• Proceedings of the PSK Conference
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• 2003.10b
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• pp.241.2-241.2
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• 2003

The purpose of this study was to investigate the effect of quercetin(2.0, 10, 20 mg/kg; combined or pretreated) on the pharmacokinetic parameters and the bioavailability of diltiazem(15mg/kg) orally to rabbits. The plasma concentration of diltiazem pretreated with quercetin(pretreated group) were increased significantly (p<0.01) compared to that of control, but those of diltiazem combined with quercetin(combined group) were not affected. Area under the plasma concentration-time curve (AUC) of diltiazem pretreated with quercetin was significantly ( p<0.01) higher than that of control (omitted)

• Korean Journal of Clinical Pharmacy
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• v.17 no.1
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• pp.33-37
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• 2007

The purpose of this study was to investigate the effect of atorvastatin on the pharmacokinetics of diltiazem (15 mg/kg) after oral administration of diltiazem with or without atorvastatin (0.5, 1.5 and 3.0 mg/kg) in rats. Coadministration of atorvastatin increased significantly (p<0.05, 3.0 mg/kg) the plasma concentration-time curve (AUC) and the peak concentration $(C_{max})$ of diltiazem compared to the control group. The total plasma clearance (CL/F) of diltiazem was decreased significantly (p<0.05, 3.0 mg/kg) compared to the control group. The relative bioavailability (RB%) of diltiazem was increased from 1.14- to 1.49-fold. Coadministration of atorvastatin did not significantly change the elimination rate constant $(K_{el})$, terminal half-life $(T_{1/2})$ and the time to reach the peak concentration $(T_{max})$ of diltiazem. Based on these results, we can make a conclusion that the significant changes of these pharmacokinetic parameters might be due to atorvastatin, which possesses the potency to inhibit the metabolizing enzyme (CYP3A4) in the liver and intestinal mucosa, and also inhibit the P-glycoprotein (P-gp) efflux pump in the intestinal mucosa.

• Korean Journal of Clinical Pharmacy
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• v.16 no.1
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• pp.57-62
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• 2006

The purpose of this study was to investigate the effect of naringenin, one of flavonoids, on the pharmacokinetics and bioavailability of diltiazem (15 mg/kg) after oral administration of diltiazem with or without naringenin (2.0, 10 and 20 mg/kg) in rabbits. Coadministration of naringenin increased the absorption rate constant $(K_a)$, the area under the plasma concentration-time curve (AUC) and peak concentration $(C_{max})$ of diltiazem compared to the control group, but only significantly (p<0.05) by 10mg/kg of naringenin coadministration. The absolute bioavailability (AB%) of diltiazem by coadministration ranges from 7.8% to 10.3%, increased more than control (7.2%), and relative bioavailability (RB%) of diltiazem is increased from 1.08- to 1.43-fold. Coadministration caused on significant changes in the terminal half-lives $(t_{1/2})$ and the time to reach the peak concentration $(T_{max})$ of diltiazem. On the other hand, coadministration of naringenin increased the AUC desacetyldiltiazem, significantly at the dose of 10mg/kg. But the metabolite ratio (MR) was decreased, significantly at 10mg/kg of naringenin. Based on these results, we can make a conclusion that the increased bioavailability and the significant changes of these pharmacokinetic parameters might be due to naringenin, which possess the potency to inhibit the metabolizing enzyme (CYP3A4) in the liver and intestinal mucosa, and also inhibit the P-glycoprotein efflux pump in the intestinal mucosa.

