The influence of edema on the bisoprolol blood concentration after bisoprolol dermal patch application: A case-control study

BACKGROUND

Beta-blocking is important for critically ill patients. Although some patients are required to continue taking beta-blockers after they no longer need critical care, some of these patients have impaired swallowing abilities. Bisoprolol dermal patches have recently been introduced and appear to be a good alternative to oral bisoprolol tablets. However, it is still unclear whether the pharmacodynamics of such patches are affected by edema in patients who have experienced critical care. This study aimed to clarify the effects of systemic edema on beta-blocker absorption from dermal patches in critically ill patients.

METHOD

Patients who exhibited tachycardia and impaired swallowing function after critical care were included in this study. They were assigned to either the edema group (n = 6) or no edema group (n = 6) depending on the presence/absence of edema in the lower extremities. A bisoprolol dermal patch was pasted onto each subject, and the blood bisoprolol concentration was checked at 8 timepoints over the next 24 hours. The area under the serum concentration time curve, maximum concentration observed (Cmax), and time of maximum concentration observed were also examined.

RESULT

The mean blood bisoprolol concentrations of the 2 groups were not significantly different at 2, 4, 6, 8, 10, 12, 16, or 24 hours after the patch application. The area under the serum concentration time curve and maximum concentration observed were not different between the groups. The mean heart rates of the 2 groups were not significantly different at 6, 12, or 24 hours after the patch application (Student t test, P = .0588, P = .1080, and P = .2322, respectively).

CONCLUSION

In this study, the blood concentration of bisoprolol and its heart rate-reducing effects after bisoprolol dermal patch application might not be affected by systemic edema in the lower extremities.

Application of physiologically based biopharmaceutics modeling to understand the impact of dissolution differences on in vivo performance of immediate release products: The case of bisoprolol

Merck KGaA observed slight differences in the dissolution of Concor® (bisoprolol) batches over the years. The purpose of this work was to assess the impact of in vitro dissolution on the simulated pharmacokinetics of bisoprolol using in vitro-in vivo relationship established with available in vitro dissolution and corresponding plasma concentrations-time data for several bisoprolol batches. A mechanistic absorption model/physiologically based pharmacokinetics model linked with a biopharmaceutics tool such as dissolution testing, namely, physiologically based biopharmaceutics modeling (PBBM), can be valuable in determining a dissolution "safe space." A PBBM for bisoprolol was built using in vitro, in silico, and clinical data. We evaluated potential influences of variability in dissolution of bisoprolol batches on its clinical performance through PBBM and virtual bioequivalence (BE) trials. We demonstrated that in vitro dissolution was not critical for the clinical performance of bisoprolol over a wide range of tested values. Based on virtual BE trials, safe space expansion was explored using hypothetical dissolution data. A formulation with in vitro dissolution reaching 70% dissolved in 15 min and 79.5% in 30 min was shown to be BE to classical fast dissolution of bisoprolol (>85% within 15 min), as point estimates and 90% confidence intervals of the maximum plasma concentration and area under the concentration-time curve were within the BE limits (0.8-1.25).

The influence of viscosity-enhancing agents on oral absorption of drugs

The objective of this study was to evaluate the influence of viscosity-enhancing agents on oral absorption of metoprolol (MPL) and bisoprolol (BPL). Although the viscosity values were similar for MPL and BPL in hydroxypropyl methylcellulose (HPMC, 1.2 % (w/w)) and polyvinyl alcohol (PVA, 8.8 % (w/w)) solutions, the order of diffusion rate constants of the drugs in media were phosphate buffer solution (reference) > HPMC solution > PVA solution. In in vivo rat intestinal absorption experiments showed that the C_max and AUC values of the drugs were lowest when they were administered into the rat jejunum in a PVA solution. In vitro binding studies showed that this may have been due to adsorption of the drugs to PVA molecules, resulting in decreased free fractions of the drugs. Our results indicated that intestinal absorption of the drugs in PVA solution was influenced both by decreased diffusion of the drugs and by interaction with PVA. Since various viscosity-enhancing agents are widely used as pharmaceutical and food additives, these findings may be of significance for understanding therapeutic efficacy and safety of oral drug products.

β-Blocker Dialyzability in Maintenance Hemodialysis Patients: A Randomized Clinical Trial

BACKGROUND AND OBJECTIVES

There is a paucity of data available to describe drug dialyzability. Of the available information, most was obtained before implementation of modern hemodialysis membranes. Our study characterized dialyzability of the most commonly prescribed β-blockers in patients undergoing high-flux hemodialysis.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

Patients on hemodialysis (n=8) were recruited to an open label, pharmacokinetic, four-way crossover trial. Single doses of atenolol, metoprolol, bisoprolol, and carvedilol were administered on separate days in random order to each patient. Plasma and dialysate drug concentrations were measured, and dialyzability was determined by the recovery clearance and arterial venous difference methods.

