Pharmacokinetics of Inhaled Liposome-encapsulated Fentanyl

1995 ◽  
Vol 83 (2) ◽  
pp. 277-284. ◽  
Author(s):  
Orlando R. Hung ◽  
Sara C. Whynot ◽  
John R. Varvel ◽  
Stephen L. Shafer ◽  
Michael Mezei
Keyword(s):  
Healthy Volunteers ◽  
Intravenous Administration ◽  
Venous Blood ◽  
Volume Of Distribution ◽  
Sustained Drug Release ◽  
Future Studies ◽  
Time To Peak ◽  
Drug Molecules ◽  
Peak Absorption ◽  
The Mean

Background Pulmonary administration of fentanyl solution can provide satisfactory but brief postoperative pain relief. Liposomes are microscopic phospholipid vesicles that can entrap drug molecules. Liposomal delivery of fentanyl has the potential to control the uptake of fentanyl by the lungs and thus provide sustained drug release. To demonstrate that inhalation of a mixture of free and liposome-encapsulated fentanyl can provide a rapid increase and sustained plasma fentanyl concentrations (CfenS), this study determined the pharmacokinetic profiles after the inhalation of free and liposome-encapsulated fentanyl in healthy volunteers. Methods After obtaining institutional approval and informed consent, ten healthy volunteers (five men, five women) were studied. Each subject received 200 micrograms intravenous fentanyl and inhaled 2,000 micrograms of free (50%) and liposome-encapsulated fentanyl (50%) on separate occasions. Frequent venous blood samples were collected, and CfenS were determined by radioimmunoassay. The pharmacokinetics and absorption characteristics of the inhaled mixture of free and liposome-encapsulated fentanyl were determined using moment analysis and least-squares numeric deconvolution. Results The mean (+/- SD) volume of distribution at steady-state and clearance of fentanyl after the intravenous administration were comparable to previous studies: 435 +/- 1821 and 0.584 +/- 0.209 l.min-1, respectively. The mean (+/- SD) peak Cfen was significantly greater for the intravenous administration compared to the aerosol mixture of free and liposome-encapsulated fentanyl (4.67 +/- 1.87 vs. 1.15 +/- 0.36 ng.ml-1). However, CfenS at 8 and 24 h after aerosol administration were greater compared to intravenous (0.25 +/- 0.14 and 0.12 +/- 0.16 ng.ml-1 for aerosol versus 0.16 +/- 0.10 and 0.05 +/- 0.06 ng.ml-1 for intravenous). The peak absorption rate, time to peak absorption, and bioavailability after inhalation were 7.02 (+/- 2.34) micrograms.min, -1(16) (+/- 8.0) min, and 0.12 (+/- 0.11), respectively. Conclusions The data suggest that this analgesic method offers a simple and noninvasive route of administration with a rapid increase of Cfen and a prolonged therapeutic fentanyl concentration. Future studies are required to determine the optimal liposome composition that would produce a sustained stable Cfen within analgesic therapeutic concentrations.

Pharmacokinetics and Arteriovenous Differences in Clevidipine Concentration following a Short- and a Long-term Intravenous Infusion in Healthy Volunteers

2000 ◽  
Vol 92 (4) ◽  
pp. 993-1001 ◽  
Author(s):  
Hans Ericsson ◽  
Ulf Bredberg ◽  
Ulf Eriksson ◽  
Åse Jolin-Mellgård ◽  
Margareta Nordlander ◽  
...  
Keyword(s):  
Blood Pressure ◽  
Steady State ◽  
Healthy Volunteers ◽  
Venous Blood ◽  
Volume Of Distribution ◽  
Pharmacokinetic Parameters ◽  
Blood Levels ◽  
Blood Concentrations ◽  
Arterial Blood ◽  
The Mean

