以紅血球作為藥物包裝與釋放系統的研究

藥物動力研究的主要目的為增進藥物的效果，與降低藥物的副作用。因此，藥物運輸與釋放系統的研發，便是為了達到選擇性藥物釋放的目的；而於適當目標器官的局部藥物釋放，不僅能夠增加局部區域藥物的濃度，而且能夠減少其他器官接受不必要的藥物浸潤；因此這樣的技術發展，對於例如腫瘤的化學藥物治療方面，這種副作用極大的藥物投與，具有重要的意義。然而要達到上述之區域選擇性藥物釋放的目的，需要於體外有一個能控制藥物釋放的外場來進行。而於生物應用上，磁性控制為首選之外加控制場，而以磁性奈米粒子作為控制藥物釋放的標的。我們選擇二丁卡因(Dibucaine hydrochloride；DH+)作為包覆之標的藥物，其為一種具有三級胺結構之局部麻醉藥物；此外，它還可以作為酸檢指示劑。二丁卡因之學名為(2-butoxy-N-[2-(diethylamino)ethyl]-4-quinolinecarboxamide)，其於胺基上之質子可以為不帶電、一價或者是二價的型式，而與其所處之水溶液酸鹼值有關。我們選擇以細胞層級之藥物載體，包含紅血球ghost、大腸桿菌與乳酸菌等，來包覆二丁卡因藥物；並以紫外與可見光光譜(UV-vis)、核磁共振光譜(NMR)、螢光與磷光光譜、掃描式與穿透式電子顯微鏡，與熱重量分析等技術作藥物載體之包覆分析。其中由於二丁卡因具有雙環之奎寧(quinoline)結構，其核磁共振訊號出現於化學位移δ=7-9之間，而紫外與可見光光譜之訊號則出現於300-350 nm處，與其他藥物載體之訊號不同，可作為載體藥物包覆之判斷。而於熱重量分析中，二丁卡因則於290℃處裂解。另外於螢光光譜之分析中，我們則可以得知經由紅血球包覆，而進入其膜內的二丁卡因為不帶電的情形，而藥物釋放後之二丁卡因則呈現一價的型式，證實紅血球不只是進行物理性質的包覆，也會造成包覆藥物於其化學構形上之變化。最後我們並以350 nm之波長處的紫外與可見光光譜數值，進行載體之包覆與藥物釋放等定量分析，實驗結果發現紅血球載體呈現一級之藥物釋放曲線，且無突釋現象與延遲釋放之反應。我們也合成奈米磁性粒子作為藥物之區位選擇性釋放控制，並將其包覆於紅血球之內，且以穿透式電子顯微鏡觀察其晶格，呈現面心立方結構。經由以上結果，我們期待本研究可作為未來之選擇性藥物釋放設計的參考。

關鍵字

二丁卡因；藥物載體；螢光光譜；核磁共振

並列摘要

Drug efficiency and side effect minimization are very important in pharmaceutical research. Thus researches for drug delivery systems in selected target organ loading could prolong the survival for the later stage cancer managements. To achieve this goal, drug carriers controlled by external forces needs to be designed, and magnetic field seems to be the most suitable external force to provide drug-releasing control in biological systems. In this study, an anesthetic agent, dibucaine•HCl (DH+) is encapsulated in ghost of the red blood cells as a drug delivery system. Dibucaine (2-butoxy-N-[2-(diethylamino)ethyl]-4-quinolinecarboxamide) is a tertiary amine local anesthetic drugs, and we have used it for membrane change transfer study. It represents the neutral free base form of the anesthetic, containing a quinoline analog and an amide group. Dibucaine can also exist as a monocation in which the aliphatic tertiary amine N is protonated and/or a dication in which the aromatic N is also protonated. The equilibrium of dibucaine free base (D), monocation (DH+), and dication (DH22+) dibucaines depends on the pH in the medium. Local anesthetics can also exist as hydrogen-bonded and aggregate species depending on the nature of their solubilizing environments (polar/nonpolar solvent, biomembranes, lipids, proteins, cells, etc.). Encapsulation of dibucaine•HCl (DH+) by ghost red blood cells within magnetic nanoparticles inside in our study is characterized then by the optical spectroscopic analysis of FTIR, Raman, NMR, and emission/excitation analysis. The results indicated that photophysical properties of neutral (uncharged or free base), protonated (charged), hydrogen-bonded, and aggregate species of the encapsulated local anesthetics are quite different and clearly distinguishable from one another. The binding sites, via aliphatic tertiary amine N, amide O, and/or aromatic N are visible from FTIR, Raman, and NMR spectra. The drug uptake amount and uptake rate into the cells were analyzed by UV-visible spectroscopy recorded and read at 350 nm (a strong absorption peak for dibucaine). The quantitative results show that the uptake of drug displays a linear relationship with the amount of the dried substrates (e.g., RBC) used up to 4 mg. The rate of increasing the drug uptake is shown to level off at 4.8 mg/ml for DH+ species. The thermal stability of the drug-encapsulated cells was investigated by thermogravimetric analysis (TG/DTA). SEM/TEM were used to view the possible cell morphology changes upon the encapsulation and complexty of drugs. Chemotherapy seems to be the only choice in the late, or even terminal stage cancer management with metastasis. Thus elevation of its efficiency by drug delivery system improvement may reduce drug resistance and prolong survival. Hope this kind of drug carrier design can provide some hints toward drug delivery system promotions.

並列關鍵字

Dibucaine hydrochloride (DH+) ； Drug carrier ； Encapsulation ； Red blood cell (RBC) ghosts ； Nuclear magnetic resonance (NMR) ； Fluorescence spectroscopy

參考文獻

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國際替代計量

以紅血球作為藥物包裝與釋放系統的研究

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