Plasma Binding Of Drugs Research Articles

Using the Dynamic Well-Stirred Model to Extrapolate Hepatic Clearance of Organic Anion-Transporting Polypeptide Transporter Substrates without Assuming Albumin-Mediated Hepatic Drug Uptake.

Extrapolating in vivo hepatic clearance from in vitro uptake data is a known challenge, especially for organic anion-transporting polypeptide transporter (OATP) substrates, and the well-stirred model (WSM) commonly yields systematic underpredictions for those anionic drugs, hypothetically due to "albumin-mediated hepatic drug uptake". In the present study, we demonstrate that the WSM incorporating the dynamic free fraction (f D), a measure of drug protein binding affinity, performs reasonably well in predicting hepatic clearance of OATP substrates. For a selection of anionic drugs, including atorvastatin, fluvastatin, pravastatin, rosuvastatin, pitavastatin, cerivastatin, and repaglinide, this dynamic well-stirred model (dWSM) correctly predicts hepatic plasma clearance within 2-fold error for six out of seven OATP substrates examined. The geometric mean of clearance ratios between the predicted and the observed values falls in the range of 1.21-1.38. As expected, the WSM with unbound fraction (f u) systematically underpredicts hepatic clearance with greater than 2-fold error for five out of seven drugs, and the geometric mean of clearance ratios between the predicted and the observed values is in the range of 0.20-0.29. The results suggest that, despite its simplicity, the dWSM operates well for transporter-mediated uptake clearance, and that clearance under-prediction of OATP substrates may not necessarily be associated with the chemical class of the anionic drugs, nor is it a result of albumin-mediated hepatic drug uptake as currently hypothesized. Instead, the superior prediction power of the dWSM confirms the utility of the dynamic free fraction in clearance prediction and the importance of drug plasma binding kinetics in hepatic uptake clearance. SIGNIFICANCE STATEMENT: The traditional well-stirred model (WSM) consistently underpredicts organin anion-transporting polypeptide transporter (OATP)-mediated hepatic uptake clearance, hypothetically due to the albumin-mediated hepatic drug uptake. In this manuscript, we apply the dynamic WSM to extrapolate hepatic clearance of the OATP substrates, and our results show significant improvements in clearance prediction without assuming albumin-mediated hepatic drug uptake.

Hollow Fiber-in-Syringe Equilibrium Sampling Through Supported-Liquid Membrane for Evaluation of Drug-Plasma Binding.

Aim: The aim was to evaluate drug-plasma binding (DPB).by employing Hollow Fiber-in-Syringe Equilibrium Sampling Through Supported Liquid Membrane (HFiS ESTSLM) and RP-HPLC analysis.Materials & Methods: HFiS ESTSLM and RP-HPLC were used to evaluate DPB of three weak basic drugs (Metoprolol, Diphenhydramine, and Sildenafil) with differing hydrophilicity and binding ability to blood plasma.Results: The results exhibited an increasing drug-dependent magnitude of DPB for the three model drugs. This trend of DPB confirmed that HFiS ESTSLM has the required sensitivity for determining DPB of the drugs. The DPB was drug concentration-dependent within the tested drug concentration range, especially at high concentration.Conclusion: HFiS ESTSLM and RP-HPLC offered a simple, easy and cost-effective procedure to evaluate DPB of these basic drugs.

Comparative Study for Prediction of Low and High Plasma Protein Binding Drugs by Various Machine Learning-Based Classification Algorithms

<p>In the drug discovery path, most drug candidates failed at the early stages due to their pharmacokinetic behavior in the system. Early prediction of pharmacokinetic properties and screening methods can reduce the time and investment for lead discoveries. Plasma protein binding is one of these properties which has a vital role in drug discovery and development. The focus of the current study is to develop a computational model for the classification of Low Plasma Protein Binding (LPPB) and High Plasma Protein Binding (HPPB) drugs using machine learning methods for early screening of molecules through WEKA. Plasma protein binding drugs data was collated from the Drug Bank database where 617 drug candidates were found to interact with plasma proteins, out of which an equal proportion of high and low plasma protein binding drugs were extracted to build a training set of ~300 drugs. The machine learning algorithms were trained with a training set and evaluated by a test set. We also compared various machine learning-based classification algorithms i.e., the Naïve Bayes algorithm, Instance-Based Learner (IBK), multilayer perceptron, and random forest to determine the best model based on accuracy. It was observed that the random forest algorithm-based model outperforms with an accuracy of 99.67% and 0.9933 kappa value on training set and on test set as compared to other classification methods and can predict drug plasma binding capacity in the given data set using the WEKA tool.</p>

Canine orosomucoid (alpha-1 acid glycoprotein) variants and their influence on drug plasma protein binding.

