Studies of the absorption and removal of propranolol in hypertensive patients during therapy

3D Printed Buccal Films for Prolonged-Release of Propranolol Hydrochloride: Development, Characterization and Bioavailability Prediction

Gelatin-polyvinylpyrrolidone (PVP) and gelatin-poly(vinyl alcohol) (PVA) mucoadhesive buccal films loaded with propranolol hydrochloride (PRH) were prepared by semi-solid extrusion 3D printing. The aim of this study was to evaluate the effects of the synthetic polymers PVP and PVA on thermal and mechanical properties and drug release profiles of gelatin-based films. The Fourier-transform infrared spectroscopy showed that hydrogen bonding between gelatin and PVP formed during printing. In the other blend, neither the esterification of PVA nor gelatin occurred. Differential scanning calorimetry revealed the presence of partial helical structures. In line with these results, the mechanical properties and drug release profiles were different for each blend. Formulation with gelatin-PVP and PRH showed higher tensile strength, hardness, and adhesive strength but slower drug release than formulation with gelatin-PVA and PRH. The in silico population simulations indicated increased drug bioavailability and decreased inter-individual variations in the resulting pharmacokinetic profiles compared to immediate-release tablets. Moreover, the simulation results suggested that reduced PRH daily dosing can be achieved with prolonged-release buccal films, which improves patient compliance.

Extracorporeal treatment for poisoning to beta-adrenergic antagonists: systematic review and recommendations from the EXTRIP workgroup

BACKGROUND

β-adrenergic antagonists (BAAs) are used to treat cardiovascular disease such as ischemic heart disease, congestive heart failure, dysrhythmias, and hypertension. Poisoning from BAAs can lead to severe morbidity and mortality. We aimed to determine the utility of extracorporeal treatments (ECTRs) in BAAs poisoning.

METHODS

We conducted systematic reviews of the literature, screened studies, extracted data, and summarized findings following published EXTRIP methods.

RESULTS

A total of 76 studies (4 in vitro and 2 animal experiments, 1 pharmacokinetic simulation study, 37 pharmacokinetic studies on patients with end-stage kidney disease, and 32 case reports or case series) met inclusion criteria. Toxicokinetic or pharmacokinetic data were available on 334 patients (including 73 for atenolol, 54 for propranolol, and 17 for sotalol). For intermittent hemodialysis, atenolol, nadolol, practolol, and sotalol were assessed as dialyzable; acebutolol, bisoprolol, and metipranolol were assessed as moderately dialyzable; metoprolol and talinolol were considered slightly dialyzable; and betaxolol, carvedilol, labetalol, mepindolol, propranolol, and timolol were considered not dialyzable. Data were available for clinical analysis on 37 BAA poisoned patients (including 9 patients for atenolol, 9 for propranolol, and 9 for sotalol), and no reliable comparison between the ECTR cohort and historical controls treated with standard care alone could be performed. The EXTRIP workgroup recommends against using ECTR for patients severely poisoned with propranolol (strong recommendation, very low quality evidence). The workgroup offered no recommendation for ECTR in patients severely poisoned with atenolol or sotalol because of apparent balance of risks and benefits, except for impaired kidney function in which ECTR is suggested (weak recommendation, very low quality of evidence). Indications for ECTR in patients with impaired kidney function include refractory bradycardia and hypotension for atenolol or sotalol poisoning, and recurrent torsade de pointes for sotalol. Although other BAAs were considered dialyzable, clinical data were too limited to develop recommendations.

CONCLUSIONS

BAAs have different properties affecting their removal by ECTR. The EXTRIP workgroup assessed propranolol as non-dialyzable. Atenolol and sotalol were assessed as dialyzable in patients with kidney impairment, and the workgroup suggests ECTR in patients severely poisoned with these drugs when aforementioned indications are present.

Oxandrolone Coadministration Does Not Alter Plasma Propranolol Concentrations in Severely Burned Pediatric Patients

The systemic impact of severe burn injury results in a variety of disorders that require therapeutic intervention. Propranolol, a nonselective β₁, β₂-adrenergic receptor antagonist, reduces resting heart rate and cardiac work caused by elevated circulating catecholamines. Oxandrolone, a testosterone mimetic, promotes protein synthesis and anabolism to counter muscle wasting. Coadministration of these drugs is expected to synergistically improve patient outcomes. Testosterone administration is known to alter β-adrenergic receptor-mediated signaling. Here, we determined whether the coadministration of oxandrolone alters plasma propranolol concentrations. Ninety-two pediatric patients with burns covering ≥30% of the TBSA were enrolled in this institutional review board-approved study and randomized to receive propranolol (n = 49) or oxandrolone + propranolol (n = 43). Plasma propranolol concentrations were determined following two dosing strategies: Q6 (liquid formulation; n = 86) and Q24 (extended-release capsule; n = 22). Samples were drawn before drug administration and at regular intervals throughout the next two dosing periods. Heart rate and blood pressure were recorded throughout the study. Propranolol half-life was 3.3 hours for the Q6 drug dosing frequency (P < .0001) and 11.2 hours for the Q24 strategy (P < .0001). Percentage of predicted heart rate declined by 2.8% for each doubling of the propranolol concentration in the Q6 dosing schedule (P < .0001). Percentage of predicted heart rate declined by 2.5% for each doubling of propranolol concentration on the Q24 dosing schedule (P < .0001). Maximum and minimum propranolol plasma concentrations were similar with either dosing regimen. The addition of oxandrolone did not affect any of the measured parameters. Oxandrolone coadministration does not alter propranolol’s plasma concentration, half-life, or effect on heart rate. This study is registered at clincialtrials.gov: NCT00675714.

Propranolol kinetics in plasma from severely burned adults

OBJECTIVES

The aim of this study was to determine the appropriate propranolol dosing strategy for reducing heart rate in severely burned adults.

METHODS

A total of 26 patients (≥18 years) with burns covering ≥30% of the total body surface area were included in this IRB-approved study. Plasma propranolol concentrations were determined in a placebo group (n=10) or following one of three dosing strategies: Q6 (n=4), Q8 (n=6), and Q24 (n=6). Blood was collected just before dosing and at regular intervals over two dosing periods with corresponding heart rate and blood pressure recordings. Statistical significance was determined by one-way ANOVA followed by the appropriate post-hoc test.

