Assay of azathioprine, 6‐mercaptopurine and a novel thiopurine metabolite in human plasma.

Maddocks, J L

doi:10.1111/j.1365-2125.1979.tb01014.x

Cited by 38 publications

(7 citation statements)

References 10 publications

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“…The assay of 6-mercaptopurine was modified from that of Maddocks (1979a) by the addition of 100 ,ul 10 mM dithiothreitol per 1 ml plasma prior to freezing the plasma samples and the omission of the ether wash. Thioguanine nucleotide was assayed fluorimetrically after extraction from 8 x 108 red blood cells (approximately 100 ,ul packed cells) .…”

Section: 92)mentioning

confidence: 99%

Azathioprine metabolism in kidney transplant recipients.

Lennard¹,

Brown²,

Fox³

et al. 1984

Brit J Clinical Pharma

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Sheffield S10 2JF 1 Azathioprine metabolite concentrations were studied in 54 kidney transplant recipients. Thirty-seven of these patients were studied over a 6 month period to investigate the intrapatient variation in metabolite concentrations. All patients had stable functioning grafts and normal peripheral white blood cell counts. 2 The metabolites measured were plasma 6-mercaptopurine and red blood cell 6-thioguanine nucleotide. 3 There was no correlation between azathioprine dose and plasma 6-mercaptopurine concentration but there was a significant correlation between dose and red blood cell 6-thioguanine nucleotide concentration (r, = 0.41, P < 0.005). The individual transplant recipient showed little variation in metabolite concentrations over several months. 4 Using this group as a control we studied metabolite concentrations in patients with kidney transplants who developed leucopenia. Our preliminary findings indicate that elevated red cell 6-thioguanine nucleotide concentrations, above the control range, can be associated with bone marrow depression.

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Section: 92)mentioning

confidence: 99%

Azathioprine metabolism in kidney transplant recipients.

Lennard¹,

Brown²,

Fox³

et al. 1984

Brit J Clinical Pharma

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“…Die Kombination von Azathioprin und Prednisolon (je 1 mg/kg/Tag) führte bei einem 18 jährigem Vollblut Wallach zur Remission des Pemphigus und beide Medikamente konnten ohne Rezidiv ausgeschlichen werden (Follow up 1-3 Jahre) (Vandenabeele et al 2004 gewicht per os zeigte eine schlechte Bioverfügbarkeit, was durch schlechte Absorption oder einen hohen "First-PassEffekt" erklärt werden kann (White et al 2005). Beim Menschen wird ein hoher "First-Pass-Effekt" vermutet, da Azathioprin ebenfalls eine schlechte Bioverfügbarkeit, jedoch eine gute klinische Wirksamkeit zeigt (Maddocks 1979 …”

Section: Nachdem Auch Die Dosiserhöhung Des Prednisolons In Unserem Funclassified

Therapy of pemphigus foliaceus with azathioprin and prednisolone in a warm blood mare

Mayer¹,

Niedermaier²,

Gehlen³

et al. 2010

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“…6-mercaptopurine is removed from the cooled solution using a novel extraction procedure which involves conversion of 6-MP into a phenyl mercury derivative (Maddocks, 1979a). The phenyl mercury derivative is much less polar than the parent drug and is readily extracted into toluene.…”

Section: Principle Of Assaymentioning

confidence: 99%

“…(Maddocks, 1979a). Whole blood is required for this cleavage, plasma alone is unable to metabolize azathioprine.…”

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confidence: 99%

Assay of thioinosinic acid, an active metabolite of azathioprine, in human lymphocytes.

Fletcher¹,

Maddocks²

1980

Brit J Clinical Pharma

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A specific assay for the measurement of thioinosinic acid, in human lymphocytes, has been developed with a sensitivity of 50 ng of thioinosinic acid per 5 x 106 lymphocytes. 2 Thioinosinic acid is precipitated from purified lymphocytes as the lanthanum salt. Acid hydrolysis results in the formation of 6-mercaptopurine which, when converted into its phenyl mercury derivative, can be easily extracted into toluene. Back-extraction of the toluene layer with 0. IN HCI regenerates 6-mercaptopurine which is then assayed fluorometrically. 3 Blood samples were taken from renal transplant recipients 3 h after an oral dose of 50 mg azathioprine. The results from 5 patients gave a range of 54 to 173 ng of thioinosinic acid per 5 x 106 lymphocytes, with a mean of 110 ng. 4 In an in vitro incubation of azathioprine, ImM with fresh human blood, 160 and 180 ng of thioinosinic acid per 5 x 106 lymphocytes was formed after 0.5 h and 5 h respectively. 5The assay is suitable for the study of the kinetics of thioinosinic acid formation in lymphocytes of patients with kidney transplants. It could also prove useful in the study of thioinosinic acid formation in leukaemia patients undergoing 6-mercaptopurine treatment.

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Assay of azathioprine, 6‐mercaptopurine and a novel thiopurine metabolite in human plasma.

Cited by 38 publications

References 10 publications

Azathioprine metabolism in kidney transplant recipients.

Azathioprine metabolism in kidney transplant recipients.

Therapy of pemphigus foliaceus with azathioprin and prednisolone in a warm blood mare

Assay of thioinosinic acid, an active metabolite of azathioprine, in human lymphocytes.

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