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EJHP Science • Volume 13 • 2007 • Issue 2 • P. 27-32 © 2007 The European Journal of Hospital Pharmacy Science. All rights reserved 1781-7595 €20 www.ejhp.eu Viability of micro-organisms in novel anticancer drug solutions Astrid Karstens, PhD, Irene Krämer, PhD ABSTRACT Study objectives: In determining expiry dates of aseptically prepared drugs, chemical, physical, toxicological and microbiological factors must be considered. This is especially true because many antineoplastic drugs introduced on to the market are already known to lack antimicrobial activity. The purpose of this study was to evaluate the growth of four different micro-organisms in diluted solutions of novel chemical or biopharmaceutical drugs (i.e. monoclonal antibody drugs) with antineoplastic activity. Methods: Drug products were aseptically reconstituted according to the manufacturer’s recommendations and further diluted if suitable for administration. Inoculations were performed by adding drug solution to bacterial (Staphyloccus aureus, Enterococcus faecium, Pseudomonas aeruginosa) or fungal (Candida albicans) suspensions in order to produce concentrations of approximately 104 micro-organisms per millilitre. Pure vehicle solutions inoculated in the same manner with microorganisms, served as positive controls. Inoculated solutions were stored at a raised temperature of 22°C. Samples of the test solutions were withdrawn up to 120 hours after inoculation, transferred to suitable growth media, and colony-forming units were then counted. Results: Most of the drugs did not show any antimicrobial activity. Only one drug solution with significant antimicrobial activity was identified, namely busulfan injection concentrate. Moderate antibacterial activity was seen in diluted solutions of busulfan. The streptozocin test solutions exhibited moderate antibacterial activity and moderate antifungal activity. Species-specific weak antibacterial activity was seen with pemetrexed test solutions against S. aureus strains. A nutritive value of sodium folinate solution or antibody drug solutions was not detected. The lack of antibacterial and antifungal properties should be considered when assigning extended expiry dates to ready-touse solutions of antineoplastic drugs. Monoclonal antibody drug solutions showed neither growth-retarding nor growthsupporting properties, and should be handled in the same manner as other antineoplastic drugs. Except for solutions containing busulfan or streptozocin, end-product sterility testing can be performed without further dilution or inactivation. Conclusion: Micro-organisms can survive in diluted solutions of antineoplastic drugs and proliferate when transferred to proper growth media. KEYWORDS Mirco-organisms, antineoplastic drugs, monoclonal antibody drugs, microbiological stability INTRODUCTION The microbiological quality of preparations for parenteral use is directly related to the equipment and methods used during the preparation process. To ensure adequate microContact for correspondence: Irene Krämer Department of Pharmacy Johannes Gutenberg-University Hospital 1 Langenbeckstrasse D-55101 Mainz, Germany Tel: +49 6131177209 Fax: +49 6131175525 [email protected] Received 30 October 2006; revised manuscript received: 13 February 2007; accepted 13 February 2007 European Association of Hospital Pharmacists biological stability of the preparations, proper environmental conditions for