[CANCER RESEARCH 42. 556-562, February 1982]0008-5472/82/0042-OOOOS02.00

Chlorpromazine Distribution in Hamsters and Mice BearingTransplantable Melanoma1

Ralph G. Fairchild,2 Dennis Greenberg, Karen P. Watts, Samuel Packer, Harold L. Atkins, Prantika Som,

Stephen J. Hannon, A. Bertrand Brill, Irwin Fand, and William P. McNally

Brookhaven National Laboratory, Associated Universities, Inc., Upton, New York 11973 [R. G. F., D. G., K. P, W., S. P., H. L. A., P. S., S. J. H., A. B. B.], andDepartment of Psychiatry and Behavioral Science, Stony Brook University, Stony Brook, New York 11 794 [l. F., W. P. M.]

ABSTRACT

Chlorpromazine (CPZ) distribution was measured in tissuesof Syrian golden hamsters bearing Greene melanoma and inBALB/c mice bearing Harding-Passey melanoma. Distribution

was evaluated as a function of time (0.5 to 14 days) and as afunction of single and multiple doses (up to five) of from 5 to50 mg CPZ per kg body weight. Routes of administration (¡.p.,i.V., p.o.) were compared. The physiological behavior of CPZis of interest as it is used extensively as a tranquilizing drug(Thorazine). Further, since CPZ binds to the pigment melanin,the possibility exists of using CPZ to transport diagnostic ortherapeutic agents to melanoma. It was found that, at 2 dayspostinjection, tumor/tissue concentration ratios exceeded 10for metabolizing organs, such as liver, and 100 for "background" tissues, such as blood and muscle. Absolute concen

trations of CPZ in tumor exceeding 100 ¡igCPZ per g tumorwere obtained with both single and multiple doses. This selective high concentration in tumor would make CPZ an idealvehicle for the transport of boron to tumor for use in neutroncapture therapy via the 10B(n,a)7Li reaction.

INTRODUCTION

The distribution of CPZ3 in tissues as a function of dose and

time is of interest as CPZ is used extensively as a tranquilizingdrug (Thorazine) (11). The high therapeutic index of CPZ allowsdaily doses in humans varying from 25 to 5000 mg (12). A lowpercentage of patients subjected to chronic high doses develops melanosis (3). CPZ, as well as other nitrogen-substituted

phenothiazines and related polycyclic aromatic compounds,binds to the pigment melanin. Pigmented tissues such aschoroid are known to accumulate CPZ and to retain it with abiological fVfe in the order of days, while a relatively rapidwashout is observed for other tissues (1,28). This physiologicaland selective localization of CPZ in pigmented tissues raisesthe possibility of utilizing CPZ to transport diagnostic or therapeutic agents to melanoma. In particular, the distribution ofCPZ is of interest as it might be used as a vehicle for thetransport of boron to tumors for NCT. Of the various polycyclicaromatic compounds of which the relative affinities for melaninhave been listed by Potts (29), CPZ is advantageous becauseits toxicity is well known and because a borated analog isdescribed in the literature (23).

' Work supported by National Cancer Institute Grant R01-CA22749 andUnited States Department of Energy Contract DE-AC02-76CH00016.

2 To whom requests for reprints should be addressed, at Medical Dept.,

Brookhaven National Laboratory, Upton. N. Y. 11973.3 The abbreviations used are: CPZ. Chlorpromazine; NCT, neutron capture

therapy: WBAR, whole-body autoradiography.Received March 30, 1981; accepted October 27, 1981.

Information is available regarding the early distribution (min)of CPZ (20) and for relatively low doses (5 mg/kg) out to 30days (28). Less is known about the uptake in tumors, as thisdepends upon pigment (melanin) concentration and dilutioneffects due to tumor growth. The only data on tumor uptake ofCPZ are those provided by Blois ef al. (1), but they were notcorrelated with melanin content or presented in terms of absolute CPZ concentration. Consequently, it was decided toquantitate CPZ uptake in animal melanoma models. Given theabsolute value of CPZ uptake, it then becomes possible toestimate its possible usefulness for transporting boron to tumors. A minimum of ~20 fig 10Bper g tumor is needed (9).

