Apparent biological half-life values determined by administration of drug by methods other than rapid intravenous injection

1974 ◽  
Vol 26 (S1) ◽  
pp. 62P-63P ◽  
Author(s):  
ROBERT E. NOTARI ◽  
DALIA R. KAVALIUNAS ◽  
HOWARD N. BOCKBRADER
Keyword(s):  
Intravenous Injection ◽  
Half Life ◽  
Biological Half Life ◽  
Life Values

Surfactant metabolism of newborn lamb lungs studied in vivo

1980 ◽  
Vol 49 (6) ◽  
pp. 1091-1098 ◽  
Author(s):  
A. Jobe ◽  
M. Ikegami ◽  
I. Sarton-Miller ◽  
L. Barajas
Keyword(s):  
Palmitic Acid ◽  
Intravenous Injection ◽  
Half Life ◽  
Lamellar Body ◽  
Lung Parenchyma ◽  
Newborn Lamb ◽  
Specific Activities ◽  
Life Values ◽  
Surfactant Metabolism

Surfactant, microsomal, and lamellar body fractions were isolated from the lungs of 5-day-old lambs 0.21-55 h after the intravenous injection of radiolabeled palmitic acid. The specific activities as cpm/mumol phospholipid phosphate of phosphatidylcholine, saturated phosphatidylcholine, phosphatidylglycerol, and phosphatidylethanolamine were measured. The palmitate-labeled phospholipids disappeared from the lung parenchyma with a half-life of approximately 50 h. The radiolabel disappeared from phosphatidylcholine, saturated phosphatidylcholine, phosphatidylglycerol, and phosphatidylethanolamine of microsomal fractions with initial half-life values of 4.5, 4.6, 1.9, and 23.9 h, respectively. The labeled phospholipids rapidly appeared in the lamellar body fraction and accumulated in the surfactant of the lambs in a linear fashion for 35 h. The curves for the labeling of surfactant with radiolabeled saturated phosphatidylcholine, phosphatidylglycerol, and phosphatidylethanolamine were similar to the curve for phosphatidylcholine.

scholarly journals Radionuclide biological half-life values for terrestrial and aquatic wildlife

2015 ◽  
Vol 150 ◽  
pp. 270-276 ◽  
Author(s):  
N.A. Beresford ◽  
K. Beaugelin-Seiller ◽  
J. Burgos ◽  
M. Cujic ◽  
S. Fesenko ◽  
...  
Keyword(s):  
Half Life ◽  
Biological Half Life ◽  
Aquatic Wildlife ◽  
Life Values

THE EFFECT OF INTRAVENOUSLY INJECTED CORTICOTROPHIN IN MAN

1963 ◽  
Vol 44 (2) ◽  
pp. 250-258 ◽  
Author(s):  
Pavo Hedner ◽  
Yngve Einerth
Keyword(s):  
Intravenous Injection ◽  
Half Life ◽  
Active Plasma ◽  
Maximal Effect ◽  
Acth Level ◽  
Plasma Acth ◽  
Single Intravenous Injection ◽  
Clinical Therapy ◽  
Adrenocortical Activity ◽  
Biological Half Life

ABSTRACT A single intravenous injection of 10 U. S. P. units of a purified ACTH preparation in man produced a maximal effect for at least 4 hours, and the effect was still significant 8 hours after the injection. The biological half life of this preparation was calculated and found to be about 1 hour. When given as an infusion over 8 hours this preparation was calculated to give a maximally active plasma ACTH level for 9½ hours. A significantly increased plasma corticosteroid level was present 12 hours after the beginning of the infusion, and a comparable response was obtained by the same amount of ACTH twice injected intravenously with 4 hours interval. A maximal adrenocortical activity was obtained with 50 U. S. P. units of the same ACTH injected intramuscularly and this persisted for at least 8 hours. The result of this investigation is not consistent with the view often held that the biological half life of exogenous ACTH is short and this discrepancy may be explained by the purified ACTH preparation used here. The relation between different methods of ACTH administration and their significance in clinical therapy is discussed.