aseptic processing, correct aseptic techniques and quality assurance programmes are necessary [1-4]. Quality assurance programmes for prepared sterile products include environmental monitoring, personnel monitoring, process validation and end-product validation. Personnel involved with production are responsible for ensuring that shelf-lives or expiry dates (USP <797>) are properly assigned to the prepared products. In determining the appropriate expiry dates, chemical, physical, toxicological and microbiological aspects must be considered [5]. Microbiological stability implies sterility or resistance to microbial growth of the aseptically prepared solutions. The lack of antimicrobial properties should also be considered • Volume 13 • 2007/2 • www.ejhp.eu • 27 Viability of micro-organisms in novel anticancer drug solutions Astrid Karstens and Irene Krämer The European Journal of Hospital Pharmacy Science Table 1: Characteristics of antineoplastic drug solutions inoculated with micro-organisms Drug Manufacturer Alemtuzumab Medac Schering Bortezomib Janssen-Cilag Busulfan injection Pierre Fabre Pharma Busulfan Pierre Fabre diluted infusion Pharma solution Cetuximab Merck Etoposide Bristol-Myers phosphate Squibb Irinotecan Aventis Pharma Liposomal Essex Pharma doxorubicin Sodium folinate Medac Pemetrexed Lilly Rituximab Roche Streptozocin Trastuzumab Upjohn Roche Lot Vehicle 42016F 4EBS001 AQ1003 Concentration (mg/mL) 0.9% NaCl solution 0.03 1.0 6.0 AQ1003 0.9% NaCl solution 0.5 19 h 12 CT16392064 4C84542 0.9% NaCl solution 2.0 0.09 28 d 28 d Data on file, Merck 13 D4A879 0412213 0.9% NaCl solution 5% dextrose solution 0.35 0.15 28 d 7d 14 M40824AA FF4S91S B2018, B299, B2019 39MCC B1083 0.9% NaCl solution 0.9% NaCl solution 0.9% NaCl solution 1.5 9.0 1.0 72 h 28 d 48 h 15 16 0.9% NaCl solution 0.9% NaCl solution 3.0 0.4 96 h 24 h 17 18 when assigning extended expiry dates to ready-to-use antineoplastic drug solutions to be administered by infusion [6]. In previous papers [6-8], we have already described the lack of antimicrobial activity with most of the 40 antineoplastic drug solutions tested. Significant antibacterial activity was discovered or confirmed within our specified experimental conditions for solutions of carboplatin, cisplatin, dacarbazine, 5-fluorouracil, mitomycin, oxaliplatin and treosulfan. Moderate antifungal activity was seen with amsacrine, carmustine, epirubicin, mitozantrone, pentostatin, and treosulfan [6-8]. No direct link between chemical structure or pharmacological principles and antimicrobial activity was obvious [8]. Moreover, no correlation exists between antifungal and antibacterial activity, and antimicrobial activity proved to be species-specific [8]. Over the past several years, novel antineoplastic drugs, especially biopharmaceutical monoclonal antibodies, have been introduced on to the market for the treatment of cancer. Little is known about the antimicrobial activity of the reconstituted and/or diluted solutions. The purpose of this study was to evaluate the growth of four different microorganisms in diluted solutions of these novel drugs. As in previous experiments [6-8], the micro-organisms selected are commonly associated with nosocomial infections, and the test conditions selected support growth of microorganisms in the drug solutions. 