scholarly journals Effect of Concomitant Artesunate Administration and Cytochrome P4502C8 Polymorphisms on the Pharmacokinetics of Amodiaquine in Ghanaian Children with Uncomplicated Malaria

2008 ◽  
Vol 52 (12) ◽  
pp. 4400-4406 ◽  
Author(s):  
George O. Adjei ◽  
Kim Kristensen ◽  
Bamenla Q. Goka ◽  
Lotte C. G. Hoegberg ◽  
Michael Alifrangis ◽  
...  
Keyword(s):  
Body Weight ◽  
Uncomplicated Malaria ◽  
Population Distribution ◽  
Parasite Clearance ◽  
Compartment Model ◽  
Volume Of Distribution ◽  
Maximum Plasma ◽  
Two Compartment Model ◽  
Elimination Half ◽  
Wide Variability

ABSTRACT Artesunate (AS) is used in combination with amodiaquine (AQ) as first-line treatment for uncomplicated malaria in many countries. We investigated the effect of concomitant AS administration on the pharmacokinetics of AQ and compared concentrations of desethylamodiaquine (DEAQ), the main metabolite of AQ, in plasma between patients with different variants of the cytochrome P4502C8 (CYP2C8) gene. A two-compartment model was fitted to 169 plasma DEAQ concentrations from 103 Ghanaian children aged 1 to 14 years with uncomplicated malaria treated either with AQ alone (n = 15) or with AS plus AQ (n = 88). The population clearance of DEAQ appeared to increase nonlinearly with body weight, and the central volume of distribution of DEAQ was higher (P < 0.001) in the AS-plus-AQ group than in the AQ-only group. The maximum plasma DEAQ concentration was higher (P < 0.001), and the population distribution half-life was shorter (P < 0.01), in the AQ-only group than in the AS-plus-AQ group. The total areas under the plasma DEAQ concentration-time curves (P = 0.68) and elimination half-lives (P = 0.39) were similar for the two groups. There was a high frequency (0.179) of the non-wild-type allele of CYP2C8, but no differences between CYP2C8 genotypes with regard to AQ efficacy or safety were evident. The sample size, however, was limited, so monitoring of AQ toxicity in the study area is still indicated. The nonlinear clearance of DEAQ and the wide variability in kinetic parameters have safety implications for weight-based dosing of higher-body-weight children with AQ. The pharmacokinetics of artemisinin combination therapies should be studied in malaria patients, because the rapid parasite clearance caused by the artemisinin may affect the kinetics of the partner drug and the combination.

scholarly journals Pharmacokinetics and Efficacy of Piperaquine and Chloroquine in Melanesian Children with Uncomplicated Malaria

2007 ◽  
Vol 52 (1) ◽  
pp. 237-243 ◽  
Author(s):  
Harin A. Karunajeewa ◽  
Kenneth F. Ilett ◽  
Ivo Mueller ◽  
Peter Siba ◽  
Irwin Law ◽  
...  
Keyword(s):  
Half Life ◽  
Uncomplicated Malaria ◽  
Active Metabolite ◽  
High Performance ◽  
Compartment Model ◽  
Volume Of Distribution ◽  
Two Compartment Model ◽  
Elimination Half ◽  
Median Volume ◽  
Intensive Sampling

