ANTIMICROBIAL AGENTS AND CHEMOTHERAPY, Apr. 1979, p. 592-596 66-484/79/4-592/5$2./ Vol. 15, No. 4 Effect of Time nd Concentrtion Upon Interction Between Gentmicin, Tobrmycin, Netilmicin, or Amikcin nd Crbenicillin or Ticrcillin LARRY K. PICKERING* AND PAM GEARHART Progrm in Infectious Diseses nd Clinicl Microbiology nd Deprtment of Peditrics, The University of Texs Medicl School, Houston, Texs 773 Received for publiction 18 Jnury 1978 An minoglycoside ntibiotic nd crbenicillin or ticrcillin re widely used in the tretment of ptients with grm-negtive bcillus infections. This study evluted the effect of time upon in vitro interction between mixtures of four minoglycosides t two concentrtions with crbenicillin or ticrcillin t four concentrtions. By liner regression nlysis, the inctivtion of ech minoglycoside ws shown to be directly proportionl to the concentrtion of crbencillin (P <.1). Inctivtion ws significntly (P <.1) greter for gentmicin nd tobrmycin thn for mikcin or netilmicin t ll crbenicillin concentrtions. At crbenicillin concentrtions of 3 nd 6 i.g/ml, significntly (P <.5) less inctivtion of mikcin occurred when compred to netilmicin. Ticrcillin produced significnt (P <.25) inctivtion of gentmicin nd tobrmycin, with inctivtion being directly proportionl to ticrcillin concentrtion. No inctivtion of mikcin or netilmicin ctivity occurred unless the ticrcillin concentrtion ws 6,ug/ml. No significnt chnge in minoglycoside ctivity occurred when stored with ticrcillin or crbenicillin t concentrtions rnging from 1 to 6 ug/ml t -7 C for 56 dys. When n minoglycoside nd crbenicillin or ticrcillin re indicted in ptients with renl filure, this study supports the use of ticrcillin with either mikcin or netilmicin. Aminoglycoside ntibiotics in combintion with crbenicillin or ticrcillin frequently re used for tretment of ptients with infections due to grm-negtive bcilli (3, 8, 12; J. L. Hoecker, L. K. Pickering, D. Groschel, S. Kohl, nd J. vn Eys, Cncer, in press). The combintion of crbenicillin or ticrcillin with n minoglycoside provides brod spectrum of ctivity ginst grm-negtive bcilli nd hs been shown to be synergistic ginst Pseudomons eruginos nd vrious Enterobctericee (1, 2, 6, 11, 13, 17). Conversely, inctivtion of minoglycoside ntibiotics hs been shown to be cused by either ticrcillin or crbenicillin (7, 1, 15, 16, 18, 21). McLughlin nd Reeves (16) demonstrted in vitro inctivtion of gentmicin by crbenicillin nd suggested tht some ntgonistic effect might occur in vivo by combintion tht hd been regrded s synergistic. Riff nd Jckson (21) studied the hlf-life of gentmicin in four ptients receiving hemodilysis nd found tht when crbenicillin nd gentmicin were dministered concomitntly in dosge rtio of 8:1, the hlf-life of gentmicin ws mrkedly reduced. Dvies nd ssocites (7) evluted eight ptients with renl filure nd 592 found tht 25 to 74% reduction in the hlf-life of gentmicin resulted from the concomitnt dministrtion of therpeutic doses of crbenicillin nd ticrcillin. Holt et l. (1) showed tht crbenicillin nd ticrcillin inctivted gentmicin, tobrmycin, sisomicin, nd mikcin t concentrtion of 5:1 nd tht this inctivtion ws lest in pooled humn ser nd gretest in phosphte buffer t ph 7.4. This