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

Pharmacokinetic Variability of Drugs Used for Prophylactic Treatment of Migraine

In this review, we evaluate the variability in the pharmacokinetics of 11 drugs with established prophylactic effects in migraine to facilitate 'personalized medicine' with these drugs. PubMed was searched for 'single-dose' and 'steady-state' pharmacokinetic studies of these 11 drugs. The maximum plasma concentration was reported in 248 single-dose and 115 steady-state pharmacokinetic studies, and the area under the plasma concentration-time curve was reported in 299 single-dose studies and 112 steady-state pharmacokinetic studies. For each study, the coefficient of variation was calculated for maximum plasma concentration and area under the plasma concentration-time curve, and we divided the drug variability into two categories; high variability, coefficient of variation >40%, or low or moderate variability, coefficient of variation <40%. Based on the area under the plasma concentration-time curve in steady-state studies, the following drugs have high pharmacokinetic variability: propranolol in 92% (33/36), metoprolol in 85% (33/39), and amitriptyline in 60% (3/5) of studies. The following drugs have low or moderate variability: atenolol in 100% (2/2), valproate in 100% (15/15), topiramate in 88% (7/8), and naproxen and candesartan in 100% (2/2) of studies. For drugs with low or moderate pharmacokinetic variability, treatment can start without initial titration of doses, whereas titration is used to possibly enhance tolerability of topiramate and amitriptyline. The very high pharmacokinetic variability of metoprolol and propranolol can result in very high plasma concentrations in a small minority of patients, and those drugs should therefore be titrated up from a low initial dose, depending mainly on the occurrence of adverse events.

Efficacy and Tolerability of Nisoldipine Coat-Core vs Diltiazem Retard in Combination with a Beta-Blocker in Patients with Stable Exertional Angina Pectoris

A randomised, double-blind, placebo-controlled, parallel-group trial with forced titration study to investigate possible equivalence of efficacy and tolerability between nisoldipine coat-core (CC) 40mg once daily, and diltiazem retard 120mg twice daily, was carried out in 176 patients with stable angina pectoris who were already receiving beta-blocker therapy. A total of 164 patients were included in the tolerability analysis and 135 patients were evaluable for efficacy (nisoldipine CC, n = 69; diltiazem retard, n = 66). During bicycle exercise tolerance tests, time to 1mm ST-segment depression, total exercise time, and time to angina were assessed at baseline and at the end of the treatment period. The number of angina attacks and of consumed nitroglycerin tablets were recorded in weekly diaries. Time to onset of 1mm ST-segment depression increased by 69.4 +/- 100.0 seconds with nisoldipine CC and by 65.9 +/- 87.6 seconds with diltiazem retard. The two treatment regimens were equally effective in time to onset of 1mm ST-segment depression, time to angina pectoris, and in exercise duration. A beneficial effect on angina attacks and nitroglycerin consumption was achieved with both treatments. Patient compliance, as assessed by the number of returned tablets, was high, at over 80%. Six patients withdrew from the treatment because of adverse events. Mild and transient adverse events were reported by 24 patients during treatment. One patient experienced a severe circulatory shock on the combination of diltiazem retard and atenolol. Peripheral oedema and headache were more common on nisoldipine CC. We concluded that the two treatments were equally efficacious and tolerated in patients with stable angina pectoris.

