On the calculation of absorption rate constant of linear one-compartment open models using peak blood level or peak urinary excretion rate and post-absorptive data

The number of amalgam-covered surfaces and the occlusal area of the fillings, the concentrations of total mercury in plasma, erythrocytes and urine, the urinary excretion rate, and the absorbed daily doses estimated by two separate methods from intra-oral Hg emission were determined in 29 volunteers with a low amalgam load. The transfer ofHg from the fillings via the oral cavity and blood to urinary excretion was evaluated by multiple correla tions between these variables. In addition, the combina tion of variables most representative of the entire compartmental transfer of amalgam Hg was determined. Urinary excretion (1), Hg concentration in plasma (2) and absorbed dose (3) were most closely correlated to each other, followed by correlations with the variables of the fillings (4). Correlation coefficients were 0.75 for variables 1 vs 2 and 2 vs 3, and 0.49 for variables 3 vs 4. It was concluded that variables 1-3 best reflected the transfer of mercury from amalgam fillings throughout the organism and that they were relatively insensitive to dietary mercury. The determination of total mercury in plasma and of its urinary excretion rate appears, under practical aspects, most suitable for the investigation of Hg uptake from amalgam.

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Absorption Enhancing Effect of Sodium Dodecyl Sulfate on Metformin Hydrochloride in Rat Colon

Key Engineering Materials ◽

10.4028/www.scientific.net/kem.544.426 ◽

2013 ◽

Vol 544 ◽

pp. 426-430

Author(s):

Dong Dong Jing ◽

Yu Liu ◽

Ruo Yu Liu ◽

Hua Fan ◽

Guo Feng Li ◽

...

Keyword(s):

Sodium Dodecyl Sulfate ◽

Rate Constant ◽

Absorption Rate ◽

Sodium Dodecyl ◽

Rat Colon ◽

Metformin Hydrochloride ◽

Loop Model ◽

Absorption Rate Constant ◽

Enhancing Effect ◽

Dodecyl Sulfate

The aim of this study was to observe the absorption enhancing effect of sodium dodecyl sulfate on metformin hydrochloride in colon of rat. Using in vivo intestinal loop model in rat while the ileum was took as blank group and colon as the experiment groups with different concentration of sodium dodecyl sulfate (1%, 2%, 4%). The colon/ileum ratio of the absorption rate constant of metformin hydrochloride was evaluated through calculating the residual dose of circulating solution in presupposition time points. Intergroup absorption rate constant and the rising percent of the absorption rate constant were different significantly (P<0.05). The absorption rate constant of colon were -0.22±0.03, -0.37±0.06, -0.89±0.09, -0.86±0.05μg•h-1•cm-1 (n=6) and the rising percent of the constant absorption value were 68.66 ± 8.28%, 304.88 ± 28.76%, 293.75 ± 33.19% (n=6), respectively. The result showed that the absorption of metformin hydrochloride was increased with the concentration of sodium dodecyl sulfate. However, the absorption rate constant reached maxium when the concentration of sodium dodecyl sulfate was 2%, this may be because the circulating metformin hydrochloride solution could be more viscous which affect the absorption of metformin hydrochloride when sodium dodecyl sulfate was raised. In conclusion, the absorption of metformin hydrochloride can be promoted by sodium dodecyl sulfate in the colon of rat and this can provide biophamaceutics data for novel pharmaceutical preparation.

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Theoretical consideration for the cases where absorption rate constant approaches elimination rate constant in the linear one-compartment open models

International Journal of Pharmaceutics ◽

10.1016/0378-5173(82)90106-5 ◽

1982 ◽

Vol 12 (4) ◽

pp. 351-354 ◽

Cited By ~ 6

Author(s):

M. Barzegar-Jalali ◽

M. Toomanian

Keyword(s):

Rate Constant ◽

Theoretical Consideration ◽

Absorption Rate ◽

Elimination Rate ◽

Elimination Rate Constant ◽

Absorption Rate Constant

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Pregnancy Enhances the Angiotensin (Ang)-(1–7) Vasodilator Response in Mesenteric Arteries and Increases the Renal Concentration and Urinary Excretion of Ang-(1–7)

Endocrinology ◽

10.1210/en.2003-0009 ◽

2003 ◽

Vol 144 (8) ◽

pp. 3338-3343 ◽

Cited By ~ 35

Author(s):

Liomar A. A. Neves ◽

Aleck F. Williams ◽

David B. Averill ◽

Carlos M. Ferrario ◽

Michael P. Walkup ◽

...

Keyword(s):

Urinary Excretion ◽

Excretion Rate ◽

Virgin Female ◽

Cardiovascular Regulation ◽

Mesenteric Arteries ◽

Female Rats ◽

Resistance Arteries ◽

Urinary Excretion Rate ◽

Response Curves ◽

Mesenteric Vessels

Abstract The vasoactive effect of angiotensin (Ang)-(1–7) in mesenteric resistance arteries together with its plasma and kidney concentration and urinary excretion was assessed in pregnant and virgin rats. Mesenteric arteries (230–290 μm) were mounted in a pressurized myograph system and Ang-(1–7) concentration-dependent response curves (10−10–10−5m) were determined in arteries preconstricted with endothelin-1 (10−7m). The Ang-(1–7) response was investigated in vessels with and without pretreatment with the Ang-(1–7) antagonist [d-[Ala7]-Ang-(1–7)] (10−7m). Ang-(1–7) caused a significantly enhanced, concentration-dependent dilation of mesenteric vessels (EC50 = 2.7 nm) from pregnant compared with virgin female rats. d-[Ala7]-Ang-(1–7) eliminated the vasodilator effect of Ang-(1–7). There was no significant change in plasma concentration of Ang-(1–7) in pregnant animals. On the other hand, 24 h urinary excretion and kidney concentration of Ang-(1–7) were significantly higher in pregnant animals. The increased mesenteric dilation to Ang-(1–7) with enhanced kidney concentration and 24 h urinary excretion rate of Ang-(1–7) suggests an important role for this peptide in cardiovascular regulation during pregnancy.