RESULTS

Heart rate was 86±2 bpm for Q6, 93±3 bpm for Q8, and 90±4 bpm for Q24. The Q8 group had a significantly higher heart rate than the Q6 group (p=0.0001). Plasma propranolol concentrations were significantly higher in the Q6 dosing strategy than in the Q8 dosing strategy (p=0.02).

CONCLUSIONS

Heart rate can be decreased to a similar degree with Q6 and Q24 dosing strategies, with the Q8 dosing strategy being less effective. Q6 dosing is recommended to maintain reduced heart rate throughout dosing periods.

Understanding the pharmacokinetics of anxiolytic drugs

INTRODUCTION

Anxiety disorders are considered the most common mental disorders and they can increase the risk for comorbid mood and substance use disorders, significantly contributing to the global burden of disease. For this reason, anxiolytics are the most prescribed psychoactive drugs, particularly in the Western world.

AREAS COVERED

This review aims to analyze pharmacokinetic profile, plasma level variations so as the metabolism, interactions and possible relation to clinical effect of several drugs which are used primarily as anxiolytics. The drugs analyzed include benzodiazepines, anticonvulsants (pregabalin, gabapentin), buspirone, β-blockers and antihistamines (hydroxyzine). Regarding the most frequently used anxiolytic benzodiazepines, data on alprazolam, bromazepam, chlordesmethyldiazepam, chlordiazepoxide, clotiazepam, diazepam, etizolam, lorazepam, oxazepam, prazepam and clonazepam have been detailed.

EXPERT OPINION

There is a need for a more balanced assessment of the benefits and risks associated with benzodiazepine use, particularly considering pharmacokinetic profile of the drugs to ensure that patients, who would truly benefit from these agents, are not denied appropriate treatment. An optimal pharmacological approach involving an integrative pharmacokinetic and pharmacodynamic optimization strategy would ensure better treatment and personalization of anxiety disorders. So it would be desirable for the development of new anxiolytic drug(s) that are more selective, fast acting and free from the unwanted effects associated with the traditional benzodiazepines as tolerance or dependence.

Stereoselective transport and uptake of propranolol across human intestinal Caco-2 cell monolayers

The transport and uptake of individual propranolol (PPL) enantiomers were studied in human intestinal Caco-2 cell monolayers, and a reversed-phase HPLC-UV assay was used for quantitative analysis. S-PPL and R-PPL across Caco-2 cell monolayers was determined in the concentrations range of 10-500 microM in both apical (AP) to basolateral (BL) and BL to AP directions. S-PPL exhibited greater permeability than R-PPL in the AP to BL direction, whereas in the BL to AP direction S-enantiomer transported less than R-enantiomer. Uptake of R-PPL was significantly higher than that of S-PPL either from AP side or from BL side. The statistically significant differences in uptake were observed at the concentrations range from 10 to 50 microM. Furthermore, the apparent Michaelis constant (K(m)) and maximal velocity (V(max)) also showed significant difference between the two enantiomers. Moreover, the AP to BL transport of PPL enantiomer was markedly decreased by lowering the pH of the apical side but it did not affect the stereoselectivity of PPL across Caco-2 cell monolayers. The transport and uptake of PPL in the BL to AP direction was not influenced by several protein inhibitors. The results suggest that PPL enantiomers showed stereoselective transport and uptake across the Caco-2 cell monolayers. A special transport mechanism capable of directing the PPL enantiomers might be present in the Caco-2 monolayers.

Uptake of propranolol, a cardiovascular pharmaceutical, from water into fish plasma and its effects on growth and organ biometry

Pharmaceuticals in the environment (PIE) are of importance since these compounds are designed to affect biological receptors/enzymes that are often conserved across vertebrate families. Across-species extrapolation of these therapeutic targets suggests potential for impacting amphibia and fish in the aquatic environment. Due to the scarcity of relevant ecotoxicological data, the long-tem impact of PIE remains a research question. Efficient use of mammalian data has been proposed to better understand and predict the potential for a given pharmaceutical to impact the environment. Using a model cardiovascular pharmaceutical (propranolol, a non-specific beta(1)/beta(2)-adrenergic antagonist), the hypothesis that mammalian data can be used to predict toxicity in fish was tested. Rainbow trout (Oncorhynchus mykiss (Walbaum)) have beta-adrenergic signalling mechanisms analogous to human cardiovascular receptors that respond to pharmacological doses of agonists and antagonists. Trout absorbed propranolol from water such that after 40 days of exposure, the linear relationship was [plasma] - 0.59[water] (n - 31, r - 0.96). Growth rate was affected only at very high aqueous concentrations (10-day (growth)NOEC - 1.0 and (growth)LOEC - 10 mg/l). Growth recovered with time (40-day (growth)NOEC - 10 mg/l), suggesting possible adaptation to the pharmaceutical, although the internal plasma concentration in trout exposed to 10mg propranolol/l of water was higher than the mammalian therapeutic plasma concentration. Additional endpoints suggested subtle changes of liver and heart size at much lower concentrations may have occurred, although these were not concentration-related. There was, however, a dose-dependent effect upon overall body condition. The trout plasma concentrations at these effective aqueous concentrations fell within the range of mammalian effective plasma concentrations, supporting the potential for developing 'read-across' from mammalian pharmacology safety data to fish ecotoxicology. Despite these effects at relatively high concentrations, propranolol is not expected to pose a risk to fish at the concentrations considered to be present in the aquatic environment.

The influence of bile salts on the absorption in vitro and in vivo of propranolol

The lipophilicity of propranolol is increased by some bile salts which form ion-pairs. In the presence of taurodeoxycholate, the logarithm of the apparent partition coefficient (log P) of propranolol is increased. Moreover, the apparent diffusion constants in vitro of propranolol as ion-pairs at pH 3.0-6.0 are about 5-6 times higher than those of propranolol alone. The area under the curve values of plasma concentration-time profiles of propranolol, following its oral administration to rabbits together with taurodeoxycholate, are about 1.4 times higher than those after administration of propranolol alone. Moreover, after the administration of propranolol with taurodeoxycholate the plasma concentration rises more rapidly, with a point of inflection between 0.5 and 1.5 h, than after administration of propranolol alone. Taurodeoxycholate does not modify the first-pass effect of propranolol in rabbits following intravenous and intraportal administration. The absorption of an oral dose of propranolol in the presence of taurodeoxycholate increases from 70% to 100%, due to the higher lipophilicity of the ion-pair. The plasma concentration-time curves suggest the hypothesis that greater absorption of the ion-pair occurs mainly in the upper region of the gastrointestinal tract.

