Neur05c1ence• 8106ehav10ra1Rev1ew5.V01. 15. pp. 123-128. Per9am0n Pre55p1c. 1991. Pr1nted1n the U.5.A.
"0149"~/631t/91:$~3.00 + .00
En2yme5 a5 Pretreatment Dru95 f0r 0r9an0ph05phate 70x1c1ty 8 H U P E N D R A P. D 0 C 7 0 R , * L1LY R A V E H , ~ A L A N D. W 0 L F E , * D 0 N A L D M . MAXWELL•1" A N D Y A C 0 V A5HAN1~:
*D1v1510n 0f 810chem15try, Wa1ter Reed Arm)~ 1n5t1tUte 0f Re5earCh, Wa5h1n9t0n, DC 20307-5100 ~Un1ted 5tate5 Arm), Med1Ca1 Re5earCh h25t1tUte 0f Chem1Ca1 Defen5e A6erdeen Pr0v1n9 6r0und, MD 21010-5425 and +,-15rae11n5t1tute 0f 8101091Ca1 Re5earch, P.0. 80a 19, Ne55-210na, 15rae1
D0C70R, 8. P., L. RAVEH, A. D. W0LFE, D. M. MAXWELL AND Y. A5HAN1. En2yme5a5 pretream2entdru95f0r 0r9an0ph05phate t0x1c10,. NEUR05C1 8108EHAV REV 15(1) 123-128, 1991.--We have 5ucce55fu11y dem0n5trated that ex09en0u51y adm1n15tered acety1- 0r 6utyry1ch011ne5tera5e(ACHE, 8ChE re5pect1ve1y) w1115e4ue5ter 0r9an0ph05phate5 (0P5) 6ef0re they reach the1r phy5101091ca1tar9et5. 1n add1t10n, a th1rd en2yme, end09en0u5 car60xy1e5tera5e 15 kn0wn t0 6e capa61e 0f 5caven91n9 0P5. 1n the5e 5tud1e5, we have adm1n15tered AChE and 8ChE t0 three d1fferent 5pec1e5 0f an1ma15 (m1ce, marm05et5 and m0nkey5) wh1ch were cha11en9ed w1th three d1fferent 0P5 (VX, MEPQ and 50man). Re5u1t5 06ta1ned fr0m the5e 5y5temat1c 5tud1e5 dem0n5trate that: (a) a 4uant1tat1ve 11nearc0rre1at10n ex15t5 6etween 6100d AChE 1eve15and the pr0tect10n aff0rded 6y ex09en0u51y adm1n15teredChE5 1n an1ma15cha11en9ed w1th 0P, (6) appr0x1mate1y 0ne m01e 0f e1ther AChE 0r 8ChE 5e4ue5ter5 0ne m01e 0f 0P, (c) 5uch pr0phy1act1c mea5ure5 are 5uff1c1ent t0 pr0tect an1ma15 a9a1n5t 0P5 w1th0ut the adm1n15trat10n0f any 5upp0rt1ve dru95.7hu5 the 0P d05e, the 6100d-1eve1 0f e5tera5e, the rat10 0f the c1rcu1at1n9en2yme t0 0P cha11en9e, and the rate 0f react10n 6etween them determ1ne the 0vera11 eff1cacy 0f an en2yme a5 a pretreatment dru9. 7he 610chem1ca1 mechan15m under1y1n9 the 5e4ue5trat10n 0f var10u5 0P5 6y the u5e 0f ex09en0u51y adm1n15tered 5caven91n9 e5tera5e5 15 the 5ame 1n a11 5pec1e5 0f an1ma15 5tud1ed. 7heref0re, the extrap01at10n 0f the re5u1t5 06ta1ned 6y the u5e 0f ChE pr0phy1ax15 1n an1ma15 t0 human5 5h0u1d 6e m0re re11a61e and effect1ve than extrap01at1n9 the re5u1t5 fr0m current1y u5ed mu1t1dru9 ant1d0ta1 m0da11t1e5. Acety1ch011ne5tera5e 8utyry1ch011ne5tera5e
0r9an0ph05phate t0x1c1ty Car60xy1e5tera5e VX
En2yme5 a5 pretreatment dru95 MEPQ
50man
5caven9er
E5tera5e
the t0x1C a9ent. 5ec0nd, 1t 5h0u1d have a 10n9 ha1f-11fe 1n v1v0. 7h1rd, 1t 5h0u1d 6e read11y ava11a61e 1n 5uff1C1ent 4uant1t1e5. F0urth, 1t 5h0u1d n0t 6e 1mmun0react1ve. F1na11y, the 5t01ch10metry 6etween 5caven9er en2yme and t0x1c a9ent5 5h0u1d appr0ach 1:1 f0r 13-e5tera5e5. Much Pr09re55 ha5 6een made 1n the pa5t f1ve year5, 6y 5evera1 9r0up5 0f 1nve5t19at0r5, 1n exp10r1n9 the p0tent1a1 u5e 0f an en2yme t0 c0unteract the t0x1c1ty 0f 0P5. Am0n9 the en2yme5 wh1ch h01d pr0m15e a5 5caven9er5 0f h19h1y t0x1c 0 P nerve a9ent5, 519n1f1cant advance5 have 6een made u51n9 ChE5. 51nce the 610chem1ca1 mechan15m under1y1n9 the pr0phy1ax15 6y ex09en0u5 e5tera5e5 5uch a5 ChE5 15 e5ta6115hed and te5ted 1n 5evera1 5pec1e5, th15 c0ncept 5h0u1d ena61e a re11a61e extrap01at10n 0f re5u1t5 fr0m an1ma1 exper1ment5 t0 human app11cat10n. 1n th15 rep0rt, we rev1ew the re5u1t5 0f 1nve5t19at10n5 1n wh1ch acety1ch011ne5tera5e (ACHE) and 6utyry1ch011ne5tera5e (8ChE) were 5ucce55fu11y u5ed f0r the 5e4ue5trat10n 0f h19h1Y t0x1c 0 P ant1-ChE5, w1th0ut the 0ccurrence 0f 51de effect5 0r perf0rmance decrement5.
