Rebinding: or why drugs may act longer<i>in vivo</i>than expected from their<i>in vitro</i>target residence time

Vauquelin, Georges

doi:10.1517/17460441.2010.512037

Cited by 83 publications

(96 citation statements)

References 90 publications

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“…Salmeterol had equal duration of action across all the receptors, despite large differences in affinity. Rebinding to the receptor of salmeterol that had previously partitioned into the membrane and therefore not removed by washing would prolong the apparent receptor residence time and mask changes in the duration of action at the receptor itself (Vauquelin, 2010;Vauquelin and Charlton, 2010;Sykes et al, 2014). This would also apply to previous studies that observed a long duration of action of salmeterol (e.g., Bradshaw et al, 1987;Ball et al, 1991;Coleman et al, 1996).…”

Section: Discussionmentioning

confidence: 91%

Salmeterol’s Extremeβ2 Selectivity Is Due to Residues in Both Extracellular Loops and Transmembrane Domains

2014

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Salmeterol is a long-acting b2-agonist, widely used as an inhaled treatment of asthma and chronic obstructive pulmonary disease. It has very high b2-affinity (log K D 28.95) and is very selective for the b2-adrenoceptor (1000-fold selectivity over the b1-adrenoceptor). This study used a mutagenesis approach to determine the exact amino acids in the human b2-adrenoceptor responsible for this very high selectivity. Wild-type b2-and b1-adrenoceptors, chimeric b2/b1-adrenoceptors, and receptors with single-point mutations were transfected into Chinese hamster ovary-K1 cells, and affinity and function were studied using [ ]cAMP accumulation. Extracellular loop 3 (and specifically amino acid K305) had the largest single effect by reducing salmeterol's affinity for the b2-adrenoceptor by 31-fold. H296 in transmembrane 6 also had a major effect (18-fold reduction in salmeterol affinity). Combining these, in the double mutant b2-H296K-K305D, reduced salmeterol's affinity by 275-fold, to within 4-fold of that of the b1-adrenoceptor, without affecting the affinity or selectivity of other b2-agonists (salbutamol, formoterol, fenoterol, clenbuterol, or adrenaline). Another important amino acid was Y308 in transmembrane 7, although this also affected the affinity and selectivity of other agonists. F194 in extracellular loop 2 and R304 in extracellular loop 3 also had minor effects. None of these mutations (including the double mutant b2-H296K-K305D) affected the efficacy or duration of action of salmeterol. This suggests that the high affinity and selectivity of salmeterol are due to specific amino acids within the receptor itself, but that the duration of action is at least in part due to other factors, for example lipophilicity.

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Section: Discussionmentioning

confidence: 91%

Salmeterol’s Extremeβ2 Selectivity Is Due to Residues in Both Extracellular Loops and Transmembrane Domains

2014

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“…rational drug design now becomes clearer; a compound with a high affinity may result from high specific affinity for the receptor site (low value of k off ) or a high K mem (membrane partition coefficient), which results in an increase in the value of k on , or a combination of these two factors. Importantly a drug whose higher affinity can be attributed to a higher K mem value will be present at higher concentrations in biologic membranes, likely contributing to increased compound duration of action (Vauquelin and Charlton, 2010) in part due to an increase in a compounds' apparent k on , which directly affects receptor rebinding (Vauquelin, 2010). However, increasing lipophilicity to increase potency for membraneassociated targets may be detrimental in terms of the overall drug profile being targeted (Lipinski et al, 2001).…”

Section: Discussionmentioning

confidence: 99%

Observed Drug-Receptor Association Rates Are Governed by Membrane Affinity: The Importance of Establishing “Micro-Pharmacokinetic/Pharmacodynamic Relationships” at the β₂-Adrenoceptor

et al. 2014

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Current pharmacological models for determining affinity and kinetics of drugs for membrane receptors assume the interacting molecules are homogeneously distributed in the bulk aqueous phase. The phospholipid membrane can, however, provide a second compartment into which drugs can partition, particularly lipophilic/basic compounds. In this study we measured the phospholipid affinity and receptor binding kinetics of several clinically relevant b 2 -adrenoceptor agonists and antagonists and demonstrated that the degree of phospholipid interaction directly affects the observed kinetic association rate (k on ) and dissociation constant (K d ), but not the dissociation rate (k off ) from the target, by concentrating drug in the local environment around the receptor. When the local drug concentration was accounted for, the k on was comparable across the cohort and the corrected K d was directly related to the k off . In conclusion, we propose a new approach to determining the pharmacology of drugs for membrane targets that accounts for differences in local drug concentration brought about by direct affinity for phospholipids, establishing "micro-pharmacokinetic/pharmacodynamic relationships" for drugs.

