共晶體是由兩種或兩種以上的分子借由非共價鍵與一定的化學劑量比所形成的結晶，共結晶是改善活性藥物成分（API）的溶解度與機械性能的方法之一，在本研究中，我們選擇茶鹼和乙醯胺酚來製備1：1茶鹼－乙醯胺酚共晶體，並通過與乙醯胺酚共結晶來提高茶鹼的溶解度和機械化學性質，我們使用三種不同方法製備1：1茶鹼－乙醯胺酚共晶體：（a）直接共晶組裝，（b）再結晶，（c）無溶劑球磨，針對不同方法製備的1：1茶鹼－乙醯胺酚共晶體的溶解速率進行了比較，此外也探討1：1茶鹼－乙醯胺酚共晶體的機械化學機理。據我們所知，已有一些研究文獻提及濕粒法和共晶體配方的溶解速率測試，在濕粒法中，水可以做為粘合劑液體。本研究發現經過濕粒法後1：1茶鹼－乙醯胺酚共晶體不會受賦形劑和粘合劑影響，證實其具有高化學穩定性，在溶解度測試中，使用符合美國藥典(USP)規定之溶出裝置 - 溶離槳式（37℃）對從不同製備方法獲得的1：1茶鹼－乙醯胺酚共晶體進行溶解試驗。儘管其他研究組已經把濕粒法與共結晶相結合，但無溶劑球磨完全是無溶劑的步驟且與濕粒法分離。本篇研究提供了五個優點：（1）共晶體形成過程可被清楚地監測，（2）沒有檢測到其他不純相，（3）茶鹼的藥物釋放速率（T50 = 3.6分鐘）可藉由與乙醯胺酚共結晶而有所提升（T50 = 2.8〜3.0分鐘），（4）濕粒法不會影響1：1茶鹼－乙醯胺酚共晶體的化學穩定性與茶鹼的藥物釋放速率（T50 = 3.8分鐘），和（5）以無溶劑球磨機方法為綠色製程，且所製備之1：1茶鹼－乙醯胺酚共晶體與其他常規溶液結晶方法製備之共晶體質量與溶解度測試結果一樣。;A co-crystal is formed when the assembly of two or more distinct molecular species in a definite stoichiometric ratio occurred through the interactions of hydrogen bonds and non-covalent bonds in a long range order. Co-crystallization is a way to alter or enhance the solubility and mechanical properties of active pharmaceutical ingredient (API). In this research, acetaminophen and theophylline were chosen to generated the 1:1 co-crystal of acetaminophen-theophylline (1:1 Ace-Thy co-crystal) to enhance the solubility and mechanochemical properties of theophylline by co-crystallized with acetaminophen. The mechanism for mechanochemistry of 1:1 Ace-Thy co-crystal was also discussed. Three preparation methods for 1:1 Ace-Thy co-crystal were studied: (a) direct co-crystal assembly, (b) re-crystallization, and (c) solvent-less ball-milling. The dissolution rates of pure 1:1 Ace-Thy co-crystals prepared by different methods also be conducted and compared. To the best of our knowledge, a few studies had investigated the wet granulation and the dissolution of formulated co-crystals. In this research, USP Dissolution Apparatus – Paddle (37°C) was chosen to do the dissolution test for the formulated granules of 1:1 Ace-Thy co-crystals obtained from different preparation methods. Although co-crystallization had been integrated with high-shear and wet granulation by other research groups, co-crystallization in ball mill was completely a solvent-less step because it was separated from wet granulation. The chemical stability of 1:1 Ace-Thy co-crystals in the presence of excipients and binders was studied and verified in this research. Water could be the binder liquid, but not acetone, for wet granulation. Five advantages were offered: (1) co-crystal formation was clean and easy to be monitored by characterization tools, (2) no other impure phase was detected, (3) the theophylline drug release was increased (T50 = 3.6 min) by the co-crystal formation (T50 = 2.8 to 3.0 min), (4) in the presence of formulation and water, no influence of co-crystal formation (T50 = 3.5 to 3.9 min) on chemical stability or on theophylline drug release (T50 = 3.8 min), and (5) the environmentally benign solvent-less ball mill methods was as good as the other conventional solution crystallization methods in terms of the co-crystal quality and dissolution behavior of the same particle size.