PRE5EN7 treatment f0r p0150n1n9 6y 0r9an0ph05phate ant1ch011ne5tera5e c0mp0und5 c0n515t5 0f a c0m61nat10n 0f dru95 5uch a5 car6amate5, ant1mu5car1n1c5, react1vat0r5 and ant1c0nvu15ant5 1n pre- and p05texp05ure m0da11t1e5 (9, 12, 18). M05t 0f the5e re91men5 are effect1ve a9a1n5t many ant1ch011ne5tera5e5. H0wever, p05texp05ure 5ympt0m5, 5uch a5 trem0r5, c0nvu1510n5, apnea, fa5c1cu1at10n5 and 9enera1 1ncapac1tat10n, are c0mm0n1y 065erved and re5u1t 1n perf0rmance decrement5 1n human 5u6ject5. 0 n e effect1ve appr0ach t0 a11ev1ate the5e 51de effect5 15 the u5e 0f an en2yme a5 a pretreatment dru9 (2, 3, 5, 7, 8, 10, 16, 17), rather than the c1a551ca1 mu1t1p1e dru9 re91men5. F0r examp1e, 0ne can env1510n the u5e 0f the cata1yt1c act1v1ty 0f en2yme5 5uch a5 ph05ph0ry1ph05phata5e5 [e.9., DFPa5e, 50mana5e, etc. (10)] 0r e5tera5e5 (2, 3, 7, 8, 16, 17) t0 rap1d1y hydr01y2e ant1ch011ne5tera5e5 t0 n0nt0x1c pr0duct5. 7hu5, ch011ne5tera5e5 (ChE5) and car60xy1e5tera5e (CaE) may 6e u5ed a5 5caven9er5 t0 rem0ve 0r9an0ph05phate5 6ef0re they reach the1r phy5101091ca1 tar9et5 (2, 3, 5, 7, 8, 14, 16, 17). Ant160d1e5 t0 0r9an0ph05phate5 1n the1r tran51t10n 5tate5 may a150 6e de519ned and 9enerated t0 cata1y2e the hydr01y515 0f the5e c0mp0und5. 7here are certa1n re4u1rement5 f0r an en2yme t0 6e an effect1ve 5caven9er f0r 0r9an0ph05phate t0x1c1ty 1n v1v0. F1r5t, 1t 5h0u1d have a re1at1ve1y h19h rate 0f react1v1ty w1th 0r9an0ph05phate5; the h19her the rate, the fa5ter the en2yme w111 neutra112e
DEM0N57RA710N 0F U5E 0F E57ERA5E A5 5CAVEN6ER 0F 0R6AN0PH05PHA7E5 7he f1r5t 5ucce55fu1 dem0n5trat10n 0f the u5e 0f e5tera5e a5 a 5caven9er 0f 0 P 1n m1ce wa5 5h0wn 6y W01fe et a1. (17) wh0
123
124
D 0 C 7 0 R E7 AL.