Antihypertensive therapy: special focus on drug interactions

Today, the lifetime risk of patients aged 55-65 years to receive antihypertensive drugs approaches 60%. Yet, recent trials suggest that hypertension is not adequately controlled in the majority of patients. The prevalence of hypertension increases with advancing age, as does the prevalence of comorbid conditions and the total number of medications taken. Multi-drug therapy, advancing age and comorbid conditions are also key risk factors for adverse drug reactions and drug interactions. In this review, the authors evaluate the most frequently used antihypertensive drugs (diuretics, beta-adrenergic blockers, angiotensin-converting enzyme inhibitors, calcium channel blockers, angiotensin II receptor Type 1 blockers and alpha-adrenergic blockers) with special reference to pharmacodynamic and pharmacokinetic drug interactions. As the spectrum of drugs prescribed is constantly changing, safety yesterday does not imply safety today and safety today does not imply safety tomorrow. Furthermore, therapeutic efficacy should not be neglected over concerns regarding drug interactions. Many patients are at risk of clinically relevant drug interactions involving antihypertensive drugs but, presently, even more patients may be at risk of suffering from the consequences of their inadequately treated hypertension. In this respect, the authors discuss controversial viewpoints on the overall clinical relevance of drug interactions occurring at the level of cytochrome P450 metabolism.

Influence of nicardipine and nifedipine on plasma carvedilol disposition after oral administration in rats

The effect of two kinds of 1,4-dihydropyridine calcium-channel blockers, nicardipine hydrochloride and nifedipine, on the disposition of carvedilol, was studied in rats. Blood samples were assayed for carvedilol levels using solid-phase extraction and high-performance liquid chromatography. The plasma carvedilol concentration was found to be significantly higher, and the area under the concentration-time curve up to 24 h (AUC0-->24) was 6.7 and 3.0 times higher after simultaneous oral administration of 20 mg kg(-1) carvedilol with 40 mg kg(-1) nicardipine hydrochloride, or with 40 mg kg(-1) nifedipine, respectively, than after administration of carvedilol alone. The pharmacokinetic interaction between carvedilol and dihydropyridine calcium-channel blockers is thought to be attributable to vasodilator-induced changes in hepatic first-pass metabolism, inhibition in the absorption barrier by P-glycoprotein and in the metabolism of carvedilol.

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.

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 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.

Calcium antagonists. Drug interactions of clinical significance

The interaction of calcium antagonists, including the dihydropyridine calcium antagonists (e.g. nifedipine), verapamil and diltiazem, with drugs from other classes has major clinical ramifications as the use of drug combinations increases in frequency. Combinations are used in the treatment of disorders ranging from hypertension to cardiac rhythm disturbances, angina pectoris and peripheral vasospastic disease. In this era of organ transplantation, drugs like cyclosporin are coming into potential conflict with an ever-growing list of drugs. Drug combinations used as part of long term therapies are also making their appearance in toxic drug reactions, including antituberculous and anticonvulsant agents. Bronchodilators and H2-blockers also fall into this category of potential culprits of combined drug toxicity, and the interactions of calcium antagonists with beta-blockers and antiarrhythmic agents are also becoming a matter of concern.

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.

Nimodipine. Potential for drug-drug interactions in the elderly

Nimodipine is indicated for a variety of conditions in elderly patients. Elderly patients often have multiple morbidity and receive treatment with a variety of drugs. Therefore, it is important to investigate the possible pharmacokinetic and pharmacodynamic interactions of nimodipine with various drugs commonly prescribed for elderly patients. There were no clinically relevant interactions of nimodipine with any of the following specific agents studied: the antiarrhythmics mexiletine, propafenone, disopyramide or quinidine, digoxin, the beta-adrenoceptor antagonists propranolol or atenolol, nifedipine, warfarin, diazepam, indomethacin, ranitidine or glibenclamide (glyburide). However, there were some notable interactions. In epileptic patients taking the anticonvulsants carbamazepine, phenobarbital (phenobarbitone) and/or phenytoin, there was a 7-fold decrease in the area under the plasma concentration versus time curve (AUC) and an 8- to 10-fold decrease in the maximum plasma concentration of nimodipine. These effects were to be expected, considering the hepatic enzyme-inducing properties of these anticonvulsant drugs. Therefore concomitant use of these agents with oral nimodipine is not recommended. In contrast, epileptic patients treated with nimodipine and valproic acid (sodium valproate) showed an increase in both the AUC (approximately 50%) and maximum plasma concentrations (approximately 30%) of nimodipine, which may be explained by valproic acid inhibiting the presystemic oxidative metabolism of nimodipine. Concomitant administration of cimetidine produced an approximate doubling of the bioavailability of nimodipine. This again was to be expected, considering the known inhibitory effect of cimetidine on cytochrome P450. However, no changes in haemodynamics, clinical or laboratory status or tolerability were observed, and dose adjustment did not appear to be clinically necessary.

