Binding of Sulfonylureas to Serum Proteins

Judis, Joseph

doi:10.1002/jps.2600610116

Cited by 69 publications

(24 citation statements)

References 17 publications

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“…Albumin has a high binding capacity for sulphonylureas [26] and has been shown to lower tolbutamide binding to islet cells [27]. To permit comparisons of the ionic and secretory effects of tolbutamide (measured in the presence of albumin) with its electrical effects (measured in the absence of albumin), different concentrations of the sulphonylurea were used.…”

Section: Methodsmentioning

confidence: 99%

Distinct mechanisms for two amplification systems of insulin release

Henquin

Bozem

Schmeer

et al. 1987

Biochemical Journal

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The mechanisms whereby activation of the cyclic AMP-dependent protein kinase A or the Ca2+-phospholipid-dependent protein kinase C amplifies insulin release were studied with mouse islets. Forskolin and the phorbol ester 12-O-tetradecanoylphorbol 13-acetate (TPA) were used to stimulate adenylate cyclase and protein kinase C respectively. The sulphonylurea tolbutamide was used to initiate insulin release in the presence of 3 mM-glucose. Tolbutamide alone inhibited 86Rb+ efflux, depolarized ,-cell membrane, triggered electrical activity, accelerated 45Ca2+ influx and efflux and stimulated insulin release. Forskolin alone only slightly inhibited 86Rb+ efflux, but markedly increased the effects of tolbutamide on electrical activity, 45Ca2+ influx and effilux, and insulin release. In the absence of Ca2+, only the inhibition of 86Rb+ efflux persisted. TPA (100 nM) alone slightly accelerated 45Ca2+ efflux and insulin release without affecting 45Ca2+ influx or fl-cell membrane potential. It increased the effects of tolbutamide on 45Ca2+ efflux and insulin release without changing 86Rb+ efflux, 45Ca2+ influx or electrical activity. Omission of extracellular Ca2+ suppressed all effects due to the combination of TPA and tolbutamide, but not those of TPA alone. Though ineffective alone, 10 nM-TPA amplified the releasing action of tolbutamide without affecting its ionic and electrical effects. In conclusion, the two amplification systems of insulin release involve at least partially distinct mechanisms. The cyclic AMP but not the protein kinase C system increases the initiating signal (Ca2+ influx) triggered by the primary secretagogue.

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Section: Methodsmentioning

confidence: 99%

Distinct mechanisms for two amplification systems of insulin release

Henquin

Bozem

Schmeer

et al. 1987

Biochemical Journal

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“…Salicylate appears to produce substantial changes in the plasma protein binding of a variety of anionic substances (2,6,12,14) and its potential effect on the protein binding of indomethacin appears also to require emphasis.…”

Section: Discussionmentioning

confidence: 99%

Protein Binding of Indomethacin: Binding of Indomethacin to Human Plasma Albumin and its Displacement from Binding by Ibuprofen, Phenylbutazone and Salicylate, <i>in vitro</i>

Mason

McQueen²

1974

Pharmacology

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The reversible binding of indomethacin to human plasmaprotein and the manner in which this may be modified by ibuprofen, phenylbutazone and salicylate was studied by ultrafiltration at 37 °C and pH 7.4. Indomethacin is much more highly bound than has previously been considered. The affinity constant for the single primary binding site is 3 x 10⁵ l/mol and for the seven secondary binding sites 1.4 x 10⁴ l/mol. The protein binding of indomethacin is increased by the presence of phenylbutazone and decreased by the presence of ibuprofen and salicylate. Salicylate in vitro, at concentrations observed clinically, significantly decreases the protein binding of indomethacin.

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“…It is extensively bound to plasma proteins (mainly albumin) [7], is metabolised by the P450IIC9 isozyme and is hydroxylated by an additional related enzyme, P450IIC8 [8]. Investigation of the effects of co-administration of tenidap and tolbutamide on the pharmacokinetics and plasma protein binding of tolbutamide will not only show the likelihood of a clinically significant interaction between these two agents, but may also indicate the potential for other drugs, which are also metabolised by the P450IIC9 isozyme, to interact with tenidap.…”

Section: Introductionmentioning

confidence: 99%