Pharmacokinetics of Oral Doses of Telmisartan and Nisoldipine, Given Alone and in Combination, in Patients With Essential Hypertension

This randomized, single-blind, parallel-group study was performed to assess pharmacokinetic interactions potentially occurring during concomitant use of telmisartan and nisoldipine. Patients with essential hypertension (n = 37) were treated with once-daily doses of telmisartan, nisoldipine, or their combination for 6 weeks. The regimen was started at low dose with an increase of dosage after 3 weeks of treatment. AUC(ss) (132%; P < .01) of telmisartan applied in doses of 80 mg was significantly higher after concomitant application with nisoldipine (10 mg), whereas CL/f(ss) (-54%; P < .05) and Vz/f(ss) (-72%; P < .05) were significantly lower. Regarding pharmacokinetic parameters of nisoldipine, significant differences between treatment groups were not detected. In conclusion, the results of this study strongly suggest that concomitant treatment with nisoldipine enhances telmisartan bioavailability in hypertensive individuals. Larger crossover trials will have to establish these observations and investigate whether interaction of both drugs affects telmisartan efficacy and tolerability in clinical use.

Validated LC–MS–MS method for determination of m-nisoldipine polymorphs in rat plasma and its application to pharmacokinetic studies

A sensitive and specific liquid chromatography-tandem mass spectrometric (LC-MS-MS) method has been developed to determine m-nisoldipine in rat plasma. Sample was pretreated by a single-step protein precipitation with acetonitrile, in contrast to the liquid-liquid procedure frequently used for the extraction of 1,4-dihydropyridines from biologic samples. Separation of analyte and internal standard (I.S.) was performed on a Symmetry RP-C(18) analytic column (50 mm x 4.6 mm, 3.5 microm) with a mobile phase consisting of acetonitrile-water (80:20, v/v) at a flow rate of 0.5 ml/min. The API 4000 triple quadrupole mass spectrometer was operated in multiple reaction monitoring (MRM) scan mode using TurboIonSpray ionization (ESI) source. The method was sensitive with a lower limit of quantification (LLOQ) of 0.2 ng/mL, with good linearity (r>or=0.9982) over the linear range of 0.2-20 ng/mL. All the validation data, such as accuracy, precision, and inter-day repeatability, were within the required limits. The method was successfully applied to pharmacokinetic and relative bioavailability studies of m-nisoldipine polymorphs in rats.

Dynamic and kinetic disposition of nisoldipine enantiomers in hypertensive patients presenting with type-2 diabetes mellitus

OBJECTIVE

Nisoldipine (N) is a dihydropyridine calcium antagonist marketed as a racemic mixture and used for the treatment of hypertension. In the present study, we investigated the influence of type-2 diabetes mellitus (DM) on the enantioselective pharmacokinetic and dynamic parameters of N.

METHODS

Seventeen hypertensive patients, nine of them with DM, were investigated in a cross-over study with administration of rac-N as coat-core tablets (20 mg day(-1)) or placebo for 15 days each. Serial blood samples (0-24 h) were collected on the 15th day, and 24-h ambulatory blood pressure (BP) monitoring was simultaneously evaluated. N enantiomers in plasma samples were analysed using chiral high-performance liquid chromatography combined with gas chromatography/mass spectrometry. The enantiomeric ratios differing from one were evaluated using the Wilcoxon test, and the results are reported as means with the 95% confidence intervals. A lidocaine (L) test was carried out as an in vivo marker of CYP3A4 (and CYP1A2) activities.

RESULTS

The following differences were observed between the (+)-N and (-)-N enantiomers, respectively, in the patients presenting with DM (means and ranges): C(max) 3.9 (1.7-6.1) ng ml(-1) versus 0.7 (0.4-1.0) ng ml(-1), AUC(0-24) 51.5 (29.0-74.0) ng ml(-1) h versus 9.4 (5.9-12.8) ng ml(-1) h, and Cl/f 3.6 (1.9-5.4) l h(-1) kg(-1) versus 18.7 (11.7-25.7) l h(-1) kg(-1). The Cl/f value of (+)-N was lower (Mann-Whitney test) in patients with DM: 6.0 (4.3-7.5) l h(-1) kg(-1) versus 3.6 (1.9-5.4) l h(-1) kg(-1). The same observation was made for the (-)-N, with Cl/f reaching 38.8 (26.8-51.0) l h(-1) kg(-1) and 18.7 (11.7-25.7) l h(-1) kg(-1) for the non-diabetic and DM groups, respectively. The L test resulted in higher ratios (P < 0.05) of plasma L/MEGX concentrations (30 min after i.v. L) for DM (11.1 vs 18.6). N significantly reduced systolic and diastolic BP (P < 0.05, Wilcoxon test) in all patients investigated relative to placebo. No differences in BP reduction were observed between diabetic and non-diabetic patients. N significantly increased noradrenaline concentrations in plasma of both patient groups. The data also demonstrated that the plasma concentrations of noradrenaline 30 min after N administration were lower (P < 0.05) in diabetic (mean 2.86 pmol ml(-1)) than in non-diabetic patients (4.80 pmol ml(-1)).

CONCLUSIONS

The present data permit us to infer that type-2 diabetes mellitus alters the kinetic disposition of the (+)-N eutomer and (-)-N distomer, presumably due to a lower activity of CYP3A4, although it does not modify the clinical effect brought about by the reduction in BP.