RESULTS

Using the recovery clearance method, the dialytic clearance values for atenolol, metoprolol, bisoprolol, and carvedilol were 72, 87, 44, and 0.2 ml/min, respectively (P<0.001). Applying the arterial venous difference method, the dialytic clearance values of atenolol, metoprolol, bisoprolol, and carvedilol were 167, 114, 96, and 24 ml/min, respectively (P<0.001).

CONCLUSIONS

Atenolol and metoprolol are extensively cleared by hemodialysis compared with the negligible dialytic clearance of carvedilol. Contrary to estimates of dialyzability on the basis of previous literature, our data indicate that bisoprolol is also dialyzable. This finding highlights the importance of conducting dialyzability studies to definitively characterize drug dialytic clearance.

Preparation of bisoprolol fumarate nasal spray and its nasal delivery in rats

The aim of the present work was to prepare a nasal spray of bisoprolol fumarate (BF). The Pharmacokinetics and relative bioavailability of the BF nasal formulation were evaluated in Wistar rats. The BF nasal spray after administration exhibited very fast absorption and higher plasma drug concentration. The maximum plasma concentration (C(max)) and the time to reach it (T(max)) were 409.5 ng/ml and 3.6 min for the BF nasal spray, 39.4 ng/ml and 26.7 min for the drug solution, respectively. The bioavailability of the BF nasal spray was greater than 1500.0%. Meantime, the effect of the BF nasal spray on nasal mucociliary movement was also studied with a toad palate model. The BF nasal preparation showed minor ciliotoxicity, but the adverse effect was temporary and reversible.

IN VITRO TESTING OF XANTHAN/LIGNIN HYDROGELS AS CARRIERS FOR CONTROLLED DELIVERY OF BISOPROLOL FUMARATE

AIM

To develop sustained release matrix tablets based on xanthan as highly water-soluble, cost-effective, non-toxic, easily available, and suitable hydrophilic systems.

MATERIAL AND METHODS

Xanthan and lignin epoxy-modified resin (LER) mixture were crosslinked using epichlorohydrin as crosslinking agent leading to superabsorbent hydrogels with high swelling rate in aqueous mediums.

RESULTS AND CONCLUSIONS

These hydrogels were tested as carries by the loading/delivery behaviour of bisoprolol fumarate in physiological conditions and based on the obtained results these hydrogels may show interest for application in medical and pharmaceutical areas. The amount of drug loaded in polymer networks was found to be ranging between 14.4% and 19.2%. Drug release was retarded and the release mechanism of the active principle was found to depend on matrix composition.

[Assessment of therapeutic equivalence of original bisoprolol and its generics in patients with ischemic heart disease with concomitant chronic obstructive pulmonary disease]

Therapeutic equivalence of original bisoprolol (Concor) and its two generics (Biprol and Biol) was studied in 102 patients with ischemic heart disease (IHD) combined with chronic obstructive pulmonary disease (COPD). Concor, Biprol and Biol were given for 12 weeks to 36, 36, and 30 patients, respectively. Methods comprised test with endothelium dependent vasodilation, 24-hour ECG monitoring, pulmonary ventilation tests, and measurement of blood concentrations of nitrous oxide metabolites. Hypotensive and antiischemic effects were similar in all groups. However significant improvement of endothelial function occurred only among Concor treated patients. No negative changes of parameters of pulmonary ventilation took place after 4 weeks of therapy but after 12 weeks their significant lowering was observed among Biprol treated patients. We conclude that in this study on patients with IHD and COPD original bisoprolol demonstrated higher clinical efficacy and better tolerability than its generics.

[Bisoprolol: opportunities in the treatment of hypertension]

Bisoprolol (bisoprolol fumarate) - -cardioselective blocker, does not possess intrinsic sympathomimetic and membrane stabilizing activity. The main indications for bisoprolol are arterial hypertension (AH) and heart failure. This article provides an overview of the literature on the potential uses of bisoprolol in the treatment of hypertension. The features of the pharmacokinetics of the drug. The data on the effectiveness of bisoprolol in hypertension and tolerability in patients with concomitant disorders: diabetes, chronic obstructive pulmonary disease, peripheral atherosclerosis. Proofs of the high efficiency of antianginal bisoprola and justified the use of the drug in patients with hypertension and coronary heart disease. The capabilities of bisoprolol in the perioperative correction of hypertension. The data and pharmacoeconomic properties of bisoprolol generic counterparts.

[Potentialities of medicinal correction of cerebrovascular disturbances in patients with arterial hypertension]

The use of up-to-date diagnostic methods for the examination of 72 patients presenting with grade II-III arterial hypertension and high risk of cardiovascular complications made it possible to estimate the state of brachiocephalic arteries before and after combined antihypertensive therapy that continued during 14 days. The following variables were measured: blood flow rate, peripheral vascular resistance indices at the extra- and intracranial levels, metabolic indices of cerebrovascular responsiveness, and coefficient of variability as an indicator of the cerebrovascular reserve capacity under conditions of antihypertensive treatment. Three antihypertensive therapeutic regimens were employed, viz. lisinopril plus indapamide, bisoprolol plus indapamide, and amlodipine plus indapamide. It was shown that all the three regimen resulted in positive changes in the parameters of blood flow and peripheral vascular resistance. At the same time, the use of amlodipine plus indapamide ensured a more gradual reduction of peripheral vascular resistance and the most pronounced increase of cerebrovascular reserve capacity compared with the two remaining regimens. It is concluded that the parameters of peripheral vascular resistance and metabolic indices of cerebrovascular responsiveness are the most sensitive and informative end points for the pharmacotherapeutic treatment of cerebral hemodynamics in the patients presenting with grade II-III arterial hypertension and high risk of development of cardiovascular complications.

