Usefulness of the final filter of the IV infusion set in intravenous administration of drugs--contamination of injection preparations by insoluble microparticles and its causes.

The purpose of this study is to clarify the presence of so much insoluble microparticles in the injections and to confirm the usefulness of the final filter for its removal. The test drugs used were Doyle 1 g vial, Cefotax 1 g vial, Minomycin 100 mg vial, Omegacin 0.3 g vial, Maxipime 1 g vial, Rocephin 1 g vial, Isovorin 25 mg vial, Diamox 500 mg vial and Fungizone 50 mg vial. 1) An appropriate volume of physiological saline was poured into the test drug vial from the 500 ml physiological saline bag. 2) The dissolution of the preparation was checked. 3) That test drug solution was returned into the same 500 ml physiological saline bag. 4) 5 ml of test drug solution was extracted from the inside of the 500 ml physiological saline bag. 5) The number of insoluble microparticles in the each test drug solution at pre- and post-filtrations were counted by using a particle counter for the solution. Two results were shown as follows (microparticle size: 5 microm or greater), (a) Doyle 1 g (ASPC): The number of insoluble microparticles in pre- and post-filtrations of a Doyle 1 g vial were 250 +/- 45 and 0/5 ml, respectively (microparticle size: < or =5 microm 1662/5 ml, 5-10 microm: 238/5 ml, >10 microm: 11/5 ml). (b) Diamox 500 mg (acetazolamide): The number of insoluble microparticles in pre- and post-filtrations of Diamox were 158 +/- 53 and 0.3 +/- 0.47/5 ml, respectively (microparticle size: < or =5 microm 4030/5 ml, 5-10 microm: 144/5 ml, >10 microm: 14/5 ml). The presence of great numbers of insoluble microparticles in several injection preparations was clarified. Although the all test drugs used cleared the criteria of the number of insoluble microparticles of the Japanese Pharmacopoeia, it was suggested to be not suitable that great numbers of insoluble microparticles were administrated in the body fluid of patients, because a possibility to occlude capillaries and/or to injure the tissues by them was been thought. But we could remove them nearly completely by passing the solutions of drugs through an infusion filter. Otherwise, in this examination, we found that so much insoluble microparticles derived from the disposable syringe (10 ml) were used for dissolving freeze-dried preparations routinely (microparticle size: < or =5 microm 329/5 ml, 5-10 microm: 125/5 ml, >10 microm: 39/5 ml). These results suggest that incorporation of a final filter in the IV line is extremely necessary not only for the prevention of bacterial infections, but also for elimination of insoluble microparticles.