• Journal of Pharmaceutical Investigation
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• v.33 no.4
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• pp.299-304
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• 2003

The purpose of this study was to investigate the effect of coadministration (2.5, 10, 20 mg/kg) and 3 or 7 days-pretreatment (10 mg/kg) of diltiazem on the pharmacokinetic parameters of paclitaxel (50 mg/kg) given orally in rats. The plasma concentrations of paclitaxel coadministered or pretreated with diltiazem were significantly (p<0.05 at 20 mg/kg coadmin., p<0.05 at pretreat.) increased compared to that of control, from 0.5 hr to 24 hr. Area under the plasma concentration-time curve (AUC) of paclitaxel coadministered or pretreated with diltiazem was significantly (p<0.05 at 20 mg/kg coadmin., p<0.01 at pretreat.) higher than that of control. Peak concentrations $(C_{max})$ of paclitaxel with diltiazem were significantly (p<0.05 at 20 mg/kg coadmn. and pretreat.) increased compared to that of control. Elimination rate constants $(K_{el})$ of paclitaxel with diltiazem were significantly (p<0.05 at 20 mg/kg and 7 days-pretreat.) reduced compared to those of control. Half-life $(t_{1/2})$ and mean residence time (MRT) of paclitaxel with diltiazem was significantly (p<0.05 at 20 mg/kg ad 7 days-pretreat.) prolonged compared to those of control. Absolute bioavailability (AB%) of paclitaxel with diltiazem was significantly (p<0.05 at 20 mg/kg and 3 days-pretreat, p<0.01 at 7 days -pretreat.) increased compared to that of control. Based on these results, it might be considered that diltiazem may inhibit cytochrome $P_{450}$ and P-glycoprotein, which are respectively engaged in paclitaxel absorption and metabolism in liver and gastrointestinal mucosa.

• Biomolecules & Therapeutics
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• v.1 no.1
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• pp.84-92
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• 1993

This study was performed to elucidate the mechanism of antidiuretic action of diltiazem by infusion into the vein and carotid artery, of diuretic action into a renal artery in dog. Renal denervation caused a reversal of the effect of diltiazem from the antidiuretic to the diuretic when infused into vein or carotid artery, and potentiated the diuretic effect when infused into a renal artery. The changes of renal function in diuretic circumstances as described above included the increase in renal plasma flow, osmolar clearance, the amounts of sodium and potassium excreted in urine and the decrease in reabosrption rate of sodium and potassium in renal tubules. Above results suggest that antidiuretic action of diltiazem may be mediated by central nervous system, not by endogenous substance, diuretic action by direct renal action.

• Journal of Pharmaceutical Investigation
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• v.23 no.1
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• pp.27-32
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• 1993

Pharmacokinetic drug interaction between phenytoin and diltiazem was investigated following i.v. administration concomitantly to rabbits. Diltiazem was coadministered at doses of 1, 2 and 3 mg/kg, respectively, with phenytoin (5 mg/kg) to rabbits. Plasma concentration and AUC of phenytoin were increased significantly, but volume of distribution and total body clearance were decreased significantly (p<0.05) at doses of 2 mg and 3 mg/kg of diltiazem. From the results of this experiment, it is desirable that dosage regimen of phenytoin should be adjusted and that therapeutic drug monitoring should be practiced for reduction of side or toxic effect when phenytoin should be administered with diltiazem in clinical practice.

• YAKHAK HOEJI
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• v.38 no.5
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• pp.568-578
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• 1994

This study was performed in order to investigate the effect of diltiazem, which is a $Ca^{2+}$ channel blocker of benzothiazepine derivatives, on renal function in the dog. Diltiazem, when infused into the vein or carotid artery, produced the antidiuresis accompanied with the decreased excretion rates of sodium and potassium in urine$(E_{Na},\;E_K)$ and the increased reabsorption rates of sodium and potassium in renal tubules$(R_{Na},\;R_K)$. Diltiazem, when infused into a renal artery, exhibited the diuresis along with the increased renal plasma flow(RPF), osmolar clearance$(C_{osm})$, $E_{Na}$ and $E_K$, and decreased $R_{Na}$ and $R_K$ in only infused kidney. Above results suggest that diltiazem possess both antidiuretic action through central action and diuretic action by direct inhibition of electrolytes reabsorption rates in renal tubules, mainly distal tubule.