CPZ distributions were evaluated for single doses of from 5to 50 mg/kg. The higher level (50 mg/kg) approaches thevalue of ~70 mg/kg tolerated in daily doses by humans and

also the mean lethal dose of 125 and 115 mg/kg found forhamsters and mice, respectively4 (11). Multiple-dose distribu

tions were also investigated in order to measure the effects oftissue loading and to try to optimize tumor CPZ content as wellas tumor/tissue CPZ ratios.

Previous work has demonstrated that both Greene melanomain Syrian golden hamsters and Harding-Passey melanoma in

BALB/c mice are representative of human melanotic melanomawith respect to level of pigmentation (37). Thus, these 2 modelswere used. The distribution of CPZ is being evaluated in parton the assumption that information obtained might be applicable to a borated analog. It is recognized that the attachment ofa chemical moiety on a carrier produces a new compound, thephysiological behavior of which may be different. Nevertheless,the incorporation of nuclides into biochemicals or their precursors (such as halogenated pyrimidines and the labeling ofcertain proteins) has at times been successful (33).

At physiological pH, CPZ exists as a monoprotonated cation(13). The work of Larsson and Tjälve(16) indicated that non-

electrostatic forces are involved in the binding of CPZ tomelanin (i.e., a charge transfer reaction with melanin as theelectron donor). It is thought that binding is a property of thephenothiazine ring rather than the nitrogen side chain. Thus,additions, subtractions, and/or substitutions of diagnostic ortherapeutic elements on this chain may not adversely affectbinding. The distribution of CPZ as described in this papershould be useful in the evaluation of such CPZ analogs.

MATERIALS AND METHODS

CPZ. [35S]CPZ hydrochloride (r'/i>, 87.2 days) was used as obtained

from Amersham/Searle Corp. (Arlington Heights, III.) (radiochemicalpurity, 99%). Specific activity at the time of purchase was ~15 mCi/

4 R. Fairchild and S. Packer, unpublished data.

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CPZ Distribution in Various Tissues

mmol. High-dose-level studies of CPZ were carried out with lower-level

activity material such that absorbed doses to tumor (as calculated frommeasured count rates) were estimated to be <10 rads/day.

Animal Models. Previous work has shown that Greene melanoma inSyrian golden hamster (melanin content, ~0.4% by weight) and Hard-ing-Passey melanoma in BALB/c mice (~0.7% by weight melanin)

were representative of human melanotic melanoma with respect tomelanin content (0.1 to 0.9% by weight melanin; average, -0.35%).Further, the average melanin content of hamster whole eye (~0.45%

by weight) is analogous to that in human melanoma and may indeedserve as a more useful model of the latter which has a doubling time of—¿�42days (37). The rapid tumor volume doubling time of Greenemelanoma (-2 days) makes interpretation of long-term drug studiesdifficult. The longer and less variable doubling time of the Harding-

Passey model permitted acquisition of data which were much morereproducible with respect to CPZ uptake. Both models were used,however, in order to facilitate intercomparison with other work, as datafrom models have been reported extensively in the literature. Hamstersweighed -130 g; mice weighed -20 g.

Counting Procedures. Multiple tissue samples were taken whenpossible. Each data point represents the average of 3 to 4 animals.Tissue samples with wet weights between 100 and 200 mg wereprepared for liquid scintillation counting. A mixture of perchloric acid(70%) and hydrogen peroxide (30%) was used for wet oxidation ofsamples (18). Samples were counted in a Beckman LS 300 counter(Beckman Instruments, Inc., Mountainside, N. J.). The external standard method was used for efficiency correction. Correlation between theexternal standard and reduction in efficiency from chemical and colorquenching was made through experimental quenching curves obtainedfor each tissue type (internal standard method). Each experimentincorporates data from the same or adjacent tumor passages; nosignificant change in tumor characteristics (i.e., histológica! appearance, pigmentation, doubling time) was observed during the course ofthis work.