Orosomucoid polymorphisms influence plasma drug binding in humans; however, canine variants and their effect on drug plasma protein binding have not yet been reported. In this study, the orosomucoid gene (ORM1) was sequenced in 100 dogs to identify the most common variant and its allele frequency determined in 1,464 dogs (from 64 breeds and mixed-breed dogs). Plasma protein binding extent of amitriptyline, indinavir, verapamil, and lidocaine were evaluated by equilibrium dialysis using plasma from ORM1 genotyped dogs (n=12). Free and total drug plasma concentrations were quantified by liquid chromatography-mass spectrometry. From the five polymorphisms identified in canine ORM1, two were nonsynonymous. The most common was c.70G>A (p.Ala24Thr) with an allele frequency of 11.2% (n=1464). Variant allele frequencies varied by breed, reaching 74% in Shetland Sheepdogs (n=21). Free drug fractions did not differ significantly (p>.05; Mann-Whitney U) between plasma collected from dogs with c.70AA (n=4) and those with c.70GG (n=8) genotypes. While c.70G>A did not affect the extent of plasma protein binding in our study, the potential biological and pharmacological implication of this newly discovered ORM1 variant in dogs should be further investigated.

Very Short and Stable Lactoferricin-Derived Antimicrobial Peptides: Design Principles and Potential Uses.

The alarming rate at which micro-organisms are developing resistance to conventional antibiotics represents one of the global challenges of our time. There is currently ample space in the antibacterial drug pipeline, and scientists are trying to find innovative and novel strategies to target the microbial enemies. Nature has remained a source of inspiration for most of the antibiotics developed and used, and the immune molecules produced by the innate defense systems, as a first line of defense, have been heralded as the next source of antibiotics. Most living organisms produce an arsenal of antimicrobial peptides (AMPs) to rapidly fend off intruding pathogens, and several different attempts have been made to transform this versatile group of compounds into the next generation of antibiotics. However, faced with the many hurdles of using peptides as drugs, the success of these defense molecules as therapeutics remains to be realized. AMPs derived from the proteolytic degradation of the innate defense protein lactoferrin have been shown to display several favorable antimicrobial properties. In an attempt to investigate the biological and pharmacological properties of these much shorter AMPs, the sequence dependence was investigated, and it was shown, through a series of truncation experiments, that these AMPs in fact can be prepared as tripeptides, with improved antimicrobial activity, via the incorporation of unnatural hydrophobic residues and terminal cappings. In this Account, we describe how this class of promising cationic tripeptides has been developed to specifically address the main challenges limiting the general use of AMPs. This has been made possible through the identification of the antibacterial pharmacophore and via the incorporation of a range of unnatural hydrophobic and cationic amino acids. Incorporation of these residues at selected positions has allowed us to extensively establish how these compounds interact with the major proteolytic enzymes trypsin and chymotrypsin and also the two major drug-binding plasma proteins serum albumin and α-1 glycoprotein. Several of the challenges associated with using AMPs relate to their size, susceptibility to rapid proteolytic degradation, and poor oral bioavailability. Our studies have addressed these issues in detail, and the results have allowed us to effectively design and prepare active and metabolically stable AMPs that have been evaluated in a range of functional settings. The optimized short AMPs display inhibitory activities against a plethora of micro-organisms at low micromolar concentrations, and they have been shown to target resistant strains of both bacteria and fungi alike with a very rapid mode of action. Our Account further describes how these compounds behave in in vivo experiments and highlights both the challenges and possibilities of the intriguing compounds. In several areas, they have been shown to exhibit comparable or superior activity to established antibacterial, antifungal, and antifouling commercial products. This illustrates their ability to effectively target and eradicate various microbes in a variety of settings ranging from the ocean to the clinic.

CDPBC: A Software Application for Estimation of Concentration Dependent Plasma Binding Capacity of Small Molecule.