LC-ESI-MS method for the determination of bisoprolol in human plasma

A sensitive liquid chromatography-electrospray ionization-mass spectrometry (LC-ESI-MS) method has been developed and validated for the determination of bisoprolol in human plasma, using metoprolol as internal standard (I.S.). After alkalization with sodium hydroxide, the samples were extracted with ethyl acetate and separated by HPLC on a ZORBAX SB-C18 column with a mobile phase of 10 mM ammonium acetate buffer containing 0.1% formic acid-methanol (32:68, v/v) at a flow rate of 1 ml/min. The chromatographic separation was achieved in less than 5 min. The linearity was established over the concentration range of 0.05-120 ng/ml. The intra- and inter-run standard deviation was less than 3.8 and 7.5%, respectively. The method had been successfully applied to study the relative bioavailability of bisoprolol fumarate tablets in healthy Chinese volunteers. The pharmacokinetic parameters of the reference and test tablets have been compared.

Liquid chromatographic–electrospray tandem mass spectrometric determination of bisoprolol in human plasma

An analytical method for the determination of bisoprolol in human plasma has been developed based on liquid chromatography-tandem mass spectrometry (LC-MS/MS). The analyte and internal standard (IS) diphenhydramine were cleaned up by protein precipitation with acetonitrile, reconstituted in mobile phase and separated by reversed-phase high-performance liquid chromatography (HPLC) using methanol:10 mm ammonium acetate:formic acid (70:30:0.1 v/v/v) as mobile phase. Detection was carried out by multiple reaction monitoring (MRM) on an LC-MS/MS system and was completed within 2.5 min. The assay was linear over the range 0.5-100 ng/mL with a limit of quantitation (LOQ) of 0.5 ng/mL. The intra- and inter-day precision levels were within 5.54 and 9.95%, respectively, while the accuracy was in the range 89.4-113%. This method has been utilized in a pharmacokinetic study, where healthy volunteers were treated with an oral dose of 5 mg bisoprolol.

A novel transdermal patch incorporating isosorbide dinitrate with bisoprolol: in vitro and in vivo characterization

The combination therapy of nitrate and selective beta-adrenoceptor antagonist has shown benefits for treatment of hypertension and heart disease than either drug alone. The objectives of the present study were to define effects on the anti-hypertension activity and pharmacokinetics of a novel transdermal patch incorporating isosorbide dinitrate (ISDN) with bisoprolol (BP). The 3:2 ratio of ISDN to BP (mg/mg) in the transdermal patches exhibited better anti-hypertension effect synergistically with a similar inhibiting heart rates effect to that of BP alone in renovascular hypertensive rats, and was therefore selected as a final formulation. The in vitro transdermal penetration of both ISDN and BP from the patches displayed a zero-order process, and the penetration rate constants were 7.4 microg/(cm(2)h) for ISDN, and 5.9 microg/(cm(2)h) for BP, respectively. After transdermal administration at single dose or multiple doses, the synergistic anti-hypertension effect was confirmed in spontaneously hypertensive rats also. The effect of each patch lasts for 3 days, and increased with the total dose of two drugs (2mg/cm(2), ISDN:BP=3:2, mg/mg), showing a dose dependant manner. After transdermal administration to rabbits, the absolute bioavailabilities were 33.6% for ISDN, and 31.3% for BP, respectively. The maximal concentrations (C(max)) of both drugs were significantly reduced while the areas under the plasma concentration-time curve (AUC), and mean residence times (MRT) were evidently increased and extended, respectively. As a patient-friendly, convenient, and multi-day dosing therapeutic system, the transdermal patches incorporating ISDN and BP could be promising for prevention and treatment of hypertension.

Comparing Beta-Blocking Effects of Bisoprolol, Carvedilol and Nebivolol

OBJECTIVE

Bisoprolol, carvedilol and nebivolol have been shown to be effective in the treatment of heart failure. However, the beta-blocking effects of these drugs have never been compared directly.

METHODS

Therefore, we performed a randomized, double-blind, placebo-controlled, cross-over trial in 16 healthy males. Subjects received 10 mg bisoprolol, 50 mg carvedilol, 10 mg nebivolol and placebo on the first morning followed by 5 mg bisoprolol once daily, 25 mg carvedilol twice daily, 5 mg nebivolol once daily and placebo for 1 week. Heart rate and blood pressure were measured at rest and exercise 3 and 24 h following intake of the first dose, and immediately before and 3 hours following intake of the last dose of each drug. In addition, effects of the drugs on nocturnal melatonin release were determined, and quality of life (QOL) was evaluated.