ABSTRACT The disposition of chloroquine (CQ) and the related 4-aminoquinoline, piperaquine (PQ), were compared in Papua New Guinean children with uncomplicated malaria. Twenty-two children were randomized to 3 days of PQ phosphate at 20 mg/kg/day (12 mg of PQ base/kg/day) coformulated with dihydroartemisinin (DHA-PQ), and twenty children were randomized to 3 days of CQ at 10 mg base/kg/day with a single dose of sulfadoxine-pyrimethamine (CQ-SP). After a 42-day intensive sampling protocol, PQ, CQ, and its active metabolite monodesethyl-chloroquine (DECQ) were assayed in plasma by using high-performance liquid chromatography. A two-compartment model with first-order absorption was fitted to the PQ and CQ data. There were no significant differences in age, gender, body weight, or admission parasitemia between the two groups. The PCR-corrected 42-day adequate clinical and parasitological responses were 100% for DHA-PQ and 94% for CQ-SP, but P. falciparum reinfections during follow-up were common (33 and 18%, respectively). For PQ, the median volume of distribution at steady state, allowing for bioavailability (V ss/F), was 431 liters/kg (interquartile range [IQR], 283 to 588 liters/kg), the median clearance (CL/F) was 0.85 liters/h/kg (IQR, 0.67 to 1.06 liters/h/kg), the median distribution half-life (t 1/2 α) was 0.12 h (IQR, 0.05 to 0.66 h), and the median elimination half-life (t 1/2 β) was 413 h (IQR, 318 to 516 h). For CQ, the median V ss/F was 154 liters/kg (IQR, 101 to 210 liters/kg), the median CL/F was 0.80 liters/h/kg (IQR, 0.52 to 0.96 liters/h/kg), the median t 1/2 α was 0.43 h (IQR, 0.05 to 1.82 h), and the median t 1/2 β was 233 h (IQR, 206 to 298 h). The noncompartmentally derived median DECQ t 1/2 β was 290 h (IQR, 236 to 368 h). Combined molar concentrations of DECQ and CQ were higher than those of PQ during the elimination phase. Although PQ has a longer t 1/2 β than CQ, its prompt distribution and lack of active metabolite may limit its posttreatment malaria-suppressive properties.

Steady-State Pharmacokinetics of Cefoperazone and Sulbactam in Patients with Acute Appendicitis

1994 ◽  
Vol 28 (6) ◽  
pp. 703-707
Author(s):  
Larry H. Danziger ◽  
Stephen C. Piscitelli ◽  
Donna J. Occhipinti ◽  
Daniel J. Resnick ◽  
Keith A. Rodvold
Keyword(s):  
Steady State ◽  
Acute Appendicitis ◽  
Dosage Reduction ◽  
Area Under The Curve ◽  
Compartment Model ◽  
Hepatic Function ◽  
Volume Of Distribution ◽  
Two Compartment Model ◽  
Elimination Half ◽  
G Prior

OBJECTIVE: To determine the steady-state pharmacokinetics of intravenously administered cefoperazone and sulbactam when given in combination to patients with acute appendicitis. METHODS: Six patients with normal renal and hepatic function received cefoperazone 2 g with sulbactam 1 g prior to appendectomy and then every 12 hours. Serial blood samples were collected after each patient received at least three doses of cefoperazone/sulbactam. RESULTS: Cefoperazone and sulbactam could be best described by a two-compartment model. Mean ± SD values for cefoperazone steady-state volume of distribution (Vssd), elimination half-life (t1/2β), clearance (Cl), and area under the curve (AUC0-t) were 19.8 ± 8.0 L, 3.97 ± 1.06 h, 62.6 ± 16.3 mL/min, and 556.9 ± 122.0 mg·h/L, respectively. Sulbactam Vssd, t1/2β, Cl, and AUC0-t were 34.7 ± 13.9 L, 1.39 ± 0.4 h, 288.6 ± 68.2 mL/min, and 64.8 ± 24.5 mg·h/L, respectively. CONCLUSIONS: Compared with data from healthy volunteers, cefoperazone exhibited a decreased Cl and increased Vssd and t1/2β in patients with acute appendicitis. An increased Vssd also was observed for sulbactam. The disposition of cefoperazone/sulbactam is altered in this group of patients; however, these changes are not likely to warrant a dosage reduction.

Trastuzumab (T) and everolimus (E) pharmacokinetics (PK) in HER2 positive (+) primary breast cancer (BC) patients (pts): Unicancer RADHER trial results.

2013 ◽  
Vol 31 (15_suppl) ◽  
pp. 2599-2599
Author(s):  
Guillemette Bernadou ◽  
Keyvan Rezai ◽  
Jean-Louis Merlin ◽  
Mario Campone ◽  
Francois Lokiec ◽  
...  
Keyword(s):  
Body Weight ◽  
Half Life ◽  
Tumor Volume ◽  
Compartment Model ◽  
Her2 Positive ◽  
Elimination Half Life ◽  
A Value ◽  
Two Compartment Model ◽  
Elimination Half ◽  
The Impact