study ws conducted to determine the effect of time nd concentrtion upon the inctivtion of four minoglycoside ntibiotics when exposed to vrious concentrtions of ticrcillin or crbenicillin. (This pper ws presented t the 18th Interscience Conference on Antimicrobil Agents nd Chemotherpy, Atlnt, Georgi, October, 1978.) MATERIALS AND METHODS Amikcin bse (92 u.g/mg; Bristol Lbortories, Syrcuse, N.Y.), gentmicin sulfte (586 tg/mg), nd netilmicin sulfte (583,ug/mg; Schering Corportion, Bloomfield, N.J.), tobrmycin sulfte (968 glg/mg; Eli Lilly & Co., Indinpolis, Ind.), disodium ticrcillin (87 ug/mg; Beechm Lbortories, Bristol, Tenn.), nd disodium crbenicillin (Roerig, New York, N.Y.)
VOL. 15, 1979 were dissolved in pooled humn ser obtined from three donors to chieve finl concentrtions of 5 nd 1 ug/ml for gentmicin, netilmicin, nd tobrmycin, nd 1 nd 2,ug/ml for mikcin. At the sme time, these concentrtions of ech minoglycoside ntibiotic were mixed seprtely with 1, 2, 3, nd 6 pg/ ml concentrtions of ticrcillin or crbenicilin in pooled humn ser. All smples were djusted to ph of 7.4. Immeditely fter mixing, portion of ech specimen ws ssyed for specific minoglycoside ctivity. Ech mixture then ws divided nd subjected to the following: (i) incubtion t 37C, with further portions being ssyed for minoglycoside ctivity t 1 nd 3 dys; (ii) storge t -7 C, with portions being thwed nd ssyed for residul minoglycoside ctivity t 1, 3, 7, nd 56 dys. Results of residul minoglycoside ctivity for ech smple re expressed s percent ctivity when compred to ctivity t zero time. All smples were ssyed in duplicte. Concentrtions of gentmicin nd tobrmycin were determined by rdioenzymtic ssy, using n denyltrnsferse enzyme (4, 22). Netilmicin nd mikcin were determined by rdioenzymtic ssy, using n cetyltrnsferse enzyme (5). Ech ssy hs stndrd curve liner from 1 to 1 ilg/ml nd withinnd-between ssy precision of 6%. Smples contining tobrmycin nd netilmicin lso were ssyed for ctivity by using microbiologicl nd rdioimmune ssys s previously reported by us (4, 5). Bcillus globogii nd Klebsiell pneumonie were used s the test orgnisms for tobrmycin nd netilmicin, respectively. Results were compred nd correlted with the rdioenzymtic ssy results. Sttisticl nlysis ws performed by using pired t test within nd between groups nd liner regression nlysis to determine the effect of crbenicillin concentrtions (Fig. 1). Vlues expressed represent men ± 1 stndrd error of the men of three to four seprte experiments. RESULTS Incubtion t 37 C. The percent ctivity of the vrious minoglycoside ntibiotics fter incubtion with crbenicillin t 37 C t concentrtion rnging from 1 to 6 Ag/ml for periods of 1 to 3 dys re shown in Tble 1. The ctivity of gentmicin, tobrmycin, netilmicin, nd mikcin showed no significnt decrese with time when crbenicillin ws not present. When either 5 or 1,ig of gentmicin per ml ws incubted with 1,ug of crbenicillin per ml, significnt inctivtion of gentmicin occurred fter 24 h (P <.2) nd 72 h (P <.5). As the concentrtion of crbenicillin incresed, the inctivtion of gentmicin becme more significnt, with the gretest inctivtion occurring t crbenicillin concentrtions of 6 pg/ml. Tobrmycin nd crbenicillin interction results were