Stability of antimycobacterial drugs in susceptibility testing.
Aqueous solutions of 0.02% isoniazid, 0.2% streptomycin, 0.2% para-aminosalicylate, and 0.5% ethambutol and ethylene glycol solutions of 0.5% ethionamide stored at 3 to 7 degrees C remained stable for 1 year, as did aqueous solutions of 0.05% ethionamide hydrochloride, 0.05% kanamycin, 0.05% viomycin, and 0.1% capreomycin stored at -20 degrees C. The ethambutol and capreomycin solutions were tested by microbiologic methods; the other solutions were tested by both spectrophotometric and microbiologic methods. Prepared susceptibility testing media made with cycloserine, rifampin, and the above solutions incorporated into Middlebrook 7H10 medium showed acceptable stability when stored at 3 to 7 degrees C for 1 month. During incubation of the test medium at 37 degrees C, approximately half of the activity of isoniazid, ethionamide, ethambutol, cycloserine, and rifampin was lost after periods ranging from 2 to 4 days for ethambutol to 2 weeks for rifampin.
Griffith
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ME
Microbial Diseases Laboratory, California State Department of Health Services, Berkeley 94704.
Bodily
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HL
D000995:Antitubercular Agents / Q000737:chemistry* / Q000494:pharmacology; D002626:Chemistry, Pharmaceutical; D003080:Cold Temperature; D004355:Drug Stability; D004356:Drug Storage; D005615:Freezing; D007538:Isoniazid / Q000737:chemistry / Q000494:pharmacology; D008826:Microbial Sensitivity Tests; D009169:Mycobacterium tuberculosis / Q000187:drug effects; D012996:Solutions / Q000737:chemistry; D013696:Temperature; D013997:Time Factors
D000995:Antitubercular Agents; D012996:Solutions; D007538:Isoniazid