2599 Background: T has greatly modified the prognosis of HER2+ BC, but few studies have analyzed its PK. The RADHER study evaluated the interest of adding E to T as preoperative therapy for primary HER2+ BC. It also aimed at describing the PK of T and studying the impact of E with T in primary BC. Methods: Eligible pts with HER2+ operable primary BC were randomized to receive T alone (loading dose 4 mg/kg, then 2 mg/kg/week (W)) or T + E (10 mg/day (D)) for a 6-W pre-operative treatment. Blood samples were collected to measure T and E concentrations. For T, plasma samples were collected in all pts before each infusion, and at Hour (H) 1, D1, D3, W1, W2, W4, W8 and W12 after the last infusion. E concentrations were determined on whole blood collected at H0, H0.5, H1, H2, H4, H6, H12 and H24 after the first T infusion, and again after the last E intake. T and E PK were described using population compartment analyses. Results: From 82 pts randomized, 79 were evaluable for T and 22 for E PK. Mean estimated PK parameters of T were (interindividual coefficient of variation %): central (Vc) and peripheral (Vp) volumes of distribution = 2 L (24%) and 1.3 L (39%), systemic (CL) and intercompartment (Q) clearances = 0.22 L/day (19%) and 0.36 L/day, respectively. Vc increased with body weight and decreased with age, while CL increased with body weight and with tumor volume. Elimination half-life was 11 days, a value lower than that previously reported in metastatic BC (28 days). E PK was best described by a two-compartment model. Mean estimated PK parameters (RSE%) of E were: CL = 3.96 L/h (22%), Q = 29.1 L/h (7%), Vc = 119 L (11%), Vp = 1530 L (24%). E did not influence T PK. E PK was similar to that previously reported in other indications. Conclusions: This is the first study describing the PK of T and E in primary BC. Notably, T CL increases with tumor volume and the elimination half-life is only 11 days, lower than expected from previous results in metastatic BC. The differences in PK between primary and metastatic BC might lead to take a second look at trastuzumab dose regimen in primary BC. Clinical trial information: NCT00674414.

PHARMACOKINETICS OF THE LONG-ACTING CEFTIOFUR CRYSTALLINE-FREE ACID IN ARABIAN SHE-CAMELS (Camelus dromedarius)

2021 ◽  
Vol 58 (3) ◽  
Author(s):  
Wael Mohamed El-Deeb ◽  
Mahmoud Kandeel ◽  
Mahmoud Fayez ◽  
Ibrahim Ghoneim
Keyword(s):  
Serum Concentration ◽  
Residence Time ◽  
Free Acid ◽  
Compartment Model ◽  
Camelus Dromedarius ◽  
Free Form ◽  
Maximum Plasma ◽  
Two Compartment Model ◽  
Elimination Half ◽  
Long Acting

