Roivas L, Neuvonen P J
Department of Pharmacology, University of Turku, Finland.
Methods Find Exp Clin Pharmacol. 1994 Jun;16(5):367-72.
The in vitro adsorption of metoprolol, pindolol, salbutamol, furosemide and clonidine onto activated charcoal was determined. The affinity of the drugs for charcoal decreased with increasing hydrophilicity. Also the rate of adsorption of clonidine onto four charcoal preparations having different particle sizes was studied. The equilibrium was reached rapidly with the charcoal having the smallest particle size, and the adsorption rate decreased as the particle size of the charcoal increased. The desorption of drugs from charcoal was investigated in the Sartorius dissolution apparatus at constant initial drug:charcoal ratio. The desorption had a two-step kinetics. The quantity of the initial rapid release, indicating the development of equilibrium, agreed with the adsorption data determined under the same conditions, except for salbutamol and furosemide at pH 7. The same was true for the Langmuir isotherms determined for adsorption and desorption. The following release step was slow and there were only minor differences between the release rates of the different drugs. The desorption rate (time to reach equilibrium) from the different charcoals was studied using a batch technique. An increase in the particle size of charcoal had, however, only limited sustaining effect on desorption. Although the affinity of the drugs for charcoal was in good agreement with their hydrophobicity, their desorption behavior was not necessarily proportional to their hydrophilicity. The in vitro release of the drugs from charcoal was retarded and was not significantly affected by the charcoal particle size.
测定了美托洛尔、吲哚洛尔、沙丁胺醇、呋塞米和可乐定在活性炭上的体外吸附情况。药物对活性炭的亲和力随亲水性增加而降低。还研究了可乐定在四种不同粒径的活性炭制剂上的吸附速率。粒径最小的活性炭能迅速达到平衡，且随着活性炭粒径增大，吸附速率降低。在赛多利斯溶出装置中，以恒定的初始药物：活性炭比例研究了药物从活性炭上的解吸情况。解吸呈现两步动力学。表明平衡发展的初始快速释放量，除了pH值为7时的沙丁胺醇和呋塞米外，与在相同条件下测定的吸附数据一致。吸附和解吸的朗缪尔等温线情况也是如此。接下来的释放步骤缓慢，不同药物的释放速率之间只有微小差异。采用分批技术研究了不同活性炭的解吸速率（达到平衡的时间）。然而，活性炭粒径的增加对解吸的持续影响有限。尽管药物对活性炭的亲和力与其疏水性高度一致，但其解吸行为不一定与其亲水性成正比。药物从活性炭上的体外释放受到延迟，且不受活性炭粒径的显著影响。