Drug-plasma binding (DPB) is an important aspect during pharmacokinetics (PK) studies. DPB of small molecule cannot be evaluated through computational means. Here we present CDPBC; a standalone application for evaluation of small molecule for its capacity (concentration dependent) of binding with plasma proteins. This application is freely available at URL (https://github.com/undwive di/CDPBC.git). The application is enriched with evaluation of five major proteins of plasma. Input for application is a docked complex against the suggested PDBs of plasma proteins. As part of the analysis, software compares interaction of query compound with control compound. Main output comes as plot as well as table displaying percentage of binding in reference of concentration gradient of small molecule used in docking. The application is an advanced add-on component to ADME analysis of small molecules as well as lead optimization.

The impact of the concentration of drug binding plasma proteins on drug distribution according to Øie-Tozer’s model

1. New equations have been developed from an updated version of Øie-Tozer’s model expressing how the free concentration and volume of distribution change in relation to changes in the concentration of drug binding plasma proteins. This updated model accommodates more than one drug binding plasma protein to contribute to the plasma protein binding.2. Demonstrations of the model show that variability in the concentration of one plasma protein has considerably less impact on the free drug concentration and volume of distribution if other plasma proteins contribute to binding, than if they don’t.

Visualization of plasma and tissue binding using dose fractions parameter.

A novel concept of dose fractions, based on the distribution of total bioavailable dose between the six combinations of location and binding state in Øie-Tozer's model is suggested as a way to visualize the distribution pharmacokinetics of a drug. The concept of dose fractions provides a sharper terminology in discussions of drug distribution allowing for a more precise description of the state and location of a drug within a system. In medicinal chemistry literature, the free fraction of a drug in plasma is a commonly discussed factor affecting the exposure to free drug while tissue binding is less well addressed. The free dose fraction, defined as the fraction of the bioavailable dose existing in free form, is suggested as a potentially valuable term for such discussions. Presently, drugs with high (>95%) plasma protein binding are viewed with skepticism, the rational behind which is questioned. The plasma protein bound dose fraction defined as the fraction of the total available dose, which is bound to plasma proteins, is suggested as a measure of the risk for problems related to fluctuations in free drug exposure due to variations in the concentration of drug binding plasma protein.

Influence of ORM1 polymorphisms on the maintenance stable warfarin dosage

ORM1 is a plasma drug binding protein. Its polymorphism rs17650 (S>F) has been reported to be an important factor affecting the binding ability and effect of antiretroviral protease inhibitors. The aim of this study was to determine whether the ORM1 rs17650 polymorphism also influences warfarin therapy. A total of 191 Chinese patients with steady-dose warfarin therapy were enrolled in this study. The patients were studied for warfarin maintenance dose, the ORM1 rs17650 polymorphism, and two polymorphisms previously demonstrated to affect warfarin response [CYP2C9 rs1057910 (3) and VKORC1 rs7294 (-1639 G>A)]. Warfarin dose was partially correlated with the VKORC1 rs7294, CYP2C9 rs1057910 and ORM1 rs17650 polymorphisms. Patients carrying the wild-type of these three genes (n = 96) took a mean dose of 3.0 ± 1.1 mg warfarin, which was significantly higher than that taken by the 52 S patients (2.7 ± 0.7) and 11 S S patients (2.5 ± 0.6 mg) (p = 0.048). We identified ORM1 as another polymorphic gene affecting warfarin dose requirements. ORM1 S carriers require lower maintenance doses to achieve and maintain an optimal level of anticoagulation.

ChemInform Abstract: Tissue Binding versus Plasma Binding of Drugs: General Principles and Pharmacokinetic Consequences

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

The drug binding site of human α 1-acid glycoprotein: Insight from induced circular dichroism and electronic absorption spectra