Determination of propranolol concentration in small volume of rat plasma by HPLC with fluorometric detection

A simple, rapid and sensitive fluorescence high performance liquid chromatographic method was developed to determine propranolol concentration in the small volume of rat plasma without the solvent extraction step using pronethanol as the internal standard. The analysis was accomplished using a 5 microm CAPCELL PAK analytical cyano column at room temperature and a mobile phase consisted of 1% aqueous acetic acid containing 0.2% triethylamine and acetonitrile (65:35, v/v; pH 3.8). The flow-rate was kept at 0.5 mL/min and column effluent was monitored with a fluorescence detector at an excitation wavelength of 230 nm and an emission wavelength of 340 nm. Retention times for pronethalol and propranolol were 8.5 min and 10.5 min, respectively. Linear regressions for the standard curves were linear in the range 2-800 ng/mL, giving correlation coefficients above 0.998. The detection limit was 1.34 ng/mL. No analytical interference was observed from endogenous components in rat plasma. This simple and sensitive assay method was feasibly applied to the pharmacokinetic study of propranolol after intravenous administration of 2 mg/kg of propranolol to normal and carbon tetrachloride-induced liver cirrhotic rats.

Pharmacokinetics and pharmacodynamics of propranolol in hypertensive patients after sublingual administration: systemic availability

The bioavailability of propranolol depends on the degree of liver metabolism. Orally but not intravenously administered propranolol is heavily metabolized. In the present study we assessed the pharmacokinetics and pharmacodynamics of sublingual propranolol. Fourteen severely hypertensive patients (diastolic blood pressure (DBP) > or = 115 mmHg), aged 40 to 66 years, were randomly chosen to receive a single dose of 40 mg propranolol hydrochloride by sublingual or peroral administration. Systolic (SBP) and diastolic (DBP) blood pressures, heart rate (HR) for pharmacodynamics and blood samples for noncompartmental pharmacokinetics were obtained at baseline and at 10, 20, 30, 60 and 120 min after the single dose. Significant reductions in BP and HR were obtained, but differences in these parameters were not observed when sublingual and peroral administrations were compared as follows: SBP (17 vs 18%, P = NS), DBP (14 vs 8%, P = NS) and HR (22 vs 28%, P = NS), respectively. The pharmacokinetic parameters obtained after sublingual or peroral drug administration were: peak plasma concentration (CMAX): 147 +/- 72 vs 41 +/- 12 ng/ml, P < 0.05; time to reach CMAX (TMAX): 34 +/- 18 vs 52 +/- 11 min, P < 0.05; biological half-life (t1/2b): 0.91 +/- 0.54 vs 2.41 +/- 1.16 h, P < 0.05; area under the curve (AUCT): 245 +/- 134 vs 79 +/- 54 ng h-1 ml-1, P < 0.05; total body clearance (CLT/F): 44 +/- 23 vs 26 +/- 12 ml min-1 kg-1, P = NS. Systemic availability measured by the AUCT ratio indicates that extension of bioavailability was increased 3 times by the sublingual route. Mouth paresthesia was the main adverse effect observed after sublingual administration. Sublingual propranolol administration showed a better pharmacokinetic profile and this route of administration may be an alternative for intravenous or oral administration.

Mechanism for the enhancement effect of fatty acids on the percutaneous absorption of propranolol

The effects of a series of fatty acids on the percutaneous absorption of propranolol (PL) through rabbit skin and the mechanism by which fatty acids facilitate the skin penetration of PL were examined in vitro and in vivo using a gel base. Lauric and myristic acids, at the fatty acid:PL molar ratio of 1:1 were the most potent agents in increasing the skin penetration, giving the largest penetration rate (Js) and penetration coefficient (Kp) of PL. The molar ratio of 2:1 also exerted a large enhancing effect, comparable to that with a molar ratio of 1:1. When the enhancing effects of lauric acid, its amide, and its methyl ester were compared, the free acid gave the highest Js and Kp values. The plasma PL concentrations were significantly higher and more sustained after a single percutaneous application of the formulation with lauric acid than those after the formulation without the acid. The mechanism for the enhancing effect was examined by measuring IR and 13C NMR spectra, the solubility in buffer, and the apparent partition coefficient of PL. Additionally, the penetration of PL and lauric acid, as co-penetrants, through rabbit skin and shed snake skin were evaluated. The IR spectra of the mixture of PL with lauric acid (molar ratio, 1:1) was characterized by an extreme shift of the CO peak. Comparison of the NMR spectra of PL, lauric acid, and the mixture suggested that the carbonyl group of lauric acid interacted with the amino and hydroxyl groups of PL, probably by charge interaction.(ABSTRACT TRUNCATED AT 250 WORDS)

Pharmacokinetics and pharmacodynamics of conventional and controlled-release formulations of metipranolol in man

The pharmacokinetics and beta-adrenoceptor blocking effects of conventional and sustained-release metipranolol have been studied in 6 healthy male volunteers given a single oral dose of 40 mg. Plasma drug concentrations determined by TLC and a radioreceptor assay, and the inhibition of exercise-induced tachycardia, were monitored for 48 h. Relevant amounts of active metabolites other than deacetylmetipranolol were not found. Compared to conventionally formulated metipranolol, the controlled-release product had a prolonged mean residence time (10.7 vs 5.5 h), the peak drug concentration was halved and the time to peak drug concentrations was delayed. Relatively constant plasma concentrations (cideal = 6.5 ng/ml) and a clinically significant reduction of exercise-induced tachycardia were maintained throughout a 24 h dosing interval. An individual deacetylmetipranolol plasma concentration-effect relationship was evaluated using the Emax model. Mean parameters were Emax 26% and C50 2.9 ng/ml.