Ceftiofur is an important broad-spectrum 3rd generation cephalosporin antibiotic. Owing to its time-dependent antimicrobial actions, the length of time of being above bacterial MIC is the critical point in using ceftiofur for chemotherapy rather than its peak of concentration. Consequently, this experiment was carried out to evaluate, for the first time, the pharmacokinetics of the long-acting ceftiofur crystalline acid-free form (ceftiofur-CAF) in camels. Ceftiofur-CAF 200 mg/ml suspension sterile solution was injected i/m at a dose 6.6 mg/kg. Blood samples were collected from the jugular vein in vacutainer tubes at 0, 0.13, 0.25, 0.5, 1, 2, 4, 8, 12, 24, 48, 72, 96, 120, and 144 hours after administration of the drug. Ultrahigh Performance Liquid Chromatography-Mass Spectrometry (UPLC MS/MS) was used to measure serum concentration. Pharmacokinetic modeling was by a two-compartment model. Pharmacokinetics of ceftiofur-CAF after single i/m injection in she-camels was best modeled in the two-compartment model, where the drug slowly distributed to a second compartment with poor tissue penetration and high preference to the central compartment. In this study, the maximum plasma concentration (Cmax) was 9.29±0.42 μg/ml at Tmax equals 9.41±1.35 h. The area under the curve (AUC0-∞) was 354.1±57.22 μg/ml*h. The distribution and elimination half-lives were 7.42 and 46.13 h, respectively. The mean residence time (MRT) was 42.01 h. Compared with the rapidly absorbed form of ceftiofur (ceftufor-RAF) in camels, there was almost similar maximal serum concentration but with delayed time to maximal concentration (Tmax), longer means residence time (MRT) and higher distribution and elimination half-lives. In terms of antibacterial efficacy, ceftiofur-CAF stayed above a previously recommended level of 0.2 μg/ml for 7 days, which can be achieved after a single i/m injection of 6.6 mg/kg. The obtained pharmacokinetics data in camels recommends repeated administration of 2 days apart for bacteria requiring MIC levels above 2 μg/ml.Key words: Ceftiofur; pharmacokinetics; camel; cephalosporinsFARMAKOKINETIKA DOLGODELUJOČE CEFTIOFURNE KRISTALINIČNE PROSTE KISLINE PRI SAMICAH ARABSKIH KAMEL (Camelus dromedarius) Izvleček: Ceftiofur je pomemben širokospektralni antibiotik 3. generacije cefalosporinov. Zaradi njegovih časovno odvisnih protimikrobnih učinkov je čas, ko je raven ceftiofura nad bakterijskim MIC in ne pri njegovem vrhu koncentracije kritična točka pri uporabi tega antibiotika. Poskus je bil izveden z namenom ovrednotenja farmakokinetike dolgo delujoče ceftiofurjeve kristalinične brezkislinske oblike (ceftiofur-CAF) pri kamelah. Ceftiofur-CAF v koncentraciji 200 mg/ml suspenzije sterilne raztopine smo injicirali i/m v odmerku 6,6 mg/kg. Vzorci krvi so bili zbrani iz vratne vene v vakuumskih epruvetah ob injiciranju antibiotika in nato 8, 15 in 30 minut po injiciranju ter 1, 2, 4, 8, 12, 24, 48, 72, 96, 120 in 144 ur po injiciranju antibiotika. Za merjenje serumske koncentracije je bila uporabljena tekočinska kromatografija ultra visoke ločljivosti (UPLC MS/MS). Farmakokinetično modeliranje je bilo izvedeno z dvokomponentnim modelom. Farmakokinetiko ceftiofur-CAF-a po enkratnem i/m injiciranju v kamele je bilo najbolje modelirati v modelu z dvema predelkoma, kjer se je zdravilo počasi razdeljevalo v drugi predelek s slabo penetracijo v tkiva in veliko prednostjo do osrednjega predelka. Najvišja koncentracija antibiotika v plazmi (Cmax) je bila 9,29 ± 0,42 μg/ml pri Tmax 9,41 ± 1,35 ure. Površina pod krivuljo (AUC0-∞) je bila 354,1 ± 57,22 μg/ml*h. Razpolovni čas razporeditve in izločanja je bil 7,42 oziroma 46,13 ure. Povprečni čas prisotnosti antibiotika (MRT) je bil 42,01 h. V primerjavi s hitro absorbirano obliko ceftiofurja (ceftufor-RAF) pri kamelah je bila skoraj podobna največja koncentracija v serumu, vendar z zakasnjenim časom do največje koncentracije (Tmax), daljšim časom zadrževanja (MRT) in večjim razpolovnim časom porazdelitve in izločanja. Ceftiofur-CAF ostal dni nad predhodno priporočeno ravnijo učinkovitosti 0,2 μg/ml kar 7 dni, kar je bilo mogoče doseči po enkratni i/m injekciji 6,6 mg/kg. Pridobljeni podatki o farmakokinetiki v kamelah priporočajo večkratno dajanje v razmaku 2 dni za bakterije, ki potrebujejo ravni MIC nad 2 μg/ml.Ključne besede: Ceftiofur; farmakokinetika; kamela; cefalosporini 

scholarly journals Serum bactericidal activities and comparative pharmacokinetics of meropenem and imipenem-cilastatin.