7A8LE 1
7A8LE 2
PR07EC710N 0F M1cE A6A1N57 vX 8Y PRE7REA7MEN7 w17H F85-AChE
EFFEC7 0F C8DP 0N 50MAN 70X1C17Y* C0ntr01
VX D05e LD5051
5urv1v0r5 (+ ACHE)
1.00
5/5 5/5 4/5 1/5 0/5
2.00 3.00 4.24 5.99
M1ce were adm1n15tered 1P 10.89 nm01 F85-AChE appr0x1mate1y 20 h 6ef0re cha11en9e w1th VX (1ML 1 LD50=56.3 nm01 VX/k9:1 LD50 w1th F85-AChE = 201.3 nm01 VX/k9. Pr0tect1verat10= 3.6. Repr0duced w1th perm15510n fr0m Fundam. App1. 70x1c01. (17).
u5ed 1ar9e 4uant1t1e5 0f AChE pur1f1ed fr0m feta1 60v1ne 5erum (6.15) a5 a 5caven9er f0r VX (7aMe 1) and t0 50me de9ree a9a1n5t 50man. 7he5e re5u1t5 5u65tant1ated the hyp0the515 that AChE c0u1d 5erve a5 a pretreatment dru9/pr0phy1act1c a9ent t0 prevent 0 P p0150n1n9.7hey were a61e t0 pr0tect m1ce a9a1n5t appr0x1mate1y 3.5 LD50 0f VX w1th n0 apparent 519n5 0f c1a551ca1 0 P t0x1c1ty. 7w0 0ther 065ervat10n5 fr0m the5e 5tud1e5 were 0f 1mp0rtance: 1) 1n v1v0 1nh161t10n 0f ex09en0u51y adm1n15tered AChE 1n 6100d wa5 pr0p0rt10na1 t0 the am0unt 0f 0 P adm1n15tered a5 cha11en9e, a re5u1t c0n515tent w1th 1n v1tr0 exper1ment5, and 2) the am0unt 0f AChE re4u1red t0 pr0tect m1ce a9a1n5t VX wa5 c0n51dera61y 1e55 than t0 pr0tect a9a1n5t 50man [the LD505 (1M) 0f VX and 50man 1n m1ce are 56 and 577 nm01/k9 re5pect1ve1y]. Human 5erum 8ChE ha5 a150 6een dem0n5trated t0 c0nfer pr0tect10n a9a1n5t 50man p0150n1n9 1n m1ce wh1ch were pretreated w1th ex09en0u5 e5tera5e5 (2,3). Car60xy1e5tera5e 15 an examp1e 0f an end09en0u5 e5tera5e capa61e 0f 5e4ue5ter1n9 0P5 1n c1rcu1at10n. F0r examp1e, the t0x1c1ty 0f 50man appear5 t0 vary am0n9 d1fferent 5pec1e5 0f an1ma15 (14) and th15 var1at10n 15 attr16uted t0 the pre5ence 0f d1fferent am0unt5 0f car60xy1e5tera5e 1n the1r p1a5ma. 7he am0unt 0f 50man re4u1red t0 cau5e 1etha11ty para11e1ed the p1a5ma CaE 1eve15 1n the5e an1ma15.7he ev1dence f0r the 5e4ue5trat10n 0f 50man 6y CaE wa5 pr0v1ded 6y 5tud1e5 (4,5) 1n wh1ch the CaE 1nh161t0r, 2-(0-cre5y1)-4H- 1:3:2-6en20d10xaph05ph0r1n-2-0x1de (C8DP) (4) wa5 adm1n15tered t0 an1ma15 1n 0rder t0 1nh161t 5erum CaE pr10r t0 the adm1n15trat10n 0f 50man (14). 7he5e 5tud1e5 5h0wed that 5uch pretreatment 1ncrea5ed the t0x1c1ty 0f 50man (10wered the LD50) 1n an1ma15 1n pr0p0rt10n t0 the am0unt 0f CaE 1n the1r p1a5ma. 7a61e 2 5ummar12e5 the5e re5u1t5.1n add1t10n, m1ce were pretreated w1th 60th C8DP (2 m9/k9) and F85-AChE (257 nm01/ k9), and cha11en9ed w1th 50man. 7a61e 3 5h0w5 that the adm1n15trat10n 0f C8DP, a10ne, t0 m1ce reduced the LD50 0f 50man fr0m 620 nm01/k9 t0 53 nm01/k9. When m1ce were pretreated w1th F85-AChE, 1n add1t10n t0 C8DP, the LD50 0f 50man 1ncrea5ed t0 120 nm01/k9, thu5 y1e1d1n9 a pr0tect1ve rat10 0f 2.26. 1N v1v0 57A81L17Y 0F cH0L1NE57ERA5E5 1n 0rder f0r an en2yme t0 6e an effect1ve pretreatment dru9 f0r pr0tect10n a9a1n5t t0x1c c0mp0und5, 5uch a5 pe5t1c1de5 0r chem1ca1 warfare a9ent5, 1t 5h0u1d have a re1at1ve1y 10n9 ha1f-11fe 1n v1v0. 1n add1t10n, 1t5 therma1 5ta6111ty 0n pr010n9ed 5t0ra9e and 1t5 r0ute 0f adm1n15trat10n are 0f pr1me 1mp0rtance t0 1t5 u5efu1ne55 a5 an ant1d0te. 1t 5h0u1d 6e phy5101091ca11y and 1mmun01091ca11y c0mpat161e, and 6e ava11a61e 1n 1ar9e 4uant1t1e5.0ur 5e1ect10n
