目的：测定甲硝唑控释药膜在体内外不同时相点甲硝唑释放量。方法：³H标记甲硝唑（放射性比强度5.44×10⁴Bq·mmol^-1，放化纯度≥95%)按原工艺做成控释药膜［每块重(19.0±0.1)mg，含甲硝唑(5.59±0.03)mg]，置于豚鼠牙周部位及放100μl生理盐水的微量板小孔中测定释放量。结果：实验表明该控释药膜能有效地降低过高峰，推迟过早峰，能在预定48h内在龈沟液持续释放相对恒定的有效浓度(200μg·ml^-1)。结论：³H标记甲硝唑能不断释放β射线，通过放射性探测仪器可随时追踪药物在体内的数量与位置，这在药动学和药物示踪研究中值得推广应用。

OBJECTIVE: To measure the release profile of metronidazole from controlled release strip in different time phases in vivo and vitro. METHOD: Tritium labelled metronidazole (specific activity=5.44×10⁴Bq·mmol^-1, purification ≥95%) was prepared for metronidazole controlled release strip [weight (19.0±0.1)mg, containing metronidazole (5.59±0.03)mg] according to original art. The release was measured by inserting into the periodontal site of guinea pig and 100 μl normal saline in microplate. RESULTS: The results turned out that it can decrease the superhigh peak and delay the previous peak. It can constantly release effective level about 200 μg·ml^-1 metronidazole in gingival crevicular fluid within 48 h. CONCLUSION:³H labelled metronidazole could release β redial which could be traced the amount and location of the drug in vivo from time to time. This is a good method for development and application in pharmacokinetics and drug tracer.