1996 ◽  
Vol 40 (1) ◽  
pp. 105-109 ◽  
Author(s):  
M Dreetz ◽  
J Hamacher ◽  
J Eller ◽  
K Borner ◽  
P Koeppe ◽  
...  
Keyword(s):  
Compartment Model ◽  
Pharmacokinetic Parameters ◽  
Time Curve ◽  
Dose Administration ◽  
Microdilution Method ◽  
Two Compartment Model ◽  
Elimination Half ◽  
Renal Clearances ◽  
The Mean ◽  
Bactericidal Activities

The pharmacokinetics and serum bactericidal activities (SBAs) of imipenem and meropenem were investigated in a randomized crossover study. Twelve healthy male volunteers received a constant 30-min infusion of either 1 g of imipenem plus 1 g of cilastatin or 1 g of meropenem. The concentrations of the drugs in serum and urine were determined by bioassay and high-pressure liquid chromatography. Pharmacokinetic parameters were based on an open two-compartment model and a noncompartmental technique. At the end of infusion, the mean concentrations of imipenem and meropenem measured in serum were 61.2 +/- 9.8 and 51.6 +/- 6.5 mg/liter, respectively; urinary recoveries were 48.6% +/- 8.2% and 60.0% +/- 6.5% of the dose in 12 h, respectively; and the areas under the concentration-time curve from time zero to infinity were 96.1 +/- 14.4 and 70.5 +/- 10.3 mg.h/liter, respectively (P < or = 0.02). Imipenem had a mean half-life of 66.7 +/- 10.4 min; that of meropenem was 64.4 +/- 6.9 min. The volumes of distribution at steady state of imipenem and meropenem were 15.3 +/- 3.3 and 18.6 +/- 3.0 liters/70 kg, respectively, and the mean renal clearances per 1.73 m2 were 85.6 +/- 17.6 and 144.6 +/- 26.0 ml/min, respectively. Both antibiotics were well tolerated in this single-dose administration study. The SBAs were measured by the microdilution method of Reller and Stratton (L. B. Reller and C. W. Stratton, J. Infect. Dis. 136:196-204, 1977) against 40 clinically isolated strains. Mean reciprocal bactericidal titers were measured 1 and 6 h after administration. After 1 and 6 h the median SBAs for imipenem and meropenem, were 409 and 34.9 and 97.9 and 5.8, respectively, against Staphylococcus aureus, 19.9 and 4.4 and 19.4 and 4.8, respectively, against Pseudomonas aeruginosa, 34.3 and 2.2 and 232 and 15.5, respectively, against Enterobacter cloacae, and 13.4 and 2.25 and 90.7 and 7.9, respectively, against Proteus mirabilis. Both drugs had rather short biological elimination half-lives and a predominantly renal route of elimination. Both carbapenems revealed high SBAs against clinically important pathogens at 1 h; meropenem had a higher SBA against E. cloacae and P. mirabilis, and the SBA of imipenem against S. aureus was greater than the SBA of meropenem.

scholarly journals Treatment of gastrointestinal cytomegalovirus infection with twice-daily foscarnet: a pilot study of safety, efficacy, and pharmacokinetics in patients with AIDS.

1997 ◽  
Vol 41 (6) ◽  
pp. 1226-1230 ◽  
Author(s):  
D T Dieterich ◽  
M A Poles ◽  
E A Lew ◽  
S Martin-Munley ◽  
J Johnson ◽  
...  
Keyword(s):  
Body Weight ◽  
Steady State ◽  
Gastrointestinal Disease ◽  
Elimination Rate ◽  
Volume Of Distribution ◽  
Open Label ◽  
Laboratory Observation ◽  
Patient Reports ◽  
Elimination Half ◽  
Days Of Therapy

Ten patients with AIDS and cytomegalovirus (CMV) gastrointestinal infection were included in an open-label study to evaluate the safety, efficacy, and pharmacokinetics of 90 mg of intravenous foscarnet/kg of body weight twice daily accompanied by (pre)hydration of 500 to 750 ml. Efficacy was documented endoscopically, while safety was evaluated clinically by patient reports and physical and laboratory observation. The pharmacokinetics of foscarnet was evaluated after the first dose and following approximately 20 days of therapy. Nine patients (90%) responded histopathologically, nine (90%) responded endoscopically, and nine (90%) responded symptomatically to foscarnet therapy. Adverse events resulted in discontinuance of medication in the case of one patient. The mean maximal concentration was 621 microM following the first dose and 687 microM at steady state (P = 0.11). The apparent elimination rate constant and elimination half-life were not different between dose 1 and steady state. There were no significant changes in foscarnet excretion or renal clearance between dose 1 and steady state. The steady-state volume of distribution was 23.4 liters following the first dose and 19.0 liters at steady state (P < 0.002). Twice-daily foscarnet appeared to be safe and efficacious in the treatment of CMV gastrointestinal disease in this study, resulting in endoscopic or histologic improvement in 9 of the 10 (90%) patients. Minor changes in clearance and volume of distribution noted at steady state compared to single-dose administration are readily explained by study design, known information about foscarnet pharmacokinetics, and changes in body weight and creatinine clearance in the patients.