[Effect of grapefruit pulp on the pharmacokinetics of the dihydropyridine calcium antagonists nifedipine and nisoldipine]

The effect of the intake of 200 g of grapefruit pulp (corresponding to one grapefruit) on the pharmacokinetics of the calcium antagonists nifedipine (NF) and nisoldipine (NS) were investigated in 8 healthy Japanese male volunteers. A crossover design was used for the study: group I did not ingest any grapefruit (control group); group II ingested grapefruit 1 h after drug administration; and group III ingested grapefruit 1 h before drug administration. The intake of grapefruit pulp increased the plasma concentrations of both NF and NS, an effect that has previously been reported with grapefruit juice. The increase was most marked when grapefruit was eaten before drug administration. For both NF and NS, subjects who ingested grapefruit 1 h before drug administration exhibited a greater Cmax and AUC0-24 than did subjects in the control group. For NF, the Cmax was 1.4 times higher and the AUC0-24 1.3 times larger in group III than in group I. For NS, the Cmax was 1.5 times higher and the AUC0-24 1.3 times larger in group III than in group I. The increase in the AUC0-24 was significant for both drugs (p < 0.05). The finding that the ratios of Cmax and AUC0-24 for unchanged drug and metabolites did not vary greatly among the three groups for either drug suggests that the increase in serum concentration produced by grapefruit intake may be due to other factors than an inhibitory effect on drug metabolism. Also, the increases in Cmax and AUC0-24 of NS produced by grapefruit intake were smaller than those produced by grapefruit juice intake, indicating that grapefruit pulp and juice have different effects on the pharmacokinetics.

Enantioselective assay of nisoldipine in human plasma by chiral high-performance liquid chromatography combined with gas chromatographic-mass spectrometry: applications to pharmacokinetics

Nisoldipine, a second-generation dihydropyridine calcium antagonist, is a racemate compound used in the treatment of hypertension and coronary heart disease. This study presents an enantioselective HPLC-GC-MS method for the analysis of nisoldipine in human plasma and establishes confidence limits for its application to pharmacokinetic studies. Plasma samples were basified and extracted with toluene. The enantiomers were resolved on a Chiralcel OD-H column using hexane-ethanol (97.5:2.5, v/v) and the (+)- and (-)-fractions were collected separately with the diode array detector switched off. For the quantification of the nisoldipine enantiomers a GC-MS with an Ultra 1 Hewlett-Packard column was used with the detector operated in the single-ion monitoring mode with electron-impact ionization (m/z 371.35 and 270.20 for nisoldipine and m/z 360.00 for the internal standard, nitrendipine). The method proved to be suitable for pharmacokinetic studies based on the low quantification limit (0.05 ng/ml for each enantiomer) and the broad linear range (0.05-50.0 ng/ml for each enantiomer). Low coefficients of variation (<15%) were demonstrated for both within-day and between-day assays. No interference from drugs associated with nisoldipine treatment was observed. The enantioselective pilot study on the kinetic disposition of nisoldipine administered in the racemic form to a hypertensive patient using a multiple dose regimen revealed the accumulation of the (+)-enantiomer with an AUC(0-24) (+)/(-) ratio of approximately 8. Both enantiomers were quantified in plasma at a time interval of 24 h. This HPLC-GC-MS method is reliable, selective and sensitive enough to be used in clinical pharmacokinetic studies on the enantioselective disposition of nisoldipine in humans.

Relationship between time after intake of grapefruit juice and the effect on pharmacokinetics and pharmacodynamics of nisoldipine in healthy subjects

A clinical study was performed in eight healthy volunteers to investigate the effect of various timing of grapefruit juice intake on nisoldipine pharmacokinetics and pharmacodynamics, and to validate our pharmacokinetic model. The subjects were given 10 mg oral nisoldipine with water (control), or 5 mg oral nisoldipine with 200 mL grapefruit juice (G0) or with water at 14 (G14), 38 (G38), 72 (G72) or 96 hours (G96) after a 7-day period of thrice-daily intake of grapefruit juice. Grapefruit juice ingestion did not affect heart rate or the effect area during the first 8 hours of heart rate after nisoldipine administration, although significant decreases of systolic and diastolic blood pressure were caused in G0 by coadministration of grapefruit juice with nisoldipine. Headaches were reported by 3, 2, and 1 persons in G0, G14, and G38, respectively, but no subjects in G72 and G96 reported headaches. Compared with the control group, the maximum plasma concentration of nisoldipine was significantly increased after grapefruit juice intake in G0 and G14, and the plasma concentration was significantly increased at each time in G0 to G72. Therefore the effect of grapefruit juice decreased time dependently and lasted for at least 3 days after intake. Furthermore, our model gave predicted values in good agreement with the observed values. It is therefore necessary to withhold grapefruit juice for at least 3 days before administration of the drug to prevent grapefruit juice-nisoldipine interaction.

Rapid-release and coat-core formulations of nisoldipine in treatment of hypertension, angina, and heart failure

Nisoldipine, a dihydropyridine calcium antagonist, has greater vascular selectivity than other calcium channel antagonists and does not depress the intact myocardium in vivo. It should be taken on an empty stomach. Both rapid-release and coat-core formulations are available for clinical use, but only the coat-core formulation extends antihypertensive, antiischemic, and antianginal effects throughout the dosing interval when given once daily. The coat-core formulation in daily doses of 10 to 40 mg does not cause the proischemic effects reported with the rapid-release formulation. When given as monotherapy, the coat-core formulation is highly effective in lowering blood pressure to a similar extent as other long-acting calcium channel blockers, diuretics, beta-blockers, or angiotensin-converting enzyme (ACE) inhibitors. The antihypertensive effects are potentiated when the coat-core formulation of nisoldipine is given in combination with lisinopril. In patients with stable angina pectoris nisoldipine coat-core increases exercise duration, reduces anginal frequency and myocardial ischemia, and is effective as monotherapy or in combination with a beta-blockers. In monotherapy the drug is as effective as other long-acting calcium channel blockers or a beta-blocker. The effects of nisoldipine coat-core in patients with heart failure are unclear at present.

The effect of ketoconazole on the pharmacokinetics, pharmacodynamics and safety of nisoldipine

OBJECTIVE

The primary aim of the present study was to investigate the effect of ketoconazole on the pharmacokinetics of nisoldipine.