similr to those of gentmicin nd crbenicillin, with tobrmycin inctivtion being directly proportionl to crbenicillin concentrtion (P < - 8' I- 4 6- w Ou 4'- -l Z 2- i 4 FOUR AMINOGLYCOSIDES 593 1 2 3 4 5 6 CARBENICILLIN CONC. (pg/ml) FIG. 1. Liner regression nlysis of gentmicin (Gent.), tobrmycin (Tobr.), netilmicin (Neti.), nd mikcin (Amik.) ctivity fter exposure to vrious concentrtions of crbenicillin t 37 C for 72 h (n = 16 for ech minoglycoside)..1). A similr inctivtion of tobrmycin occurred when 5 nd 1 pg of tobrmycin per ml were incubted with 1 pg of crbenicillin per ml (1:2 nd 1:1, respectively) or when 5 nd 1 pug of tobrmycin per ml were exposed to 3 pg of crbenicillin per ml (1:6 nd 1:3, respectively). No chnge in netilmicin ctivity occurred when exposed to 1 ug of crbenicillin per ml; however, s the concentrtion of crbenicillin incresed, inctivtion occurred, most noticebly fter 72 h of incubtion. This inctivtion ws significntly (P <.1) less thn seen in gentmicin or tobrmycin t ll crbenicillin concentrtions studied. A similr degree of inctivtion occurred when 5 nd 1 pg of netilmicin per ml were incubted with 3 pg of crbenicillin per ml (1:6 nd 1:3, respectively). Decreses in mikcin ctivity were significntly (P <.1) less t ll times nd concentrtions tested thn chnges tht occurred in gentmicin nd tobrmycin ctivity. At cliniclly relevnt concentrtions, mikcin inctivtion ws not different thn netilmicin inctivtion t crbenicillin concentrtions of 1 nd 2,ug/ml; however, t crbenicillin concentrtions of 3 nd 6 ug/ml, significntly (P <.5) less inctivtion of mikcin occurred when compred to netilmicin. Figure 1 depicts liner regression nlysis of gentmicin, tobrmycin, netilmicin, nd mikcin ctivity when exposed to vrious concentrtions of crbenicillin t 37C for 72 h. There ws direct reltionship between the concentrtion of crbenicillin nd the inctivtion of ech minoglycoside. The higher the concentrtion of crbenicillin in the rection mixture, the greter the inctivtion of gentmicin, tobrmycin, netilmicin, nd mikcin (P <.1).
594 PICKERING AND GEARHART I.. 1. N B c. I C Q r..4.i 4.1 IU. es - - em - - q - me eq e t-~ eq o~q"c) +lizr 'Hzc'z eq) M - cl r rz - O, tm -M ~ 3 t~- t t-o eq-ō tm- eqo 'H4'ImH'H P- 2 - - ēqst.m.m mm In toc ( ~~E- Z.4tC z z i 2) 4. I '5 1 Q 41) F. - r. X4 I 2 2 *: *5D 1.4 ANTIMICROB. AGENTS CHEMOTHER. Tble 2 shows the percent ctivity of gentmicin, tobrmycin, netilmicin, nd mikcin when incubted with ticrcillin t concentrtions of 1 to 6 ug/ml for 72 h t 37C. No significnt chnge in minoglycoside ctivity occurred when ticrcillin ws not present. Ticrcillin concentrtions of 2, 3, nd 6,ug/ml produced significnt (P <.25) inctivtion of gentmicin nd tobrmycin, with inctivtion being directly proportionl to the ticrcillin concentrtion. The ctivity of netilmicin (5 nd 1,ug/ml) nd mikcin (1 nd 2 ug/ml) ws constnt t ticrcillin concentrtions of 1, 2, nd 3,ug/ml. At ticrcillin concentrtion of 6,tg/ml, netilnicin nd mikcin mintined 83 ± 2.4% nd 9 ± 2.6% ctivity, respectively. These ctivities were significntly (P <.1) greter thn remining ctivity of gentmicin nd tobrmycin t the sme concentrtion. Tble 3 shows percent minoglycoside ctivity fter mixing with 3 or 6,ug of crbenicillin or