LD50 (p.9/k9)
5pec1e5 M0u5e Rat 6u1nea p19 Ra661t
125.0 116.0 32.3 22.8
2 m9/k9 C8DP
16 m9/k9 C8DP
LD50 % Decrea5e LD50 % Decrea5e (V.9/k9) w1thC8DP (p.9/k9) w1thC8DP 12.2 15.6 12.3 11.8
90 87 62 48
7.5 13.3 9.3 8.4
94 89 71 70
*C8DP wa5 adm1n15tered5C 1 h 6ef0re 50man (1M1. Repr0duced w1th perm15510n fr0m 70x1c01. Lett. (14). 0f the appr0pr1ate f0rm5 0f ch011ne5tera5e5, F85-AChE and human 5erum 8ChE t0 u5e a5 pretreatment te5t dru95 wa5 6a5ed 0n the fact that 60th the5e en2yme5 are 9106u1ar 1n f0rm, ea511y pur1f1ed fr0m 5erum, and are re1at1ve1y 5ta61e en2yme5 (6,15). 7he 1n v1v0 ha1f-11fe 0f F85-AChE 1n m1ce wa5 determ1ned 6y 1V 1nject10n and mea5urement 0f the 6100d en2yme 1eve1 0ver a per10d 0f 72 h0ur5 (16). 7he 5ame am0unt 0f en2yme wa5 a150 adm1n15tered 1P t0 c0mpare the r0ute5 0f adm1n15trat10n. 7he re5u1t5 5h0wn 1n F19. 1 1nd1cate that 6100d AChE 15 ma1nta1ned at a c0n5tant 1eve1 dur1n9 a per10d 0f 2-5 h, re9ard1e55 0f r0ute 0f adm1n15trat10n (7here 15 a fa9 0f a60ut 1.5 h after 1P 1nject10n 6ef0re the 6100d AChE 1eve1 peak5). A11 1n v1v0 0 P t1trat10n5 were c0nducted dur1n9 the per10d when the ex09en0u51y adm1n15tered AChE 1eve15 reached the1r p1ateau, there6y av01d1n9 the err0r5 1ntr0duced 6y var1at10n 1n 1eve15 due t0 c1earance 0f en2yme. C0n51dera61e en2yme act1v1ty wa5 065erved even after 72 h. 7he pr0f11e f0r c1earance 0f en2yme wa5 a60ut the 5ame u51n9 e1ther r0ute 0f adm1n15trat10n. 51m11ar re5u1t5 were 06ta1ned u51n9 human 5erum 8ChE 1n m1ce (2) and F85-AChE 1n marm05et5 and rhe5u5 m0nkey5 (7,8). 80th the5e en2yme5 have re1at1ve1y 10n9 ha1f f1ve5 and appear phy5101091ca11y c0mpat161e, pr06a61y 6ecau5e they 60th are 5erum pr0te1n5. 7he re1at1ve1y 510w c1earance 0f ChE5 fr0m 6100d 15 0f 9reater 519n1f1cance when 1t 15 c0mpared t0 the c1earance rate5 0f 0ther c1a551ca1 pr0phy1act1c and treatment dru95 5uch a5 car6amate5 and 0x1me5. F1na11y, 1t 5h0u1d 6e n0ted that ra151n9 the 6100d 1eve1 0f th15 en2yme m0re than a th0u5and-f01d d0e5 n0t appear t0 have any adver5e effect 0n a11 5pec1e5 0f an1ma15 te5ted. 1N v17R0 AND 1N v1v0 5701cH10ME7RY 0F 0P: 5cAvEN6ER 1N7ERAc710N Up0n 5u65tant1at10n 0f the hyp0the515 that ex09en0u51y ad7A8LE 3 EFFEC7 0F PRE7REA7MEN70F M1cE W17H c8DP AND F85-AchE 0N 50MAN 70x1c17Y 50man 70x1c1ty LD50 Pretreatment
1x9/k9
C0nf1dence L1m1t5
nm01/k9
N0ne +C8DP +C8DP + F85-AChE
113.0 9.6 21.8
( 9 4 . 6 - 135.2) ( 6 . 0 - 12.6) (17.9 - 25.0)
620 53 120
F85-AChE (257 nm01/k9) wa5 adm1n15tered 1P t0 9r0up 0f 5 m1ce 19 h0ur5 pr10r t0 adm1n15trat10n 0f C8DP (2 m9/k9). 7he an1ma15 were cha11en9ed 1M w1th 50man 0ne h0ur after C8DP adm1n15trat10n. C0nf1dence 11m1t5at p
"0149"~/631t/91:$~3.00 + .00
En2yme5 a5 Pretreatment Dru95 f0r 0r9an0ph05phate 70x1c1ty 8 H U P E N D R A P. D 0 C 7 0 R , * L1LY R A V E H , ~ A L A N D. W 0 L F E , * D 0 N A L D M . MAXWELL•1" A N D Y A C 0 V A5HAN1~:
*D1v1510n 0f 810chem15try, Wa1ter Reed Arm)~ 1n5t1tUte 0f Re5earCh, Wa5h1n9t0n, DC 20307-5100 ~Un1ted 5tate5 Arm), Med1Ca1 Re5earCh h25t1tUte 0f Chem1Ca1 Defen5e A6erdeen Pr0v1n9 6r0und, MD 21010-5425 and +,-15rae11n5t1tute 0f 8101091Ca1 Re5earch, P.0. 80a 19, Ne55-210na, 15rae1