RESULTS

Heart rate at exercise was decreased at 3 h following intake of the first single dose of each drug by bisoprolol (-24%), carvedilol (-17%) and nebivolol (-15%), and at 24 h following intake of the respective last dose of each drug following 1 week of chronic administration by bisoprolol (-14%), carvedilol (12 h; -15%) and nebivolol (-13%) (p < 0.05 in all cases). Thus, trough-to-peak-ratios at long-term were as follows: Bisoprolol, 58%; carvedilol (12 h), 85%; nebivolol, 91%. Nocturnal melatonin release was decreased by bisoprolol (-44%, p < 0.05) whereas nebivolol and carvedilol had no effect. QOL with carvedilol was slightly but significantly lower than with the other drugs, whereas bisoprolol and nebivolol did not alter QOL.

CONCLUSIONS

These data show that peak beta-blocking effects of bisoprolol appear stronger than those of nebivolol and carvedilol. On the other hand, nebivolol exerts the highest trough-to-peak-ratio. However, beta-blocking effects of all the three drugs are similar at trough. Only bisoprolol but neither nebivolol nor carvedilol decreased nocturnal melatonin release, a feature which might cause sleep disturbances. Finally, only carvedilol slightly decreased QOL, whereas nebivolol and bisoprolol did not affect QOL. We conclude that different beta-blockers may exert clinically relevant different effects.

Pharmacokinetics and Pharmacodynamics of Bisoprolol in Rats with Bilateral Ureter Ligation-induced Renal Failure

The effect of renal failure on the pharmacokinetics and pharmacodynamics of bisoprolol was investigated in bilateral ureter-ligated (BUL) rats. The blood bisoprolol concentrations following 30-min intravenous infusion at a rate of 60 microg/kg/min were higher in renal artery-occluded (RAO) rats than in control rats, and were higher in BUL rats than in RAO rats. Increased blood bisoprolol concentrations accompanied decreased mean systemic clearances: 50.7, 36.4, and 26.2 mL/min/kg in control, RAO, and BUL rats, respectively. The finding indicated that approximately 30% of administered bisoprolol was excreted via the kidney, and that not only the renal clearance but also non-renal clearance of bisoprolol was decreased in BUL rats. The beta-blocking action of bisoprolol was assessed by the reduction in isoproterenol-induced increases in the heart rate. The relationship between blood concentration and the beta-blocking action of bisoprolol in BUL rats was similar to that in control rats. These results suggested that renal excretion and hepatic metabolism of bisoprolol were significantly reduced in BUL rats, but that pharmacodynamics of bisoprolol was not altered by acute renal failure.

Pharmacokinetic variability of routinely administered bisoprolol in middle-aged and elderly Japanese patients

The nonlinear mixed effects model (NONMEM) was used to analyze the pharmacokinetics of routinely administered bisoprolol in middle-aged and elderly Japanese patients. The subjects consisted of 29 males and 11 females with a mean age of 63.5+/-10.1. Data on the plasma concentration of bisoprolol from 94 blood samples obtained at steady-state following repetitive oral administration were analyzed using the NONMEM program, where a one-compartment model with repetitive bolus dosing was parameterized in terms of oral clearance (CL/F) and apparent volume of distribution (V/F). Individual CL/F values were correlated with body weight (WT) and creatinine clearance (CLcr). The relation between CLcr and the CL/F of bisoprolol was not altered by the CYP2D6 and CYP2C19 genotypes, gender, or age. The mean CL/F value estimated with NONMEM was 0.0612.WT+1.15.CLcr (l/h), and the mean V/F value was 2.61.WT (l). The residual interindividual variability of CL/F and V/F were 22.0% and 12.6%, respectively. The pharmacokinetic variability of bisoprolol is small even in routinely treated Japanese patients, provided that both body weight and renal function are taken into account for the prediction of oral clearance of the drug.

Increased Plasma Concentration of Natriuretic Peptides by Selective β1-Blocker Bisoprolol

Beta-blocker therapy has been shown to be associated with an increase in the plasma concentration of A-type natriuretic peptide (ANP). Whether the plasma concentration of B-type natriuretic peptide (BNP), which is mainly derived from ventricular tissue, is also increased and whether this increase is caused by increased production or decreased metabolism by down-regulation of the natriuretic peptide-clearance receptor remains to be established. In a double-blind crossover study effects of 8 weeks' treatment of bisoprolol,10 mg once daily, and losartan, 50 mg once daily, on plasma concentrations of ANP, BNP, and N-terminal (Nt)-ANP and ambulatory blood pressure (ABP) were measured in 24 hypertensive patients. With bisoprolol plasma concentrations of ANP and BNP increased (P < 0.001) by 93 +/- 88% (mean +/- SD) and 148 +/- 117%, whereas these parameters did not change with losartan. Nt-ANP, which is not metabolized by the NP clearance receptor, increased by 83 +/- 45%, and increments in ANP and Nt-ANP were related (r =0.77, P < 0.001). The decrease in ABP was greater with bisoprolol than with losartan. Monotherapy with bisoprolol, but not with losartan, is associated with substantial increments in plasma concentrations of ANP, Nt-ANP, and BNP. As the magnitude of the increase in ANP and Nt-ANP was comparable, the beta-blocker-induced increase in NPs is not likely to be explained by a decrease in NP clearance receptor density.

