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  • 1990-1994  (2)
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  • 1
    ISSN: 1573-904X
    Keywords: ICRF-187 (ADR-529) ; hydrolysis ; pH-rate profile ; imide ; acidic degradation ; bell-shaped profile ; facilitation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The hydrolysis of the cardioprotectant and anticancer agent, ICRF-187 (or ADR-529) and the structurally similar model compound, 4-methylpiperazine-2,6-dione (4-MP), was investigated in the acid to neutral pH range at 25°C and an ionic strength of 0.5 (sodium chloride). Their solution stability was shown to be compromised compared to 3-methylglutarimide (3-MG) and other imides. It appears that the tertiary piperazine nitrogens of ICRF-187 and 4-MP significantly contributed to the instability of these compounds over this pH range. Unexpectedly, bell-shaped curves were observed in the pH-rate profiles. A change in the rate-determining step from tetra-hedral intermediate formation in the weakly acidic pH region to breakdown of the tetrahedral intermediate in the more acidic pH regions was proposed as an explanation for the bell-shaped curves. The piperazine nitrogen was implicated in the hydrolytic pathways that occur within these pH regions; the mechanism of involvement was dependent on the state of ionization of the parent molecule and the tetrahedral intermediate.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Pharmaceutical research 9 (1992), S. 1076-1082 
    ISSN: 1573-904X
    Keywords: hydrolysis ; imide ; ICRF-187 (ADR-529) ; pH dependency ; glutamides ; cardioprotectant
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The hydrolysis of ICRF-187 and two model compounds, 4-methylpiperazine-2,6-dione (4-MP) and 3-methylglutarimide (3-MG), was investigated over the neutral to alkaline pH range at 25°C and an ionic strength of 0.5 (sodium chloride). The purpose of the study was to correlate the influence of molecular changes to the reactivity of these imides. Additionally, an improved chromatographic resolution of all the components of the degradation and NMR confirmation of the identity of the degradation products are presented. Based on the study of 4-MP, which is essentially half of an ICRF-187 molecule, and 3-MG, which has a carbon in place of the piperazine nitrogen, several conclusions can be drawn with regard to the stability of ICRF-187. The tertiary piperazine nitrogen/s of 4-MP and ICRF-187 contributed to the base-catalyzed hydrolysis of these compounds above pH 7 and caused a significant decrease in the pK a values of the imide moiety of ICRF-187 and 4-MP compared with 3-MG. One 2,6-piperazinedione ring of ICRF-187 was shown to affect only minimally the rate of hydrolysis of the second ring. ICRF-187 hydrolyzes by parallel consecutive pathways forming two monoacids with one ring opened and, subsequently, the diacid with both rings hy-drolyzed._________________________________
    Type of Medium: Electronic Resource
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