METHODS

A single dose of nisoldipine 5 mg immediate-release tablet was administered either alone or in combination with ketoconazole 200 mg (4 days pretreatment and concomitant administration) in a randomized crossover trial in seven healthy male Caucasian volunteers. Plasma concentration-versus-time profiles of nisoldipine and its metabolite M9 were determined.

RESULTS

Pre-treatment with and concomitant administration of ketoconazole resulted in a 24-fold and 11-fold, increase in mean AUC and Cmax of nisoldipine, respectively, compared with treatment with nisoldipine 5 mg alone. The ketoconazole-induced increase in plasma concentration of the metabolite M9 was of similar magnitude.

CONCLUSION

The interaction is attributed to inhibition of cytochrome 3A4-mediated first-pass metabolism. Ketoconazole and other antifungal drugs of the substituted imidazole type as well as other potent inhibitors of cytochrome 3A4 should not be used concomitantly with nisoldipine.

Nisoldipine coat-core and heart rate response during treatment of hypertension

Nisoldipine coat-core (nisoldipine CC), an extended-release once-daily formulation, is an effective treatment for mild-to-moderate hypertension, providing sustained blood pressure control over the 24-hour dosing interval. Nisoldipine CC is highly vascular selective. It causes neither reflex tachycardia nor symptomatic bradycardia; it lacks significant negative inotropy at therapeutic doses; and it does not affect circadian variation in blood pressure or heart rate. Data suggest that the lack of reflex sympathetic activation in response to the blood pressure-lowering effect of nisoldipine CC is due to the smooth onset of action of nisoldipine CC, causing resetting of the baroflex. The neutral heart rate profile of nisoldipine CC confers potential therapeutic advantages over several other calcium channel blockers, in particular, the short-acting agents, in the treatment of hypertension.

Clinical pharmacokinetics of nisoldipine coat-core

Nisoldipine, a calcium antagonist of the dihydropyridine type, is the active ingredient of the controlled release nisoldipine coat-core (CC) formulation. In humans, the absorption from nisoldipine CC occurs across the entire gastrointestinal tract with an increase in bioavailability in the colon because of the lower concentrations of metabolising enzymes in the distal gut wall. Although nisoldipine is almost completely absorbed, its absolute bioavailability from the CC tablet is only 5.5%, as a result of significant first-pass metabolism in the gut and liver. Nisoldipine is a high-clearance drug with substantial interindividual and relatively lower intraindividual variability in pharmacokinetics, dependent on liver blood flow. Nisoldipine is highly (> 99%) protein bound. Its elimination is almost exclusively via the metabolic route and renal excretion of metabolites dominates over excretion in the faeces. Although nisoldipine is administered as a racemic mixture, its plasma concentrations are almost entirely caused by the eutomer as a result of highly stereoselective intrinsic clearance. Nisoldipine CC demonstrates linear pharmacokinetics in the therapeutic dose range and its steady-state pharmacokinetics are predictable from single dose data. Steady-state is reached with the second dose when the drug is given once daily and the peak-trough fluctuations in plasma concentration is minimal. Plasma-concentrations of nisoldipine increase with age. Careful dose titration according to individual clinical response is recommended in the elderly. Nisoldipine CC should not be used in patients with liver cirrhosis, though dosage adjustments in patients with renal impairment are not necessary. Inter-ethnic differences in its pharmacokinetics are not evident. Owing to inhibition of metabolising enzymes, a small dosage adjustment decrement for nisoldipine CC may be required when it is given in combination with cimetidine. Concomitant ingestion of nisoldipine with grapefruit juice should be avoided. Inducers of cytochrome P450 (CYP) 3A4, e.g. rifampicin (rifampin) and phenytoin should not be combined with nisoldipine CC, as they may reduce its bioavailability and result in a loss of efficacy. The concomitant use of other drugs which may produce marked induction or inhibition of CYP3A4 is contraindicated. Concomitant intake of the CC tablet with high fat, high calorie foods resulted in an increase in the maximum plasma concentrations of nisoldipine. The 'food-effect' can be avoided by administration of the CC tablet up to 30 minutes before the intake of food [corrected]. Plasma concentrations of nisoldipine are related to its antihypertensive effect via a maximum effect model. Nisoldipine CC once daily produce reductions in blood pressure which are maintained over 24 hours in the absence of relevant effects on heart rate.

Pharmacokinetics of the controlled-release nisoldipine coat-core tablet formulation

The pharmacokinetics, safety, and tolerability of the novel once-daily "coat-core" formulation of the calcium antagonist nisoldipine were investigated in 4 randomized nonblind studies A-D in 52 healthy volunteers. Immediate-release or intravenous formulations were administered as reference in 3 studies. The objective of the present studies was to select the optimum controlled-release formulation (A), compare it to the immediate-release tablet at steady-state (B), determine the absolute bioavailability (C), and investigate bioequivalence after a small change in composition (D). Comparative pharmacokinetic properties: Mean residence time and apparent terminal half-life of nisoldipine in the coat-core formulation were significantly increased in comparison to administration via the intravenous route or the oral immediate-release formulation. Concentration profiles could be described with a 3-segment input model. Steady-state conditions were established with the second dose of nisoldipine coat-core and accumulation from first dose to steady-state accounted for 46% as expected due to the contribution of AUC beyond 24 h. At steady-state the coat-core formulation produced a plateau-shaped profile of nisoldipine plasma concentrations throughout the 24 h dosing interval and the peak-trough fluctuation was reduced by approximately 4-fold, compared to the immediate-release tablet in a b.i.d. regimen. While the absolute bioavailability of the drug in the coat-core tablet was 5.5%, its relative bioavailability was greater by 1.5-fold compared to the immediate-release tablet. This can be attributed to release of drug in the colon where the contribution of the gut wall to presystemic metabolism is reduced resulting in an increase in bioavailability as compared to stomach and small intestine. The intersubject variability of nisoldipine coat-core pharmacokinetics was comparable to that of the immediate-release tablet. The within-subject (intraindividual) variability was considerably smaller. Based on its pharmacokinetic profile the side chain-hydroxylated metabolite M 9 is not expected to contribute significantly to the antihypertensive effect of nisoldipine coat-core. In vitro/in vivo correlation: There was a rank order correlation between in vitro release rate of 3 different nisoldipine coat-core formulations and their noncompartmental pharmacokinetic parameters, a decrease in dissolution rate leading to increased bioavailability in vivo. Likewise, the mean dissolution times in vitro and in vivo were correlated in rank order. A linear (level A) correlation could be established within approximately 0-6 hours (in vitro) corresponding to 0-12 hours in vivo. The change in slope of the correlation curve after approximately 12 hours (in vivo) most likely reflects changes in both rate and extent of nisoldipine absorption in different sections of the gastrointestinal tract.