ticrcillin per ml nd storge t -7 C for 8 weeks. Amikcin nd netilmicin underwent no significnt chnge when stored with either crbenicillin or ticrcillin t either concentrtion. Gentmicin nd tobrmycin underwent slight decrese in ctivity when stored with crbenicillin or ticrcillin t 3 or 6,ug/ml concentrtions; however, these chnges were not significnt. No chnges were noted when crbenicillin or ticrcillin concentrtions of 2 ug or less per ml were used. Comprison of the tobrmycin rdioenzymtic ssy with the microbiologicl ssy nd the rdioimmune ssy gve correltion coefficients of.97 nd.95, respectively (n = 2. Comprison of the netilmicin rdioenzymtic ssy with the microbiologicl ssy nd the rdioimmune ssy yielded correltion coefficients of.82 nd.9, respectively (n = 22). DISCUSSION Ptients with proven or suspected infections due to Pseudomons eruginos often receive crbenicillin or ticrcillin in ddition to n minoglycoside ntibiotic (3, 8, 12; Hoecker et l., in press). The combintion of one of these penicillin derivtives with n minoglycoside hs been shown to be synergistic ginst P. erugnos. Conversely, inctivtion of minoglycosides such s gentmicin occurs in the presence of crbenicillin (7, 16). In ptients with norml renl function, studies hve shown no pprent inctivtion of gentmicin by crbenicillin (9, 21, 23), provided the ntibiotics were dministered seprtely nd not mixed in the sme bottle (7, 15, 18). In most ptients, these drugs re excreted t rte fster
VOL. 15, 1979 FOUR AMINOGLYCOSIDES 595 TABLE 2. Aminoglycoside-ticrcillin interction fter 72-h mixture t 37 C Activity t the following ticrcillin concn (pg/ml): Aminoglycoside CQncn (pg/ml) 1 2 3 6 Gentmicin 5 1 ± 1. 1 ±.5 9 ± 2.9 8 ± 2.4 3 ± 2.1 1 98t2.1 95±1.5 ND 81±3.6 ND Tobrmycin 5 98 ± 2.1 89 ± 3. 85 ± 1.8 74 ± 3.1 25 ± 4. 1 1±1.1 89 ± 1.5 ND 76 ± 2.3 ND Netilmicin 5 1 ± 1.6 1 ±.5 96 1.9 94 ± 1. 83 ± 2.4 1 99 ± 1.7 97 ± 1.5 ND 96 ± 1.9 ND Amikcin 1 1 ± 2.1 98 ± 1.3 98,± 2. 97 ± 1.1 9 ± 2.6 2 99 ± 1.6 1 ± 2. ND 98 ± 2. ND Vlues represent percent minoglycoside ctivity expressed s men ± stndrd error of the men. ND, Not done. TABLE 3. Aminoglycoside ctivity fter mixture with crbenicillin or ticrcillin t -7C for 8 weeks Activity with:- Aminoglycoside Crbeniciflin (pg/mi) Ticrcillin (pg/ml) 3 6 3 6 Amnikcin 98 + 2.8 96 ± 2.4 96 ± 1.4 1 ± 1.2 1 ±.8 Netilmicin 98 ± 1.9 1 ± 2.1 1 ±.8 1 ± 2.1 1 ± 1.8 Gentmicin 97 ± 1.6 92 ± 2.7 9 ± 2.7 9 ± 2.3 89 ± 3.4 Tobrmycin 98 ± 1.4 94 ± 3.1 89 ± 2.8 86 ± 2.9 87 ± 3.1 Vlues represent percent minoglycoside ctivity expressed s men ± stndrd error of the men. thn the interction between them. Presumbly, the effect of the minoglycoside on bcteri tkes plce before ny significnt loss of ctivity due to inctivtion. However, in ptients with impired renl function, n ccumultion of these ntibiotics will occur ifthe dosge schedule is not modified. Approprite use of minoglycoside ntibiotics in ptients with renl filure is often chieved by determining concentrtions in serum; however, crbenicillin nd ticrcillin concentrtions in these ptients re rrely monitored, since the therpeutic-to.toxic rtio is wide. If the dosge schedule of ticrcillin or crbenicillin is not modified (19) in ptients with renl filure, serum concentrtions