D0C70R, 8. P., L. RAVEH, A. D. W0LFE, D. M. MAXWELL AND Y. A5HAN1. En2yme5a5 pretream2entdru95f0r 0r9an0ph05phate t0x1c10,. NEUR05C1 8108EHAV REV 15(1) 123-128, 1991.--We have 5ucce55fu11y dem0n5trated that ex09en0u51y adm1n15tered acety1- 0r 6utyry1ch011ne5tera5e(ACHE, 8ChE re5pect1ve1y) w1115e4ue5ter 0r9an0ph05phate5 (0P5) 6ef0re they reach the1r phy5101091ca1tar9et5. 1n add1t10n, a th1rd en2yme, end09en0u5 car60xy1e5tera5e 15 kn0wn t0 6e capa61e 0f 5caven91n9 0P5. 1n the5e 5tud1e5, we have adm1n15tered AChE and 8ChE t0 three d1fferent 5pec1e5 0f an1ma15 (m1ce, marm05et5 and m0nkey5) wh1ch were cha11en9ed w1th three d1fferent 0P5 (VX, MEPQ and 50man). Re5u1t5 06ta1ned fr0m the5e 5y5temat1c 5tud1e5 dem0n5trate that: (a) a 4uant1tat1ve 11nearc0rre1at10n ex15t5 6etween 6100d AChE 1eve15and the pr0tect10n aff0rded 6y ex09en0u51y adm1n15teredChE5 1n an1ma15cha11en9ed w1th 0P, (6) appr0x1mate1y 0ne m01e 0f e1ther AChE 0r 8ChE 5e4ue5ter5 0ne m01e 0f 0P, (c) 5uch pr0phy1act1c mea5ure5 are 5uff1c1ent t0 pr0tect an1ma15 a9a1n5t 0P5 w1th0ut the adm1n15trat10n0f any 5upp0rt1ve dru95.7hu5 the 0P d05e, the 6100d-1eve1 0f e5tera5e, the rat10 0f the c1rcu1at1n9en2yme t0 0P cha11en9e, and the rate 0f react10n 6etween them determ1ne the 0vera11 eff1cacy 0f an en2yme a5 a pretreatment dru9. 7he 610chem1ca1 mechan15m under1y1n9 the 5e4ue5trat10n 0f var10u5 0P5 6y the u5e 0f ex09en0u51y adm1n15tered 5caven91n9 e5tera5e5 15 the 5ame 1n a11 5pec1e5 0f an1ma15 5tud1ed. 7heref0re, the extrap01at10n 0f the re5u1t5 06ta1ned 6y the u5e 0f ChE pr0phy1ax15 1n an1ma15 t0 human5 5h0u1d 6e m0re re11a61e and effect1ve than extrap01at1n9 the re5u1t5 fr0m current1y u5ed mu1t1dru9 ant1d0ta1 m0da11t1e5. Acety1ch011ne5tera5e 8utyry1ch011ne5tera5e
0r9an0ph05phate t0x1c1ty Car60xy1e5tera5e VX
En2yme5 a5 pretreatment dru95 MEPQ
50man
5caven9er
E5tera5e
the t0x1C a9ent. 5ec0nd, 1t 5h0u1d have a 10n9 ha1f-11fe 1n v1v0. 7h1rd, 1t 5h0u1d 6e read11y ava11a61e 1n 5uff1C1ent 4uant1t1e5. F0urth, 1t 5h0u1d n0t 6e 1mmun0react1ve. F1na11y, the 5t01ch10metry 6etween 5caven9er en2yme and t0x1c a9ent5 5h0u1d appr0ach 1:1 f0r 13-e5tera5e5. Much Pr09re55 ha5 6een made 1n the pa5t f1ve year5, 6y 5evera1 9r0up5 0f 1nve5t19at0r5, 1n exp10r1n9 the p0tent1a1 u5e 0f an en2yme t0 c0unteract the t0x1c1ty 0f 0P5. Am0n9 the en2yme5 wh1ch h01d pr0m15e a5 5caven9er5 0f h19h1y t0x1c 0 P nerve a9ent5, 519n1f1cant advance5 have 6een made u51n9 ChE5. 51nce the 610chem1ca1 mechan15m under1y1n9 the pr0phy1ax15 6y ex09en0u5 e5tera5e5 5uch a5 ChE5 15 e5ta6115hed and te5ted 1n 5evera1 5pec1e5, th15 c0ncept 5h0u1d ena61e a re11a61e extrap01at10n 0f re5u1t5 fr0m an1ma1 exper1ment5 t0 human app11cat10n. 1n th15 rep0rt, we rev1ew the re5u1t5 0f 1nve5t19at10n5 1n wh1ch acety1ch011ne5tera5e (ACHE) and 6utyry1ch011ne5tera5e (8ChE) were 5ucce55fu11y u5ed f0r the 5e4ue5trat10n 0f h19h1Y t0x1c 0 P ant1-ChE5, w1th0ut the 0ccurrence 0f 51de effect5 0r perf0rmance decrement5.