Background Clevidipine is an ultra-short-acting calcium antagonist developed for reduction and control of blood pressure during cardiac surgery. The objectives of the current study were to determine the pharmacokinetics of clevidipine after 20-min and 24-h intravenous infusions, and to determine the relation between the arterial and venous concentrations and the hemodynamic responses to clevidipine in healthy volunteers. Methods Four volunteers received clevidipine for 20 min, and eight subjects were administered clevidipine intravenously for 24 h at two different dose rates. Arterial and venous blood samples were drawn for pharmacokinetic evaluation, and blood pressure and heart rate were recorded. Results A triexponential disposition model described the pharmacokinetics of clevidipine. The mean arterial blood clearance of clevidipine was 0.069l/kg-1/min-1 and the mean volume of distribution at steady state was 0.19 l/kg. The duration of the infusion had negligible effect on the pharmacokinetic parameters, and the context-sensitive half-time for clevidipine, simulated from the mean pharmacokinetic parameters derived after 24 h infusion at the highest dose, was less than 1 min. The arterial blood levels reached steady state within 2 min of the start of infusion and were about twice as high as those in the venous blood at steady state. The peak response preceded the peak venous concentration and was slightly delayed from the peak arterial blood concentration. Conclusion Clevidipine is a high clearance drug with a small volume of distribution, resulting in extremely short half-lives in healthy subjects. The initial rapid increase in the arterial blood concentrations and the short equilibrium time between the blood and the biophase suggest that clevidipine can be rapidly titrated to the desired effect.

Pharmacokinetics of Prilocaine after Intravenous Administration in Volunteers 

1999 ◽  
Vol 90 (4) ◽  
pp. 988-992 ◽  
Author(s):  
Auke Dirk van der Meer ◽  
Anton G. L. Burm ◽  
Rudolf Stienstra ◽  
Jack W. van Kleef ◽  
Arie A. Vletter ◽  
...  
Keyword(s):  
Intravenous Administration ◽  
High Performance ◽  
Equilibrium Dialysis ◽  
Plasma Concentrations ◽  
Volume Of Distribution ◽  
Metabolic Clearance ◽  
Unbound Fraction ◽  
Blood Samples ◽  
The Mean ◽  
The Difference

Background Prilocaine exists in two stereoisomeric configurations, the enantiomers S(+)- and R(-)-prilocaine. The drug is clinically used as the racemate. This study examined the pharmacokinetics of the enantiomers after intravenous administration of the racemate. Methods Ten healthy male volunteers received 200 mg racemic prilocaine as a 10-min intravenous infusion. Blood samples were collected for 8 h after the start of the infusion. Plasma concentrations were measured by stereoselective high-performance liquid chromatography (HPLC). Unbound fractions of the enantiomers in blank blood samples, spiked with racemic prilocaine, were determined using equilibrium dialysis. Results The unbound fraction of R(-)-prilocaine (mean +/- SD, 70%+/-8%) was smaller (P < 0.05) than that of S(+)-prilocaine (73%+/-5%). The total plasma clearance of R(-)-prilocaine (2.57+/-0.46 l/min) was larger (P < 0.0001) than that of S(+)-prilocaine (1.91+/-0.30 l/min). The steady-state volume of distribution of R(-)-prilocaine (279+/-94 l) did not differ from that of S(+)-prilocaine (291+/-93 l). The terminal half-life of R(-)-prilocaine (87+/-27 min) was shorter (P < 0.05) than that of S(+)-prilocaine (124+/-64 min), as was the mean residence time of R(-)-prilocaine (108+/-30 min) compared with S(+)-prilocaine (155+/-59 min; P < 0.005). Conclusions The pharmacokinetics of prilocaine are enantioselective. The difference in clearance is most likely a result of a difference in intrinsic metabolic clearance. The difference in the pharmacokinetics of the enantiomers of prilocaine does not seem to be clinically relevant.