scholarly journals A Bioavailability and Pharmacokinetic Study of Oral and Intravenous Hydroxyurea

Blood ◽  
1998 ◽  
Vol 91 (5) ◽  
pp. 1533-1541 ◽  
Author(s):  
Gladys I. Rodriguez ◽  
John G. Kuhn ◽  
Geoffrey R. Weiss ◽  
Susan G. Hilsenbeck ◽  
John R. Eckardt ◽  
...  
Keyword(s):  
Oral Administration ◽  
Oral Bioavailability ◽  
Interindividual Variability ◽  
Plasma Concentrations ◽  
Rest Period ◽  
Compartment Model ◽  
Volume Of Distribution ◽  
Harmonic Mean ◽  
Maximum Plasma ◽  
Urine Sampling

Abstract Despite the widespread usage of hydroxyurea in the treatment of both malignant and nonmalignant diseases and a recent expansion in the recognition of its potential therapeutic applications, there have been few detailed studies of hydroxyurea's pharmacokinetic (PK) behavior and oral bioavailability. Parenteral administration schedules have been evaluated because of concerns about the possibility for significant interindividual variability in the PK behavior and bioavailability of hydroxyurea after oral administration. In this PK and bioavailability study, 29 patients with advanced solid malignancies were randomized to treatment with 2,000 mg hydroxyurea administered either orally or as a 30-minute intravenous (IV) infusion accompanied by extensive plasma and urine sampling for PK studies. After 3 weeks of treatment with hydroxyurea (80 mg/kg orally every 3 days followed by a 1-week washout period), patients were crossed over to the alternate route of administration, at which time extensive PK studies were repeated. Three days later, patients continued treatment with 80 mg/kg hydroxyurea orally every 3 days for 3 weeks, followed by a 1-week rest period. Thereafter, 80 mg/kg hydroxyurea was administered orally every 3 days. Twenty-two of 29 patients had extensive plasma and urine sampling performed after treatment with both oral and IV hydroxyurea. Oral bioavailability (F) averaged 108%. Moreover, interindividual variability in F was low, as indicated by 19 of 22 individual F values within a narrow range of 85% to 127% and a modest coefficient of variation of 17%. The time in which maximum plasma concentrations (Cmax) were achieved averaged 1.22 hours with an average lag time of 0.22 hours after oral administration. Except for Cmax, which was 19.5% higher after IV drug administration, the PK profiles of oral and IV hydroxyurea were very similar. The plasma disposition of hydroxyurea was well described by a linear two-compartment model. The initial harmonic mean half-lives for oral and IV hydroxyurea were 1.78 and 0.63 hours, respectively, and the harmonic mean terminal half-lives were 3.32 and 3.39 hours, respectively. For IV hydroxyurea, systemic clearance averaged 76.16 mL/min/m2 and the mean volume of distribution at steady-state was 19.71 L/m2, whereas Cloral/F and Voral/F averaged 73.16 mL/min/m2 and 19.65 L/m2, respectively, after oral administration. The percentage of the administered dose of hydroxyurea that was excreted unchanged into the urine was nearly identical after oral and IV administration—36.84% and 35.82%, respectively. Additionally, the acute toxic effects of hydroxyurea after treatment on both routes were similar. Relationships between pertinent PK parameters and the principal toxicity, neutropenia, were sought, but no pharmacodynamic relationships were evident. From PK, bioavailability, and toxicologic standpoints, these results indicate that there are no clear advantages for administering hydroxyurea by the IV route except in situations when oral administration is not possible and/or in the case of severe gastrointestinal impairment.