PRE5EN7 treatment f0r p0150n1n9 6y 0r9an0ph05phate ant1ch011ne5tera5e c0mp0und5 c0n515t5 0f a c0m61nat10n 0f dru95 5uch a5 car6amate5, ant1mu5car1n1c5, react1vat0r5 and ant1c0nvu15ant5 1n pre- and p05texp05ure m0da11t1e5 (9, 12, 18). M05t 0f the5e re91men5 are effect1ve a9a1n5t many ant1ch011ne5tera5e5. H0wever, p05texp05ure 5ympt0m5, 5uch a5 trem0r5, c0nvu1510n5, apnea, fa5c1cu1at10n5 and 9enera1 1ncapac1tat10n, are c0mm0n1y 065erved and re5u1t 1n perf0rmance decrement5 1n human 5u6ject5. 0 n e effect1ve appr0ach t0 a11ev1ate the5e 51de effect5 15 the u5e 0f an en2yme a5 a pretreatment dru9 (2, 3, 5, 7, 8, 10, 16, 17), rather than the c1a551ca1 mu1t1p1e dru9 re91men5. F0r examp1e, 0ne can env1510n the u5e 0f the cata1yt1c act1v1ty 0f en2yme5 5uch a5 ph05ph0ry1ph05phata5e5 [e.9., DFPa5e, 50mana5e, etc. (10)] 0r e5tera5e5 (2, 3, 7, 8, 16, 17) t0 rap1d1y hydr01y2e ant1ch011ne5tera5e5 t0 n0nt0x1c pr0duct5. 7hu5, ch011ne5tera5e5 (ChE5) and car60xy1e5tera5e (CaE) may 6e u5ed a5 5caven9er5 t0 rem0ve 0r9an0ph05phate5 6ef0re they reach the1r phy5101091ca1 tar9et5 (2, 3, 5, 7, 8, 14, 16, 17). Ant160d1e5 t0 0r9an0ph05phate5 1n the1r tran51t10n 5tate5 may a150 6e de519ned and 9enerated t0 cata1y2e the hydr01y515 0f the5e c0mp0und5. 7here are certa1n re4u1rement5 f0r an en2yme t0 6e an effect1ve 5caven9er f0r 0r9an0ph05phate t0x1c1ty 1n v1v0. F1r5t, 1t 5h0u1d have a re1at1ve1y h19h rate 0f react1v1ty w1th 0r9an0ph05phate5; the h19her the rate, the fa5ter the en2yme w111 neutra112e
DEM0N57RA710N 0F U5E 0F E57ERA5E A5 5CAVEN6ER 0F 0R6AN0PH05PHA7E5 7he f1r5t 5ucce55fu1 dem0n5trat10n 0f the u5e 0f e5tera5e a5 a 5caven9er 0f 0 P 1n m1ce wa5 5h0wn 6y W01fe et a1. (17) wh0
123
124
D 0 C 7 0 R E7 AL.