Measuring Ethanol in Blood and Breath for Legal Purposes: Variability between Laboratories and between Breath-Test Instruments

1992 ◽  
Vol 38 (5) ◽  
pp. 743-747 ◽  
Author(s):  
A W Jones ◽  
K M Beylich ◽  
A Bjørneboe ◽  
J Ingum ◽  
J Mørland
Keyword(s):  
Healthy Volunteers ◽  
Coefficient Of Variation ◽  
Breath Test ◽  
Venous Blood ◽  
Mean Difference ◽  
The Mean ◽  
Highly Correlated

Abstract We determined the concentrations of ethanol in nearly simultaneous specimens of venous blood (BAC) and end-expired breath (BrAC) after healthy volunteers drank moderate amounts of alcohol. BAC was measured at two laboratories and BrAC was analyzed with two instruments (Intoxilyzer 5000) from the same manufacturer. The mean difference in BAC between laboratories was 0.0105 mg/g (SD 0.0219); 95% of the differences ranged from -0.0333 to 0.0543 mg/g. The mean difference in BrAC between instruments was 0.0153 mg/L (SD 0.0136), and 95% of the differences ranged from -0.0119 to 0.0425 mg/L. The coefficient of variation (CV) between laboratories was 2.9% compared with 4.5% between breath-test instruments. Venous BAC (y) and BrAC (x) were highly correlated (r = 0.978). However, when the Intoxilyzer instruments indicated that BrAC had reached zero, the actual BAC was 0.135 mg/g, according to the average forensic laboratory reports. The Intoxilyzer 5000 breath analyzers used in this study seem to have a constant analytical bias.

scholarly journals Naloxone and nalmefene absorption delivered by hollow microneedles compared to intramuscular injection

2021 ◽  
Author(s):  
Mark G. Papich ◽  
Roger J. Narayan
Keyword(s):  
Peak Concentration ◽  
Plasma Sample ◽  
Area Under The Curve ◽  
Mass Spectrometry Detection ◽  
Plasma Analysis ◽  
Future Studies ◽  
Time To Peak ◽  
Hollow Microneedle ◽  
The Mean ◽  
Epaxial Muscles

Abstract Naloxone and nalmefene were administered to seven research Beagle dogs, (mean weight approximately 12 kg) at a dose of 0.04 mg/kg and 0.014 mg/kg for naloxone and nalmefene, respectively. Each dose was administered intramuscularly (IM) with a standard IM injection and with a hollow microneedle device array using needles of 1 mm in length. The IM injection was delivered in the epaxial muscles, and the microneedle injection was delivered in the skin over the shoulder of each dog. Each dog received the same injections in a cross-over design. Following the injection, blood samples were collected for plasma analysis of naloxone and nalmefene by high pressure liquid chromatography with mass spectrometry detection (LCMS). The plasma sample concentrations were plotted for observed patterns of absorption and analyzed with non-compartmental pharmacokinetic methods (NCA). The results showed that the injection of naloxone from the microneedle device produced a higher peak concentration (CMAX) by 2.15x compared the IM injection of the same dose, and time to peak concentration (TMAX) was similar. For the nalmefene injection, the peak was not as high (lower CMAX) by 0.94x for the microneedle injection compared to the IM injection of the same dose. The microneedle produced an exposure, measured by area under the curve (AUC)) that was 0.85x and 0.58x as high for naloxone and nalmefene, respectively, than the injection by the IM route. We also observed that although the dose for naloxone was approximately 3x higher for naloxone compared to nalmefene, the mean peak concentration achieved from the naloxone injection was more than 12x higher than the nalmefene injection. These studies were designed to test the feasibility of using the hollow microneedle array as an effective method of naloxone and nalmefene delivery for emergency treatment of opioid-induced respiratory depression (OIRD). The results of these studies will form the basis of future studies, using the dog as a model, for development of hollow microneedle microarray devices to deliver opioid antagonists for treatment of OIRD in people.

