Kiuchi Yoshiaki, Terakawa Nobue, Nakata Tomoko, Yamasaki Kunio, Saito Yoshihiro, Ito Nami, Okada Kohei
Department of Ophthalmology, Osaka National Hospital, Osaka, Japan.
Jpn J Ophthalmol. 2004 Jan-Feb;48(1):34-6. doi: 10.1007/s10384-003-0010-6.
The purpose of this study was to compare the binding affinity of bunazosin and dorzolamide to synthetic melanin relative to that of timolol.
Synthetic melanin was prepared from dopa by the action of tyrosinase. Timolol, dorzolamide, and bunazosin were incubated separately at a concentration of 10(-4) M in 2 ml of 0.066 M phosphate buffer containing 5 mg of synthetic melanin. After centrifugation, the absorbance of each free drug in the supernatant was measured at its optimum wavelength. The percentage of each drug bound to melanin was calculated directly from the change in absorbance relative to the initial value.
The increase in the binding rates of all three drugs seemed to reach a plateau after 30 min. After incubating for 60 min, the binding rate of timolol was 22.2% +/- 4.9%, bunazosin 36.3% +/- 2.5%, and dorzolamide 8.5% +/- 1.9%. There were statistically significant differences between the binding rates of each drug.
Under our study conditions, the order of binding affinity of these ocular hypotensive agents to synthetic melanin seems to be as follows: bunazosin>timolol>dorzolamide.
本研究旨在比较布那唑嗪和多佐胺与合成黑色素的结合亲和力，并与噻吗洛尔进行对比。
通过酪氨酸酶的作用，由多巴制备合成黑色素。将噻吗洛尔、多佐胺和布那唑嗪分别以10⁻⁴ M的浓度在含有5 mg合成黑色素的2 ml 0.066 M磷酸盐缓冲液中孵育。离心后，在各游离药物的最佳波长处测量上清液中各药物的吸光度。根据吸光度相对于初始值的变化直接计算每种药物与黑色素结合的百分比。
所有三种药物的结合率在30分钟后似乎都达到了平台期。孵育60分钟后，噻吗洛尔的结合率为22.2%±4.9%，布那唑嗪为36.3%±2.5%，多佐胺为8.5%±1.9%。每种药物的结合率之间存在统计学显著差异。
在我们的研究条件下，这些降眼压药物与合成黑色素的结合亲和力顺序似乎如下：布那唑嗪>噻吗洛尔>多佐胺。