7A8LE 1
7A8LE 2
PR07EC710N 0F M1cE A6A1N57 vX 8Y PRE7REA7MEN7 w17H F85-AChE
EFFEC7 0F C8DP 0N 50MAN 70X1C17Y* C0ntr01
VX D05e LD5051
5urv1v0r5 (+ ACHE)
1.00
5/5 5/5 4/5 1/5 0/5
2.00 3.00 4.24 5.99
M1ce were adm1n15tered 1P 10.89 nm01 F85-AChE appr0x1mate1y 20 h 6ef0re cha11en9e w1th VX (1ML 1 LD50=56.3 nm01 VX/k9:1 LD50 w1th F85-AChE = 201.3 nm01 VX/k9. Pr0tect1verat10= 3.6. Repr0duced w1th perm15510n fr0m Fundam. App1. 70x1c01. (17).
u5ed 1ar9e 4uant1t1e5 0f AChE pur1f1ed fr0m feta1 60v1ne 5erum (6.15) a5 a 5caven9er f0r VX (7aMe 1) and t0 50me de9ree a9a1n5t 50man. 7he5e re5u1t5 5u65tant1ated the hyp0the515 that AChE c0u1d 5erve a5 a pretreatment dru9/pr0phy1act1c a9ent t0 prevent 0 P p0150n1n9.7hey were a61e t0 pr0tect m1ce a9a1n5t appr0x1mate1y 3.5 LD50 0f VX w1th n0 apparent 519n5 0f c1a551ca1 0 P t0x1c1ty. 7w0 0ther 065ervat10n5 fr0m the5e 5tud1e5 were 0f 1mp0rtance: 1) 1n v1v0 1nh161t10n 0f ex09en0u51y adm1n15tered AChE 1n 6100d wa5 pr0p0rt10na1 t0 the am0unt 0f 0 P adm1n15tered a5 cha11en9e, a re5u1t c0n515tent w1th 1n v1tr0 exper1ment5, and 2) the am0unt 0f AChE re4u1red t0 pr0tect m1ce a9a1n5t VX wa5 c0n51dera61y 1e55 than t0 pr0tect a9a1n5t 50man [the LD505 (1M) 0f VX and 50man 1n m1ce are 56 and 577 nm01/k9 re5pect1ve1y]. Human 5erum 8ChE ha5 a150 6een dem0n5trated t0 c0nfer pr0tect10n a9a1n5t 50man p0150n1n9 1n m1ce wh1ch were pretreated w1th ex09en0u5 e5tera5e5 (2,3). Car60xy1e5tera5e 15 an examp1e 0f an end09en0u5 e5tera5e capa61e 0f 5e4ue5ter1n9 0P5 1n c1rcu1at10n. F0r examp1e, the t0x1c1ty 0f 50man appear5 t0 vary am0n9 d1fferent 5pec1e5 0f an1ma15 (14) and th15 var1at10n 15 attr16uted t0 the pre5ence 0f d1fferent am0unt5 0f car60xy1e5tera5e 1n the1r p1a5ma. 7he am0unt 0f 50man re4u1red t0 cau5e 1etha11ty para11e1ed the p1a5ma CaE 1eve15 1n the5e an1ma15.7he ev1dence f0r the 5e4ue5trat10n 0f 50man 6y CaE wa5 pr0v1ded 6y 5tud1e5 (4,5) 1n wh1ch the CaE 1nh161t0r, 2-(0-cre5y1)-4H- 1:3:2-6en20d10xaph05ph0r1n-2-0x1de (C8DP) (4) wa5 adm1n15tered t0 an1ma15 1n 0rder t0 1nh161t 5erum CaE pr10r t0 the adm1n15trat10n 0f 50man (14). 7he5e 5tud1e5 5h0wed that 5uch pretreatment 1ncrea5ed the t0x1c1ty 0f 50man (10wered the LD50) 1n an1ma15 1n pr0p0rt10n t0 the am0unt 0f CaE 1n the1r p1a5ma. 7a61e 2 5ummar12e5 the5e re5u1t5.1n add1t10n, m1ce were pretreated w1th 60th C8DP (2 m9/k9) and F85-AChE (257 nm01/ k9), and cha11en9ed w1th 50man. 7a61e 3 5h0w5 that the adm1n15trat10n 0f C8DP, a10ne, t0 m1ce reduced the LD50 0f 50man fr0m 620 nm01/k9 t0 53 nm01/k9. When m1ce were pretreated w1th F85-AChE, 1n add1t10n t0 C8DP, the LD50 0f 50man 1ncrea5ed t0 120 nm01/k9, thu5 y1e1d1n9 a pr0tect1ve rat10 0f 2.26. 1N v1v0 57A81L17Y 0F cH0L1NE57ERA5E5 1n 0rder f0r an en2yme t0 6e an effect1ve pretreatment dru9 f0r pr0tect10n a9a1n5t t0x1c c0mp0und5, 5uch a5 pe5t1c1de5 0r chem1ca1 warfare a9ent5, 1t 5h0u1d have a re1at1ve1y 10n9 ha1f-11fe 1n v1v0. 1n add1t10n, 1t5 therma1 5ta6111ty 0n pr010n9ed 5t0ra9e and 1t5 r0ute 0f adm1n15trat10n are 0f pr1me 1mp0rtance t0 1t5 u5efu1ne55 a5 an ant1d0te. 1t 5h0u1d 6e phy5101091ca11y and 1mmun01091ca11y c0mpat161e, and 6e ava11a61e 1n 1ar9e 4uant1t1e5.0ur 5e1ect10n