28 • • Volume 13 • 2007/2 • www.ejhp.eu Physicochemical stability at 2-8°C 24 h 28 d 28 d Reference 10 11 9 METHODS The drugs were tested in two consecutive sessions (S. aureus and P. aeruginosa in parallel; E. faecium and C. albicans in parallel), as indicated in Tables 2-5. Drugs were aseptically reconstituted according to the manufacturer’s recommendations and further diluted if appropriate. Dilution solvent and container material were selected in order to achieve maximal chemical and physical stability. Dilution was aseptically performed by injecting a calculated aliquot of each stock solution into a polypropylene bag containing 0.9% sodium chloride solution (Freeflex, Fresenius Kabi, lot SK721202) or 5% dextrose solution (Freeflex, Fresenius Kabi, lot SB7210) to achieve the desired final concentrations. Cetuximab injection solution (2 mg/mL, Merck) was transferred to empty ethylenvinyl acetate bags (Baxter), without further dilution. The final concentrations of the diluted solutions were the lowest concentrations ordered by our physicians and/or concentrations recommended by the manufacturers for administration. In addition, 5 mL aliquots of busulfan injection concentrate were prepared in polypropylene syringes (B Braun) [9]. The drug products, their final concentrations and the in-house physicochemical stability data considered are shown in Table 1. Physicochemical stability data were determined in our pharmacy department (busulfan stock solution, diluted (busulfan infusion solutions (Busulfex, Busilvex); irinotecan (Campto)) or were carefully evaluated from the literature. European Association of Hospital Pharmacists Viability of micro-organisms in novel anticancer drug solutions Astrid Karstens and Irene Krämer The European Journal of Hospital Pharmacy Science Table 2: Viability of S. aureus in drug solutions and control solutions Drug/control solution S. aureus (CFU log/mL) 0 min 15 min 30 min 60 min 4.7 4.8 4.8 4.7 4.8 4.7 4.7 4.7 5% Dextrose solution 4.8 4.8 4.7 4.7 4.7 4.7 4.8 4.7 Alemtuzumab 4.7 4.7 4.7 4.7 4.7 4.7 4.7 4.7 Bortezomib* 4.7 4.7 4.7 4.7 Busulfan concentrate* 4.7 4.4 3.1 3.1 Busulfan diluted 4.7 4.7 4.7 4.7 4.7 4.7 4.7 4.7 Cetuximab 4.7 4.7 4.7 4.7 4.7 4.7 4.7 4.7 Etoposide phosphate 4.7 4.7 4.7 4.7 4.7 4.7 4.7 4.7 Irinotecan 4.8 4.7 4.7 4.7 4.7 4.7 4.8 4.7 Liposomal Doxorubicin 4.7 4.7 4.7 4.7 4.7 4.7 4.7 4.7 Sodium folinate 4.8 4.7 4.7 4.7 4.8 4.8 4.8 4.7 Pemetrexed 4.7 4.8 4.7 4.7 4.8 4.7 4.7 4.7 Rituximab 4.8 4.8 4.7 4.7 4.7 4.7 4.7 4.7 Streptozocin 4.7 4.7 4.7 4.7 4.7 4.7 4.7 4.7 Trastuzumab 4.7 4.7 4.7 4.7 4.7 4.7 4.7 4.7 CFU = colony-forming units, h = hour, min = minute, *one test solution 0.9% NaCl solution 2h 4.8 4.7 4.7 4.7 4.7 4.7 4.7 0 4.7 4.7 4.7 4.7 4.7 4.7 4.7 4.7 4.7 4.7 4.7 4.7 4.7 4.7 4.7 4.7 4.7 4.7 4.7 4.7 3h 4.7 4.7 4.7 4.7 4.7 4.7 4.7 0 4.7 4.7 4.7 4.7 4.7 4.7 4.7 4.7 4.7 4.7 4.7 4.7 4.7 4.7 4.7 4.7 4.7 4.7 4.7 4.7 4h 4.7 4.7 4.7 4.7 4.7 4.7 4.7 0 4.6 4.6 4.7 4.7 4.7 4.7 4.7 4.7 4.7 4.7 4.7 4.7 4.7 4.7 4.7 4.7 4.7 4.7 4.7 4.7 24 h 4.7 4.7 4.7 4.7 4.7 4.7 4.3 0 0 0 4.7 4.7 4.7 4.7 4.7 4.7 4.7 4.7 4.7 4.7 4.7 4.7 4.7 4.7 0 0 4.7 4.7 48 h 4.6 4.6 4.6 4.6 4.6 4.7 4.7 0 0 0 4.7 4.7 4.7 4.7 4.7 4.7 4.7 4.7 4.7 4.7 4.6 4.6 4.7 4.7 0 0 4.6 4.6 120 h 2.4 2.3 1.8 1.6 2.8 2.8 1.9 0 0 0 2.7 2.7 1.3 1.6 2.6 2.5 2.2 2.3 2.6 2.5 0 0 2.8 2.6 0 0 2.6 2.4 Table 3: Viability of E. faecium in drug solutions and control solutions Drug/control solution 0.9% NaCl solution 5% dextrose solution Alemtuzumab Busulfan diluted Cetuximab Etoposide phosphate Irinotecan Liposomal doxorubicin E. faecium (CFU log/mL) 0 min 5.4 5.4 5.4 5.4 5.4 5.4 5.4 5.4 