Hepatic clearance of drugs. III. Additional experimental evidence supporting the “wellstirred” model, using metabolite (MEGX) generated from lidocaine under varying hepatic blood flow rates and linear conditions in the perfused rat liverin situ preparation

1977 ◽  
Vol 5 (6) ◽  
pp. 681-699 ◽  
Author(s):  
K. Sandy Pang ◽  
Malcolm Rowland
1983 ◽  
Vol 17 (2) ◽  
pp. 110-120 ◽  
Author(s):  
Eugene M. Sorkin ◽  
Diane L. Darvey

The literature on cimetidine drug interactions has been thoroughly reviewed. Several different mechanisms have been proposed for cimetidine-related drug interactions. These mechanisms include: (1) impaired hepatic drug metabolism due to inhibition of hepatic microsomal enzymes, (2) reduced hepatic blood flow, resulting in decreased clearance of drugs that are highly extracted by the liver, (3) increased potential for myelosuppression when administered concurrently with other drugs capable of causing myelosuppression, and (4) altered bioavailability of acid-labile drugs. Cimetidine binds reversibly to the hepatic cytochrome P-450 and P-448 systems, resulting in decreased metabolism of drugs that undergo Phase I reactions (e.g., dealkylation and hydroxylation). In contrast, glucuronidation pathways are unaffected. The rapid onset and reversal of cimetidine's inhibition of hepatic metabolism indicates an effect on hepatic enzyme systems. Cimetidine also has been reported to decrease hepatic blood flow. Drugs that are highly extracted by the liver, such as propranolol, lidocaine, and morphine, may be postulated to have a decreased hepatic clearance. Cimetidine, through its effect on gastric pH, may increase the absorption of acid-labile drugs or may decrease the absorption of drugs. There have been reports of increased potential for myelosuppression when cimetidine is administered concurrently with drugs capable of causing bone marrow suppression. An understanding of the mechanisms involved in cimetidine drug interactions allows the clinician to prevent and predict these interactions.


1990 ◽  
Vol 11 ◽  
pp. S24
Author(s):  
JC García-Paqán ◽  
F Feu ◽  
L Ruiz del Arbol ◽  
I Cirera ◽  
P Pizcueta ◽  
...  

1994 ◽  
Vol 20 (6) ◽  
pp. 792-796 ◽  
Author(s):  
Juan Carlos García-Pagán ◽  
Fausto Feu ◽  
Angelo Luca ◽  
Mercedes Fernández ◽  
Pilar Pizcueta ◽  
...  

Pharmacology ◽  
1981 ◽  
Vol 23 (5) ◽  
pp. 237-246 ◽  
Author(s):  
James R. Gillette ◽  
Wilford F. Saul ◽  
Harriet M. Mating

1976 ◽  
Vol 68 (2) ◽  
pp. 257-264 ◽  
Author(s):  
I. R. McDONALD ◽  
KHIN AYE THAN

SUMMARY Brush-tailed opossums were prepared surgically with indwelling hepatic and jugular venous catheters for blood sampling without disturbance in the conscious state. Hepatic extraction of [125I]Rose Bengal was 21 ± 3 (s.d.)% and hepatic clearance, used as a measure of hepatic blood flow, was 42·5 ± 7 ml/kg/min. Hepatic release of new glucose, calculated from the thoracic vena caval-hepatic venous difference in glucose specific activity at equilibrium during i.v. infusion of [14C]glucose and hepatic blood flow, was 3·5 ± 0·8 mg/ kg/min. This was not changed by i.v. infusion of 10% ethanolic saline or cortisol in ethanolic saline, at 1 mg/kg/h for 90 min, although the cortisol infusion caused the peripheral blood glucose concentration to rise from 56·5 ± 7·3 to 83·2 ± 10·3 mg/100 ml. The rate of metabolic clearance of glucose fell from 6·1 ± 1·1 to 4·2 ± 0·9 ml/kg/min during i.v. cortisol infusion. Daily i.m. injection of 1 mg cortisol acetate/kg for 5 days caused an increase in hepatic new glucose release to 8·0 ± 1·6 mg/kg/min. The findings support the proposition that, in this marsupial, the short-term effect of cortisol on plasma glucose concentration is due to inhibition of peripheral glucose utilization, whereas the long-term effect is due to increased hepatic glucose production.


1965 ◽  
Vol 20 (3) ◽  
pp. 384-394 ◽  
Author(s):  
Loring B. Rowell ◽  
John R. Blackmon ◽  
Richard H. Martin ◽  
John A. Mazzarella ◽  
Robert A. Bruce

At 78 and 110 F hepatic clearance of indocyanine green (ICG), O2 intake, heart rate, blood lactate, and rectal temperature were measure on nine men unacclimatized to heat during treadmill exercise, requiring 45–95% of maximal O2 intake (max Vo2). Percentage of resting ICG clearance was inversely proportional to percentage of maximal O2 intake at 78 F (ggr = -0.78) and 110 F (ggr = -0.81). Clearance of ICG was 20% less at 110 F than at 78 F at all metabolic rates above 26% of maximal Vo2. Measurements of hepatic blood flow in three men at 110 F validate these estimates of percentage decrements in hepatic blood flow. Submaximal and maximal Vo2 and maximal heart rates were unaltered by heat, but maximal heart rates were reached during submaximal work at 110 F. Decreased work capacity at 110 F was unrelated to rectal temperature or blood lactate; the latter was unaffected by temperature. The liver and the kidneys may divert to the skin sufficient blood to obviate the need for additional increments in cardiac output during work at high temperature. Maximal decrements in hepatic blood flow at lower work intensities may contribute to diminished work capacity at 110 F. hepatic blood flow during exercise; lactic acid and heat stress; rectal temperature; heart rate and temperature; maximal o2 intake, influence of temperature; temperature redistribution of blood flow; work capacity, effect of heat Submitted on October 30, 1964


1977 ◽  
Vol 55 (1) ◽  
pp. 7-12 ◽  
Author(s):  
W. Wayne Lautt ◽  
F. Steve Skelton

Hepatic blood flow and hepatic uptake of lidocaine were determined in cats during constant intravenous infusion of lidocaine. Lidocaine clearance is directly linked to hepatic blood flow with reductions in flow being reflected in equal reductions in hepatic clearance. Altered blood flow did not result in altered rates of lidocaine extraction. Lidocaine extraction ratio was 28%.Hepatic blood flow and lidocaine metabolism were measured before and 60 min after an intramuscular injection of SKF-525A (50 mg/kg). SKF-525A produced a reduction in hepatic clearance of lidocaine to 60% of control values, entirely as a result of a reduction in hepatic extraction ratios. Hepatic blood flow and vascular conductance were not affected by SKF-525A.


1963 ◽  
Vol 44 (6) ◽  
pp. 733-739 ◽  
Author(s):  
Kathleen M. Wartnaby ◽  
I.A.D. Bouchier ◽  
C.E. Pope ◽  
Sheila Sherlock

1959 ◽  
Vol 36 (1) ◽  
pp. 112-119 ◽  
Author(s):  
Joseph S. Burkle ◽  
Marvin L. Gliedman

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