Bioavailability of propranolol hydrochloride tablet formulations: application of multiple dose crossover studies

Two multiple dose crossover pharmacokinetic studies were carried out to determine the steady-state bioavailability of newly formulated generic propranolol HCl tablets relative to Inderal tablets. In Study I, 24 healthy volunteers were dosed with 4 x 10 mg test tablets, 1 x 40 mg test tablet, 4 x 10 mg Inderal tablets, and 40 mg of propranolol HCl in solution. In Study II, 24 healthy volunteers were dosed with 1 x 80 mg test tablet, 1 x 80 mg Inderal tablet, and 80 mg of propranolol HCl in solution. Both studies were of randomized design with each formulation administered every 8 h for 15 doses. Serial plasma samples were obtained for 8 h after morning doses on Days 4 and 5 of each treatment period and assayed for propranolol using a validated HPLC method. Mean plasma concentration-time data for test tablets and reference tablets were superimposable in both studies. Pharmacokinetic parameters from Days 4 and 5 were combined for statistical analysis since subjects were determined to have reached steady-state. Mean AUC, Cmax, tmax, and Cmin values were not statistically different between test tablets and Inderal tablets in either study. Based on these findings, the test tablets demonstrated the same rate and extent of propranolol absorption as did corresponding Inderal tablets. Therefore, the test tablets and Inderal tablets were determined to be bioequivalent.

Uptake of propranolol by microvessels isolated from bovine brain

To study the transport system of propranolol (PL), a basic drug, in the blood-brain barrier, the uptake of PL into isolated bovine brain microvessels was investigated. The uptake of PL was a concentrative one via saturable process (Km = 42.5 microM) that was decreased by hypothermia (Q10 = 2.2), but not by metabolic inhibitors (2,4-dinitrophenol, KCN, ouabain). Although basic drugs such as quinidine and imipramine decreased both the initial rate of uptake and the steady-state cell-to-medium concentration ratio (C/M) of PL, acidic drugs (phenobarbital, salicylic acid) did not affect them. These results suggest that PL is taken up by the endothelial cells of the isolated brain microvessels by facilitated diffusion which is specific for basic drugs and then binds to certain binding sites in the cells.

Versatile isocratic high-performance liquid chromatographic assay for propranolol and its basic, neutral and acidic metabolites in biological fluids

A comprehensive high-performance liquid chromatographic method was developed for quantitating propranolol and its known metabolites in serum, bile and urine. Analysis was performed before and after incubation of the samples with beta-glucuronidase-arylsulfatase to quantitate both free and conjugate forms of the oxidative metabolites. Fractionation of the basic, neutral and acidic metabolites was achieved by differential pH solvent extraction. The basic and neutral metabolites were extracted from the biological samples at pH 10.5 with 2% n-butanol in dichloromethane. Additional clean-up of the basic fraction by back-extraction into dilute acid was needed for those samples that were subjected to enzymatic hydrolysis. The original aqueous sample was titrated with acid to pH 1, followed by extraction of the remaining acidic metabolites into either n-butanol-dichloromethane (with unhydrolyzed serum) or carbon tetrachloride (with all other samples). Chromatographic separation of the metabolites in the different extracts was achieved on a reversed-phase C18 column, using a single isocratic mobile phase consisting of 0.044 M pH 2.7 phosphate buffer, tetrahydrofuran, methanol and acetonitrile, with the addition of n-butylamine as a competing base to control retention volume and peak shape. Detection and quantitation of propranolol and its metabolites in the low nanogram to sub-nanogram range was afforded by fluorescence at a low UV excitation wavelength. The coefficients of variation for replicate assay of spiked samples were uniformly less than 6% for all the analytes.

Controlled-release formulations of propranolol and verapamil

The in vitro and clinical behavior of new controlled-release formulations of propranolol and verapamil are reviewed. In vitro dissolution studies have proved to be of little value in determining the clinical activity of these new dosage forms. There is a difference between the blood levels found with the new formulations and those of the reference products. The once-daily verapamil product was evaluated in black hypertensive patients with promising results and suggests that this dosage form of verapamil may be successful as monotherapy for treating this patient population.

Theoretical Michaelis-Menten elimination model for propranolol

A pharmacokinetic model, with Michaelis-Menten elimination, has been developed for drugs and propranolol in particular. The theory is given and the relationship between the area under the theoretical plasma level curve and the absorption rate constant is discussed. This approach allows for an explanation of many of the observed pharmacokinetics of 'Inderal' and particularly 'Inderal' LA; a sustained release preparation of propranolol. In particular, the bioavailability, as measured by area under the curve, is found to be strongly dependent on the absorption half-life in agreement with experimentally observed data.

Plasma concentration-response relationships of two formulations of propranolol

The time-course of beta blockade induced by two formulations of propranolol was compared to their plasma concentration-time curves. Graded infusions of isoproterenol were used to assess the degree of beta blockade at different times after oral administration of 80 mg of propranolol to 11 healthy volunteers. The time-course of drug effect was measured as the decline of the systolic pressor dose 20 (SPD 20) and the chronotropic dose 20 (CD 20). Variability of plasma propranolol concentration was small, varying within subjects from 27% to 36% and between subjects from 19% to 28% at the various sampling times. Pharmacodynamic effects showed a similar reproducibility: intra-individual variation was 15% to 28% for CD 20 and 17% to 32% for SPD 20; interindividual variation was 10% to 24% for CD 20 and 13% to 23% for SPD 20. Pooling of the data of all subjects indicated a parallel decline of drug concentration and effect. However, three of the 11 subjects showed drug effects declining at a faster rate than drug levels. This dissociation between serum concentrations and effects points out the clinical relevance of complementing kinetic studies of propranolol with pharmacodynamic studies. The good reproducibility within subjects and the small interindividual variation suggests that isoproterenol dose-response curves may be a useful tool for such studies.