5.4 5.4 5.4 5.4 5.4 5.4 15 min 5.4 5.4 5.4 5.4 5.4 5.4 5.4 5.4 5.4 5.4 5.4 5.4 5.4 5.4 30 min 5.4 5.4 5.4 5.4 5.4 5.4 5.4 5.4 5.4 5.4 5.4 5.4 5.4 5.4 60 min 5.4 5.4 5.4 5.4 5.4 5.4 5.4 5.4 5.4 5.4 5.4 5.4 5.4 5.4 2h 5.4 5.4 5.4 5.4 5.4 5.4 5.4 5.4 5.4 5.4 5.4 5.4 5.4 5.4 3h 5.4 5.4 5.4 5.4 5.4 5.4 5.4 5.4 5.4 5.4 5.4 5.4 5.4 5.4 4h 5.4 5.4 5.4 5.4 5.4 5.4 5.4 5.4 5.4 5.4 5.4 5.4 5.4 5.4 24 h 5.4 5.4 5.4 5.4 5.4 5.4 2.0 1.9 5.4 5.4 5.4 5.4 5.4 5.4 48 h 5.4 5.4 5.4 5.4 5.4 5.4 0 0 5.4 5.4 5.4 5.4 5.4 5.4 120 h 5.4 5.4 5.3 5.4 5.4 5.4 0 0 5.4 5.4 5.4 5.4 5.4 5.3 5.4 5.4 5.4 5.4 5.4 5.4 5.4 5.4 5.4 5.4 5.4 5.4 5.4 5.4 5.4 5.4 5.4 5.4 5.4 5.4 5.4 5.4 5.4 5.4 5.4 5.4 5.4 5.4 5.4 5.4 5.4 5.4 5.4 5.4 5.4 5.4 5.4 5.4 5.4 5.4 5.4 5.4 5.4 5.4 5.4 5.4 5.4 5.4 5.1 5.1 5.4 5.4 5.4 5.4 5.4 5.4 2.3 2.5 5.4 5.4 5.4 5.4 5.4 5.4 0 0 5.4 5.4 5.4 5.4 5.4 5.4 0 0 5.4 5.4 5.4 5.4 5.4 5.4 0 0 5.4 5.4 Sodium folinate 5.4 5.4 5.4 5.4 Rituximab 5.4 5.4 5.4 5.4 Streptozocin 5.4 5.4 5.4 5.4 Trastuzumab 5.4 5.4 5.4 5.4 CFU = colony-forming units, h = hour, min = minute European Association of Hospital Pharmacists • Volume 13 • 2007/2 • www.ejhp.eu • 29 Viability of micro-organisms in novel anticancer drug solutions Astrid Karstens and Irene Krämer The European Journal of Hospital Pharmacy Science The preparation of inocula of S. aureus (ATCC 6538), E. faecium (ATCC 6057), P. aeruginosa (ATCC 15442) and C. albicans (ATCC 10231) were carried out as previously described [8]. In general, inoculations were performed by Table 4: Viability of P. aeruginosa in drug solutions and control solutions Drug/control solution P. aeruginosa (CFU log/mL) 0 min 15 min 30 min 5.1 5.2 5.1 5.1 5.1 5.2 5% dextrose solution 5.1 5.1 5.1 5.2 5.2 5.1 Alemtuzumab 5.0 5.0 5.1 5.0 5.0 5.1 Busulfan diluted 5.0 5.0 5.2 5.1 5.1 5.2 Cetuximab 5.0 5.0 5.0 5.1 5.1 5.1 Etoposide phosphate 5.2 52 5.1 5.2 5.2 5.1 Irinotecan 5.2 5.2 5.1 5.2 5.2 5.1 Liposomal doxorubicin 5.2 5.2 5.1 5.2 5.2 5.1 Sodium folinate 5.2 5.2 5.1 5.2 5.2 5.1 Pemetrexed 5.2 5.2 5.2 5.2 5.2 5.2 Rituximab 5.2 5.2 5.2 5.3 5.2 5.2 Streptozocin 5.3 5.3 5.2 5.2 5.2 5.2 Trastuzumab 5.2 5.2 5.1 5.2 5.2 5.1 CFU = colony-forming units, h = hour, min = minute 0.9% NaCl solution 60 min 5.1 5.1 5.2 5.2 5.1 5.1 5.1 5.1 5.1 5.1 5.1 5.1 5.1 5.1 5.1 5.1 5.1 5.1 5.2 5.2 5.2 5.2 5.2 5.2 5.1 5.1 2h 5.2 5.1 5.1 5.1 5.1 5.1 5.0 5.0 5.1 5.1 5.1 5.1 5.1 5.1 5.1 5.1 5.1 5.1 5.1 5.1 5.1 5.1 4.6 4.6 5.1 5.1 3h 5.1 5.1 5.1 5.2 5.1 5.1 4.7 4.7 5.1 5.1 5.1 5.1 5.1 5.1 5.1 5.1 5.1 5.1 5.1 5.1 5.0 5.1 4.2 4.2 5.1 5.1 4h 5.1 5.1 5.1 5.2 5.1 5.0 4.3 4.3 5.1 5.1 5.1 5.1 5.2 5.1 5.1 5.1 5.1 5.1 5.1 5.1 5.0 5.1 4.2 4.2 5.1 5.1 24 h 5.1 5.1 5.1 5.1 5.0 5.1 1.6 0 5.1 5.1 5.1 5.1 5.1 5.2 5.1 5.1 5.1 5.1 5.1 5.1 5.0 5.1 0 0 5.0 5.1 48 h 4.8 4.8 4.8 4.8 4.4 4.8 0 0 4.8 4.8 4.8 4.8 4.8 4.8 4.9 4.8 4.8 4.8 4.8 4.8 4.8 4.8 0 0 4.8 4.8 120 h 4.9 4.9 4.3 4.3 4.9 4.8 0 0 4.9 4.9 4.5 4.5 4.7 4.6 5.0 5.0 4.8 4.9 4.9 4.9 4.9 4.9 0 0 4.9 4.9 Table 5: Viability of C. albicans in drug solutions and control solutions Drug/control solution 0.9% NaCl solution 5% dextrose solution Alemtuzumab C. albicans (CFU log/mL) 0 min 5.2 5.2 5.2 5.2 5.2 5.2 15 min 5.2 5.2 5.2 5.2 5.2 5.2 Busulfan concentrate* 30 min 5.2 5.2 5.2 5.2 5.2 5.2 60 min 5.2 5.2 5.2 5.2 5.2 5.2 5.2 3.1 2.8 2.3 Busulfan diluted 5.2 5.2 5.2 5.2 5.2 5.2 5.2 5.2 Cetuximab 5.2 5.2 5.2 5.2 5.2 5.2 5.2 5.2 Etoposide phosphate 5.2 5.2 5.2 5.2 5.2 5.2 5.2 5.2 Irinotecan 5.2 5.2 5.2 5.2 5.2 5.2 5.2 5.2 Liposomal