Dosage. Single and multiple doses (up to 5) of from 5 to 50 mg CPZper kg body weight were administered i.p. Routes of administration(P.O., i.v.) were investigated at low doses (5 mg CPZ per kg). Unlessotherwise noted (i.e., single-dose distribution as a function of time),

animals were sacrificed 48 hr after the last injection.WBAR. The technique described by Ullberg (36) and developed by

Fand and McNally (10) was used to produce WBARs of 30-nm sections

from tissues of BALB/c mice sacrificed at 6 and 48 hr postinjection of[35S]CPZ. Doses of 5 ng CPZ per g tissue were given i.v. with an

activity of 6 /zCi per 100 g.

RESULTS

Route of Administration. Clinically, CPZ is generally givenP.O., while with animal experiments (and in the present work),i.p. injections are often used for convenience. Tissue distribution in hamsters was measured at 2 days after injection of 5mg/kg. No consequential difference in distribution betweeni.p. and p.o. routes of administration was noted. Similarly, P.O.,i.p., and i.v. routes were investigated with BALB/c mice carrying Harding-Passey melanoma. Again, little variation was ob

served among routes. Uptake in analogous tissues of hamsterand mouse was found to be similar when results were expressed in terms of /ig CPZ per g tissue.

Single Dose as a Function of Time (Hamsters). CPZ distribution in various tissues is shown in Chart 1, from 0.5 to 14days (administered dose, 5 /¿gCPZ per g tissue; total dose,650 ftg). Excretion is seen to be mainly through the bladder;major accumulations occur in lung and liver. From these data,it is clear that 2 days should be allowed to elapse for CPZ toaccumulate in pigmented tissues and to clear other tissues. At

•¿�URINE•¿�EYE•¿�LUNGx LIVERa SPLEENo KIDNEYx MUSCLEûBLOOD

I 5 6 7 8 9 IO II I2 I3 I4DAYS POST INJECTION

Chart 1. CPZ distribution in hamsters for various times following single dosesof 5 /ig/g. Each point represents the average of 3 to 4 animals. Experimentalerror is similar to that shown in Tables 1 and 2; bars have been omitted forsimplicity.

2 days, most organs (with the exception of liver) are lower thanwhole eye by ~ 10-fold (liver lower by ~4-fold) with "background" tissues, such as blood and muscle, lower by ~100-

fold. Tumor uptake at 2 days averaged ~0.3%/g but varied by

factors of 2 between tumors, or between multiple samples ofthe same tumor, due in part to dilution effects caused by rapidand uneven growth.

As noted above, hamster whole eye has a melanin contentsimilar to the average value found for human melanotic melanoma. Thus, the value for eye in Chart 1 may be representativeof drug uptake in human melanoma. The tumor volume doublingtime for human melanoma of 6 to 7 weeks (25, 32) is "long"

compared to the study duration of 0.5 to 14 days, while therapid doubling time (~2 days) of Greene melanoma made data

beyond 2 to 6 days postinjection difficult to evaluate.Single-Dose Distribution as a Function of Dose Magnitude

(Hamsters). Percentage of uptake is shown in Chart 2 forinjected doses of 5, 25, and 50 fig/g (total doses of 650, 3250,and 6500 fig). The higher dose approaches the maximum dailydose advised for humans and the median lethal dose of ~120

mg/kg for i.p. injection in mice and hamsters. The medianlethal dose for p.o. administration would be 3-fold higher (11).

These data were obtained at 2 days postinjection in order toallow clearance from nonpigmented tissues as indicated in thetime distribution study. The effects of tissue loading are evident.As the injected dose is increased by a factor of 10, from 5 to50 mg/kg, the fraction taken up by pigmented tissues (eye,tumor) is reduced by ~25%, while the fraction taken up bynonpigmented tissues is reduced by a factor of 4. (Concomi-

tantly, the fraction in urine is seen to rise.)Clearly, the loading of pigmented tissues with CPZ would

best be accomplished by multiple large doses administered

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R. G. Fairchild et al.

every 2 days. Large doses would increase pigmented/nonpig-mented tissue ratios, while the 2-day wait would allow tissueclearance and reduce physiological trauma.