Beta blockers in hypertension

Beta-adrenoceptor antagonists are effective in the management of patients with mild-to-moderate hypertension. Noncardioselective agents, cardioselective agents and beta blockers with intrinsic sympathomimetic activity (ISA) are equally effective, provided they are used in equipotent doses. Beta blockers can be used as first-line therapy in the management of hypertension and can be safely combined with diuretics, vasodilators, or both, for a better control of blood pressure. The exact mechanism by which beta blockers decrease blood pressure remains speculative, but they all reduce cardiac output during long-term therapy; drugs with ISA lower cardiac output and heart rate less than do drugs without ISA. Pharmacokinetic properties of beta blockers differ widely; drugs metabolized by the liver have shorter plasma half-lives than drugs primarily excreted by the kidneys. Although many of the side effects of various beta blockers are similar, differences in water and lipid solubility account for a higher incidence of central nervous system side effects with lipid-soluble drugs (such as propranolol and metoprolol) than with hydrophilic drugs (such as atenolol and timolol). The incidence of cold extremities has been reported to be less with drugs with ISA, and the incidence of bronchospasm less with cardioselective drugs. In the management of uncomplicated mild-to-moderate hypertension, all beta blockers are equally effective and produce less troublesome side effects than alternative antihypertensive agents. For effective therapy beta blockers can be used in 2 divided daily doses or even once daily.(ABSTRACT TRUNCATED AT 250 WORDS)

Long-acting propranolol (Inderal LA): pharmacokinetics, pharmacodynamics and therapeutic use

Long-acting propranolol (Inderal LA) is a new formulation of propranolol that allows release of the drug in a controlled manner, so that the plasma concentration at 24 hr after dosing is greater with long-acting propranolol than with conventional tablets. A single dose of 160 mg of long-acting propranolol can produce cardiac beta-adrenoceptor blockade throughout a 24 hr period without variability due to multiple peak concentrations. It has been shown that this formulation is as effective in the treatment of angina pectoris, hypertension and hyperthyroidism as the standard formulation. Studies with long-acting propranolol in cardiac dysrhythmias are lacking. This new dosage form would be a means of simplifying dosing regimens and thereby hopefully enhancing patient convenience and compliance.

Evidence for a therapeutic effect of dl-propranolol in benign and malignant insulinoma: report of three cases

Two patients suffering from benign and one patient suffering from malignant insulinoma experienced frequent incapacitating hypoglycemic attacks which did not respond to treatment with streptozotocin, diazoxide and/or diphenylhydantoin. Dl-propranolol, in dosages ranging from 30-240 mg/day, successfully abolished the symptoms of hypoglycemia, prevented recurrent hypoglycemic attacks, and normalized blood glucose levels concomitant with a reduction in pulse rate to 60/min. The main mechanism of the drug's effect seems to be the suppression of insulin release. However, other mechanisms may be involved such as increased peripheral insulin resistance. No side effects of treatment with dl-propranolol were noted. In patients suffering from insulinoma who are refractory to other forms of treatment, and for those who need symptomatic relief before surgery, dl-propranolol may play an important therapeutic role.

Effect of a twelve-hour hiatus in propranolol therapy on exercise tolerance in patients with angina pectoris

To determine whether propranolol can be administered twice daily without any loss of antianginal effect, we studied nine men receiving long-term propranolol therapy for stable angina pectoris. Each patient performed bicycle exercise to the point of angina on two consecutive mornings. By means of double-blind placebo-propranolol administration before the test, the study created a situation whereby on one day the exercise took place 12 hours after the last dose of propranolol, and on the other day 1 1/2 hours after a dose. Despite markedly lower blood levels of propranolol on the day that exercise was performed 12 hours after the last dose, exercise time to angina was nearly identical on the 2 days. We conclude that long-term therapy with propranolol for angina pectoris can be administered on a twice daily basis with no loss of effectiveness.

Biphasic nature of propranolol's microelectrophysiologic effects

The microelectrophysiologic effects of d,l-propranolol were observed to be biphasic when a wide range of concentrations was used in canine atrial tissue; therefore, the 2 isomers were used separately to test the hypothesis that the opposite effects of propranolol could be separated by isomeric isolation. Whole atria were detached from dog hearts and 3 by 0.5 cm strips were cut from the atria. Transmembrane action potentials were monitored from the atrial strips mounted in an isolation chamber containing Tyrode's solution. Concentrations of d-propranolol, l-propranolol, and the d,l-racemate ranging from 0.03 to 1.0 micrograms/ml were added to the bath and the effects observed for 60 minutes. In lower concentrations d,l-propranolol decreased the effective refractory period and activation time while increasing maximal rise velocity, action potential amplitude, and resting membrane potential. Higher concentrations produced the opposite effects. The l-isomer produced effects very similar to those of the lower concentrations of the racemate, whereas the d-form mimicked those effects of the higher concentrations of the racemic mixture. We conclude that d,l-propranolol is capable of exerting 2 opposite electropharmacologic actions, which may be demonstrated by varying the concentration of d,l-propranolol or by separating the isomers.

Comparative pharmacological and pharmacokinetic observations on propranolol (long acting formulation) and bendrofluazide administered separately and concurrently to volunteers

1 The effect of long-acting (LA) propranolol, LA propranolol and bendrofluazide, and a new combined formulation of LA propranolol/bendrofluazide (Inderex) on exercise tachycardia was studied in ten normal volunteers. 2 The preparations were given in random order, double-blind, on three separate study weeks. Observations were made 0, 1, 3, 6, 8, 24, 33 and 48 h after drug administration. 3 The three preparations produced a significant reduction in exercise tachycardia up to 48 h after drug administration, and the effects of the three preparations were not significantly different from each other. 4 Following LA propranolol, LA propranolol and bendrofluazide, and the combined formulation the mean reductions in exercise heart rate 24 h after drug administration were 16.7 +/- 2.1%, 13.0 +/- 1.8% and 16.2 +/- 1.7% respectively. 5 Plasma levels of propranolol and bendrofluazide were measured at 0, 1, 2, 3, 6, 8, 10, 12, 24, 33 and 48 h after dose administration. 6 There was no significant difference in plasma propranolol levels, Cmax propranolol or AUCo-x following the three preparations. The mean apparent t1/2 beta of propranolol after LA propranolol alone was significantly shorter than following the other two preparations (P less than 0.05), but this was not associated with a different pharmacodynamic response. 7 There was no significant difference in the pharmacokinetic parameters of bendrofluazide following the two preparations containing bendrofluazide. No bendrofluazide was detected in plasma after LA propranolol alone. 8 The new combined formulation produces similar pharmacodynamic and pharmacokinetic responses to LA propranolol and bendrofluazide given separately, and to LA propranolol given alone, and so may be of value in the treatment of hypertension.