Ceftriaxone Pharmacokinetics during Iatrogenic Hydroxyethyl Starch-induced Hypoalbuminemia

2000 ◽  
Vol 93 (3) ◽  
pp. 735-743 ◽  
Author(s):  
Olivier Mimoz ◽  
Stéphan Soreda ◽  
Christophe Padoin ◽  
Michel Tod ◽  
Olivier Petitjean ◽  
...  
Keyword(s):  
Healthy Volunteers ◽  
Hydroxyethyl Starch ◽  
Venous Blood ◽  
Drug Distribution ◽  
Volume Of Distribution ◽  
Reversed Phase ◽  
Pharmacokinetic Parameters ◽  
Antibiotic Administration ◽  
Time Curve ◽  
The Impact

Background Although various drugs used by anesthesiologists highly bind to plasma proteins, the impact of iatrogenically induced hypoproteinemia on their pharmacologic effects has never been investigated. The authors determined the pharmacokinetics of ceftriaxone, a cephalosporin that binds strongly to albumin in postsurgical patients with hydroxyethyl starch-induced hypoalbuminemia. Methods Eleven hypoalbuminemic (serum albumin < 25 g/l) patients and age (+/- 5 yr)-, sex-, and body surface area (+/- 10%)-matched healthy volunteers received a 2-g ceftriaxone dose infused over a 15-min period. Fourteen venous blood samples were collected during the 24-h study period. Free ceftriaxone concentrations were determined by ultrafiltration. Antibiotic concentrations in plasma and ultrafiltrate were measured by ion-paired reversed-phase chromatography. The pharmacokinetic parameters derived from total and free antibiotic concentrations were determined using a noncompartmental method. Data are expressed as median and range. Results The pharmacokinetic parameters derived from total ceftriaxone concentrations were similar for the two groups, except for the median corrected volume of distribution at steady state, which was increased (P = 0.05) to 0.18 l/kg (range, 0. 11-0.29 l/kg) in patients, compared with 0.15 l/kg (range, 0.13-0.22 l/kg) in volunteers. The area under the free ceftriaxone concentration-time curve was twice as high in patients as in volunteers (median 192, range 114-301 vs. median 122, range 84-169 h. mg-1. l-1;P = 0.03). Moreover, the free ceftriaxone concentration remained more than 4 mg/l during more time in patients (median, 16. 7; range, 12.6-21.4 vs. median, 11.1; range, 6.0-19.0 h; P = 0.03). Conclusions Compared with healthy volunteers, patients with iatrogenic hypoalbuminemia have higher free ceftriaxone concentrations during the 24 h after antibiotic administration. This modification increases drug distribution into extravascular space and may enhance effectiveness.

scholarly journals Pharmacokinetics of oral and intravenous ofloxacin in children with multidrug-resistant typhoid fever.

1996 ◽  
Vol 40 (9) ◽  
pp. 2167-2172 ◽  
Author(s):  
D B Bethell ◽  
N P Day ◽  
N M Dung ◽  
C McMullin ◽  
H T Loan ◽  
...  
Keyword(s):  
Oral Administration ◽  
Typhoid Fever ◽  
Apparent Volume ◽  
Salmonella Typhi ◽  
Multidrug Resistant ◽  
Volume Of Distribution ◽  
Systemic Clearance ◽  
Time To Peak ◽  
The Mean ◽  
Intravenous And Oral Administration