doxorubicin 5.2 5.2 5.2 5.2 5.2 5.2 5.2 5.2 Sodium folinate 5.2 5.2 5.2 5.2 5.2 5.2 5.2 5.2 Rituximab 5.2 5.2 5.2 5.2 5.2 5.2 5.2 5.2 Streptozocin 5.2 5.2 5.2 5.2 5.2 5.2 5.2 5.2 Trastuzumab 5.2 5.2 5.2 5.2 5.2 5.2 5.2 5.2 CFU = colony-forming units, h = hour, min = minute, * one test solution 30 • • Volume 13 • 2007/2 • www.ejhp.eu 2h 5.2 5.2 5.2 5.2 5.2 5.2 3h 5.2 5.2 5.2 5.2 5.2 5.2 4h 5.2 5.2 5.2 5.2 5.2 5.2 24 h 5.2 5.2 5.2 5.2 5.2 5.2 48 h 5.2 5.2 5.2 5.2 5.2 5.2 120 h 4.4 4.3 4.3 4.2 5.1 5.1 0 5.2 5.2 5.2 5.2 5.2 5.2 5.2 5.2 5.2 5.2 5.2 5.2 5.2 5.2 5.2 5.2 5.2 5.2 0 5.2 5.2 5.2 5.2 5.2 5.2 5.2 5.2 5.2 5.2 5.2 5.2 5.2 5.2 5.2 5.2 5.2 5.2 0 5.2 5.2 5.2 5.2 5.2 5.2 5.2 5.2 5.2 5.2 5.2 5.2 5.2 5.2 5.2 5.2 5.2 5.2 0 5.2 5.2 5.2 5.2 5.2 5.2 5.2 5.2 5.2 5.2 5.2 5.2 5.2 5.2 0 0 5.2 5.2 0 5.2 5.2 5.2 5.2 5.1 5.1 5.2 5.2 5.2 5.2 5.2 5.2 5.2 5.2 0 0 5.2 5.2 0 4.8 4.8 4.7 4.8 2.8 2.6 4.8 4.8 5.2 5.2 4.3 4.5 4.7 4.7 0 0 5.1 5.0 European Association of Hospital Pharmacists Viability of micro-organisms in novel anticancer drug solutions Astrid Karstens and Irene Krämer The European Journal of Hospital Pharmacy Science adding 9 mL of a drug solution to 1 mL of bacteria or C. albicans suspension to produce concentrations of approximately 104 micro-organisms per millilitre. With the exception of bortezomib and busulfan, duplicate test suspensions were prepared per micro-organism for each drug, Because of financial restrictions, only 3.5 mL of bortezomib reconstituted solution (directly withdrawn from the vial) and 5 mL of busulfan injection concentrate were added to the microorganism suspensions. For the same reason, bortezomib reconstituted solution, busulfan injection concentrate and pemetrexed diluted solutions were added to selected microorganism suspensions only. Sodium chloride solution 0.9% inoculated in the same manner with micro-organisms, served as positive control. Dextrose solution 5% inoculated with micro-organisms in the same way, served as positive control for the liposomal doxorubicin test solution (Essex Pharma). The storage of test solutions (22°C, light-protected), sampling (at 0, 15, 30 and 60 minutes and 2, 3, 4, 24, 48 and 120 hours after inoculation), and the quantitative determination of colony-forming units (CFU) were performed as described in our previous publications [7, 8]. Samples were transferred to tryptic soy agar and incubated at 36°C for 24 hours. RESULTS The viability of S. aureus, E. faecium, P. aeruginosa and C. albicans in the drug solutions tested and in control solutions are shown in Tables 2-5. Most of the drugs did not show any antimicrobial activity. The selected micro-organism strains remained viable up to 120 hours after inoculation in the control solutions and in the drug solutions of alemtuzumab, bortezomib (S. aureus), cetuximab, etoposide phosphate, irinotecan, liposomal doxorubicin, sodium folinate, rituximab and trastuzumab (Tables 2-5). The decreasing viability of S. aureus after 48 hours was also observed in our previous experiments and is most likely to be caused by exhaustion of nutritive substances. A nutritive value of sodium folinate or the solutions containing monoclonal antibodies was not detected. There was only one drug solution with significant antimicrobial activity that was identified, namely busulfan injection concentrate. The loss of viability of S. aureus and C. albicans inoculated into busulfan injection concentrate was seen two hours after inoculation. Because busulfan