EFFECTS OF DIETARY IODINE ON THE UTILIZATION OF RADIOACTIVE IODIDE BY THE RAT

1963 ◽  
Vol 41 (7) ◽  
pp. 1547-1555 ◽  
Author(s):  
G. A. Robinson
Keyword(s):  
Thyroid Gland ◽  
Half Life ◽  
Sprague Dawley ◽  
High Iodine ◽  
In Vivo Measurements ◽  
Biological Half Life ◽  
Sprague Dawley Rats ◽  
Lower Protein ◽  
Life Values

Sprague–Dawley rats were fed on diets ranging from 40 μg I/kg to 3885 μg I/kg. Single doses of iodide-131 were injected intraperitoneally into each of the rats. In vivo measurements of radioisotope levels were made at intervals for 11 to 15 days over the neck and thorax. Thyroidal I131 curves were obtained by using a fraction of the thoracic counts to correct for the extrathyroidal component of the neck counts. Animals on low-iodine diets concentrated I131 in their thyroids more rapidly and to greater peak values, had lower protein-bound iodine (I127) concentrations, and lower total thyroidal iodide (I127) content than did rats in the high-iodine groups. An attempt was made to compensate the thyroidal counts for the continuing decrease in the concentration of iodide-131 in the plasma. From this attempt was derived the "thyroidal index", a parameter which may be related to the rate of exchange of the total thyroidal iodine stores. Biological half-life values (I131 in thyroid gland) for the low-iodine groups were larger than those for the high-iodine animals. The hypothesis is advanced that, at least for the conditions reported here, the biological half-life does not adequately reflect thyroidal activity; exchange of iodine between the rat and its environment is considered to be the more important factor in controlling the numerical value of this parameter.

EFFECTS OF DIETARY IODINE ON THE UTILIZATION OF RADIOACTIVE IODIDE BY THE RAT

1963 ◽  
Vol 41 (1) ◽  
pp. 1547-1555 ◽  
Author(s):  
G. A. Robinson
Keyword(s):  
Thyroid Gland ◽  
Half Life ◽  
Sprague Dawley ◽  
High Iodine ◽  
In Vivo Measurements ◽  
Biological Half Life ◽  
Sprague Dawley Rats ◽  
Lower Protein ◽  
Life Values

Sprague–Dawley rats were fed on diets ranging from 40 μg I/kg to 3885 μg I/kg. Single doses of iodide-131 were injected intraperitoneally into each of the rats. In vivo measurements of radioisotope levels were made at intervals for 11 to 15 days over the neck and thorax. Thyroidal I131 curves were obtained by using a fraction of the thoracic counts to correct for the extrathyroidal component of the neck counts. Animals on low-iodine diets concentrated I131 in their thyroids more rapidly and to greater peak values, had lower protein-bound iodine (I127) concentrations, and lower total thyroidal iodide (I127) content than did rats in the high-iodine groups. An attempt was made to compensate the thyroidal counts for the continuing decrease in the concentration of iodide-131 in the plasma. From this attempt was derived the "thyroidal index", a parameter which may be related to the rate of exchange of the total thyroidal iodine stores. Biological half-life values (I131 in thyroid gland) for the low-iodine groups were larger than those for the high-iodine animals. The hypothesis is advanced that, at least for the conditions reported here, the biological half-life does not adequately reflect thyroidal activity; exchange of iodine between the rat and its environment is considered to be the more important factor in controlling the numerical value of this parameter.

scholarly journals Hydroxocobalamin

Blood ◽  
1966 ◽  
Vol 27 (2) ◽  
pp. 227-233 ◽  
Author(s):  
GEORGE B. JERZY GLASS ◽  
DUK HO LEE
Keyword(s):  
Intravenous Injection ◽  
Half Life ◽  
Intramuscular Injection ◽  
Human Subjects ◽  
Biological Half Life ◽  
Double Label ◽  
Normal Human ◽  
The Mean

Abstract The mean hepatic biological half-life of Co57-hydroxocobalamin injected to 5 normal human subjects was similar to that of Co60-cyanocobalamin, as shown by double-label hepatic surface counting during the first 30 weeks after intramuscular or intravenous injection of cobalamins. In 2 cases in whom the counting was extended over a year’s period, the clearance of hepatic radioactivity following the intramuscular injection of hydroxocobalamin has slowed down as compared to that of cyanocobalamin, between the 30th and 52nd week after injection.

THE BIOLOGICAL HALF-LIFE OF K42 IN THE COW AND THE OBESE PIG

1961 ◽  
Vol 39 (7) ◽  
pp. 1125-1131 ◽  
Author(s):  
G. A. Robinson ◽  
K. G. McNeill ◽  
R. M. Green ◽  
H. C. Rowsell
Keyword(s):  
Half Life ◽  
Sodium Iodide ◽  
Constant Depth ◽  
Background Error ◽  
Biological Half Life ◽  
Urinary Potassium ◽  
Life Values ◽  
Total Potassium

Potassium-42 was used as a tracer of the total exchangeable body potassium in six cows and five large sows. One millicurie of K42 solution was injected intravenously into each animal and samples of urine and faeces were collected in 8-liter plastic pails, at intervals, for 70 hours. The radioisotope content of the samples was determined by dipping an unshielded sodium iodide scintillometer into the pails to a constant depth. Background error was reduced by setting the discriminator levels to accept only pulses corresponding to the photopeak of the K42 emission. The rate of excretion of K42 decreased for approximately 16 hours, then appeared to remain constant for the rest of the experiment. Means of biological half-life values, as calculated for the period from 22 to 70 hours, were 10.5 days for the cows and 45.6 days for the pigs. Percentages by weight of total potassium in the animals were 0.21 for the cows and 0.24 for the pigs, as estimated from flame photometric determinations of urinary potassium and biological half-life values. These results are compared with caesium and potassium studies reported by other investigators.