SAFETY

In the present studies the drug was safe and well tolerated, adverse events related to peripheral vasodilatation being less frequent with the coat-core tablet compared to intravenous or immediate-release formulations.

What does nisoldipine coat core (CC) add to current therapy that is clinically meaningful?

Nisoldipine coat core (CC) is a long-acting dihydropyridine with good tolerability. Ambulatory blood pressure measurements in a large, South African multicenter trial show that it has an excellent trough:peak ratio, and that it reduces the early morning rise in blood pressure without any tachycardia. Nisoldipine CC is an effective antihypertensive agent in both black and nonblack South African ethnic groups. In another South African study, regression of left ventricular hypertrophy was achieved in black patients with severe diastolic hypertension. Safety issues are discussed against the background of the testing of this drug in postinfarct left ventricular dysfunction.

Nisoldipine coat-core. A review of its pharmacodynamic and pharmacokinetic properties and clinical efficacy in the management of ischaemic heart disease

Nisoldipine coat-core is an extended-release once-daily formulation of a dihydropyridine calcium antagonist effective in the treatment of chronic stable angina pectoris. With immediate-release formulations of nisoldipine, plasma drug concentrations that produce therapeutic effects result rapidly, but are not sustained and do not maintain the effects throughout a 12-hour dosage interval. In contrast, with nisoldipine coat-core, a gradual increase in plasma nisoldipine concentrations occurs over 12 hours and therapeutic concentrations are then maintained for the duration of a 24-hour dosage interval. In dosages of 10 to 60 mg once daily, nisoldipine coat-core controls symptoms of angina and improves exercise-induced signs of ischaemia in patients with stable angina. Compared with placebo, daily nisoldipine coat-core doses of > or = 20 mg provide statistically significant increases in total exercise time and time to produce angina and a trend towards an increase in the time to produce 1 mm ST segment depression, in exercise tests conducted approximately 23 hours postdose. When administered in 20 and 40 mg daily doses, nisoldipine coat-core produces improvements in exercise test parameters that are similar to those seen with amlodipine 5 or 10 mg/day or regular-release or sustained-release (SR) diltiazem 240 mg/day. The frequency of daily angina attacks and consumption of short-acting nitrates are also reduced by nisoldipine to a similar extent to that observed with these other agents. After longer term (1 year) administration of 10 to 60 mg daily, improvements in exercise test parameters are maintained, with equivalent anti-ischaemic efficacy seen in patients receiving nisoldipine coat-core alone or with background nitrate or beta-blocker therapy. Adverse events associated with nisoldipine coat-core are typical of the dihydropyridine class of calcium antagonists, with peripheral oedema and headache being most common. Nisoldipine coat-core appears to be associated with fewer deaths than placebo, notably in the DEFIANT-II (Doppler Flow and Echocardiography in Functional Cardiac Insufficiency: Assessment of Nisoldipine Therapy II) study, where only 1 death occurred with nisoldipine compared with 7 in the placebo group. Nisoldipine should not be taken during phenytoin therapy. In addition, grapefruit juice should be avoided during nisoldipine therapy and nisoldipine should not be taken concurrently with high-fat meals. Thus, the coat-core formulation of nisoldipine appears to have overcome the limitations of the shorter duration of action of immediate-release nisoldipine. Nisoldipine coat-core is well tolerated and once-daily administration produces a long duration of effective anti-ischaemic relief in patients with chronic stable angina pectoris.

Nisoldipine CC: clinical experience in hypertension

Nisoldipine coat core (CC) is a long-acting formulation of the dihydropyridine calcium channel blocker nisoldipine, suitable for once-daily administration in the treatment of patients with hypertension. Data are reported from three randomized, controlled trials. In two of these, nisoldipine CC was shown to be equivalent in efficacy and tolerability to atenolol in patients with mild to moderate hypertension and to enalapril in elderly patients with hypertension. In a third study using ambulatory blood pressure monitoring in black patients with severe hypertension, nisoldipine CC maintained blood pressure control over the 24-hour dosing period. In addition, regression of left ventricular (LV) mass and improvement in LV function were observed at the end of the 4-month treatment period. Further data are presented from a pharmacokinetic pharmacodynamic modelling study investigating the potential effects of dose-dumping of nisoldipine from the controlled-release formulation, which may occur when the drug is taken with food. This study illustrates the superior control of plasma nisoldipine concentrations and blood pressure provided by the CC compared with an immediate-release formulation, and indicates that an interaction between nisoldipine CC and food is unlikely to cause adverse events. The results of these trials provide further support for the use of nisoldipine CC as an effective agent for the treatment of patients with hypertension, providing consistent antihypertensive efficacy and good tolerability with once-daily administration.