could be well bove the therpeutic rnge for extended periods of time. This could result in significnt inctivtion of the concurrently dministered minoglycoside ntibiotic. McLughlin nd Reeves (16) observed gentmicin inctivtion in vivo in ptient who received dily 2-g dose of crbenicillin by continuous infusion over 24 h, which provided crbenicillin concentrtion of 1,,ug/ml in blood. Inctivtion of ech of the minoglycoside ntibiotics in our study ws shown to occur by using three different ssy procedures. Comprison of the results of these ssys showed significnt correltion. One of the methods ws microbiologicl ssy indicting tht ny inctivtion products which were formed were not microbiologiclly ctive; however, the potentil renl nd ototoxicity of these products is unknown. Further work needs to be undertken to define these products nd to determine whether they re cpble of producing side effects. The finding of inctivtion of these minoglycosides in combintion with crbenicillin nd ticrcillin t 37 C indictes tht these specimens should be centrifuged nd frozen immeditely to ensure ccurte determintion when perforned. If the smple to be tested does not contin penicillin derivtive in ddition to the minoglycoside, then trnsfer or storge of the sterile smple t room temperture will not cuse or result in ny decrese in minoglycoside ctivity (2). However, if penicillic derivtive such s crbenicillin or ticrcillin is present, then inctivtion my occur (, nd the specimen should be frozen for trnsport. Some ntibiotics such s chlormphenicol undergo no chnge in ctivity when incubted nd stored t room temperture with numerous other ntibiotics, including penicillin derivtives (2). The results of our in vitro studies show tht ticrcillin cused significntly less inctivtion of ll minoglycosides, prticulrly mikcin nd netilmicin, thn did crbenicillin. When n minoglycoside nd either crbenicillin or ticrcillin re indicted in ptient with renl filure,
596 PICKERING AND GEARHART either mikcin or netilmicin nd ticrcillin should be used. ACKNOWLEDGMENTS We thnk Steve Kohl nd Chrles Ericsson for suggestions nd Irm Bujnoch for help in preprtion of the mnuscript. LITERATURE CITED 1. Anderson, E. L., P. K. Grmling, P. R. Vestl, nd W. E. Frrr, Jr. 1975. Susceptibility of Pseudomons eruginos to tobrmycin or gentmicin lone nd combined with crbenicillin. Antimicrob.,Agents Chemother. 8:3-34. 2. Andrioli, V. T. 1974. Antibiotic synergy in experimentl infection with Pseudomons. II. The effect of crbenicillin, cephlothin or cephnone combined with tobrmycin or gentmicin. J. Infect. Dis. 129:124-133. 3. Bodey, G. P., R. Feld, nd M. A. Burgess. 1976.,- Lctm ntibiotics lone or in combintion with gentmicin for therpy of grm-negtive bcillry infections in neutropenic ptients. Am. J. Med. Sci. 271: 179-186. 4. Broughton, A., J. E. Strong, L K. Pickering, nd G. P. Bodey. 1976. Rdioimmunossy of iodinted tobrmycin. Antimicrob. Agents Chemother. 1:652-656. 5. Broughton, A., J. E. Strong, L. K Pickering, J. Knight, nd G. P. Bodey. 1978. Rdioimmunossy nd rdioenzymtic ssy of new minoglycoside ntibiotic, netilmicin. Clin. Chem. 24:717-719. 6. Comber, K. R., M. J. Bsker, C. D. Osborne, nd R. Sutherlnd. 