Turnover of Human Extrinsic (Tissue-Type) Plasminogen Activator in Rabbits

1981 ◽  
Vol 46 (03) ◽  
pp. 658-661 ◽  
Author(s):  
C Korninger ◽  
J M Stassen ◽  
D Collen
Keyword(s):  
Plasminogen Activator ◽  
Intravenous Injection ◽  
Active Site ◽  
Half Life ◽  
Degradation Products ◽  
Gel Filtration ◽  
Tissue Type ◽  
Organ Distribution ◽  
Small Rise

SummaryThe turnover of highly purified human extrinsic plasminogen activator (EPA) (one- and two-chain form) was studied in rabbits. Following intravenous injection, EPA-activity declined rapidly. The disappearance rate of EPA from the plasma could adequately be described by a single exponential term with a t ½ of approximately 2 min for both the one-chain and two-chain forms of EPA.The clearance and organ distribution of EPA was studied by using 125I-labeled preparations. Following intravenous injection of 125I-1abeled EPA the radioactivity disappeared rapidly from the plasma also with a t ½ of approximately 2 min down to a level of 15 to 20 percent, followed by a small rise of blood radioactivity. Gel filtration of serial samples revealed that the secondary increase of the radioactivity was due to the reappearance of radioactive breakdown products in the blood. Measurement of the organ distribution of 125I at different time intervals revealed that EPA was rapidly accumulated in the liver, followed by a release of degradation products in the blood.Experimental hepatectomy markedly prolonged the half-life of EPA in the blood. Blocking the active site histidine of EPA had no effect on the half-life of EPA in blood nor on the gel filtration patterns of 125I in serial plasma samples.It is concluded that human EPA is rapidly removed from the blood of rabbits by clearance and degradation in the liver. Recognition by the liver does not require a functional active site in the enzyme. Neutralization in plasma by protease inhibitors does not represent a significant pathway of EPA inactivation in vivo.

Gastroretentive System of Fluvastatin Sodium by Using Natural Mucilage and Synthetic Polymer

2014 ◽  
Vol 4 (2) ◽  
Author(s):  
Umamaheswara G. ◽  
Anudeep D.
Keyword(s):  
Half Life ◽  
Release Kinetics ◽  
Kinetic Studies ◽  
Diffusion Path ◽  
Synthetic Polymer ◽  
In Vitro Dissolution ◽  
Direct Compression ◽  
Drug Content ◽  
Biological Half Life

Fluvastatin sodium is a novel compound used as cholesterol lowering agent which acts through the inhibition of 3- hydroxyl-3- methyl glutaryl- coenzyme A (HMG-Co A) reductase. It has short biological half life (1-3h) in humans required a dosing frequency of 20 to 40mg twice a day. Due to its short variable biological half life it has been developed to a sustained gastroretentive system with a natural and synthetic polymer and to study how far the natural mucilage improves the sustained activity. Floating tablets were prepared by direct compression method using in combination of natural mucilage and synthetic polymer. Prior to the preparation of tablets the physical mixtures were subjected to FT IR studies and pre compression parameters. After preparation of tablets they were subjected to various tests like swollen index, drug content, In vitro dissolution and release kinetics with pcp disso software etc. The tablets prepared by direct compression shown good in thickness, hardness and uniformity in drug content, the prepared tablets floated more than 12h except FS1 and FS2 shows 9 and 11h. Swollen index studies shows with increase in concentration of polymer the swelling increases the diffusion path length by which the drug molecule may have to travel and cause lag time. In vitro results shows that on increasing the amount of hibiscus polymer the sustain activity is increased because of its integrity and forms a thick swollen mass and reduces the erosion property of the HypromelloseK100M, kinetic studies shows that FS 1, FS2, FS3 followed the Korsmeyer peppas model and the rest FS 4, FS 5, FS6 follows the zero order respectively. Based on n value indicating that the drug release followed super case II transport mechanism due to the erosion of the polymer.

Sign in / Sign up

Export Citation Format

Share Document