Pharmacokinetic-pharmacodynamic modelling as a tool to evaluate the clinical relevance of a drug-food interaction for a nisoldipine controlled-release dosage form

OBJECTIVE

Nisoldipine, a calcium antagonist of the dihydropyridine class, has been used in the treatment of hypertension and angina pectoris. A new controlled-release dosage form (nisoldipine coat-core, NCC) has been developed to allow once daily dosing. In addition to a formal food interaction study as requested by regulatory authorities for controlled-release dosage forms, a subsequent study was conducted to determine the clinical relevance of the changes in nisoldipine plasma concentration vs time profiles seen in the food effect study.

METHODS

After a placebo run-in phase of 6 days, 12 hypertensive patients started treatment with 20 mg NCC once daily (days 0-3, 5-6, 8-9). On days 4, 7 and 10 the NCC was substituted for 5, 10 and 20 mg nisoldipine solution, respectively, in order to obtain nisoldipine plasma concentration vs time profiles comparable to the ones resulting from the concomitant intake of food and NCC. Simultaneous measurements of blood pressure (BP) and nisoldipine concentration were performed on days 3, 4, 7 and 10.

RESULTS

The relationship between nisoldipine plasma concentrations and percentage reduction in BP [diastolic (DBP) and systolic (SBP), supine and standing] could be described by an Emax model. The mean maximum reduction (Emax) relative to baseline was about 36.4% and 37.7% (DBP, supine and standing) and 27.9% and 29.2% (SBP, supine and standing), respectively. The interindividual variability (% CV) in Emax was low, ranging from 17.6% to 28.8%. The mean nisoldipine plasma concentration corresponding to 50% of the maximum effect (EC50) ranged between 0.99 and 2.62 micrograms.l-1 with a pronounced interindividual variability (% CV) of 89.5-108.8%. Mean Cmax values after administration of the 30 and 40 mg NCC together with food were 4.5 and 7.5 micrograms.l-1, respectively. Based on the concentration-effect relationship established in the present study, the effect achieved with a concentration of 7.5 micrograms.l-1 will be about 77% of Emax for DBP and about 88% of Emax for SBP, respectively.

CONCLUSION

At the time of maximum plasma concentration the additional decrease in BP relative to baseline due to the food effect will be about 7-15% for DBP and 3-9% for SBP. After administration of the 10 mg solution with a mean Cmax of 8.7 micrograms.l-1, only headache and flush with mild severity have been reported as adverse events. These maximum concentrations are comparable to Cmax values seen after intake of 40 mg NCC with food. With regard to heart rate (HR) there were distinct differences between the two formulations: Following administration of 5, 10 and 20 mg nisoldipine solution, there were dose-dependent increases in HR by a maximum of 4, 12 and 16 beats.min-1, respectively, whereas the HR profile for the NCC was similar to that seen under placebo treatment.

A high cholesterol diet blocks the effect of calcium channel blockers on the uptake of sugars in rabbit intestine

Two classes of calcium channel blockers, nisoldipine (NIS) and verapamil (VER), alter the intestinal uptake of sugars, and varying the lipid composition of the diet also modifies intestinal transport function. This study was undertaken in adult male New Zealand rabbits to assess the effect of 3 weeks of dosing with NIS (1 mg.kg-1.day-1) or VER (4 mg.kg-1.day-1) on the in vitro jejunal uptake of D-galactose and L- or D-glucose. The value of the maximal transport rate of D-galactose (Vmax) increased with NIS and VER, compared with control vehicle. The value of the apparent Michaelis constant (K(m)) rose with NIS and fell with VER, and the value of the passive permeability coefficient (Pd) estimated from the uptake of L-glucose fell with NIS and rose with VER. These effects of NIS and VER on Vmax, K(m), and Pd were prevented by feeding a high cholesterol (2.8%) supplemented chow diet (HCD), as compared with chow alone. These effects were not due to any change in the animal's weight gain or intestinal mucosal surface area. The acute exposure of the jejunal tissue in vitro to varying concentrations of NIS but not VER reduced the uptake of D-glucose but had no effect on basal short circuit current (Isc) in either chow or HCD. Isc stimulated with glucose or theophylline was less in chow-fed rabbits compared with HCD-fed rabbits given NIS or VER. Thus, the active transport of sugars by the sodium-dependent transporter in the brush-border membrane, SGLT1, and the passive uptake by the paracellular route are variably influenced by these two classes of calcium channel blockers, and this effect is modified by the cholesterol content of the diet.

Reduced plasma nisoldipine concentrations in phenytoin-treated patients with epilepsy

PURPOSE

To assess whether phenytoin affects the pharmacokinetics of the dihydropyridine calcium antagonist nisoldipine.

METHODS

Twelve patients with epilepsy receiving chronic phenytoin therapy and 12 healthy control subjects matched for age and gender received a single oral dose of nisoldipine (40 and 20 mg, respectively). Blood samples were collected for up to 48 h for estimation of plasma nisoldipine levels by capillary gas chromatography.

RESULTS

Mean plasma nisoldipine concentrations were much lower in the patients. Geometric means for areas under the concentration-time curve (AUC0-tn) normalized to a 20-mg dose were 1.6 micrograms/L/h (95% confidence intervals, 0.6-3.8 micrograms/L/h) in the patients compared with 15.2 (10.7-21.6) micrograms/L/h in control subjects (p < 0.002).

CONCLUSIONS

These results suggest that phenytoin increases the first-pass metabolism of nisoldipine to a clinically important extent. In view of the magnitude and variability of interaction, use of nisoldipine in patients receiving chronic phenytoin therapy is contraindicated.