LD50 (p.9/k9)
5pec1e5 M0u5e Rat 6u1nea p19 Ra661t
125.0 116.0 32.3 22.8
2 m9/k9 C8DP
16 m9/k9 C8DP
LD50 % Decrea5e LD50 % Decrea5e (V.9/k9) w1thC8DP (p.9/k9) w1thC8DP 12.2 15.6 12.3 11.8
90 87 62 48
7.5 13.3 9.3 8.4
94 89 71 70
*C8DP wa5 adm1n15tered5C 1 h 6ef0re 50man (1M1. Repr0duced w1th perm15510n fr0m 70x1c01. Lett. (14). 0f the appr0pr1ate f0rm5 0f ch011ne5tera5e5, F85-AChE and human 5erum 8ChE t0 u5e a5 pretreatment te5t dru95 wa5 6a5ed 0n the fact that 60th the5e en2yme5 are 9106u1ar 1n f0rm, ea511y pur1f1ed fr0m 5erum, and are re1at1ve1y 5ta61e en2yme5 (6,15). 7he 1n v1v0 ha1f-11fe 0f F85-AChE 1n m1ce wa5 determ1ned 6y 1V 1nject10n and mea5urement 0f the 6100d en2yme 1eve1 0ver a per10d 0f 72 h0ur5 (16). 7he 5ame am0unt 0f en2yme wa5 a150 adm1n15tered 1P t0 c0mpare the r0ute5 0f adm1n15trat10n. 7he re5u1t5 5h0wn 1n F19. 1 1nd1cate that 6100d AChE 15 ma1nta1ned at a c0n5tant 1eve1 dur1n9 a per10d 0f 2-5 h, re9ard1e55 0f r0ute 0f adm1n15trat10n (7here 15 a fa9 0f a60ut 1.5 h after 1P 1nject10n 6ef0re the 6100d AChE 1eve1 peak5). A11 1n v1v0 0 P t1trat10n5 were c0nducted dur1n9 the per10d when the ex09en0u51y adm1n15tered AChE 1eve15 reached the1r p1ateau, there6y av01d1n9 the err0r5 1ntr0duced 6y var1at10n 1n 1eve15 due t0 c1earance 0f en2yme. C0n51dera61e en2yme act1v1ty wa5 065erved even after 72 h. 7he pr0f11e f0r c1earance 0f en2yme wa5 a60ut the 5ame u51n9 e1ther r0ute 0f adm1n15trat10n. 51m11ar re5u1t5 were 06ta1ned u51n9 human 5erum 8ChE 1n m1ce (2) and F85-AChE 1n marm05et5 and rhe5u5 m0nkey5 (7,8). 80th the5e en2yme5 have re1at1ve1y 10n9 ha1f f1ve5 and appear phy5101091ca11y c0mpat161e, pr06a61y 6ecau5e they 60th are 5erum pr0te1n5. 7he re1at1ve1y 510w c1earance 0f ChE5 fr0m 6100d 15 0f 9reater 519n1f1cance when 1t 15 c0mpared t0 the c1earance rate5 0f 0ther c1a551ca1 pr0phy1act1c and treatment dru95 5uch a5 car6amate5 and 0x1me5. F1na11y, 1t 5h0u1d 6e n0ted that ra151n9 the 6100d 1eve1 0f th15 en2yme m0re than a th0u5and-f01d d0e5 n0t appear t0 have any adver5e effect 0n a11 5pec1e5 0f an1ma15 te5ted. 1N v17R0 AND 1N v1v0 5701cH10ME7RY 0F 0P: 5cAvEN6ER 1N7ERAc710N Up0n 5u65tant1at10n 0f the hyp0the515 that ex09en0u51y ad7A8LE 3 EFFEC7 0F PRE7REA7MEN70F M1cE W17H c8DP AND F85-AchE 0N 50MAN 70x1c17Y 50man 70x1c1ty LD50 Pretreatment
1x9/k9
C0nf1dence L1m1t5
nm01/k9
N0ne +C8DP +C8DP + F85-AChE
113.0 9.6 21.8
( 9 4 . 6 - 135.2) ( 6 . 0 - 12.6) (17.9 - 25.0)
620 53 120
F85-AChE (257 nm01/k9) wa5 adm1n15tered 1P t0 9r0up 0f 5 m1ce 19 h0ur5 pr10r t0 adm1n15trat10n 0f C8DP (2 m9/k9). 7he an1ma15 were cha11en9ed 1M w1th 50man 0ne h0ur after C8DP adm1n15trat10n. C0nf1dence 11m1t5at p