Human α 1-acid glycoprotein (AGP) is an important drug binding plasma protein which affects pharmacokinetical properties of various therapeutic agents. For the first time, interpretation of the induced circular dichroism (ICD) spectra of drug–AGP complexes is presented yielding valuable information on the protein binding environment. ICD spectra were obtained by novel ligands of which AGP induced optical activity have never been reported (primaquine, mefloquine, propranolol, terazosin, carbamazepine, rhodamine B) and by re-investigation of ICD spectra of protein-bound drugs published earlier (chlorpromazine, dipyridamole, prazosin). Spectroscopic features of the ICD and absorption bands of drugs combined with native AGP indicated chiral non-degenerate exciton coupling between the guest chromophore and the indole ring of an adjacent tryptophan (Trp) residue. Results of additional CD experiments performed by using recombinant AGP mutants showed no changes in the ligand binding ability of W122A in sharp contrast with the W25A which was unable to induce extrinsic CD signal with either ligand. Thus, these findings unequivocally prove that, likely via π–π stacking mechanism, Trp25 is essentially involved in the AGP binding of drugs studied here as well as of related compounds. Survey of the AGP binding data published in the literature support this conclusion. Our results provide a fast and efficient spectroscopic tool to determine the inclusion of ligand molecules into the β-barrel cavity of AGP where the conserved Trp25 is located and might be useful in ligand-binding studies of other lipocalin proteins.

Changes in drug plasma concentrations of an extensively bound and highly extracted drug, propofol, in response to altered plasma binding

Cardiopulmonary bypass is known to result in a reduction in the plasma binding of drugs. The resulting effect on the hepatic clearance of drugs with low extraction is well understood. However, the situation with those that are highly extracted is less clear. Studies were, therefore, undertaken with one such drug, propofol, for which plasma binding was changed during cardiac surgery with cardiopulmonary bypass. After induction of anesthesia with midazolam in 19 patients, propofol was infused continuously at a rate of 4 mg. kg(-1). h(-1) during surgery. Propofol's concentration was measured by HPLC in blood samples collected from the radial artery and hepatic vein during surgery at predetermined intervals. The drug's unbound fraction in arterial plasma was estimated via equilibrium dialysis. The total concentration of propofol in blood was unchanged during surgery except shortly after the initiation of cardiopulmonary bypass. By contrast, the fraction of unbound propofol in blood increased by 2-fold during cardiopulmonary bypass and then decreased after the completion of cardiopulmonary bypass. The hepatic extraction ratio of propofol was greater than 0.8 and remained constant throughout surgery. The ratio of propofol concentration in erythrocytes to that in blood increased by 1.6-fold during cardiopulmonary bypass. During cardiopulmonary bypass, a significant increase in the concentration of unbound propofol occurred without alteration in the total propofol concentration in blood. The effect of the changes of propofol's protein binding on its kinetics was consistent with the predictions based on the well-stirred model of hepatic elimination for an intravenously infused high-clearance drug. Our finding on propofol pharmacokinetics may be the first example demonstrating the theoretic prediction of the well-stirred model.

Flunitrazepam, a 7-nitro-1,4-benzodiazepine that is unable to bind to the indole-benzodiazepine site of human serum albumin

Benzodiazepine (BDZ) is generally thought to bind to site II of human serum albumin (HSA), also known as the indole-BDZ site, which is located at subdomain III A of the molecule. However, differences in the binding characteristics of BDZ drugs with HSA have been reported. The photolabeling profiles of HSA with [ 3H]flunitrazepam (FNZP) in the presence and absence of diazepam (DZP) were shown to be identical, suggesting that each drug primarily binds to different regions. The results of fluorescent probe displacement experiments showed that FNZP failed to decrease the fluorescence of dansylsarcosine to an extent similar to that of DZP. In the photoinhibition experiment, site I and site II ligands failed to inhibit the photoincorporation of [ 3H]FNZP to HSA. In order to evaluate the photolabeling specificity of FNZP, an attempt was made to photolabel α 1-acid glycoprotein (AGP) which also binds BDZ with similar affinity as HSA. The effect of myristate (MYR) and DZP on the FNZP photolabeling of these two major drug binding plasma proteins was examined. Photoincorporation was inhibited when HSA was photolabeled with [ 3H]FNZP in the presence of MYR but not in the presence of DZP. Conversely, DZP inhibited the photolabeling of [ 3H]FNZP to AGP. These results suggest that FNZP interacts with HSA at regions which are not located in the preformed binding pocket of subdomain III A.

Effects of protein binding on the in vitro activity of antitumour acridine derivatives and related anticancer drugs.