Nisoldipine coat-core. A review of its pharmacology and therapeutic efficacy in hypertension

Nisoldipine coat-core is a long-acting formulation of the dihydropyridine calcium antagonist (calcium channel blocker) nisoldipine, suitable for once daily administration in the treatment of patients with hypertension. In clinical trials in patients with mild to moderate hypertension, nisoldipine coat-core has efficacy and tolerability similar to those of other calcium antagonists, and antihypertensive efficacy equivalent to that of agents from various other drug classes including beta-blockers, thiazide diuretics and ACE inhibitors. Unlike beta-blockers and thiazide diuretics, calcium antagonists (including nisoldipine coat-core) are not associated with clinically significant adverse metabolic effects on the serum lipid profile or glycaemic control. Nevertheless, published guidelines or consensus papers on the pharmacological management of patients with hypertension recommend calcium antagonists (and other drugs) as "alternative first-line' agents, while beta-blockers and diuretics are generally considered to be first-line therapy because of demonstrated benefits in terms of cardiovascular morbidity and mortality in this clinical setting. Nisoldipine coat-core maintains consistent plasma drug concentrations and antihypertensive effects throughout the 24-hour dosage interval, thereby attenuating intermittent reflex increases in sympathetic activity. This pharmacological profile may have important clinical implications; recent retrospective data suggest an association between moderate to high dosages of short-acting dihydropyridine calcium antagonists and adverse cardiovascular events, although this has yet to be confirmed in large prospective trials. In addition, the high degree of vasoselectivity of nisoldipine minimises negative inotropic effects which may be observed with less selective agents such as nifedipine. Nisoldipine coat-core is, therefore, a useful alternative to other antihypertensive agents in the management of patients with hypertension, providing consistent antihypertensive efficacy and good tolerability with once daily administration.

Pharmacokinetics and pharmacodynamics of nisoldipine in hypertensive patients with normal and mild to moderate impaired renal function

The pharmacokinetics and pharmacodynamics of nisoldipine (CAS 63675-72-9, isobutyl methyl 1,4-dihydro-2,6-dimethyl-4-(2-nitrophenyl)-3,5-pyridinedicarboxylate, Bay k 5552), a calcium antagonist, were investigated after administration of a single oral 10 mg dose and after 7 same doses on consecutive days to hypertensive patients with normal renal function (NRF) and those with mild to moderate renal dysfunction (impaired renal function, IRF). A significant decrease in blood pressure was observed after consecutive dosing of nisoldipine compared to baseline values over 24 h in both groups. There were no significant differences in plasma profiles of nisoldipine in both groups after either single or consecutive dosing. The plasma concentration-time profiles of the active metabolite, Bay r 9425, were similar to those of nisoldipine in both groups. The pharmacokinetic parameters of nisoldipine and its active metabolite in the NRF and IRF groups did not differ after the single and the consecutive dosing. In addition, there were neither prolongation of apparent elimination half-life (t1/2), nor increases in peak plasma levels (Cmax), or the area under the plasma concentration-time curve (AUC0-infinity) after consecutive dosing in both groups. Cumulative urinary excretion rates of the major metabolites, Bay s 4755 and Bay s 1869, did not differ significantly between the NRF and IRF groups in both single and consecutive studies. In the present study, mild flushing was observed in one patient with IRF. There was no deterioration in renal function during the study. These results suggest that nisoldipine may have a long-lasting antihypertensive effect during consecutive dosing and that it can be used in hypertensive patients regardless of presence of renal dysfunction.

Clinical pharmacology of nisoldipine coat core

Nisoldipine is a second-generation dihydropyridine calcium antagonist structurally related to nifedipine and used in the treatment of stable angina and arterial hypertension. It is also under investigation for the treatment of left ventricular dysfunction. It was first developed as an immediate release tablet, but this formulation was not considered optimal for once-daily administration because of the variable results obtained at peak and trough in clinical studies. Consequently, nisoldipine coat core (CC) was developed with the aim of optimizing the drug's time--effect profile over the 24-hour dosing interval. The in vitro release pattern classifies this tablet as an "extended release" formulation according to European Community guidelines. The present article outlines the pharmacokinetic and pharmacodynamic profiles of nisoldipine CC, as obtained from recent clinical studies.

The effect of age and liver disease on the pharmacokinetics of the calcium antagonist, nisoldipine

Two studies were performed-one in elderly, hypertensive patients and one in patients with chronic liver disease-to investigate the effect of age and liver disease upon the pharmacokinetics of nisoldipine, a dihydropyridine-type calcium antagonist. The effect of acute and chronic administration of nisoldipine (once and twice daily) was investigated in 17 elderly hypertensive patients. Compared with previously published data from young healthy volunteers, the values for Cmax and AUC appear to be higher in elderly hypertensive patients while Tmax and half-life were unchanged. Nisoldipine significantly reduced both systolic and diastolic blood pressure when given acutely to elderly hypertensive patients. Major alterations in the pharmacokinetics of nisoldipine were found in 7 patients with chronic liver disease when compared with the elderly hypertensives and healthy volunteers. The values for AUC, Cmax, half-life and volume of distribution were all higher than expected from the volunteer data while clearance was lower. One patient receiving primidone had very low nisoldipine levels, suggesting that the concomitant administration of agents that may induce the metabolism of nisoldipine should be discouraged. Nevertheless, comparisons of nisoldipine plasma levels after acute and chronic administration showed no evidence of any accumulation in either patient population in the doses used. The drug was generally well tolerated although 1 patient with chronic liver disease was withdrawn due to fluid retention.

Pharmacokinetic and pharmacodynamic interactions during multiple-dose administration of nisoldipine and propranolol

OBJECTIVES

The pharmacokinetic and pharmacodynamic interactions after 7 days of oral treatment with nisoldipine (10 mg twice daily) and propranolol (80 mg twice daily) were investigated in a partially randomized, placebo-controlled crossover study of 12 healthy volunteers.

METHODS

At the end of each treatment period, pharmacokinetic parameters were measured, along with blood pressure, heart rate, cardiac function, systemic hemodynamics, plasma catecholamines, forearm blood flow, and apparent hepatic blood flow (estimated by the clearance of indocyanine green dye).

