summary of sputum pharmacokinetic parameters for levofloxacin after administration of single 180 mg doses of MP-376 as a 50 or 100 mg/ml inhalation solution and after administration of 240 mg as a 100 mg/ml inhalation solution to patients with CF. Parameter* 180 mg Dose 240 mg Dose*** 50 mg/ml 100 mg/ml 100 mg/ml Cmax (mg/l) 2,563 ± 1,412 2,932 ± 2,559 4,691 ± 4,516 Tmax (h)** AUC (0-24) (h*mg/l) 1,890 ± 1,252 1,959 ± 2,110 4,507 ± 6,594 AUC (0-inf) (h*mg/l) 1,891 ± 1,252 1,961 ± 2,110 4,517 ± 6,611 T1/2 (h) 3.55 ± ± ± 2.54 * Mean ± standard deviation ** Tmax is reported as the median *** PK parameters assessed after dosing on Day 7

16 FIGURES Figure 1. Serum levofloxacin levels after aerosol dosing of 180 or 240 mg MP-376 Figure 2. Levofloxacin serum and sputum AUCs after aerosol dosing of MP-376, and comparative data for a 750 mg oral levofloxacin dose in CF subjects. (3)