We set out to measure drug binding to serum proteins. These have been shown to reduce the free plasma concentrations of a number of anticancer drugs, particularly of those of complex organic structure, in both experimental studies and clinical trials. We have used cultures of murine Lewis lung carcinoma cells as sensors of available drug to measure the effects of two drug-binding plasma proteins, alpha-acid glycoprotein (AAG) and human serum albumin (HSA), as well as of bovine serum albumin (BSA) on drug activity. The concentrations required for 50% growth inhibition (IC50 values) of a number of anticancer drugs were found to be linear functions of the added proteins. Assuming that cells respond to free drug, the data provide estimates of the product K x n, where K is the binding constant of the protein and n is the number of drug binding sites per protein molecule. Amsacrine, the amsacrine analogue asulacrine, camptothecin, DACA (N-[2-(dimethylamino)ethyl]acridine-4-carboxamide), doxorubicin, etoposide, mitoxantrone, paclitaxel and vincristine were tested. The K x n values for AAG were 30, 2,400, 8.7, 340, 29, 290 x 10(3) M(-1) and 120 x 10(3) M(-1), respectively, and the K x n values for HSA were 16, 580, 530, 10, 6.2, 4.3 x 10(3) M(-1) and 0.0 x 10(3) M(-1), respectively. The combined data allowed the estimation of free fractions of drug in plasma, assuming that AAG and HSA contributed most to protein binding. The data were in general comparable with that reported using equilibrium dialysis and ultrafiltration. Data for drug binding to BSA were different from those for HSA, in some cases by a large factor with values for HSA generally higher. The applicability of the method to analogue development was illustrated by examining the binding to AAG of a series of DACA analogues, and binding was found to be primarily related to lipophilicity. IC50 determinations provide a rapid means of estimating drug binding to plasma proteins and have utility in the assessment of new anticancer drugs.

Drug Binding in Plasma

The ligands are generally bound in plasma to a significant extent by several transport proteins (both high and low affinity), irrespective of their endogenous or exogenous origin. The protein binding of endogenous compounds (such as hormones) exhibits higher affinity and specificity than those of exogenous compounds (such as drugs). For plasma proteins that bind the same ligand(s), structural similarities or a common genetic origin may be found, although this is not a general rule. Alterations in ligand binding may be due to modifications of either the structure or the level of the binding protein. These modifications may result from genetic make up, physiology or pathology. In some situations, plasma binding may impair the distribution of drugs to tissues, with drug distribution then mainly restricted to the distribution compartment of the drug-binding protein. In other instances, the plasma drug-binding is permissive, and does not limit drug distribution to tissues. A given drug-transport protein system may have either a permissive or a restrictive effect on the drug distribution, depending on the tissue. The physiological significance of the high-affinity transport proteins is not completely understood. These proteins may increase the plasma concentration of poorly hydrosoluble ligands, ensure a more uniform tissue distribution and increase the life of the ligands. The life of the protein may also be increased by ligand binding. High-affinity transport proteins are also involved in some specific carrier mediated transfer mechanisms. It is possible to demonstrate structure-binding relationships or binding selectivity for the plasma transport proteins, but these are quite independent of relationships observed at the receptor level.

Effect of plasma binding of ortho- and para-I-benzoates on their distribution in blood and into lymph, biotransformation and excretion in rat urine.

Two positional iodine derivatives of benzoic acid, i.e. ortho- (OIB) and para- (PIB), were used alone and in combination with salicylic acid (SA) to study the effects of plasma binding on their pharmacokinetics. Their lymphatic bioavailability (central lymph), their biotransformation and urinary excretion in rats were also studied. Plasma binding of the two benzoates is different, about 95% of PIB and approximately 50% of OIB are bound. The competitive inhibition effect of SA was shown by an increase in the amount of free drug in plasma in both benzoates. Lymphatic binding is lower compared to plasma binding, an effect of SA of the free faction of drug in lymph was shown only with PIB. Kinetic parameters of benzoates are influenced by plasma binding; significant differences were found mainly in total clearance and areas under concentration curves. Lymphatic bioavailability (FL) differs only slightly with different plasma binding; a significant change in FL was, however, found in PIB after SA premedication. Significantly higher urinary excretion of OIB as compared with PIB corresponds to plasma binding of drugs, SA premedication decreases total excretion of both benzoates. SA also changes the proportion of the individual fractions of metabolites of benzoates in urine.