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Functional significance of exaggerated renal thromboxane A2 synthesis induced by cyclosporin A

AJP Renal Physiology ◽

10.1152/ajprenal.1986.251.4.f581 ◽

1986 ◽

Vol 251 (4) ◽

pp. F581-F587 ◽

Cited By ~ 3

Author(s):

N. Perico ◽

A. Benigni ◽

C. Zoja ◽

F. Delaini ◽

G. Remuzzi

Keyword(s):

Urinary Excretion ◽

Cyclosporin A ◽

Chronic Treatment ◽

Excretion Rate ◽

Thromboxane A2 ◽

Significant Negative Correlation ◽

Progressive Increase ◽

Urinary Excretion Rate ◽

Acid Clearance ◽

Selective Increase

Animals and humans undergoing a chronic treatment with cyclosporin A (CyA) show a reduction in glomerular filtration rate (GFR). The cause of this abnormality has not been established. Since CyA interferes with arachidonic acid (AA) metabolism in various cells, we wished to determine whether alterations in renal AA metabolites contribute to deteriorating renal function in rats on CyA. We show that chronic CyA treatment induces a progressive increase in the renal synthesis of thromboxane (TX) A2. This is a selective abnormality in that CyA does not influence the renal synthesis of prostaglandin E2 (PGE2) and prostacyclin (PGI2). A significant negative correlation has been found between TXB2 urinary excretion rate and inulin clearance. No correlation has been observed between TXB2 excretion and p-aminohippuric acid clearance. The withdrawal of CyA is followed by a normalization of both TXB2 urinary excretion rate and GFR. The administration of a selective TXA2 inhibitor, UK-38,485, resulted in a significant reduction in urinary excretion of TXB2 accompanied by a significant increase in GFR. We conclude that chronic treatment with CyA in rats is associated with a selective increase in renal TXA2 synthesis and suggest that this abnormality may play a role in the reduction of GFR.

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Urinary Excretion Rate of Guanidinoacetic Acid in Essential Hypertension

Guanidines 2 ◽

10.1007/978-1-4613-0821-8_18 ◽

1989 ◽

pp. 137-146

Author(s):

Yoshiyuki Takano ◽

Fumitake Gejyo ◽

Yoshio Shirokane ◽

Moto-o Nakajima ◽

Masaaki Arakawa

Keyword(s):

Essential Hypertension ◽

Urinary Excretion ◽

Excretion Rate ◽

Urinary Excretion Rate ◽

Guanidinoacetic Acid

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Pharmacokinetics of human chorionic gonadotropin after i.m. administration in goats (Capra hircus)

Reproduction ◽

10.1530/rep-12-0093 ◽

2012 ◽

Vol 144 (1) ◽

pp. 77-81 ◽

Cited By ~ 12

Author(s):

M Saleh ◽

M Shahin ◽

W Wuttke ◽

M Gauly ◽

W Holtz

Keyword(s):

Rate Constant ◽

Chorionic Gonadotropin ◽

Human Chorionic Gonadotropin ◽

Half Life ◽

Absorption Rate ◽

Elimination Rate ◽

Elimination Rate Constant ◽

Capra Hircus ◽

Absorption Rate Constant ◽

Biological Half Life

The present investigation addresses the pharmacokinetics of human chorionic gonadotropin (hCG), intramuscularly (i.m.) administered to goats. Nine pluriparous does of the Boer goat breed, 2–6 years of age and weighing 45–60 kg, were administered 500 IU hCG (2 ml Chorulon) deep into the thigh musculature 18 h after superovulatory FSH treatment. Blood samples were drawn from the jugular vein at 2 h intervals for the first 24 h, at 6 h intervals until 42 h, and at 12 h intervals until 114 h after administration. After centrifugation, plasma hCG concentrations were determined by electrochemiluminescence immunoassay. Pharmacokinetical parameters were as follows: lag time, 0.4 (s.e.m. 0.1) h; absorption rate constant, 0.34 (s.e.m. 0.002) h; absorption half-life, 2.7 (s.e.m. 0.5) h; elimination rate constant, 0.02 (s.e.m. 0.002) h; biological half-life, 39.4 (s.e.m. 5.1) h; and apparent volume of distribution, 16.9 (s.e.m. 4.3) l. The plasma hCG profile was characterized by an absorption phase of 11.6 (s.e.m. 1.8) h and an elimination phase of 70.0 (s.e.m. 9.8) h, with considerable individual variation in bioavailability and pharmacokinetical parameters. Biological half-life was negatively correlated (P<0.05) with peak concentration (r=−0.76), absorption rate constant (r=−0.78), and elimination rate constant (r=−0.87). The results indicate that after rapid absorption, hCG remains in the circulation for an extended period. This has to be taken into account when assessing the stimulatory response to hCG treatment on an ovarian level.

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