Enantioselective inhibitory effect of nicardipine on the hepatic clearance of propranolol in man

The influence of a single oral dose of 30 mg nicardipine on the pharmacokinetics of (R)- and (S)-propranolol, given orally as rac-propranolol 80 mg, was studied in 12 healthy volunteers. The plasma concentrations were higher for the (S)-enantiomer than for the (R)-enantiomer. The Cl(o) and the Cl'intr of (S)-propranolol were significantly lower than the Cl(o) and Cl'intr of (R)-propranolol. The unbound fraction of (R)-propranolol was significantly higher than that of (S)-propranolol. Coadministration of nicardipine significantly increased the AUC and Cmax and significantly decreased the Cl(o) and Cl'intr for unbound drug of (R)- and (S)-propranolol. These changes were more important for (R)- than for (S)-propranolol. The protein binding was not altered by nicardipine. The enantioselective effect of nicardipine on the metabolic clearance of propranolol appears to be due to an interaction at the level of the metabolizing enzymes. The effect on blood pressure of rac-propranolol was little affected when nicardipine was coadministered with rac-propranolol, and its bradycardic effect was reduced.

Influences of the calcium antagonists nicardipine and nifedipine, and the calcium agonist BAY-K-8644, on the pharmacokinetics of propranolol in rats

To determine the effect of dihydropyridines on the metabolism of propranolol, we studied the effects of a single oral dose of nicardipine, nifedipine, and BAY-K-8644 on the pharmacokinetics of propranolol in male Wistar rats fitted with a catheter in the jugularis vein. Oral propranolol (15 mg/kg and 1.5 mg/kg) and intravenous propranolol (1.5 mg/kg) were administered either alone or together with oral nicardipine (2.5 mg/kg). Oral propranolol (15 mg/kg) was administered with oral nifedipine (1.5 mg/kg) and with oral BAY-K-8644 (1.5 mg/kg). Nicardipine increased significantly the AUC and Cmax of oral propranolol (1.5 mg/kg and 15 mg/kg). However, the plasma concentration time curve of intravenous propranolol (1.5 mg/kg) was unaffected. Nifedipine also significantly increased the AUC and Cmax of oral propranolol (15 mg/kg), whereas with BAY-K-8644 there was only a slight increase in the bioavailability of oral propranolol (15 mg/kg). The results indicate that the dihydropyridine calcium antagonists decrease the metabolism of propranolol as a result of a decrease in first-pass clearance. Although an interaction at the level of cytochrome P450 may also be involved, the results of the present study suggest that the inhibitory effect can be largely attributed to changes in liver blood flow.

The pharmacodynamics and pharmacokinetics of the combination of nifedipine and doxazosin

In a single-blind study 12 normotensive men took nifedipine 20 mg (Group 1, n = 6) or doxazosin 2 mg (Group 2, n = 6), followed by the combination. Each subject attended on four 9-h study days for evaluation of the effects of single and multiple doses of the monotherapy and the effects of adding single and multiple doses of the second drug. Measurements of BP, HR, plasma drug concentrations, and apparent liver blood flow were recorded. The combination was generally well tolerated. BP was consistently lower with the combination than with either monotherapy: for example, average erect BP was 108/61 (Group 1) and 112/62 mmHg (Group 2) compared with 122/66 and 116/68 during steady-state monotherapy. The introduction of nifedipine in Group 2 was associated with a significant increase in liver blood flow at 1.5 h: 1560 vs 1050 ml.min-1 during monotherapy with doxazosin. There was no significant kinetic interaction. In particular, the steady-state AUC of doxazosin was unaffected by the addition of nifedipine: 257, 307, 301, and 256 ng.ml-1.h for the 4 study days (Group 2).