Estimation of the Elimination Half-Life of a Drug at Any Serum Concentration When the Kmand Vmaxof the Drug Are Known: Calculations and Validation With Phenytoin

1987 ◽  
Vol 27 (4) ◽  
pp. 318-320 ◽  
Author(s):  
Thomas R. Browne ◽  
David J. Greenblatt ◽  
James E. Evans ◽  
George K. Szabo ◽  
Barbara A. Evans ◽  
...  
Keyword(s):  
Serum Concentration ◽  
Half Life ◽  
Elimination Half Life ◽  
Elimination Half

scholarly journals Disposition kinetics of ceftriaxone and determination of its therapeutic dose in dogs

2020 ◽  
Vol 19 (8) ◽  
pp. 1735-1758
Author(s):  
Ifeanyi G. Eke ◽  
Ukamaka U. Eze ◽  
Aruh O. Anaga ◽  
Kennedy F. Chah ◽  
Boniface M. Anene ◽  
...  
Keyword(s):  
Steady State ◽  
Serum Concentration ◽  
Half Life ◽  
Therapeutic Dose ◽  
Maximum Serum ◽  
Elimination Half Life ◽  
Disposition Kinetics ◽  
Elimination Half ◽  
Significant Difference ◽  
Kinetics Of

Purpose: To evaluate the disposition kinetics of ceftriaxone (CFZ) in dogs with a view to determining its therapeutic dose and dosing frequency.Methods: Twelve (12) Basenji dogs (n = 4), divided into 3 groups (A, B and C), were used for the study. Ceftriaxone was administered intramuscularly at doses of 12.5, 25, and 50 mg/kg once to groups A, B and C respectively. Plasma CFZ concentration was determined by agar well diffusion assay at 0.25, 0.5, 1, 2, 3, 4, 6, 8, 10, 12, and 24 h post-treatment, and the pharmacokinetic parameters were determined.Results: Intramuscular injection of CFZ to dogs resulted in rapid absorption, distribution and elimination (p < 0.05). The elimination half-life was short and did not change significantly with increase in dose. Serum concentration of CFZ changed significantly (p < 0.05) with increase in dose of CFZ. The maximum serum concentration (Cmax, 15.00 ± 1.18, 141.37 ± 15.87 and 259 ± 5.21 μg/mL) for groups A, B and C respectively were significantly (p < 0.05) different. The steady state CFZ concentrations; 0.94, 8.81 and 16.19 μg/mL for groups A, B and C, respectively, were significantly (p < 0.05) different. However, there was no significant difference in the time to reach steady state concentrations (Tmax, 00±0.021, 4.00±0.10 and 4.30±0.12 for groups A, B and C respectively). The therapeutic dose of CFZ was therefore determined to be 25 – 50 mg/kg every 4 h.Conclusion: Ceftriaxone undergoes rapid elimination in dogs with a short elimination half-life, thus making it an inconvenient prescription for out-patients in veterinary clinics. Keywords: Ceftriaxone, Pharmacokinetic profile, Dogs, Therapeutic dose, Veterinary clinic

Influence of concomitant drugs on methadone elimination half-life in patients under a maintenance treatment

2001 ◽  
Vol 6 (2) ◽  
pp. 171-176 ◽  
Author(s):  
A. C. S. Lucas ◽  
A. M. Bermejo ◽  
M. J. Tabernero ◽  
P. FernÁNdez ◽  
P. CÁMpora
Keyword(s):  
Half Life ◽  
Maintenance Treatment ◽  
Elimination Half Life ◽  
Elimination Half

Lactic Acidosis, Hyperglycaemia and Convulsions following Nalidixic Acid Overdosage

1984 ◽  
Vol 3 (3) ◽  
pp. 239-243 ◽  
Author(s):  
P.J.A. Leslie ◽  
R.J. Cregeen ◽  
A.T. Proudfoot
Keyword(s):  
Plasma Concentration ◽  
Lactic Acidosis ◽  
Nalidixic Acid ◽  
Half Life ◽  
Abnormal Behaviour ◽  
Elimination Half Life ◽  
Elimination Half

1 A woman survived ingestion of 32 g nalidixic acid despite developing lactic acidosis, hyperglycaemia, convulsions and abnormal behaviour. 2 The maximum recorded plasma concentration of nalidixic acid was 185 mg/l and the elimination half-life was 3.2 h. 3 Carboxy-nalidixic acid was demonstrated in the plasma. 4 Previously reported cases of nalidixic acid overdosage are reviewed.