Bisoprolol: a review of its use in chronic heart failure

Bisoprolol is a highly selective beta(1)-adrenoceptor antagonist. Administration of bisoprolol to patients with chronic heart failure is associated with increases in left ventricular function and reductions in heart rate; increases in heart rate variability are also seen. Two major randomised, double-blind, placebo-controlled, multicentre trials have examined the clinical efficacy of bisoprolol in combination with ACE inhibitors and diuretics in patients with stable chronic heart failure (New York Heart Association class III or IV): the Cardiac Insufficiency Bisoprolol Study (CIBIS; n = 641) and CIBIS II (n = 2 647). All-cause mortality (primary endpoint) was significantly lower in bisoprolol than in placebo recipients in CIBIS II (11.8 vs 17.3%) and was reduced by bisoprolol regardless of dosage. All-cause mortality was also lower in CIBIS (16.6 vs 20.9%) although the difference did not achieve statistical significance. In a meta-analysis of CIBIS and CIBIS II (n = 3 288), a relative reduction of 29% in the incidence of all-cause mortality was seen in bisoprolol versus placebo recipients; this analysis also demonstrated that bisoprolol reduces mortality in patients with chronic heart failure regardless of aetiology or severity. In CIBIS II, there were significantly fewer cardiovascular deaths, admissions to hospital for any reason, or cardiovascular deaths or cardiovascular hospitalisations (combined endpoint) in bisoprolol, compared with placebo, recipients (secondary endpoints). Compared with standard treatment alone, the addition of bisoprolol was a cost-effective option in chronic heart failure in UK, French, German and Swedish pharmacoeconomic studies. Bisoprolol is generally well tolerated in patients with chronic heart failure. In CIBIS II, adverse events occurring more commonly in bisoprolol than placebo recipients, regardless of causal relationship with the study medication, included dizziness, bradycardia, hypotension and fatigue. Bisoprolol recipients were less likely than placebo recipients to experience worsening of heart failure, dyspnoea or tachycardia. In both CIBIS and CIBIS II there was no significant difference between bisoprolol and placebo recipients in the incidence of permanent treatment withdrawal. In conclusion, adding the highly selective beta(1)-blocker bisoprolol to a treatment regimen comprising an ACE inhibitor and a diuretic significantly improves survival in patients with stable chronic heart failure and reduces the need for hospitalisation. The use of bisoprolol in this disorder is generally well tolerated and is cost effective. Thus, bisoprolol should be considered a standard treatment option when selecting a beta-blocker for use in combination with ACE inhibitors and diuretics in patients with stable, moderate to severe chronic heart failure.

Bisoprolol: studies of potential interactions with theophylline and warfarin in healthy volunteers

Many patients receiving bisoprolol treatment might also require warfarin or theophylline therapy. Two studies were carried out in healthy volunteers to investigate the possibility that bisoprolol might interact with warfarin or theophylline, both of which have low therapeutic ratios. In a balanced, two-way, crossover study, eight men and four women took bisoprolol 10 mg daily for 14 days. They were divided into two groups of six volunteers. On the tenth day of treatment, six subjects received theophylline 375 mg (Nuelin tablets) by mouth and the pharmacokinetics of theophylline were determined. After a washout period of 7 days, they also underwent determination of single-dose theophylline kinetics. The other six subjects had single-dose theophylline kinetics determined 7 days before the first dose of bisoprolol, and then again after 10 days of bisoprolol treatment. Concurrent administration of bisoprolol did not influence the tolerability of theophylline and had no significant effect on any of the pharmacokinetic parameters for theophylline. In a separate study, 12 healthy men received warfarin daily until their prothrombin times were about 1.5 x control. They then received bisoprolol 10 mg daily p.o. for 10 days; warfarin was continued until 5 days after the end of bisoprolol treatment. Bisoprolol and warfarin treatments were well tolerated, and there was no effect on prothrombin times of either starting or stopping bisoprolol treatment. These studies show no effect of bisoprolol treatment upon theophylline pharmacokinetics, and no evidence of an effect of bisoprolol upon low-level anticoagulation with warfarin. Nevertheless, care should always be taken when changes are made in the medication of patients receiving theophylline or warfarin.

Pharmacokinetic and dynamic interactions of the angiotensin-converting enzyme inhibitor imidapril with hydrochlorothiazide, bisoprolol and nilvadipine

OBJECTIVE

The pharmacokinetic and dynamic interactions of the angiotensin-converting enzyme (ACE) inhibitor imidapril with other therapeutic principles used in hypertension and heart failure were evaluated.