1977. Synergy between ticrcillin nd tobrmycin ginst Pseudomons eruginos nd Enterobctericee in vitro nd in vivo. Antimicrob. Agents Chemother. 11:956-964. 7. Dvies, M., J. R. Morgn, nd C. Annd. 1974. Interctions of crbenicillin nd ticrcillin with gentmicin. Antimicrob. Agents Chemother. 7:431-434. 8. Europen Orgniztion for Reserch on Tretment of Cncer. 1978. Three ntibiotic regimens in the tretment of infection in febrile grnulocytopenic ptients with cncer. J. Infect. Dis. 137:14-29. 9. Hoecker, J. L., L K. Pickering, J. Swney, W. G. Krmer, J. vn Eys, S. Feldmn, nd S. Kohl. 1978. Clinicl phrmcology of tobrmycin in children. J. Infect. Dis. 137:592-596. 1. Holt, H. A., J. M. Broughll, M. McCrthy, nd D. S. Reeves. 1976. Interctions between minoglycoside ntibiotics nd crbenicilin or ticrcilin. Infection 4: 17-19. 11. Klstersky, J., A. Henri, nd L Vndenborre. 1973. Antimicrobil ctivity of tobrmycin nd gentmicin ANTIMICROB. AGENTS CHEMOTHIER. used in combintion with cephlothin nd crbenicillin. Am. J. Med. Sci. 266:13-21. 12. Klstersky, J., R. Cppel, nd D. Dneu. 1972. Clinicl significnce of in vitro synergism between ntibiotics in grm-negtive infections. Antimicrob. Agents Chemother. 2:47-475. 13. Klstersky, J., B. Nymubey, nd L Vndenborre. 1974. Antimicrobil effectiveness of knmycin, minosidin, BB-K8, sisomicin, gentmicin nd tobrmycin,combined with crbenicillin or cephlothin ginst grm-negtive rods. J. Med. Microbiol. 7:465-472. 14. Kluge, R. M., IL C. Stndiford, B. Ttem, V. M. Young, W. H. Greene, S. C. Schimpff, F. M. Cli, nd R. B. Hornick. 1974. Comprtive ctivity of tobrmycin, mikcin, nd gentmicin lone nd with crbenicillin ginst Pseudomons eruginos. Antimicrob. Agents Chemother. 6:442446. 15. Lynn, B. 1971. Crbenicillin plus gentmicin. Lncet i: 654. 16. McLughlin, J. E., nd D. S. Reeves. 1971. Clinicl nd lbortory evidence for inctivtion of gentmicin by crbenicillin. Lncet i:261-264. 17. Mrks, M. I., S. Hmmerberg, G. Greenstone, nd B. Silver. 1976. Activity of newer minoglycosides nd crbenicillin, lone nd in combintion, ginst gentmicin-resistnt Pseudomons eruginos. Antimicrob. Agents Chemother. 1:399-41. 18. Noone, P., nd J. R. Pttison. 1971. Therpeutic implictions of interction of gentmicin nd penicillins. Lncet ii:575-578. 19. Prry, M. F., nd H. C. Neu. 1976. Phrmcokinetics of ticrcillin in ptients with bnorml renl function. J. Infect. Dis. 133:46-49. 2. Pickering, L K., H. L. DuPont, nd T. K. Stterwhite. 1977. Evlution of spectinomycin nd gentmicin in the tretment of hospitlized ptients with resistnt urinry trct infections. Am. J. Med. Sci. 274:291-296. 2. Pickering, L K., J. L Hoecker, W. G. Krmer, J. G. Liehr, nd R. M. Cprioli. 1979. Rdioenzymtic, gs chromtogrphic with electron cpture nd gs chromtogrphic mss spectrometric ssys for chlormphenicol. Clin. Chem. 25:3-35. 21. Riff, L J., nd G. G. Jckson. 1972. Lbortory nd clinicl conditions for gentmicin inctivtion by crbenicilin. Arch. Intern. Med. 13:887-891. 22. Smith, A. L, nd D. IL Smith. 1974. Gentmicim denine mononucleotide trnsferse: prtil purifiction, chrcteriztion, nd use in the clinicl quntittion of gentmicin. J. Infect. Dis. 129:391-41. 23. Winters, R. E., A. W. Chow, nd RI H. Hecht. 1971. Combined use of gentmicin nd crbenicillin. Ann. Intern. Med. 75:925-927.