Multiple-Dose Distribution (Hamsters). In an effort to increase absolute uptake, the distribution following multipledoses was evaluated. Five doses of 50 fig CPZ were administered every 2 days, and 5 doses of 25 jug CPZ per g were givendaily. Results are displayed in Table 1 in terms of absolute CPZuptake. The molecular weight of CPZ hydrochloride is 355; thesodium salt of the borated compound described in Ref. 23would be 472 (twelve 10Batoms). Assuming a molecular uptake

of borated CPZ equivalent to CPZ, the uptake of boron can beestimated. Projected boron levels were obtained which areadequate for therapy in both Greene melanoma and whole eye(i.e., >20 jug 10Bper g tumor). To simplify comparison, results

<g

oo

0.00l

O.OI -

25 50CPZ DOSE (¿ig/g)

Chart 2. CPZ distribution in hamsters following single doses of 5, 25. and 50jig CPZ per g 2 days postinjection. Each point represents the average of 3 to 4animals. Experimental error is similar to that shown in Tables 1 and 2; bars havebeen omitted for simplicity. Absolute CPZ uptake is indicated numerically to allowdirect comparison with BALB/c mice.

Table 1CPZ distribution in hamsters following multiple doses

Five consecutive doses were given: 5 doses of 50 fig/g at 2-day intervals and5 doses of 25 «gg at 1-day intervals. Data were obtained at 24 hr following lasti.p. injection.

CPZ distribution Qjg/g for 5doses)TissueEyeTumorLiverSpleenKidneyLungMuscleBloodBrain50114

±17a(39)b59

±15(20)28.5±3.513.5±2.540±7.515

±2.02.1±0.47.8±

3.21.4 ± 0.42597

±10(33)38.5± 6.5(13)16±4.08.0±3.58.0±4.010±5.00.73±0.40.66±0.460.65± 0.25

were expressed in terms of percentage of dose per g in Charts1 and 2. Absolute uptake may be obtained directly by usinganimal weights of 130 g for hamsters (20 g for BALB/c mice).

Single- and Multiple-Dose Distribution (Mouse). Because of

persistent problems in obtaining reproducible results withGreene melanoma, another established model, the Harding-

Passey melanoma in BALB/c mice, was evaluated.Single-dose distributions measured at 2 days following i.p.

injection are given in Table 2 for 5, 25, and 50 ¡ng/g.Repro-ducibility of CPZ uptake in tumor was satisfactory, with experimental S.D.s similar to those of other tissues. At low doses (5jug CPZ per g), uptake in normal tissue was about the same forboth hamster and mouse (Chart 2; Table 2), while CPZ concentration in Harding-Passey melanoma was significantly

higher. At higher doses, tissue uptake increased per unit administered dose, indicating perhaps effects of reduced metabolic rate.

Multiple-dose distributions are shown in Table 2 for 5 doses

of 25 /ig CPZ per g (2 days between doses) and 3 doses of 25,50, and 50 jug CPZ per g, given every 2 days. Animals weresacrificed 2 days after the last dose. Projected borated CPZaccumulations in tumor are more than adequate for therapy.

WBAR. WBARs obtained following doses of 5 fig CPZ per gtissue are shown in Fig. 1; Fig. 1^ (6 hr) shows a fairlyubiquitous distribution as would be suggested from Chart 1.Early tumor distribution is nonuniform, while at 48 hr (Fig. 1S),activity is concentrated in the tumor with a fairly homogeneousdistribution in tumor. WBAR is a powerful technique whichallows visualization and quantitative evaluation of CPZ distribution among all organs as well as distribution within the organitself. When 35S radioactivity equivalents were measured den-

sitometrically in WBARs from the 48-hr animal, melanoma

tissue showed on average 11.6 times greater activity than didliver (Table 3). Absolute values may be obtained from Table 2.From the WBAR shown in Fig. 1 and the other WBARs studied,it is apparent that no tissues concentrate CPZ to the extentseen in the tumor.