injection concentrate (Busilvex, Busulfex) is a non-aqueous drug solution containing the drug substance dissolved in N,Ndimethylacetamide (33% w/w) and polyethylene glycol 400 (67% w/w), this result was expected. The thesis of autosterility caused by the drug formulation is supported by weaker antibacterial activity and missing antifungal activity of diluted busulfan solutions (see Tables 2-5). The loss of European Association of Hospital Pharmacists viability of S. aureus, E. faecium and P. aeruginosa strains occurred 24 or 48 hours after inoculation of the diluted busulfan solutions. The streptozocin test solutions exhibited moderate antibacterial activity against each of the bacteria species tested (Tables 24) and moderate antifungal activity against C. albicans (Table 5). The loss of viability of micro-organisms occurred 24 hours after inoculation. Because solutions for streptozocin infusion are known to be physicochemically stable for more than 48 hours when stored at room temperature [19], antimicrobial activity of streptozocin solutions is attributed to the drug substance itself and not to resulting degradation products. Species-specific weak antibacterial activity was seen with pemetrexed test solutions against S. aureus strains (Table 2). However, no antibacterial activity was observed against P. aeruginosa strains (Table 4). DISCUSSION The test conditions of the inoculation experiments were originally chosen to simulate the worst possible conditions for patients and optimal circumstances for the growth of microorganisms [6]. Therefore, all test solutions were stored at 22°C, although according to their physicochemical instability, storage under refrigeration is required [6]. In all cases, samples were withdrawn up to five days after inoculation, regardless of the physicochemical stability of the drug solutions. Bortezomib, etoposide phosphate and irinotecan test solutions, as well as busulfan injection concentrate, are known to be physicochemically stable for at least five days at room temperature. Shelf-lives of the other drug products tested are shorter than five days when stored at room temperature. However, resulting degradation products did not affect viability of the micro-organisms in our experiments. Viability of micro-organisms in the drug solutions is also encouraged by the low drug concentrations selected, which probably fell below the minimal inhibitory concentration [8]. The viability pattern of micro-organisms in the control solutions reflects the known viability of the selected species in nutrient-poor solutions over the test period. For the first time, antimicrobial activity of ready-to-use solutions of antibody drugs (alemtuzumab, cetuximab, rituximab, trastuzumab) was investigated. Because dilution is not recommended by the manufacturer, cetuximab was inoculated without further dilution. The antibody drug solutions exhibited neither antibacterial nor antifungal activity; they even lacked growth-supporting properties for the micro-organisms. Therefore, microbiological instability of biopharmaceutical drug solutions for the treatment of cancer is comparable with the microbiological instability of • Volume 13 • 2007/2 • www.ejhp.eu • 31 Viability of micro-organisms in novel anticancer drug solutions Astrid Karstens and Irene Krämer The European Journal of Hospital Pharmacy Science chemical antineoplastic drug solutions. The same is true for ready-to-use-solutions of calcium folinate, and, according