Comparative haemodynamic dose response effects of propranolol and labetalol in coronary heart disease

The immediate haemodynamic dose response effects of beta blockade (propranolol: 2 to 16 mg) were compared with those of combined alpha beta blockade (labetalol: 10 to 80 mg) in a randomised study of 20 patients with stable angina pectoris. After control measurements, the circulatory changes induced by four logarithmically cumulative intravenous boluses of each drug in equivalent beta blocking doses were evaluated at rest, after which comparison of the effects of the maximum cumulative dose of each was undertaken during a four minute period of supine bicycle exercise. Propranolol, at rest, induced significant dose related reductions in heart rate and cardiac output, with reciprocal increases in the systemic vascular resistance and pulmonary artery occluded pressure; systemic arterial pressure was unchanged. Labetalol was followed by significant dose related decreases in systemic blood pressure and vascular resistance associated with a significant increase in cardiac output; heart rate and pulmonary artery occluded pressure were unchanged. The slope of the left ventricular pumping function curve relating output to filling pressure from rest to exercise was significantly depressed by propranolol but unchanged after labetalol. The less deleterious effects on left ventricular haemodynamic performance after alpha beta blockade in contrast to beta blockade alone in ischaemic heart disease may be attributable to the concomitant reduction in left ventricular afterload associated with the alpha blocking activity of labetalol.

Stereoselective disposition and glucuronidation of propranolol in humans

Following oral dosing to steady state, the disposition of S(-)- and R(+)-propranolol and their corresponding glucuronide conjugates was studied in 4 healthy adults using doses from 40 to 320 mg/day of the racemate. Steady -state plasma concentrations of S(-)-propranolol and its corresponding glucuronide conjugate were greater than that for R(+)-propranolol and its corresponding conjugate. The average steady-state concentration of both enantiomers increased disproportionately to dose. There was a 52+/- 7 (mean +/- SD) % decrease in the intrinsic clearance (clint) of S(-)-propranolol and a 65 +/- 22% decrease in the Clint of R(+)-propranolol over the dosing range studied. The terminal elimination half-lives of S(-)-propranolol and its glucuronide conjugate were longer than for the R(+)-enantiomer at all doses. The formation of glucuzonide conjugates of S(-)- and R(+)-propranolol was best described by a saturable process in all subjects. Within individuals, the ratio of Vmax/Km for the glucuronide conjugate of S(-)-propranolol was from 2.1-to 4.9-fold greater than for the conjugate of the R(+)-enantiomer. These studies demonstrate for the first time, that propranolol undergoes stereoselective disposition in humans.

Kinetics and cardiac effects of propranolol in humans

Six healthy volunteers received single 20-mg intravenous (IV) and 80-mg oral doses of propranolol on two occasions in random sequence. Serum propranolol concentrations were determined by gas chromatography in multiple samples drawn during 24 h after each dose. Mean (+/- SE) kinetic variables for IV propranolol were: elimination half-life (t 1/2 beta), 5.3 (+/- 0.6) h; volume of distribution, 2.3 (+/- 0.3) l/kg; total clearance, 4.9 (+/- 0.3) ml/min/kg; predicted extraction ratio, 0.23 (+/- 0.02). After single oral doses, t 1/2 beta (3.8 +/- 0.2 h) tended to be smaller than after the IV dose, and actual systemic availability (0.60 +/- 0.07) was less than that based on the predicted extraction ratio. During multiple oral dosage (80 mg every 12 h), observed steady state serum levels (47 +/- 5 ng/ml) tended to be less than those predicted based on the single oral dose (61 +/- 5 ng/ml), thus providing no evidence for reduced propranolol clearance at steady-state. Echocardiographic measurements of left ventricular performance (posterior wall velocity, diastolic dimensions) made during the single-dose oral study indicated significant impairment of function; impairment was maximal at 3 h post-dosage, and corresponded to the time of the peak serum propranolol concentration (341 ng/ml).

High-performance liquid chromatographic method for the quantitative analysis of the aryloxypropanolamines propranolol, metoprolol and atenolol in plasma and tissue

A simple and rapid high-performance liquid chromatographic method is described for the quantitative analysis of three beta-receptor blocking drugs of similar molecular structure (aryloxypropanolamines, AOPAs) but with different polarities. the method consists of extraction, reversed-phase ion-pair chromatography and fluorometric detection, whereby slight modifications in these parameters allow analysis of the different AOPAs in a similar way. The method was used to determine concentrations of propranolol, metoprolol and atenolol in plasma and various organs of the rat. In samples of 1 ml of plasma and 0.5--1.7 g of tissue, drug concentrations of at least 2 ng/ml and 5 ng/g, respectively, can be measured. Extension of the method to other AOPAs is possible.

Clinical pharmacology of a new beta-adrenoceptor blocking drug, befunolol. Cross-over comparison with propranolol on repeated administration

Repeated doses of a new beta-adrenoceptor blocking agent, befunolol, were administered orally to adult male volunteers for a cross-over comparison with propranolol. The beta-adrenoceptor blocking activity of befunolol was greater than that of propranolol when assessed by the percentage reduction in exercise-induced tachycardia. The elimination half-life of drug was significantly prolonged on repeated administration of propranolol, but not of befunolol. The percentage reduction in exercise-induced tachycardia was highly correlated with the log plasma level of each drug. Both drugs produced a significant reduction in pre-exercise systolic and diastolic blood pressure, and significant attenuation of exercise-induced rise in systolic blood pressure.

Biopharmaceutical characteristics of a new propranolol/hydrochlorothiazide tablet combination

Experiments have been carried out in dogs and man to determine the effect of hydrochlorothiazide (HCT) on the pharmacokinetics of propranolol and to evaluate the bioavailability of two dosage forms containing both propranolol and HCT (40/25 and 80/25 mg, respectively). In adult male beagles, 50 mg of HCT had no apparent effect on AUC, Cmax, Tmax, and T1/2 of propranolol administered concurrently. In man, INDERIDE (40/25 mg) and INDERIDE (80/25 mg) were shown to be similar in bioavailability to the reference formulations, i.e. the same amount of drugs administered as the separate tablets of INDERAL plus HYDRODIURIL.