DISCUSSION

Greene melanoma was evaluated as a model, because it hasbeen used extensively to test melanin-affinic diagnostic andtherapeutic agents5 (22, 27). Poor reproducibility of CPZ up

take was experienced repeatedly; tumor uptake variability exceeded experimental error in all other tissues. Variation inpigment concentration is not believed to be enough to accountfor this variable uptake (37). Tumor volume doubling timeswere found to vary from ~1 to 5 days during experiments; the

latter fact no doubt contributed to the observed variation inCPZ uptake, due to dilution effects. Such variability in doublingtime and in uptake of melanin-seeking agents has been ob

served by others with Greene melanoma (22, 27).While variability is expected in human clinical trials with

spontaneous neoplasms, such characteristics are not useful ina laboratory test system used to define limits and illuminatetrends.

It is felt that the improved reproducibility obtained with Harding-Passey melanoma makes this a more useful test system.

•¿�'Mean ±S.D.6 Numbers in parentheses, boron content (jig/g) projected from CPZ content.

5 B. K. J. Panwels (Netherlands Ophthalmic Research Institute. P. O. Box

4395, 1009 AJ, Amsterdam, The Netherlands), personal communication.

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CPZ Distribution in Various Tissues

Table 2

CPZ distribution in mice following single and multiple doses

Data were obtained at 48 hr following last i.p. injection. The interval between multiple injections was 24 hr.

TissueTumor

LiverSpleenKidneyLungMuscleBloodBrainEye58.5

±1.02 ±0.14 ±0.26 ±0.12 ±0.07 ±0.023 ±0.012 ±0.024 ±1

.2°(2.9)h

0.090.040.010.020.030.0020.0020.001Single

dot2555

±4.5±1.7

±1.0±0.42

±0.31 ±¡e

(fig/g)11

(19)0.40.40.20.15

0.09Multiple

dose(/ig/'g)133

11.07.75.01.14

0.87SO±±±

±±

±25

(5doses)15(45)

1.42.51.10.37

0.1192

7.153.552.371.90.240.30±

12(31)± 0.55± 0.55± 0.02± 0.02± 0.07± 0.1425,

50182

±11 .2 ±6.2 ±2.9 ±2.9 ±0.72 ±0.29 ±,5028

(62)0.60.20.10.10.080.02

a Mean ±S.D.' Numbers in parentheses, boron content (jig/g) projected from CPZ content.

Table 3Densitometric comparison of 35Sradioactivity in Harding-Passey melanoma and

liver tissue 48 hr after i.v. administration off^SJCPZ

Absorbance

Tumor Liver

0.861.161.060.941.19

X = 1.04

dpm/sq mm = 39.5s

0.110.090.100.10

0.10

dpm/sq mm = 3.4

a Determined by calibration technique described by Cross et al. (7).

Further, correlation of CPZ uptake with melanin content (Chart3) supports the thesis that CPZ uptake is proportional tomelanin content (26). Included in Chart 3 are data from B-16melanoma in C57/BL mice and hamster and mouse whole eye.Melanin contents are from Ref. 37. CPZ uptake in Greenemelanoma is evidently not consistent with the 4 other pig-mented tissues.

The accumulation of CPZ in pigmented tissues is accompanied by a rapid and almost complete clearance from blood anda washout from other (nonpigmented) tissues over a period ofa few days, as has been reported by others (1, 28, 35). At 2days, tumor/tissue ratios exceed 10 for metabolizing organs,such as liver, and 100 for background tissues, such as bloodand muscle. Thus, CPZ would appear ideal as a vehicle fordiagnostic or therapeutic agents. Dosing procedures involvedone to 5 doses at a concentration of 5 to 50 /tg/g every 2 days.These results are in general agreement with the work of Blois(1 ). In the latter case, a spontaneous tumor (doubling time, ~2

weeks) was used and produced CPZ uptakes in tumor equal tothat of whole eye (C3H mice). Tumor pigmentation was givenas twice that of C3H whole eye. Our work with C3H miceindicated an uptake in whole eye of 4.6 pg CPZ per g tissue foran injected dose of 5 /ig/g. (C3H mouse whole eye melanincontent = 0.4% by weight, Ref. 37.) This is consistent with

uptakes of 5.2 and 8.5 fig CPZ per g tissue for hamster wholeeye and Harding-Passey melanoma. Efforts with the original

tumor used by Blois revealed that, by the 57th passage, it hadlost its pigmentation (37).