scholarly journals Population Pharmacokinetics of Nevirapine, Zidovudine, and Didanosine in Human Immunodeficiency Virus-Infected Patients

1999 ◽  
Vol 43 (1) ◽  
pp. 121-128 ◽  
Author(s):  
Xiao-Jian Zhou ◽  
Lewis B. Sheiner ◽  
Richard T. D’Aquila ◽  
Michael D. Hughes ◽  
Martin S. Hirsch ◽  
...  
Keyword(s):  
Human Immunodeficiency Virus ◽  
Body Weight ◽  
Population Pharmacokinetics ◽  
Compartment Model ◽  
Volume Of Distribution ◽  
Zero Order ◽  
Triple Combination ◽  
Entire Study ◽  
First Order ◽  
Immunodeficiency Virus

ABSTRACT The population pharmacokinetics of nevirapine (NVP), zidovudine (ZDV), and didanosine (ddI) were evaluated in a total of 175 patients infected with human immunodeficiency virus randomized to receive either a double combination of ZDV plus ddI or a triple combination of NVP plus ZDV plus ddI as a substudy of the AIDS Clinical Trials Group Protocol 241. Levels (approximating 3.5 determinations/patient) of the three drugs in plasma were measured during 44 of a total 48 weeks of study treatment, and a set of potential covariates was available for nonlinear mixed-effect modeling analysis. A one-compartment model with zero-order input and first-order elimination was fitted to the NVP data. Individual oral clearance (CL) and volume of distribution (V) averaged 0.0533 liters/h/kg of body weight and 1.17 liters/kg, respectively. Gender was the only covariate which significantly correlated with the CL of NVP. ZDV and ddI data were described by a two-compartment model with zero-order input and first-order elimination. Individual mean oral CL,V SS (volume of distribution at steady state), and V of ZDV were 1.84 liters/h/kg and 6.68 and 2.67 liters/kg, respectively, with body weight and age as correlates of CL and body weight as a correlate of V SS. The average individual oral CL, V SS, andV of ddI were 1.64 liters/h/kg and 3.56 and 2.74 liters/kg, respectively, with body weight as a significant correlate of both CL and V SS. The relative bioavailability (F) of ZDV and ddI in the triple combination compared to that in the double combination was also evaluated. No significant effects of the combination regimens on the F of ddI were detected (F TRIPLE = 1.05 andF DOUBLE = 1 by definition), but theF of ZDV was markedly reduced by the triple combination, being only 67.7% of that of the double combination. Large (>50%) intraindividual variability was associated with both ZDV and ddI pharmacokinetics. Individual cumulative area under the plasma drug level-time curve of the three drugs was calculated for the entire study period as a measure of drug exposure based on the individual data and the final-model estimates of structural and statistical parameters.

scholarly journals 1573. Population Pharmacokinetic Analyses for Cefepime in Adult and Pediatric Patients

2019 ◽  
Vol 6 (Supplement_2) ◽  
pp. S574-S575
Author(s):  
Jiajun Liu ◽  
Michael Neely ◽  
Jeffrey Lipman ◽  
Fekade B Sime ◽  
Jason Roberts ◽  
...  
Keyword(s):  
Rate Constant ◽  
Pediatric Patients ◽  
Validation Cohort ◽  
External Validation ◽  
Compartment Model ◽  
Volume Of Distribution ◽  
Information Criteria ◽  
Population Pharmacokinetic ◽  
Final Model ◽  
Two Compartment Model