METHODS

In three separate, double-blind, placebo-controlled, four-way cross-over studies in healthy volunteers (n = 16 each), single oral doses of imidapril 10 mg (I), hydrochlorothiazide 12.5 mg (H), bisoprolol 5 mg (B) and nilvadipine 8 mg (N) were administered as monotherapies, and in IH, IB and IN combinations. Plasma concentrations of imidaprilat and H were followed up to 48 h, those of B and N up to 24 h and area under the concentration time curve (AUC), maximum plasma concentration (Cmax) and time to Cmax (tmax) were determined. Blood pressure (BP), heart rate (HR) and non-invasive haemodynamics [total peripheral resistance (TPR, N and H), systolic time intervals (STI, N and H), and plasma renin activity (PRA)] were assessed up to 24 h.

RESULTS

There were no pharmacokinetic interactions between I plus H, B or N. Bioequivalence between single and combined administrations was verified for all investigational compounds [AUC point estimates (90% confidence interval CI): imidaprilat IH 109% (97.8, 122.8); IB 99.6% (91.2, 109.4); IN 105.7% (92.1, 121.3); H 96.6% (92.5, 100.8); B 103% (100.2, 105.8); N 98% (89, 108)]. The haemodynamic effects were mostly additive and without relevant pharmacodynamic interactions. I significantly reduced the BP by 5-8 mmHg, B by 4-8 mmHg and N by 4-6 mmHg. In addition, H induced a significant reduction of the preload as seen from STI, and B significantly reduced HR (-5 bpm). N induced a significant decrease in TPR (about 15% of baseline values) and showed corresponding changes in STI. PRA increased significantly following I alone (1.5-2.0 ng/ml/h), as well as combined with N (2.5 ng/ ml/h) or H (3.1 ng/ml/h). This increase was clearly blunted by the co-administration of B (0.6 ng/ml/h).

CONCLUSIONS

The combination of imidapril with a diuretic, beta-adrenoceptor antagonist or calcium-channel blocker seems a reasonable and safe treatment option when striving for additive pharmacodynamic effects not accompanied by relevant pharmacokinetic interactions.

Bisoprolol in chronic heart failure

The evidence for the use of beta-blockers in heart failure is substantial. Latest recommendations and guidelines suggest that most heart failure patients should be on a drug regimen of an angiotensin-converting enzyme inhibitor, diuretic and a beta-blocker. However, despite the evidence from trials, the majority of patient are not yet treated appropriately, with only 5% receiving a beta-blocker.

Pharmacokinetics of bisoprolol and its effect on dialysis refractory hypertension

The efficacy, safety, and pharmacokinetics of bisoprolol were investigated following oral administration once daily for 12 weeks in hyperreninemic patients with dialysis-refractory hypertension. Mean blood pressure rapidly fell from 132 to 112 mmHg in the 5.0-mg/day (n = 6) and from 142 to 128 mmHg in the 2.5-mg/day patients (n = 5), which were accompanied by a fall in plasma renin activity. On nondialysis days, Cmax and T1/2 were significantly higher in patients than in healthy control subjects. However, Cmax in the 2.5-mg/day patients was almost equal to that in healthy control subjects receiving 5.0 mg/day of bisoprolol. Plasma bisoprolol was dialyzable. During the course of the study, dialysis hypotension and bradycardia occurred in two patients receiving 5.0 mg/day of bisoprolol. In conclusion, a daily dose of 2.5 mg bisoprolol seems to be an adequate and relatively effective dose in our patients with dialysis-refractory hypertension.

Stereoselective metabolism of bisoprolol enantiomers in dogs and humans

To clarify the mechanism of the species difference in the metabolism of bisoprolol enantiomers, in vitro metabolic studies were performed using dog liver microsomes and human cytochrome P450 (CYP) isoforms. The O-deisopropylation of bisoprolol enantiomers showed biphasic kinetics in dog liver microsomes. The intrinsic clearance (Vmax/Km) for O-deisopropylation of R(+)-bisoprolol was higher than S(-)-isomer in both high-affinity and low-affinity components. The R/S ratio of the intrinsic clearance in high- and low-affinity components was 1.34 and 1.65, respectively. The inhibition studies in dog liver microsomes using CYP isoform-selective inhibitors indicated that the O-deisopropylation of both bisoprolol enantiomers was mediated via the CYP2D and CYP3A subfamily, and suggested that high-affinity oxidation was dependent on CYP2D. The kinds of CYP subfamilies in dogs, which contribute to the metabolism of bisoprolol enantiomers, were the same as those in humans. The intrinsic clearance for O-deisopropylation of R(+)bisoprolol by human recombinant CYP2D6 was also different from that of S(-)-enantiomers (R/S:1.50). However, unlike the dog microsomes, the intrinsic clearance by the human recombinant CYP3A4 did not show a stereoselective difference. Therefore, the species difference in the R/S ratio of metabolic clearance for the oxidation of bisoprolol enantiomers (dog > human) is mainly due to the species difference in the stereoselectivity of one of the cytochrome P450 subfamilies (CYP3A).