Elimination Half-Life

2010 ◽  
pp. 475-475
Author(s):  
Bart Ellenbroek ◽  
Alfonso Abizaid ◽  
Shimon Amir ◽  
Martina de Zwaan ◽  
Sarah Parylak ◽  
...  
Keyword(s):  
Half Life ◽  
Elimination Half Life ◽  
Elimination Half

scholarly journals Pharmacokinetics, tissue residues of tilmicosin phosphate (tilmicor-al®) and its in vitro and in vivo evaluation for the control of Mycoplas-ma gallisepticum infection in broiler chickens

2017 ◽  
Vol 5 (1) ◽  
pp. 11 ◽  
Author(s):  
Mohamed Elbadawy ◽  
Mohamed Aboubakr
Keyword(s):  
Half Life ◽  
Broiler Chickens ◽  
Peak Plasma ◽  
Clinical Signs ◽  
In Vivo Evaluation ◽  
Elimination Half Life ◽  
Elimination Half ◽  
Residue Study

The aim of present study was to determine the pharmacokinetics and tissue residues of tilmicosin phosphate (tilmicoral®) as well as its in vitro and in vivo evaluation for control of Mycoplasma gallisepticum (MG) infection in broiler chickens. Pharmacokinetics (single oral dose) and tissues residues (daily for five days) of tilmicosin (25 mg/kg b.wt) in broilers were investigated. Peak plasma concentration of tilmicosin was 1.25±0.0.09 μg/mL and achieved at 3.15±0.34 h. Elimination half-life was long (44.3±7.22 h) and Vdarea was large (1.25±0.082 L/kg). Residue study revealed a good distribution and penetration of tilmicosine in lung, liver, kidney and muscles. Tilmicosin could not be detected in all tested tissues (except in lung) at 6 days after last administration. The MIC of tilmicosin and tylosin against MG were 0.054 and 0.319 μg/mL, respectively. MG infected chickens and treated by tilmicosin or tylosin showed a significant (p<0.05) improvement in mean body weights gain and a significant (p<0.05) decline in mean clinical signs score, air sac lesion score and mortality rate, however tilmicosin was a superior drug. In conclusion, timicoral® was a very effective medication for controlling MG infection in broiler chickens due to its rapid absorption, long elimination half-life, rapid and extensive penetration from blood into tissues especially lungs and air sacs. Additionally, tilmicoral® had a short withdrawal time. Moreover, its superior efficacy (in vitro and in vivo) against MG.

scholarly journals In Vivo Pharmacodynamic Activity of the Glycopeptide Dalbavancin

2007 ◽  
Vol 51 (5) ◽  
pp. 1633-1642 ◽  
Author(s):  
David Andes ◽  
William A. Craig
Keyword(s):  
Half Life ◽  
Dose Range ◽  
Lung Infection ◽  
Free Drug ◽  
Infection Model ◽  
Gram Positive ◽  
Elimination Half Life ◽  
Elimination Half ◽  
Dose Dependent

ABSTRACT Dalbavancin is a lipoglycopeptide antibiotic with broad-spectrum activity against gram-positive cocci and a markedly prolonged serum elimination half-life. We used the neutropenic murine thigh and lung infection models to characterize the pharmacodynamics of dalbavancin. Single-dose pharmacokinetic studies demonstrated linear kinetics and a prolonged elimination half-life which ranged from 7.6 to 13.1 h over the dose range of 2.5 to 80 mg/kg of body weight. The level of protein binding in mouse serum was 98.4%. The time course of in vivo activity of dalbavancin over the same dose range was examined in neutropenic ICR Swiss mice infected with a strain of either Streptococcus pneumoniae or Staphylococcus aureus by using the thigh infection model. The burden of organisms for S. pneumoniae was markedly reduced over the initial 24 h of study, and organism regrowth was suppressed in a dose-dependent fashion for up to the entire 96 h of study following dalbavancin doses of 2.5 mg/kg or greater. Dalbavancin doses of 20 mg/kg or greater resulted in less killing of S. aureus but were still followed by a prolonged suppression of regrowth. Multiple-dosing-regimen studies with the same organisms were used to determined which of the pharmacodynamic indices (maximum concentration in serum [C max]/MIC, area under the concentration-versus-time curve [AUC]/MIC, or the duration of time that levels in serum exceed the MIC) best correlated with treatment efficacy. These studies used a dose range of 3.8 to 480 mg/kg/6 days fractionated into 2, 4, 6, or 12 doses over the 144-h dosing period. Nonlinear regression analysis was used to examine the data fit with each pharmacodynamic index. Dalbavancin administration by the use of large, widely spaced doses was the most efficacious for both organisms. Both the 24-h AUC/MIC and the C max/MIC parameters correlated well with the in vivo efficacy of treatment against S. pneumoniae and S. aureus (for 24-h AUC/MIC, R 2 = 78 and 77%, respectively; for C max/MIC, R 2 = 90 and 57%, respectively). The free-drug 24-h AUC/MICs required for a bacteriostatic effect were 17 ± 7 for five S. pneumoniae isolates. A similar treatment endpoint for the treatment against five strains of S. aureus required a larger dalbavancin exposure, with a mean free-drug 24-h AUC/MIC of 265 ± 143. Beta-lactam resistance did not affect the pharmacodynamic target. The dose-response curves were relatively steep for both species; thus, the pharmacodynamic target needed to achieve organism reductions of 1 or 2 log10 in the mice were not appreciably larger (1.3- to 1.6-fold). Treatment was similarly efficacious in neutropenic mice and in the lung infection model. The dose-dependent efficacy and prolonged elimination half-life of dalbavancin support the widely spaced regimens used in clinical trials. The free-drug 24-h AUC/MIC targets identified in these studies should be helpful for discerning rational susceptibility breakpoints. The current MIC90 for the target gram-positive organisms would fall within this value.

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