Pharmacokinetics, mechanisms of action, indications, and adverse effects of timolol maleate, a nonselective beta-adrenoreceptor blocking agent

Timolol, a nonselective beta-adrenoreceptor blocking agent without intrinsic sympathomimetic or membrane stabilizing activity, has been shown effective in the treatment of angina and hypertension. It is particularly useful in patients with stable angina pectoris and patients with mild to moderate hypertension. In both of these conditions, timolol appears to be comparable to propranolol. A recent study has suggested that timolol reduces mortality and reinfarction rate in patients who have recently had a myocardial infarction. When given topically timolol reduces intraocular pressure in patients with open-angle glaucoma; the drug may be used as the primary agent or as an adjunct to standard therapy. Careful selection of patients will reduce the frequency of adverse effects due to beta-receptor inhibition. Thus, timolol should not be used in patients who are predisposed to asthmatic bronchitis or cardiac failure, and it should be used with caution in patients with peripheral vascular disease or diabetes mellitus.

Pharmacokinetics of propranolol

The pharmacokinetics of propranolol after the administration of 40, 80, and 120 mg p.o. and 10 mg i.v. was studied in nine healthy male volunteers. Propranolol was analyzed after extraction and derivatization by gas-liquid chromatography. A multiexponential curve-stripping program was used for the pharmacokinetic analysis. The volume of distribution was about 6 liters . kg-1, bioavailability around 25%, with a mean terminal half-life of 6 hr. There was no evidence of either dose dependent disposition kinetics or an oral threshold dose. A slight increase in urine volume was observed after propranolol administration.

Right ventricular performance in essential hypertension after beta-blockade

Recent studies indicate that right ventricular performance is impaired even in uncomplicated systemic hypertension. Because of widespread use of beta-blockade in essentially hypertension, it is possible that such treatment often further depresses right ventricular contractility. To test this premise, and to evaluate the changes induced by different beta-adrenoceptor blocking agents on the contractility of right ventricular myocardium, 20 patients with essential hypertension were divided into two groups on a double-blind randomised basis, and maintained on oral oxprenolol or propranolol for five weeks. Cardiac catheterisation and right ventricular cineangiography were performed at the beginning and again at the end of the five week period. Right ventricular end-diastolic volume index did not change significantly in either group. In contrast, right ventricular end-systolic volume index increased, and right ventricular ejection fraction significantly decreased after chronic beta-blockade. Cardiac index decreased in both groups, but these changes were not statistically significant. When the intergroup differences were compared for all measured indices none of the changes between the two groups was statistically significant. Despite its intrinsic sympathomimetic activity, oxprenolol therefore impairs right ventricular performance to an extent nearly equal to that of propranolol. Moreover, right ventricular contractility is clearly diminished after the institution of beta-blockade in hypertensive patients--an effect that has until now been thought to be limited to the left side of the heart. Great caution must therefore be exercised when beta-blockade is initiated in patients with severely abnormal right ventricular function, because frank right ventricular decompensation may result.

A standard approach to compiling clinical pharmacokinetic data

A standard format for a Clinical Pharmacokinetic Summary is proposed. It consists of a heading, tables, notes, and references for each drug reviewed. The table presents a unified and logical set of clinically useful population pharmacokinetic parameters. They concern four major areas: absorption, distribution, elimination, and the relationship of concentration to effect. Within each major group, parameters dealing with extents and rates of processes are given. Each such parameter is really two: a population mea value (for example, average volume of distribution) and the standard deviation of individual values about this mean. The first value allows individual predictions of dosage or drug level to be made; the second allows computation of the likely proximity of subsequently observed quantities to those predictions. The table presents single consensus values for each population parameter, rather than a list of values. A procedure for computing these consensus values, and for revising them in the light of new data, or reinterpreted old data, is given. Examples of Summaries are given. The method appears applicable to a variety of drugs. We suggest our approach as a standard one for preparing Clinical Pharmacokinetic Summaries, and urge our colleagues to consider it for that purpose.

Duration and selectivity in beta-adrenoceptor blocking action of a beta-adrenoceptor blocking drug, D-32 in conscious dogs

In conscious dogs, the selectivity and duration of beta-blocking activity, and serum concentration of a beta-blocking agent, D-32 [dl-1-tert-butylamino-3-(2,3-dimethylphenoxy)-2-propanol hydrochloride] was compared to that of propranolol, pindolol, atenolol and IPS-339 [dl-1-tert-butylamino-3-(-9-fluorenylideneaminoxy)-2-propanol hydrochloride]. Ratios of doses causing a 50% inhibition of tachycardia to that on hypotension induced by isoprenaline were as follows: D-32 (0.69), propranolol (0.67), atenolol (0.03) and IPS-339 (6.3). Thus, present experiments indicate that, unlike atenolol and IPS-339, D-32, propranolol and pindolol are non-selective beta-adrenoceptor blocking agents. Atenolol and IPS-339, however, selectively blocked cardiac beta1, receptors and vascular beta2-receptors respectively, as would be expected. In an optimal dose range these two drugs can be used satisfactorily as a pharmacological tool for inhibiting responses mediated via the respective beta-receptors. After oral administration, the pharmacological half-life (time required for 50% recovery of beta-blocking action) was 15.8 +/- 4.5 h for propranolol (3 mg/kg), 21.8 +/- 6.4 h for D-32 (0.5 mg/kg), 30.5 +/- 3.1 h for atenolol (6 mg/kg) and 30-35 h for pindolol (0.2 mg/kg). The pharmacological half-life after i.v. administration was 4.4 +/- 0.7 h for propranolol (300 microgram/kg) and 5.9 +/- 0.4 h for D-32 (150 microgram/kg), whereas the serum half-like (time required for 50% decrease in serum concentration) of propranolol was 1.4 h and that of D-32 was 1.3 h. The values for pharmacological half-life and serum half-life were significantly different. Thus, for determination of administration frequency and dosage of beta-adrenoceptor blocking drugs, not only pharmacokinetic but also pharmacological data (duration of action) are essential.

Bioavailability of sustained release propranolol formulations

In this comparative bioavailability study two sustained release capsule formulations of propranolol, one a clinical trial formulation and the other the U.K. sales formulation ('Inderal' LA), were compared with a conventional 'Inderal' tablet. Twelve healthy adult male volunteers received, on cross-over basis, on three separate occasions, 160 mg oral doses of three formulations of 'Inderal'. Bioavailability was based on concentration of propranolol in whole blood. The peak blood level and area under the propranolol blood level curve fell as the dissolution time increased. The half-lives of the three formulations were inversely proportional to their dissolution rates, those of the sustained release formulations being considerably longer than that of the conventional tablet. The 160 mg 'Inderal' tablet produced a rapid 90-fold decline over 24 h in propranolol blood levels following a high initial peak. By comparison both sustained release formulations showed a less rapid fall in systemic levels and gave higher blood levels at the end of 24 h and plateau values between 8 and 14 ng ml-1. The 'Inderal' LA sustained release formulation gave consistently higher propranolol blood levels than the clinical trial sustained release formulation. This result is in good agreement with their dissolution profiles. The lowering of the systemic bioavailability as the dissolution time increases is thought to be due to an increased metabolism of propranolol.