• Korean Journal of Clinical Pharmacy
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• v.10 no.3
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• pp.120-124
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• 2000

Diltiazem inhibits calcium channels and leads to vascular smooth muscle relaxation and negative inotroic and chronotropic effects in the heart. Diltiazem (DTZ) is almost completely absorbed after oral administration, but its bioavailability is reduced because of considerable hepatic first-pass metabolism. The main metabolite of DTZ is deacetyldiltiazem. The purpose of this study was to report the pharmacokinetic changes of DTZ and its metabolite, deacetyldiltiazem (DAD) after intravenous administration of diltiazem to control rabbits and rabbits with mild and medium folate-induced renal failure (FIRRs). The area under the plasma concentration-time curves (AUC) of DTZ were significantly increased in mild and medium FIRRs. The metabolite ratio of the DAD to DTZ were significantly decreased in mild and medium FIRRs. The elimination rate constant $(\beta)$ and total body clearances (CLt) of DTZ were significantly decreased in mild and medium FIRRS. These findings suggest that the hepatic metabolism of diltiazem was inhibited and CLt and ${\beta}$ of DTZ were significantly decreased in mild and in rabbits with medium folate-induced renal failure.

• Applied Microscopy
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• v.27 no.2
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• pp.121-130
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• 1997

It has been demonstrated that majority of cells in the mammalian body such as myocytes and epithelial cells of skin and intestine respond to mechanical force or environmental factors and exhibit partial disruption of cell membrane, i. e., cell wounding, even in a physiological condition. Myocardial cells are rather apt to be wounded than other cells since they are definitely exposed to mechanical stress by contraction-relaxation and blood flow. However, the mechanism how myocardial cells protect themselves against cell wounding is not yet clarified. On this background, the present study was performed to elucidate whether albumin leakage is related to cell wounding and to assess whether diltiazem, a potent calcium channel blocker, is beneficial in isoproterenol-induced cell wounding in the heart. Hearts isolated from New Zealand White rabbits ($1.5\sim2.0kg$ body weight, n=20) were perfused with Tyrode solution by Langendorff technique. After stabilization of baseline hemodynamics, the hearts were subjected to bolus administration of isoproterenol and diltiazem as following order: $1.6{\mu}M$ isoproterenol at zero min (the beginning point): $16{\mu}M$ diltiazem at 20min; $1.6{\mu}M$ isoproterenol at 25min; $16{\mu}M$ isoproterenol at 45 min; $160{\mu}M$ diltiazem at 65 min; $16{\mu}M$ isoproterenol at 70 min. During all experiments, the left ventricular function was recorded, albumin leakage in the coronary effluents was analyzed by electrophoresis and Western blot, and myocardial cell membranes were examined by conventional transmission electron microscopy. Data were analyzed by t-test and linear regression test. Isoproterenol significantly increased the inotropic and chronotropic contractions, coronary flow, and frequency of arrhythmia, however, diltiazem did not influence on hemodynamics except decrease in the frequency of arrhythmia and a slight decrease in contractility. Isoproterenol also resulted partial disruption of myocardial cell membrane and inclose in albumin leakage, while diltiazem pretreatment showed number of electron-dense plaques in the cell membrane and a tendency of decrease in albumin leakage. These results indicate that albumin leakage may be an indirect index of cell wounding in the heart and diltiazem nay be beneficial to protect myocardial cells against isoproterenol-induced cell wounding. It is likely that diltiazem promotes resealing process of the cell membrane.

• Korean Journal of Clinical Pharmacy
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• v.3 no.2
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• pp.139-145
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• 1993

This study was attempted to investigate the pharmacokinetics of phenytoin(4mg/kg iv,) in rabbits pretreated with diltiazem(l and 2.5mg/kg) for 7 days. The plasma concentration and area under the curve(AUC) of phenytoin were increased significantly(p<0.05) in rabbits pretreated with diltiazem(2.5mg/kg) compared with those of control rabbits. Volume of distribution and total body clearance were decreased significantly(p<0,05) in rabbits pretreated with diltiazem compared with those of control rabbits. From the results of this experiment, it is desirable that dosage ragimen of phenytoin should be adjusted and that therapeutic drug monitoring should be practiced for reduction of side or toxic effect when phenytoin will be administered with diltiazem in clinical practice.