Abstract Background Cefepime (CEF) is commonly used for adult and pediatric infections. Several studies have examined CEF’s pharmacokinetics (PK) in various populations; however, a unifying PK model for adult and pediatric subjects does not yet exist. We developed a combined population model for adult and pediatric patients and validated the model. Methods The initial model includes adult and pediatric patients with a rich cefepime sampling design. All adults received 2 g CEF while pediatric subjects received a mean of 49 (SD 5) mg/kg. One- and two-compartment models were considered as base models and were fit using a non-parametric adaptive grid algorithm within the Pmetrics package 1.5.2 (Los Angeles, CA) for R 3.5.1. Compartmental model selection was based on Akaike information criteria (AIC). Covariate relationships with PK parameters were visually inspected and mathematically assessed. Predictive performance was evaluated using bias and imprecision of the population and individual prediction models. External validation was conducted using a separate adult cohort. Results A total of 45 subjects (n = 9 adults; n = 36 pediatrics) were included in the initial PK model build and 12 subjects in the external validation cohort. Overall, the data were best described using a two-compartment model with volume of distribution (V) normalized to total body weight (TBW/70 kg) and an allometric scaled elimination rate constant (Ke) for pediatric subjects (AIC = 4,138.36). Final model observed vs. predicted plots demonstrated good fit (population R2 = 0.87, individual R2 = 0.97, Figure 1a and b). For the final model, the population median parameter values (95% credibility interval) were V0 (total volume of distribution), 11.7 L (10.2–14.6); Ke for adult, 0.66 hour−1 (0.38–0.78), Ke for pediatrics, 0.82 hour−1 (0.64–0.85), KCP (rate constant from central to peripheral compartment), 1.4 hour−1 (1.3–1.8), KPC (rate constant from peripheral to central compartment), 1.6 hour−1 (1.2–1.8). The validation cohort has 12 subjects, and the final model fit the data well (individual R2 = 0.75). Conclusion In this diverse group of adult and pediatrics, a two-compartment model described CEF PK well and was externally validated with a unique cohort. This model can serve as a population prior for real-time PK software algorithms. Disclosures All authors: No reported disclosures.

scholarly journals Population Pharmacokinetics of Liposomal Amphotericin B and Caspofungin in Allogeneic Hematopoietic Stem Cell Recipients

2011 ◽  
Vol 56 (1) ◽  
pp. 536-543 ◽  
Author(s):  
Gudrun Würthwein ◽  
Charlotte Young ◽  
Claudia Lanvers-Kaminsky ◽  
Georg Hempel ◽  
Mirjam N. Trame ◽  
...  
Keyword(s):  
Stem Cell ◽  
Amphotericin B ◽  
Hematopoietic Stem Cell ◽  
Liposomal Amphotericin ◽  
Compartment Model ◽  
Volume Of Distribution ◽  
Concentration Data ◽  
Hematopoietic Stem ◽  
Two Compartment Model ◽  
Proportional Error Model

ABSTRACTLiposomal amphotericin B (LAMB) and caspofungin (CAS) are important antifungal agents in allogeneic hematopoietic stem cell transplant (aHSCT) recipients. Little is known, however, about the pharmacokinetics (PK) of both agents and their combination in this population. The PK of LAMB and CAS and the potential for PK interactions between both agents were investigated within a risk-stratified, randomized phase II clinical trial in 53 adult aHSCT recipients with granulocytopenia and refractory fever. Patients received either LAMB (n= 17; 3 mg/kg once a day [QD]), CAS (n= 19; 50 mg QD; day 1, 70 mg), or the combination of both (CAS-LAMB;n= 17) for a median duration of 10 to 13 days (range, 4 to 28 days) until defervescence and granulocyte recovery. PK sampling was performed on days 1 and 4. Drug concentrations in plasma (LAMB, 405 samples; CAS, 458 samples) were quantified by high-pressure liquid chromatography and were analyzed using population pharmacokinetic modeling. CAS concentration data best fitted a two-compartment model with a proportional error model and interindividual variability (IIV) for clearance (CL) and central volume of distribution (V1) (CL, 0.462 liter/h ± 25%;V1, 8.33 liters ± 29%; intercompartmental clearance [Q], 1.25 liters/h; peripheral volume of distribution [V2], 3.59 liters). Concentration data for LAMB best fitted a two-compartment model with a proportional error model and IIV for all parameters (CL, 1.22 liters/h ± 64%;V1, 19.2 liters ± 38%;Q, 2.18 liters/h ± 47%;V2, 52.8 liters ± 84%). Internal model validation showed predictability and robustness of both models. None of the covariates tested (LAMB or CAS comedication, gender, body weight, age, body surface area, serum bilirubin, and creatinine clearance) further improved the models. In summary, the disposition of LAMB and CAS was best described by two-compartment models. Drug exposures in aHSCT patients were comparable to those in other populations, and no PK interactions were observed between the two compounds.

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