Pharmacokinetics and metabolism of bisoprolol enantiomers in humans

The plasma concentrations and urinary excretions of bisoprolol enantiomers in four Japanese male healthy volunteers after a single oral administration of 20 mg of racemic bisoprolol were evaluated. The AUC(infinity) and elimination half-life of (S)-(-)-bisoprolol were slightly larger than those of (R)-(+)-bisoprolol in all subjects. The metabolic clearance of (R)-(+)-bisoprolol was significantly (P < 0.05) larger than that of (S)-(-)-bisoprolol (S/R ratio: 0.79+/-0.03), although the difference was small. In contrast, no stereoselective in vitro protein binding of bisoprolol in human plasma was found. An in vitro metabolic study using recombinant human cytochrome P450 (CYP) isoforms indicated that oxidation of both bisoprolol enantiomers was catalyzed by the two isoforms, CYP2D6 and CYP3A4. CYP2D6 metabolized bisoprolol stereoselectively (R > S), whereas the metabolism of bisoprolol by CYP3A4 was not stereoselective. The S/R ratio of the mean clearance due to renal tubular secretion was 0.68, indicating a moderate degree of stereoselective renal tubular secretion. These findings taken together suggest that the small differences in the pharmacokinetics between (S)-(-)- and (R)-(+)-bisoprolol are mainly due to the stereoselectivity in the intrinsic metabolic clearance by CYP2D6 and renal tubular secretion.

Pharmacokinetics of beta-adrenoceptor blockers in obese and normal volunteers

AIMS

Obesity can modify the pharmacokinetics of lipophilic drugs. As beta-adrenoceptor blockers (BB) are often prescribed for obese patients suffering from hypertension or coronary heart disease, this study compares the pharmacokinetics of lipophilic beta-adrenoceptor blockers in obese and control subjects.

METHODS

Nine obese (157 +/- 24% of ideal body weight (IBW) mean +/- s.d.) and nine non-obese healthy volunteers (98 +/- 10% IBW), aged 32 +/- 9 years, were included in the study. Subjects were randomly given a single i.v. infusion of one of the following racemic beta-adrenoceptor blockers, whose doses (expressed as base per kg of IBW) were: propranolol (0.108 mg), labetalol (0.99 mg) and nebivolol (0.073 mg). The plasma concentrations of unchanged drugs were measured by h.p.l.c. The ionisation constants and lipophilicity parameters of beta-adrenoceptor blockers were assessed.

RESULTS

The pharmacokinetic data for the three drugs were qualitatively similar. There was a trend towards a greater total distribution volume (Vss) in obese patients than in controls. However, Vss expressed per kg body weight was slightly smaller in obese patients. The relationship between Vss and lipophilicity of five beta-adrenoceptor was studied by combining the current results with those previously obtained with a moderately lipophilic drug (bisoprolol) and a hydrophilic one (sotalol). The Vss of the five drugs was positively and well-correlated (r2 = 0.90; P < 0.01) with their distribution coefficient at pH 7.4 (log D7.4), but not with their partition coefficients. The linear regression coefficients for lean and obese subjects were very similar.

CONCLUSIONS

Lipophilic beta-adrenoceptor blockers seem to diffuse less into adipose than into lean tissues. All electrical forms of the drugs (i.e. cations, neutral forms, or zwitterions) present at physiological pH contribute to their tissue distribution, in both obese and lean subjects. Their tissue distribution in obese patients could be restricted by the sum of hydrophobic forces and hydrogen bonds they elicit with macromolecules in lean tissues.

Stereoselective pharmacokinetics of bisoprolol after intravenous and oral administration in beagle dogs

The stereoselective pharmacokinetics of bisoprolol, a highly beta 1-selective adrenoceptor blocking agent, was studied in dogs. After intravenous and oral administration of the racemate, there was a difference in the plasma concentration between S(-)- and R(+)-bisoprolol. The area under the curve (AUC) of concentration versus time of S(-)-bisoprolol was approximately 1.5 times higher than that of R(+)-bisoprolol and the elimination half-life of S(-)-bisoprolol was approximately 1.4 times longer than that of R(+)-bisoprolol. However, no differences were observed in the volume of distribution, absolute bioavailability, and renal clearance between the two enantiomers. The plasma protein binding of S(-)-bisoprolol was also the same as that of the R(-)-isomer. No chiral inversion or enantiomer-enantiomer interaction was observed, when enantiomers were solely administered via the intravenous route. The comparison of the oxidative metabolic rate of two enantiomers using dog liver microsomes demonstrated that the metabolite was more slowly formed from S(-)- than from R(+)-bisoprolol. Consequently, we concluded that the stereoselective difference in the metabolic clearance between S(-)- and R(+)-bisoprolol caused the difference in the disposition of bisoprolol enantiomers.