RESULTS

After 7 days of treatment with nisoldipine and propranolol, neither drug altered the other's bioavailability or elimination parameters, and propranolol did not change the area under the plasma concentration-time curve of nisoldipine's metabolite, N-9425. Nisoldipine alone increased apparent hepatic blood flow and forearm blood flow compared with the other treatment groups but, with the addition of propranolol, both of these parameters were similar to those in the placebo group. Changes in the other hemodynamic parameters were consistent with the known effects of these drugs, and no differences in plasma catecholamine levels were detected.

CONCLUSIONS

In contrast to the findings with single-dose treatment, administration of the combination of nisoldipine and propranolol for 7 days is not associated with any measurable kinetic interactions, although significant hemodynamic interactions do occur.

Determination of the enantiomers of nisoldipine in human plasma using high-performance liquid chromatography on a chiral stationary phase and gas chromatography with mass-selective detection

A method is described that combines chiral HPLC and off-line GC with mass-selective detection for the quantitation of the enantiomers of nisoldipine [(+/-)-I] in human plasma. An isotope-labelled internal standard [nine-fold deuterated (+/-)-I] is used throughout the assay. The limit of quantification is 0.1 microgram/l for each enantiomer. Data on the precision, accuracy and selectivity of the method are presented. Enantioselective analysis was performed in subjects receiving the racemic drug in tablet form. In healthy volunteers the maximum concentration and the area under the curve of the pharmacologically more active (+)-enantiomer were greater by 9-fold and 13-fold, respectively, compared to those of the (-)-enantiomer. In elderly hypertensive patients plasma concentrations of (+)-I were ca. five times as high as those of the (-)-enantiomer. Stereoselectivity was not affected by hepatic impairment. After intravenous administration of (+/-)-I there were no relevant differences between the plasma concentrations of the enantiomers.

Enantioselective assay for the determination of nisoldipine in dog, rat and mouse plasma by chiral microbore high-performance liquid chromatography combined with gas chromatography-mass spectrometry

A sensitive, selective and validated method for the enantioselective determination of (+)- and (-)-nisoldipine in rat, mouse and dog plasma following administration of nisoldipine racemate is described. The alkalized plasma samples containing [13C4]nisoldipine racemate as internal standard (ISTD) were extracted once with toluene. The enantiomers of nisoldipine were quantitatively separated by high-performance liquid chromatography on a 250 x 2 mm I.D. column containing tris(4-methylbenzoate)-modified cellulose on silica. The fractions containing either the (+) or (-)-enantiomer of the analyte and [13C4]ISTD were analysed by gas chromatography with mass-selective detection in the single-ion monitoring mode. The limits of determination and detection were 0.5 and 0.2 ng/ml, respectively, the total precision was better than 7% (R.S.D. at 5 and 50 ng/ml, n = 35) and the accuracy was better than 10% (0.5-100 ng/ml, n = 23). The sum of the concentrations of the enantiomers determined with this assay corresponds to the concentration of the racemate determined independently by capillary gas chromatography with electron-capture detection (accuracy better than 15%, 1-80 ng/ml). The method was used for the analysis of more than 500 plasma samples obtained from toxicokinetic studies.

Effect of grapefruit juice and naringin on nisoldipine pharmacokinetics

The bioavailability of some dihydropyridine calcium antagonists can be markedly augmented by grapefruit juice and may involve the bioflavonoid naringin. The pharmacokinetics of nisoldipine coat-core tablet were studied in a Latin square-designed trial in which 12 healthy men were administered the drug with water, grapefruit juice, or encapsulated naringin powder at the same amount as that assayed in the juice. Compared with water, grapefruit juice increased the maximum concentration of nisoldipine to 406% +/- 73% (mean +/- SEM; range, 107% to 836%; p < 0.001), increased the area under the plasma concentration-time curve to 198% +/- 46% (range, 81% to 682%; p < 0.001), and reduced time to reach maximum nisoldipine concentration to 58% +/- 9% (range, 13% to 100%; p < 0.01), probably by inhibition of presystemic metabolism and possibly by enhancement of drug dissolution. The interaction could not be predicted from baseline pharmacokinetics with water and resulted in greater interindividual variability. The naringin capsule did not change nisoldipine pharmacokinetics. All treatments produced minor effects on supine blood pressure and heart rate, probably because subjects were normotensive. Current information supports the cautioning of patients about concomitant ingestion of grapefruit juice and nisoldipine.

Nisoldipine: a new dihydropyridine calcium-channel blocker

Nisoldipine is a new calcium-channel blocker of the dihydropyridine subclass, with a chemical structure similar to nifedipine. It has been used in clinical trials to assess its efficacy and safety in patients with hypertension, angina pectoris, and congestive heart failure. Similar to other dihydropyridines, nisoldipine is a potent peripheral and coronary dilator. The most optimal dosage regimen has not been established in clinical trials. The drug appears to have a favorable side-effect profile.

Multiple dose pharmacokinetics of four different doses of nisoldipine in hypertensive patients

This randomized double-blind parallel group study characterized the pharmacokinetics of the calcium channel antagonist, nisoldipine (core-coat tablets), administered once daily for 7 days in doses of 5 mg (n = 12), 10 mg (n = 13), 20 mg (n = 12), and 30 mg (n = 11) to patients with mild to moderate hypertension. Serial blood samples were obtained from 0 to 24 hours and from 0 to 48 hours after nisoldipine administration on days 1 and 7, respectively. Nisoldipine plasma concentrations were determined by gas chromatography with electron capture detection. No statistically significant difference was found in dose-normalized area under the curve between the four groups. Area under the curve (standardized to body weight) correlated to dose (r = .74, P less than .05). No significant difference existed in oral clearance (L/h/kg) when analyzed for equivalence across the four doses: 8.21 +/- 3.47 (5 mg), 11.84 +/- 13.85 (10 mg), 11.48 +/- 7.49 (20 mg), and 10.36 +/- 5.49 (30 mg). The present investigation characterizes the pharmacokinetics of nisoldipine core-coat tablets in hypertensive patients and demonstrates the dose proportionality or linearity of nisoldipine plasma concentrations and area under the curve, measured over a dose range of 5 to 30 mg.