Hepatic Drug Metabolism and Aging

Although there is considerable variation in the effect of age on drug biotransformation, the metabolism of many drugs is impaired in the elderly. Age-related physiological changes, such as a reduction in liver mass, hepatic metabolising enzyme activity, liver blood flow and alterations in plasma drug binding may account for the decreased elimination of some metabolised drugs in the elderly. It is difficult, however, to separate an effect of aging from a background of marked variation in the rate of metabolism due to factors such as individual metabolic phenotype, environmental influences, concomitant disease states and drug intake. The prevailing data suggest that initial doses of metabolised drugs should be reduced in older patients and then modified according to the clinical response. In most studies the elderly appear as responsive as young individuals to the effects of compounds which induce or inhibit the activity of cytochrome P450 isozymes. Concurrent use of other agents, which induce or inhibit drug metabolism, mandates dose adjustment as in younger patients. Many questions remain unanswered. For instance, limitations of in vitro studies prevent any firm conclusion about changes in hepatic drug metabolising enzyme activity in the elderly. With aging, some pathways of drug metabolism may be selectively affected, but this has not been adequately scrutinised. The possibility that metabolism of stereoisomers may be altered in the elderly has not been adequately tested. The effect of aging on the distribution of polymorphic drug metabolism phenotypes is still not established, despite potential implications for disease susceptibility and survival advantage.

Disease-Induced Variations in Plasma Protein Levels

Many diseases appear to lead to a decrease of drug plasma binding due either to hypoalbuminaemia or to a modification of albumin structure. In other diseases, the binding of a drug may increase due to elevated concentrations of alpha 1-acid glycoprotein or lipoproteins. However that may be, the free fraction of a drug may vary in different pathologies. But an increase or decrease of the drug free fraction does not automatically mean an increase or decrease of the free drug concentration. Whatever the drug, a variation in the volume of distribution more or less proportional to the variation in the plasma free fraction can be expected. With respect to the clearance, the problem is much more complex and depends on the hepatic extraction ratio of drug. If the extraction is related to the free fraction (fu) of drug, a variation in fu will lead to a variation in the total drug concentration but no variation in the free drug concentration and no change in the pharmacological effect. If the extraction of a drug is dependent on hepatic flow, a variation in fu will lead to a change in the free drug concentration (with no change in the total drug concentration) and hence changes in the pharmacological effect. The aim of this article is to review the literature concerning disease-induced variations in plasma protein levels during the past 10 years. Finally, possible implications for drug dosage regimens are discussed generally from examples studies in the literature.

Differences in plasma binding of drugs between Caucasians and Chinese subjects

Interracial differences in drug responsiveness can be accounted for, at least in part, by differences in drug disposition. To investigate whether reversible interactions with plasma constituents may be a contributing factor in such differences, the binding of a number of model drugs was studied in plasma obtained from healthy Caucasian and Chinese subjects (n = 8 in each group). The unbound fractions of drugs binding to sites I and II on albumin (warfarin, diazepam, and salicylic acid) were similar in the two groups, and there was no difference in the plasma albumin concentration. By contrast, the percentages of unbound diphenhydramine (26.40% +/- 6.46% versus 18.30% +/- 4.31, mean +/- SD) and propranolol (13.81% +/- 1.33% versus 11.68% +/- 2.37) were significantly (p less than 0.05) higher in Chinese subjects compared to Caucasians. A 30% difference was also observed in the nonlinear binding of disopyramide. These basic drugs interact with both alpha 1-acid glycoprotein and albumin, and the lower binding was associated with a lower plasma concentration of the acute-phase reactant in Chinese subjects. Kinetic analysis of the disopyramide binding isotherm was also suggestive of reduced binding capacity with no change in binding affinity. The reason for the racial difference in the alpha 1-acid glycoprotein level is unknown; however, for drugs extensively bound to this glycoprotein the resulting difference in unbound fraction would be expected to have predictable pharmacokinetic consequences that may result in differences in responsiveness. Determination of plasma binding, especially of drugs interacting with alpha 1-acid glycoprotein, should therefore be an essential component of comparative studies in subjects of different races.

Symposium: Plasma binding of drugs and its consequences: Ghent (Belgium), September 27–28m 1990

Symposium: Plasma binding of drugs and its consequences: Ghent (Belgium), September 27–28m 1990