通过在propranolol的β-羟基功能上引入取代基(直链烷基,支链烷基,酰氧基烷基和环烷基),合成了一系列propranolol酯类前药,旨在保护药物在口服后免受首过代谢的影响。前药的体外水解速率依次为:肝组织均质物>血浆>pH缓冲液。前药的pH-速率曲线显示在pH 4.0左右具有最大稳定性;在pH 6.8以上,水解速率急剧增加。 QSAR分析显示,取代基的疏水性(π)和电子效应(σ)在缓冲液和血浆中对前药水解起主要作用,而在肝组织均质物中的水解则不能很好地用这些参数解释。基于体外水解,选择了四种前药(O-乙酰基,O-丁酰基,O-异戊酰基和O-环丙酰基-propranolol)进行口服给予比较。在口服前药后,比格犬的propranolol的绝对生物利用度(F)约为相同剂量propranolol后的2-4倍。前药被迅速吸收,并再生propranolol,使其在0-0.5小时达到峰值血浆浓度。还观察到了完整的前药水平,其变化取决于它们在体外介质中的稳定性。得到了propranolol的F和log P之间的线性关系。F似乎还与前药在肝组织均质物中观察到的水解速率呈抛物线相关,这表明了最佳设计操纵。整体的体外和体内结果表明,具有更高的化学和酶稳定性的亲脂性前药在缓冲液和血浆中最有前途,但易于在肝组织均质物中水解,可以提高propranolol的口服生物利用度。
通过在propranolol的β-羟基功能上引入取代基(直链烷基,支链烷基,酰氧基烷基和环烷基),合成了一系列propranolol酯类前药,旨在保护药物在口服后免受首过代谢的影响。前药的体外水解速率依次为:肝组织均质物>血浆>pH缓冲液。前药的pH-速率曲线显示在pH 4.0左右具有最大稳定性;在pH 6.8以上,水解速率急剧增加。 QSAR分析显示,取代基的疏水性(π)和电子效应(σ)在缓冲液和血浆中对前药水解起主要作用,而在肝组织均质物中的水解则不能很好地用这些参数解释。基于体外水解,选择了四种前药(O-乙酰基,O-丁酰基,O-异戊酰基和O-环丙酰基-propranolol)进行口服给予比较。在口服前药后,比格犬的propranolol的绝对生物利用度(F)约为相同剂量propranolol后的2-4倍。前药被迅速吸收,并再生propranolol,使其在0-0.5小时达到峰值血浆浓度。还观察到了完整的前药水平,其变化取决于它们在体外介质中的稳定性。得到了propranolol的F和log P之间的线性关系。F似乎还与前药在肝组织均质物中观察到的水解速率呈抛物线相关,这表明了最佳设计操纵。整体的体外和体内结果表明,具有更高的化学和酶稳定性的亲脂性前药在缓冲液和血浆中最有前途,但易于在肝组织均质物中水解,可以提高propranolol的口服生物利用度。
A series of ester prodrugs of propranolol was synthesized by incorporating substituents (straight alkyl, branched alkyl, acyloxyalkyl and cycloalkyl) into the β-hydroxy function of propranolol with the aim of protecting the drug against first-pass metabolism following oral administration. The in-vitro hydrolysis rates of the prodrugs were, in increasing order, liver homogenate ≫ plasma > buffers. The pH-rate profile of the prodrugs showed maximum stability around pH 4·0; the hydrolysis rates were drastically increased over pH 6·8. QSAR analysis revealed hydrophobic (π) and electronic (σ) effects of the substituents play the main roles for prodrug hydrolysis in buffers and plasma, while hydrolysis in liver homogenate could not be well explained by any of these parameters. Four prodrugs (O-acetyl-, O-butyryl-, O-isovaleryl- and O-cyclopropanoyl-propranolol) were selected for oral administration based on their hydrolysis in-vitro. Following oral administration of prodrugs to beagle dogs the absolute bioavailabilities (F) of propranolol were about 2–4-fold that after an equivalent dose of propranolol. The prodrugs were rapidly absorbed and regenerated propranolol to attain peak plasma levels at 0–0·5 h. Intact prodrug levels were also observed, which varied depending on their respective stabilities in in-vitro media. A linear relationship between F of propranolol and log P was obtained. F further appeared to be parabolically dependent on the observed hydrolysis rates of prodrugs in liver homogenate suggesting optimal design manipulation. The overall in-vitro and in-vivo results showed that lipophilic prodrugs having higher chemical and enzymatic stability in buffers and plasma, but susceptible to hydrolysis in the liver homogenate, to be the most promising prodrugs for improving oral bioavailability of propranolol.
通过在propranolol的β-羟基功能上引入取代基(直链烷基,支链烷基,酰氧基烷基和环烷基),合成了一系列propranolol酯类前药,旨在保护药物在口服后免受首过代谢的影响。前药的体外水解速率依次为:肝组织均质物>血浆>pH缓冲液。前药的pH-速率曲线显示在pH 4.0左右具有最大稳定性;在pH 6.8以上,水解速率急剧增加。 QSAR分析显示,取代基的疏水性(π)和电子效应(σ)在缓冲液和血浆中对前药水解起主要作用,而在肝组织均质物中的水解则不能很好地用这些参数解释。基于体外水解,选择了四种前药(O-乙酰基,O-丁酰基,O-异戊酰基和O-环丙酰基-propranolol)进行口服给予比较。在口服前药后,比格犬的propranolol的绝对生物利用度(F)约为相同剂量propranolol后的2-4倍。前药被迅速吸收,并再生propranolol,使其在0-0.5小时达到峰值血浆浓度。还观察到了完整的前药水平,其变化取决于它们在体外介质中的稳定性。得到了propranolol的F和log P之间的线性关系。F似乎还与前药在肝组织均质物中观察到的水解速率呈抛物线相关,这表明了最佳设计操纵。整体的体外和体内结果表明,具有更高的化学和酶稳定性的亲脂性前药在缓冲液和血浆中最有前途,但易于在肝组织均质物中水解,可以提高propranolol的口服生物利用度。