The pharmacokinetics of oral and intravenous ofloxacin (7.5 mg.kg of body weight-1 given over 30 min) were studied in an open crossover study of 17 Vietnamese children, aged between 5 and 14 years, with acute uncomplicated typhoid fever. Following oral administration, the median (95% confidence interval [CI]) time to peak concentration of ofloxacin in serum (Cmax) was 1.7 h (1.4 to 1.9 h) and the mean (95% CI) Cmax was 5.5 mg.liter-1 (4.7 to 6.3 mg.liter-1) compared with a Cmax of 8.7 mg.liter-1 (7.6 to 9.7 mg.liter-1) following the intravenous infusion. The median (95% CI) total apparent volume of distribution following the first intravenous dose, 1.35 liter.kg-1 (1.17 to 1.73 liter.kg-1), was significantly larger than that following the second dose, 0.99 liter.kg-1 (0.86 to 1.17 liter.kg-1; P < 0.0005), although the estimates for systemic clearance were similar: 0.255 liter.kg-1 h-1 (0.147 to 0.325 liter.kg-1 h-1) compared with 0.172 liter.kg-1 h-1 (0.127 to 0.292 liter.kg-1 h-1; P = 0.14). The mean residence times (95% CI) following intravenous and oral administration were similar: 5.24 h (4.84 to 6.58 h) and 6.24 h (5.32 to 7.85 h), respectively. The mean (95% CI) oral bioavailability was 91% (74 to 109%). The peak concentrations in serum were 10 to 100 times higher than the maximum MICs for ofloxacin against multidrug-resistant Salmonella typhi isolated in this area. Although the systemic clearance values were higher than those reported previously for adults, these data overall suggest that weight-or area-adjusted dose regimens for the treatment of typhoid in older children should be the same as those for adults.

scholarly journals Pharmacokinetics of the Hypoxia-Imaging Agent [123I]IAZA in Healthy Adults Following Exercise-Based Cardiac Stress

2017 ◽  
Author(s):  
Daria Stypinski ◽  
Stephen A. McQuarrie ◽  
Alexander J.B. McEwan ◽  
Leonard I. Wiebe
Keyword(s):  
Healthy Volunteers ◽  
Venous Blood ◽  
Volume Of Distribution ◽  
Total Radioactivity ◽  
Whole Body ◽  
Strenuous Exercise ◽  
Published Data ◽  
Cardiac Stress ◽  
Myocardial Hypoxia ◽  
Total Body

Objective: &nbsp;To determine the pharmacokinetics (PK) and detect changes in cardiac uptake of [123I]IAZA, a radiopharmaceutical used to image focal tissue hypoxia, in healthy volunteers after exercise-based cardiac stress, to establish a rational basis for studies of focal myocardial hypoxia in cardiac patients using [123I]IAZA.&nbsp; Method:&nbsp; Three healthy male volunteers ran the &lsquo;Bruce&rsquo; treadmill protocol (criterion heart rate is 85 % of [220 &ndash; age]).&nbsp; Approximately one minute before reaching this level, [123I]IAZA (4.0 mCi/0.85 mg) was administered as a slow (1-3 min) single bolus i.v. injection, then the volunteer continued running for an additional 1 min.&nbsp; Serum from venous blood samples, taken at pre-determined intervals from 1 min to 45 h, was analyzed by radioHPLC.&nbsp; PK parameters were derived for [123I]IAZA and total radioactivity (total[123I]) using compartmental and noncompartmental analyses (NCA).&nbsp; Whole-body planar scintigraphic images were acquired from 0.75 to 24 h after dosing.&nbsp; PK data and scintigraphic images were compared to published data from healthy volunteers administered [123I]IAZA at rest. &nbsp;Results: &nbsp;Following strenuous exercise, both [123I]IAZA and total[123I] exhibited bi-exponential decline profiles, with rapid distribution phases [half-lives (t1/2&alpha;) of 1.2 and 1.4 min, respectively], followed by slower elimination phases [t1/2&beta; of 195 and 290 min, respectively]. &nbsp;Total body clearance (CLTB) and steady state volume of distribution (Vss) were 0.647 L/kg and 185 mL/min, respectively, for [123I]IAZA and 0.785 L/kg and 135 mL/min, respectively, for total[123I].&nbsp; The t1/2&beta;, CLTB and Vss values were comparable to those reported previously for rested volunteers.&nbsp; The t1/2&alpha; was approximately 4-fold shorter for [123I]IAZA and approximately 3-fold shorter for total[123I] under exercise relative to rested subjects. &nbsp;The heart was visualized in early whole body scintigraphic images, but overall there were no apparent differences from images reported for rested volunteers.&nbsp; Minimal uptake of radiotracer in myocardium and skeletal muscle was consistent with uptake in non-stressed muscle. &nbsp;Conclusion:&nbsp; The PK and whole-body scintigrams for [123I]IAZA in exercise-stressed healthy volunteers showed no clinically relevant differences relative to non-exercised volunteers.&nbsp; [123I]IAZA may therefore be suitable for the detection of viable, hypoxic myocardium in areas of myocardial perfusion deficiency.

