目的：茶 (Theophylline)是傳統的支氣管擴張劑，由於其治療濃度狹窄，常為藥物血中濃度監測項目之一；近年來低劑量Theophylline具有抗發炎作用的機轉不斷被揭露，有學者甚至認為低劑量臨床使用可以不必監測藥物血中濃度。考量Theophylline使用者多數為老年人，且常合併多重疾病或併用交互作用藥物，劑量究竟多少才能提供療效，又無須定期監測血中濃度而不至於發生嚴重的中毒反應呢？本研究的目的希望能訂出老年人theophylline最佳臨界劑量(cut-off dose)，使其藥物血中濃度將落在5-15 mg/L區間，以達安全有效用藥目標。
方法：2005年1月1日至12月31日止，由醫院醫療照護資訊系統擷取六十歲以上住院老年人，且有抽驗theophylline藥物血中濃度者，記錄其基本資料、theophylline劑量和藥物血中濃度等資訊。以線性回歸檢驗劑量和血中濃度的相關性，以ROC curve (receiver operating characteristic curve)統計方式找出血中濃度預期會落在5-15 mg/L區間的臨界劑量。
結果：本研究共收案604人次符合分析條件，男性佔68%，平均年齡77.5 + 7.7歲，Theophylline劑量平均344.9 +160.6 mg/day，血中濃度平均8.7 + 4.5 mg/L。預期theophylline藥物血中濃度將落在5-15 mg/L區間的臨界日劑量：單純老年組281 mg、合併COPD組252 mg、合併抽菸組327 mg、併用theophylline代謝抑制藥物組202 mg、併用theophylline代謝促進藥物組404 mg、合併心衰竭組227 mg、合併肝硬化組202 mg。
結論：本研究提供一組安全有效的theophylline日劑量，或許可供醫療人士做為處方或審核住院老年人theophylline維持劑量的參考。
 

Object: Theophylline is traditionally classified as bronchodilator and drug concentration monitoring is usually needed. The anti-inflammatory mechanism of low-dose theophylline had recently been discovered. Some researchers even claimed unnecessary to monitor serum level when low dose of theophylline was given. Most theophylline receivers in our hospital are elderly who may have multiple diseases or receiving interacting drugs. What would be appropriate dose for them to achieve effectiveness and avoid severe toxicity? The aim of this study is to find a cut off dose which may expect to give theophylline serum level of 5-15 mg/L in hospitalized elderly patients. 
Methods: Data of theophylline serum levels of hospitalized patients over 60 years old were consecutively collected for one year from Jan 1st to Dec 31st 2005. The characteristics of patients, daily doses of theophylline, sampling time, serum level, factors that influence theophylline clearance and drug interactions were reviewed. Correlation of dose with serum level was analyzed by linear regression. The cut-off dose was analyzed by ROC curve. 
Results: A total of 604 elderly patients (413 men and 191 women) were included for analysis in this study with a mean age of 77.5 + 7.7 years. The mean daily theophylline dose was 344.9 +160.6 mg. The mean serum level was 8.7 + 4.5 mg/L. After controlling the other confounding factors, ROC curve analysis shows that daily dose of theophylline 281 mg (elderly only), 252 mg (COPD), 327 mg (smoking), 202 mg (inhibited drug metabolism), 404 mg (induced drug metabolism), 227 mg (CHF), and 202 mg (liver cirrhosis group) are expected to attain a serum level of 5 -15 mg/L in various elderly patients.
Conclusions: Our study provides a serial of theophylline daily doses for medical providers to prescribe or evaluate the proper maintenance doses of theophylline in hospitalized elderly patients.