Comparative bioavailability of a metoprolol controlled release formulation and a bisoprolol normal release tablet after single oral dose administration in healthy volunteers

The bioavailability patterns of a 100 mg metoprolol controlled release tablet and a 10 mg bisoprolol normal release tablet were compared in a single dose crossover study in 12 healthy subjects. The plasma drug concentration levels were measured for 36 h post-dose, using HPLC with fluorimetric detection. The 2 formulations were equally well tolerated, headache being the most frequently reported adverse event. Episodes of bradycardia (heart rate < 50 bpm) occurred at a similar rate with both formulations. The plasma metoprolol profile differed significantly (p < 0.05) from the bisoprolol profile regarding time to maximum concentration, mean residence time, the ratio of peak concentration (Cmax) to the area under the curve (AUC) and the plateau time as estimated from the half-value duration. The average drug plasma concentration observed 24 h after administration still accounted for 54% of the Cmax value for the metoprolol controlled release tablet, but only 23% with the bisoprolol normal release tablet. A large inter-individual variability was seen in the bioavailability of metoprolol, with 3 subjects (characterised as CYP2D6 deficient) exhibiting AUC values 8 - 10 times larger than in the other subjects. The controlled release pattern of the formulation was similar in slow and fast metabolizers. No such variability pattern was apparent for bisoprolol. The findings allow to conclude that, after administration of the metoprolol controlled release tablet, the rate of absorption of the active principle is significantly slower, therefore yielding more constant plasma concentration levels over the 24 h post-dose period, than after administration of the bisoprolol normal release tablet.

Bisoprolol: is this just another beta-blocker for hypertension or angina?

OBJECTIVE

To review the pharmacology, pharmacokinetics, and clinical experience with bisoprolol and make recommendations regarding its potential clinical usefulness, as well as considerations for formulary inclusion.

DATA SOURCES

Reference citations were sought from Index Medicus and Science Citation Index. Data were collected from abstracts and articles describing experimental studies or blind clinical trials.

STUDY SELECTION

Studies designed in a randomized, blind, and placebo-controlled manner were emphasized. Studies also were included if bisoprolol was evaluated comparatively with other agents in a randomized, blind fashion.

DATA EXTRACTION

Data from human studies published in English were evaluated. Studies were assessed by sample size and the clarity of descriptions of methods and results.

DATA SYNTHESIS

Bisoprolol reduces systolic and diastolic blood pressures in patients with hypertension for a 24-hour dosing interval and is associated with beneficial hemodynamic effects in patients with myocardial ischemia. It is devoid of intrinsic sympathomimetic activity and membrane-stabilizing effects at therapeutic dosages. In patients with hypertension, bisoprolol diminishes plasma renin activity, platelet aggregation, effective renal plasma flow, and creatinine clearance. Bisoprolol has minimal effects on glucose tolerance and plasma lipid profiles. Monotherapy with bisoprolol is as effective as with atenolol, nitrendipine, or nifedipine. Low-dose combination therapy with hydrochlorothiazide is at least as effective as either bisoprolol or hydrochlorothiazide alone. Preliminary experience in the management of angina pectoris suggests that bisoprolol is at least as efficacious as atenolol or verapamil. Thus far, reported adverse effects are similar to those of other beta-blockers. No clinically important drug interactions have been reported at this time.

Dose proportionality of bisoprolol enantiomers in humans after oral administration of the racemate

Dose proportionality of racemic bisoprolol and the stereoselectivity of its enantiomers were studied after single oral dosing of 5 to 40 mg of bisoprolol hemifumarate in eight healthy male volunteers in an open-label, randomized, four-way cross-over trial. There were dose-proportional increases in mean peak plasma concentration (Cmax) and area under the plasma concentration versus time curve (AUC) values for the racemate and the individual enantiomers. No statistically significant differences were detected between the mean half life (t 1/2), Cmax, and time to reach Cmax (tmax) of the R- and S-isomers at each of the four dose levels studied. These findings support dose proportionality and absence of stereoselective pharmacokinetics for bisoprolol in the dose range studied.

Relationships between acute and chronic beta-blocking effects of bisoprolol in healthy volunteers: a practical approach to predict intensity of beta-blockade

Bisoprolol is a selective beta 1-adrenoceptor antagonist devoid of partial agonist activity that can be used for treatment of chronic and acute myocardial ischemia. In this condition, it is important to demonstrate that a stable beta-blocking effect at steady state can be predicted by a mathematical model determined by plasma concentration-effect relationship after an acute intravenous (i.v.) dose. This relation was studied in 10 healthy volunteers in a double-blind, randomized, cross-over, placebo-controlled study after a 5-min i.v. infusion of bisoprolol (5 mg) or placebo. Standardized exercise tests were recorded at different times for 48 h after infusion with simultaneous bisoprolol assay (high-performance liquid chromatography, HPLC) in plasma. After a 1-week interval, subjects received oral bisoprolol (10 mg once daily) for 5 days and exercise tests were repeated on day 5 before and 2, 3, and 4 h after dosing, with bisoprolol plasma level determined simultaneously. In the acute period, bisoprolol significantly decreased exercise heart rate (HR: peak effect -20.5 +/- 4%) as compared with placebo. There was a direct relationship (no hysteresis) between beta-blockade and plasma concentrations with a sigmoid (7 subjects) or a linear (3 subjects) best-fit model. After repeated bisoprolol administration, steady-state plasma levels were achieved and 88% of the observed decreases in exercise HR were within the 95% confidence interval (CI) for individual prediction. These data suggest that bisoprolol-induced beta-blockade after repeated oral dosing can be predicted by single-test i.v. dose administration.