Pharmacokinetics of Dirithromycin in Patients with Mild or Moderate Cirrhosis

1999 ◽  
Vol 43 (7) ◽  
pp. 1556-1559 ◽  
Author(s):  
Teresita Mazzei ◽  
Calogero Surrenti ◽  
Andrea Novelli ◽  
Maria Rosa Biagini ◽  
Stefania Fallani ◽  
...  
Keyword(s):  
Healthy Volunteers ◽  
Volume Of Distribution ◽  
Time Curve ◽  
Class A ◽  
Elimination Half ◽  
Class B ◽  
Child's Classification ◽  
Cirrhotic Patients ◽  
The Mean ◽  
Limited Basis

ABSTRACT The pharmacokinetics of dirithromycin were determined over a 72-h period following oral administration of a single 500-mg dose to 8 healthy volunteers and to 16 cirrhotic patients (8 patients with class A cirrhosis and 8 patients with class B cirrhosis according to Pugh’s & Child’s classification). Drug levels in plasma and urine were determined by microbiological assay. The mean maximum concentrations of drug in serum obtained 3 to 4 h after administration were 0.29 ± 0.22 mg/liter in volunteers and 0.48 ± 0.21 and 0.52 ± 0.38 mg/liter in patients with class A and class B cirrhosis, respectively. The elimination half-life (t 1/2β) was 23.3 ± 7.6 h in healthy subjects and 35.2 ± 11.8 h and 39.5 ± 11.0 h in patients with class A and class B cirrhosis, respectively. The mean area under the concentration-time curve (AUC) and t 1/2β were significantly higher in patients with class A and B cirrhosis than in healthy controls, while total and renal clearances were markedly reduced (P < 0.01). The time to the maximum concentration of drug in serum and the volume of distribution values appeared to be similar in all groups, and the mean recovery in urine at 72 h ranged from 3.7 to 5.7%, without significant differences among groups. These results demonstrate that some dirithromycin kinetic parameters are significantly different in cirrhotic patients in comparison to those in healthy volunteers. However, an increase in the t 1/2β or AUC, which is also observed with other semisynthetic macrolides (e.g., azithromycin), does seem to be not clinically relevant if one takes into account both the high therapeutic indices of these antibiotics and the usually short duration of therapy. Therefore, on the limited basis of single-dose administration, no modifications of dirithromycin dosage seem to be required even for patients with class B liver cirrhosis.

scholarly journals Intrapulmonary Pharmacokinetics of GSK2251052 in Healthy Volunteers

2013 ◽  
Vol 57 (7) ◽  
pp. 3334-3339 ◽  
Author(s):  
David Tenero ◽  
Gary Bowers ◽  
Keith A. Rodvold ◽  
Apurva Patel ◽  
Milena Kurtinecz ◽  
...  
Keyword(s):  
Healthy Volunteers ◽  
Vital Signs ◽  
Volume Of Distribution ◽  
Repeat Dose ◽  
Dose Administration ◽  
Epithelial Lining Fluid ◽  
Dose Cohort ◽  
The Mean ◽  
Safety Assessments ◽  
Clinically Significant

