Korean Journal of Clinical Laboratory Science (대한임상검사과학회지)

Korean Society for Clinical Laboratory Science (대한임상검사과학회)
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Evaluation of the Effects of Interfering Factors on the Bacterial Endotoxin Testing of Radiopharmaceuticals

방사성의약품의 박테리아 엔도톡신 시험에서 반응간섭인자들의 영향에 대한 평가

  • Jun Young PARK (Department of Nuclear Medicine, Severance Hospital, Yonsei University College of Medicine)
  • 박준영 (연세대학교 의과대학 세브란스병원 핵의학과)
  • Received : 2024.05.19
  • Accepted : 2024.05.30
  • Published : 2024.06.30
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Abstract

The endotoxin test is based on the reaction between Limulus Amebocyte Lysate (LAL) and the lipopolysaccharides of Gram-negative bacteria. In this study, we sought to identify factors that interfere with the LAL testing of radiopharmaceuticals and evaluated acceptable ranges. A gel-clot LAL test and a chromogenic LAL test were used as endotoxin tests. We compared the performances of the EndosafeⓇ LAL and recombinant EndosafeⓇ Recombinant Cascade Reagent (rCR) cartridges for the chromogenic test. The factors that interfered with 68Ga-DOTATOC injection were pH, 4-(2-hydroxyethyl) piperazine-1-ethanesulfonic acid (HEPES) buffer, and organic solvents, especially ethanol. However, interference by these factors was overcome by diluting the 68Ga-DOTATOC injection tenfold. In addition, no interference was observed at pH values between 4 and 8, at a HEPES concentration of 2,000 ㎍/mL, or an ethanol concentration of <1%. Furthermore, results showed that interfering factors had similar effects on the performances of the EndosafeⓇ LAL and EndosafeⓇ rCR cartridges. The results of this study are expected to be useful for evaluating factors that interfere with the endotoxin testing of new radiopharmaceuticals.

엔도톡신 시험은 투구게의 혈구세포 추출성분인 라이세이트(Limulus Amebocyte Lysate, LAL)가 그람음성균의 지질다당체와 반응하여 응고하는 원리를 이용한 in vitro 시험법이다. 엔도톡신이 혈액 내 노출될 경우 환자에게 심각한 부작용을 발생시킬 수 있으므로 진단용 방사성의약품은 제조 후 반드시 엔도톡신 시험을 통해 의약품 내 오염여부를 확인해야 한다. 진단용 방사성의약품은 유기용매와 완충용액 등을 사용하여 화학반응을 통해 제조되므로 다양한 반응간섭물질이 의약품 내 존재할 수 있다. 이에 본 연구에서는 방사성의약품에 존재하는 엔도톡신 시험의 반응간섭인자를 분석하고 이들의 허용범위를 평가하고자 하였다. 방사성의약품의 엔도톡신 시험을 위해 겔 응고 LAL시험과 비색 LAL시험을 실시하였고, 비색 LAL시험에서는 혈액 성분으로 만든 EndosafeⓇ LAL cartridge와 재조합 단백질로 만든 EndosafeⓇ rCR cartridge의 성능을 비교하였다. 방사성의약품 68Ga-DOTATOC 주사액의 엔토톡신 시험 반응간섭인자 평가 시 pH, 유기용매, 완충용액이 있었으며, 그 중 유기용매인 에탄올이 엔도톡신 시험에 간섭현상을 일으켰다. 하지만 68Ga-DOTATOC 주사액을 10배 희석할 경우 간섭현상을 극복할 수 있었다. 진단용 방사성의약품 내 존재할 수 있는 반응간섭인자들의 허용범위를 평가하였으며, pH의 경우 pH 4~8에서는 간섭현상이 없었고, 유기용매의 경우 에탄올 1% 이하에서는 간섭현상이 발생되지 않았다. 완충용액 HEPES는 2,000 ㎍/mL까지는 간섭현상이 발생되지 않았다. 본 연구를 통해 진단용 방사성의약품의 엔도톡신 시험에서 유기용매인 에탄올의 농도가 가장 중요한 반응간섭인자임을 확인하였고, 적절한 희석을 통해 1% 미만의 농도로 낮출 경우 엔도톡신 시험을 시행할 경우 간섭을 극복할 수 있음을 알 수 있었다. 또한 EndosafeⓇ LAL cartridge와 EndosafeⓇ rCR cartridge의 회수율도 비슷하게 측정되어 성능에 큰 차이가 없음을 확인할 수 있었다. 본 연구결과는 향후 새로운 진단용 방사성의약품의 엔도톡신 시험 시 반응간섭인자를 평가하는데 큰 도움이 될 것으로 기대한다.

Keywords

References

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