to this study, also for sodium folinate solutions. None of the tested ready-to-use drug solutions exhibited exceptional antimicrobial activity. Although the antimicrobial activity of antineoplastic agents is for the most part unpredictable [8], moderate antimicrobial activity was expected and recorded for streptozocin solutions. Streptozocin is a naturally occurring nitrosourea. The drug is derived from Streptomyces achromogenes and has broad antibacterial properties as well as antitumour activity. Our test method proved to be suitable in confirming the antibacterial activity of streptozocin. In addition, antifungal activity against C.albicans was detected. This contrasts with the lack of antifungal activity observed with diluted mitomycin-C drug solutions. Mitomycin-C also derives from a streptomyces species and has alkylating and antibacterial activity [8]. Bortezomib, the first in class of proteasome inhibitors, showed neither antimicrobial activity nor growth-supporting properties against the S. aureus strains tested. As no further experiments were performed, and antimicrobial activity is often species-specific and independent from the chemical structure or mechanism of action, no further conclusions can be drawn from this result. The strong antibacterial and antifungal activity of Busilvex injection concentrate is mostly caused by the formulation of the drug with organic solvents only, and not by the drug substance itself. Busulfan itself seems to have negligible antimicrobial activity according to the results seen with the diluted busulfan solutions. This suggestion is also supported by our test results observed for solutions of amsacrine. Diluted solutions of amsacrine for infusion also contain dimethylacetamide and exhibited weak antibacterial activity, but moderate antifungal activity [8]. CONCLUSIONS As was established in our earlier studies, micro-organisms can survive in diluted solutions of antineoplastic drugs and proliferate when transferred to proper growth media. Solutions containing antineoplastic drug antibodies showed neither growthretarding nor growth-supporting properties, and are to be handled in the same manner as other antineoplastic drugs. In pharmacy departments, solutions for parenteral administration are to be prepared under strict aseptic conditions and appropriate quality assurance programmes are to be established in order to guarantee the sterility of drug preparations. Except for busulfan and streptozocin, end-product sterility testing can be performed without further dilution or inactivation. The lack of antibacterial and antifungal properties should be considered when assigning extended expiry dates to ready-to-use solutions of most antineoplastic drugs. Such reconstituted solutions should be kept refrigerated whenever possible to inhibit the growth of any contaminating organisms. ACKNOWLEDGEMENT The technical assistance of Sabine Teske-Keiser at the Institute for Microbiology and Hygiene, Johannes Gutenberg-University, Mainz is acknowledged. REFERENCES 1. Bundesverband Deutscher Krankenhausapotheker (ADKA) e.V. Aseptische Herstellung und Prüfung applikationsfertiger Parenteralia. Krankenhauspharmazie 2003;6:195-201. 2. United States Pharmacopeial Convention: <797>. Pharmaceutical compounding - sterile preparations. In: United States Pharmacopeia (USP), 28rd rev./national formulary, 23th edition, Rockville MD, US, 2005. p2461-77. 3. 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