ABSTRACTThe plasma and intrapulmonary pharmacokinetics (PK) of intravenous (i.v.) GSK2251052, a novel boron-containing antimicrobial, were evaluated in healthy adult subjects. Thirty subjects underwent bronchoscopy and timed bronchoalveolar lavage (BAL) either following a single dose (cohort 1) or after 5 twice-daily doses (cohort 2) of 1,500 mg GSK2251052 i.v. Serial PK and safety assessments were obtained throughout the study. Bronchoscopy was performed on a single occasion in each subject at 2, 6, or 12 h after start of infusion. Noncompartmental analysis was performed to calculate PK parameters. Thirty subjects completed the study. The mean clearance (CL), volume of distribution at steady state (Vss), and half-life (t1/2) values were 22 liters/h, 231 liters, and 10.7 h, respectively. Approximately 30% of the dose was excreted unchanged in urine. The GSK2251052 concentrations in epithelial lining fluid (ELF) and alveolar macrophages (AM) were approximately 50% and 500 to 600%, respectively, compared to the concentration in plasma. the GSK2251052 exposures in ELF and AM were comparable following single- and repeat-dose administration. The most frequently reported drug-related adverse event (AE) was mild to moderate infusion site reactions (7 subjects) that occurred primarily in the repeat-dose cohort. No serious drug-related AEs or clinically significant trends in laboratory values, vital signs, or electrocardiograms were observed. GSK2251052 given as a 1,500-mg infusion was generally tolerated following single- or repeat-dose administration. GSK2251052 distributes into both the ELF and AM of healthy volunteers, which supports further study in patients with pneumonia.

scholarly journals Effect of Low-Dose Ritonavir on the Pharmacokinetics of the CXCR4 Antagonist AMD070 in Healthy Volunteers

2008 ◽  
Vol 52 (5) ◽  
pp. 1630-1634 ◽  
Author(s):  
Ying Jun Cao ◽  
Charles W. Flexner ◽  
Shelia Dunaway ◽  
Jeong-Gun Park ◽  
Karin Klingman ◽  
...  
Keyword(s):  
Healthy Volunteers ◽  
Geometric Mean ◽  
Apparent Volume ◽  
Volume Of Distribution ◽  
Terminal Phase ◽  
Cxcr4 Antagonist ◽  
Time Curve ◽  
Time To Peak ◽  
Immunodeficiency Virus ◽  
Male Subjects

ABSTRACT AMD070, a CXCR4 antagonist, has demonstrated antiretroviral activity in human immunodeficiency virus-infected patients. Since AMD070 is a substrate of cytochrome P450 3A4 and P-glycoprotein, both of which may be affected by ritonavir, we tested for a ritonavir effect on AMD070 pharmacokinetics. Subjects were given a single 200-mg dose of AMD070 on days 1, 3, and 17. Ritonavir (100 mg every 12 h) was dosed from day 3 to day 18. Blood samples to test for AMD070 concentrations were collected over 48 h after each administration of AMD070. Twenty-three male subjects were recruited. Among them, 21 completed the study, and 2 were discontinued for reasons other than safety. All adverse events were grade 2 or lower. AMD070 alone had the following pharmacokinetic features, given as medians (ranges): 3 h (0.5 to 4 h) for the time to peak blood concentration, 256 ng/ml (41 to 845 ng/ml) for the peak concentration (C max), 934 h·ng/ml (313 to 2,127 h·ng/ml) for the area under the concentration-time curve from 0 h to infinity (AUC0-∞), 214 liters/h (94 to 639 liters/h) for apparent body clearance, and 4,201 liters (1,996 to 9,991 liters) for the apparent volume of distribution based on the terminal phase. The initial doses of ritonavir increased the C max of AMD070 [geometric mean (90% confidence interval)] by 39% (3 to 89%) and the AUC0-∞ by 60% (29 to 100%). After 14 days of ritonavir dosing, the pharmacokinetic changes in AMD070 persisted. The plasma pharmacokinetics of ritonavir were consistent with previous reports. It is concluded that AMD070 concentrations were increased with concomitant ritonavir dosing for 14 days in healthy volunteers.

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