The interactions between nisoldipine and two beta-adrenoceptor antagonists--atenolol and propranolol

1. The interactions between the dihydropyridine calcium antagonist nisoldipine and two beta-adrenoceptor blocker drugs (atenolol and propranolol) were investigated in two groups of healthy normotensive subjects. 2. The steady state plasma concentrations of both beta-adrenoceptor blockers were significantly altered by the addition of nisoldipine: for propranolol there were significant increases in Cmax, by about 50%, and in AUC by about 30% and for atenolol there was a significant increase in Cmax, by about 20%. 3. The addition of nisoldipine was also associated with significant changes in apparent liver blood flow (measured by indocyanine green clearance) from 1.4 to 2.4 l min-1 in the atenolol group and from 1.3 to 2.3 l min-1 in the propranolol group. 4. Both nisoldipine-beta-adrenoceptor blocker combinations were associated with small enhanced blood pressure reductions e.g. from 104/60 with atenolol alone to 98/50 mm Hg with the combination but there was no alteration to the extent of beta-adrenoceptor blockade (as assessed by bicycle ergometry). 5. This pharmacodynamic profile in healthy normotensives is consistent with the known therapeutic efficacy of such combination treatments in patients with hypertension and angina. 6. It is suggested that there is a pharmacokinetic component to the efficacy of this type of combination, perhaps reflecting vasodilator-induced changes in drug absorption and/or hepatic extraction.

A comparison of the pharmacokinetics of nisoldipine in elderly and young subjects

Nine young and 12 elderly healthy volunteers received nisoldipine 10 mg once a day for 7 days. Plasma nisoldipine concentrations were measured on Day 1 and on Day 7. Higher plasma drug concentrations were observed in the elderly group than in the young group with the values for AUC being approximately doubled in the elderly group. There was no evidence of significant accumulation in either age group.

Pharmacokinetics of m-nisoldipine in rabbits and rats

A reverse phase HPLC method was devised for determination of m-Nis in plasma. A mobile phase of methanol-KH2PO4 with a flow rate of 1 ml/min was used. Diazepam was used as the internal standard. A two-compartment model featured the pharmacokinetic process of m-Nis after its iv injection to rats (30 micrograms/kg) and rabbits (50 micrograms/kg). The pharmacokinetic parameters were: T 1/2 alpha = 4.3 min, T 1/2 beta = 63.6 min, Vd = 0.805 L/kg, Cl = 9 ml/(min.kg) in rats; T 1/2 alpha = 5.0 min, T 1/2 beta = 78.3 min, Vd = 1.191 L/kg, Cl = 11 ml/(min.kg) in rabbits. The pharmacokinetics for m-Nis after ig 200 micrograms/kg to rats described one-compartment model with parameters: T 1/2 = 84.8 min, Tmax = 31.2 min, Cmax = 49.97 micrograms/L, Vd = 0.792 L/kg and Cl = 25 ml/(min.kg).

Vasodilatory effects of nisoldipine on coronary arteries--correlation with plasma levels

Vasomotion of angiographically normal and stenotic epicardial coronary arteries was analyzed up to 15 minutes after the onset of an intravenous infusion (4 minutes) of 0.5 mg (13 patients, group A) or 1 mg nisoldipine (13 patients, group B). After both doses the maximal increase of the mean diameters of normal coronary segments was achieved not before the 15th minute, averaging 11 +/- 6% in group A (p less than 0.001) and 18 +/- 9% in group B (p less than 0.001). Eleven of 15 and 8 of 9 coronary stenoses in groups A and B dilated to 5-80% and 15-70%, respectively. The nisoldipine concentration reached maximal levels at the end of the infusion (fourth minute) with an average of 8 +/- 4 ng/ml and 17 +/- 7 ng/ml in groups A and B, respectively. A significant correlation between nisoldipine plasma levels and dilation of normal coronary segments was obtained only with the individual maxima of these parameters and only in group A (p less than 0.01). The hysteresis of the coronary dilation in relation to the drug plasma levels may be due to the high receptor affinity of nisoldipine. In either group nisoldipine provoked a persistent increase in coronary sinus oxygen saturation (p less than 0.01) and a substantial and prolonged drop in systolic and diastolic aortic pressure (p less than 0.001). Both doses of nisoldipine induced a rise in heart rate (p less than 0.01) and a slight drop in the rate-pressure product (p less than 0.05).

Coronary vasodilation with dihydropyridines--a pharmacokinetic study

In 26 patients with coronary artery disease, the mean diameters of angiographically 'normal' epicardial coronary arteries were assessed with the aid of a computer-assisted contour detection system (CAAS) before and up to 15 min after onset of a 4-min intravenous-infusion of 2 mg nifedipine (13 patients, group I) or 1 mg nisoldipine (13 patients, group II). Maximal coronary dilation amounted to 20 +/- 9% (4th min) in group I and to 18 +/- 9% (15th min) in group II. In addition, in group II changes of the minimal diameters of 9 coronary obstructions were measured; the maximum increase averaged 28 +/- 15% (7th min). In order to compare the pharmacokinetic properties of these compounds the dilation of the 'normal' coronary segments was correlated with the respective drug plasma levels; maximal plasma concentrations averaged 62 +/- 21 ng ml-1 (7th min) in group I and 17 +/- 7 ng ml-1 (4th min) in group II respectively. A positive, linear correlation between coronary dilation and plasma levels was only found with nifedipine (P less than 0.05); with nisoldipine, however, coronary dilation developed in form of a hysteresis curve, when plotted against plasma levels, probably due to the high receptor affinity of this substance. The prolonged efficacy of nisoldipine could be favourable in oral long-term treatment of patients with coronary artery disease.