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“…In these experiments, the receptor-containing membranes are preincubated with the radioligand and the dissociation phase is initiated by adding a large excess of (the same or preferentially another) unlabelled drug. This will prevent or at least limit the formation of new radioligandreceptor complexes and/or rebinding phenomena (Vauquelin and Szczuka 2007;Vauquelin and Charlton 2010;Vauquelin 2010). Different variants of this procedure are depicted in Fig.…”

Section: Radioligand Bindingmentioning

confidence: 99%

“…This latter observation is sometimes interpreted in terms of receptor heterogeneity and/or non-competitivity. More information about rebinding phenomena is provided in (Vauquelin and Szczuka 2007;Vauquelin and Charlton 2010;Vauquelin 2010). Methods 3 and 4 start with preincubating the receptors with radioligand, a brief wash (method 3) or no wash (method 4) followed by washout in the presence of receptor-saturating concentration of unlabelled ligand.…”

Section: Radioligand Bindingmentioning

confidence: 99%

Clozapine, atypical antipsychotics, and the benefits of fast-off D2 dopamine receptor antagonism

Vauquelin

Bostoen

Vanderheyden

et al. 2012

Naunyn-Schmiedeberg's Arch Pharmacol

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Drug-receptor interactions are traditionally quantified in terms of affinity and efficacy, but there is increasing awareness that the drug-on-receptor residence time also affects clinical performance. While most interest has hitherto been focused on slow-dissociating drugs, D(2) dopamine receptor antagonists show less extrapyramidal side effects but still have excellent antipsychotic activity when they dissociate swiftly. Fast dissociation of clozapine, the prototype of the "atypical antipsychotics", has been evidenced by distinct radioligand binding approaches both on cell membranes and intact cells. The surmountable nature of clozapine in functional assays with fast-emerging responses like calcium transients is confirmatory. Potential advantages and pitfalls of the hitherto used techniques are discussed, and recommendations are given to obtain more precise dissociation rates for such drugs. Surmountable antagonism is necessary to allow sufficient D(2) receptor stimulation by endogenous dopamine in the striatum. Simulations are presented to find out whether this can be achieved during sub-second bursts in dopamine concentration or rather during much slower, activity-related increases thereof. While the antagonist's dissociation rate is important to distinguish between both mechanisms, this becomes much less so when contemplating time intervals between successive drug intakes, i.e., when pharmacokinetic considerations prevail. Attention is also drawn to the divergent residence times of hydrophobic antagonists like haloperidol when comparing radioligand binding data on cell membranes with those on intact cells and clinical data.

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Rebinding: or why drugs may act longerin vivothan expected from theirin vitrotarget residence time

Cited by 83 publications

References 90 publications

Salmeterol’s Extremeβ2 Selectivity Is Due to Residues in Both Extracellular Loops and Transmembrane Domains

Salmeterol’s Extremeβ2 Selectivity Is Due to Residues in Both Extracellular Loops and Transmembrane Domains

Observed Drug-Receptor Association Rates Are Governed by Membrane Affinity: The Importance of Establishing “Micro-Pharmacokinetic/Pharmacodynamic Relationships” at the β₂-Adrenoceptor

Clozapine, atypical antipsychotics, and the benefits of fast-off D2 dopamine receptor antagonism

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Rebinding: or why drugs may act longerin vivothan expected from theirin vitrotarget residence time

Cited by 83 publications

References 90 publications

Salmeterol’s Extremeβ2 Selectivity Is Due to Residues in Both Extracellular Loops and Transmembrane Domains

Salmeterol’s Extremeβ2 Selectivity Is Due to Residues in Both Extracellular Loops and Transmembrane Domains

Observed Drug-Receptor Association Rates Are Governed by Membrane Affinity: The Importance of Establishing “Micro-Pharmacokinetic/Pharmacodynamic Relationships” at the β2-Adrenoceptor

Clozapine, atypical antipsychotics, and the benefits of fast-off D2 dopamine receptor antagonism

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Product

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Observed Drug-Receptor Association Rates Are Governed by Membrane Affinity: The Importance of Establishing “Micro-Pharmacokinetic/Pharmacodynamic Relationships” at the β₂-Adrenoceptor