Correlation between propranolol in plasma and urine, renin-aldosterone system and blood pressure in essential hypertension

Thirty patients with mild or moderate essential hypertension, and a fixed elevation of diastolic blood pressure, were randomly allocated to three groups and treated with propranolol 40 mg x 4 (Group 1), 80 mg x 4 (group 2) and 160 mg x 4 (Group 3). Blood pressure (BP), pulse rate (PR), plasma renin activity (PRA), plasma aldosterone concentration (PAC), total plasma propranolol (tPP), free plasma propranolol (fPP), and 24 h urinary propranolol excretion (UP) were determined at the end of four consecutive periods: (A) after four weeks without any treatment; (B) after two to three weeks during which the propranolol dose was gradually increased to the intended level; (C) after four weeks, and (D) after eight weeks of unchanged treatment. The maximum reduction in diastolic BP occurred after period B, and in systolic BP after Period C, for Groups 2 and 3, and for all groups together; for Group 1, however, the maximum diastolic BP reduction was first seen after period C. PR was reduced to the same level in all groups after period B. After period B, PRA an PAC fell in all groups, and remained reduced during C and D Group 1. After periods C and D, PRA and PAC in Groups 2 and 3 did not differ significantly from the levels after period A; tPP, fPP and UP were significantly correlated with the propranolol dose, and were lowest in Group 1 and highest in Group 3; UP was negatively correlated with systolic but not diastolic BP in Periods B, C and D. In contrast neither fPP nor tPP were correlated with systolic or diastolic BP. There was no significant correlation between PRA, PAC and changes in PRA or PAC on the one hand and tPP, fPP, UP, BP or changes in BP on the other. It was concluded that propranolol effectively reduced BP, but diastolic BP reduction was most rapidly obtained at 320 and 640 mg daily, that the activity of the renin -aldosterone system was initially suppressed in all group, but for unknown reasons it increased towards the control level after seven to eleven weeks of therapy with 320 and 640 mg/day, and that the reduction in systolic BP increased with higher doses of propranolol and with increasing urinary propranolol excretion.

Relationship of propranolol pharmacokinetics to antihypertensive effect and beta-adrenergic blockade in the treatment of hypertension

The pharmacokinetics of propranolol in 16 hypertensive patients was compared after the first oral dose of 80 mg and during chronic treatment with 80 mg bd. The degree of beta-adrenergic blockade was estimated by the reduction in maximal exercise heart rate. No significant change in plasma half-life occurred and there was no correlation between the mean steady-state propranolol concentration and beta-adrenergic blockade or antihypertensive effect. A linear relationship was observed between the decrease in blood pressure and the reduction in heart rate during maximal exercise. Therefore, the antihypertensive effect of propranolol can be explained by it peripheral beta-adrenergic blocking properties.

Time-course of the anti-hypertensive action of atenolol: comparison of response to first dose and to maintained oral administration

To show whether repeated administration of atenolol for several days would influence its pharmacokinetic parameters and the extent and duration of the pharmacologic responses, the plasma level of atenolol and changes in heart rate, blood pressure and plasma renin activity were measured in 12 hypertensive patients at various times of day (9 a. m., 12 noon, 3 p. m. and 7 p. m.) after oral administration of the first dose of atenolol 100 mg, again during the 7th and 14th days of continued once-daily administration of the same dose, and finally during the three days following withdrawal of the drug. The peak plasma concentration of atenolol (about 600 ng/ml) was found 3 h after administration of the first dose, and measurable amounts (50-70 ng/ml) were found after 24 h. None of the pharmacokinetic characteristics were changed by administration of a single daily dose for two weeks. After withdrawal of the drug, detectable amounts of atenolol were found in plasma for at least 48 h. The first dose of atenolol caused prompt (3 h) and prolonged (up to 24 h) lowering of supine and standing systolic and diastolic blood pressures, slowing of supine and standing heart rate, reduction of the blood pressure and heart rate responses to dynamic exercise, and a decrease in plasma renin activity. The extent and time-course of all these responses were not influenced by repeated once-daily administration of the 100 mg dose for two weeks. Most of the effects continued during the withdrawal days, the lowering of blood pressure being somewhat more prolonged than the slowing of heart rate. It is concluded that a once-daily dose of atenolol 100 mg decreases blood pressure and heart rate throughout the following 24 h, without excessive daily fluctuation in its effects, and without signs of tolerance or accumulation.

Comparative pharmacodynamics and plasma levels of beta-adrenoceptor blocking drugs

1. Metoprolol (ME), pindolol (PI) and propranolol (PR) were studied in nine subjects at different doses and at 'maximum beta-adrenoceptor blockade' at a defined exercise load. Exercise tests were performed after each dosing period; isoprenaline stimulation was studied at the highest dose level. 2. ME and PR reduced heart rate at rest with most doses tested, while PI had no effect on resting heart rate. 3. Exercise heart rate was reduced with the smallest daily doses (ME 75 mg; PI 7.5 mg; PR 60 mg), and maximum reduction was from 163 to 116 beats/min (ME), 124 (PT) and 115 (PR) beats/min with daily doses of 242, 23 and 233 mg, respectively. 4. Resting blood pressure was not significantly affected by any beta-adrenoceptor blocker dose, but exercise induced blood pressure decreased from 166 to 130 (ME), 138 (PI) and 131 (PR) mm Hg, respectively. 5. Mean plasma concentrations at 'maximum beta-adrenoceptor blockade' were 158 (ME), 24 (PI) and 159 (PR) ng/ml without significant differences in the plasma level variation between beta-adrenoceptor blockers. 6. Isoprenaline doses required to increase heart rate by 30 beats/min were 3.8 microgram (control), 22 microgram (ME), 458 microgram (PI) and 200 microgram (PR), respectively. The differences may be due to different ratios of beta 1, beta 2 activity of the beta-adrenoceptor blockers tested.