While absolute uptake per g was similar for hamster andmouse at low doses, high doses produced effects of tissueloading for hamsters and an evident accumulation in mouse

O.I 0.2 0.3 0.4 0.5 0.6 0.7 0.8MELANIN CONTENT, % per gram

Chart 3. CPZ uptake in pigmented tissues from a dose of 5 ,«g.g. evaluatedat 2 days postadministration. Pigmented tissues are Greene melanoma and wholeeye from Syrian golden hamsters, Harding-Passey melanoma from BALB/c mice,B-16 melanoma from C57/BL mice, and C3H mouse whole eye. Melanin concentrations are from Ref. 37.

tissues due perhaps to reduced metabolic rate. Hamsters werefound to recover from high doses of CPZ (50 /ig/g) within 12to 24 hr, while BALB/c mice remained groggy at 48 hr.Particular sensitivity was noted in mice <6 weeks old. Datahere were from mice >10 weeks.

Route of administration experiments indicate p.o. administration would be preferable for clinical use, because toxicity isreduced without significant loss (i.e., less than ~20%) of ab

solute uptake. With animals, 2 days must elapse between highdoses to allow recovery and self-nourishment. The same re

striction would not necessarily obtain for human use. Significant reduction in sensitivity was obtained by predosing withone half-strength dose, as shown in Table 2, where maximum

uptake of CPZ was obtained.From the data given above, it follows that, if the borated

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analogs behave in the same way, the accumulation of CPZobtained in both Greene and Harding-Passey melanoma

models should be adequate for NCT.The consensus is that natural melanins are highly irregular

3-dimensional polymers made up mainly of indole units at

different oxidation levels with free radicals trapped in segmentsof the structure (2, 31). Melanin is thought to serve as anelectron trap (17, 19), while CPZ is an electron donor (14). Inthe presence of melanoproteins, CPZ has been found to forma radical ¡on(CPZ)+ (3, 5). It has been suggested that the

binding of CPZ to melanin is a result of a completed chargetransfer reaction between CPZ and the free radical of melanin(4, 16, 29). Studies with various substituted phenothiazineshave led to the assertion that the nature of the nitrogen sidechain or the position 2 substituent does not determine whetheror not storage in pigmented tissues occurs, and thus, bindingto melanin may be a property of the phenothiazine ring (28).

Melanin is known to be rich in metals such as zinc, copper,iron, and manganese (6). The strong affinity for metal ions hasbeen ascribed to electrostatic forces between the cations andanionic sites on the melanin polymer (presumably carboxylgroups) (16). Melanin cation affinity increases with the cationatomic weight. While there appears to be little or no affinitybetween melanin and cations of the alkali metals (15, 30), ona molar basis (jumol/mg melanin), heavy multivalent metalcations are bound to the same degree as CPZ. For example,the total binding capacity of melanin for Ni2+ and CPZ was

found to be 0.69 and 0.77 /imol/mg melanin, respectively (16).This is in basic agreement with the value of ~0.5 jumol CPZ per

mg melanin found by Potts (29) (based on 50% melanin permg pigment granules). Of the various metal ions investigated invitro, Gd3* is bound with the greatest avidity (15). The binding

of CPZ has been found to be predominantly nonelectrostaticand to occur at different sites than the metal ions, with differentassociation constants (16). Thus, heavy metal cations might bebound simultaneously with CPZ. 155Gd, 157Gd,or 149Sm[o(n,y)

= 61,000, 250,000, and 42,000 barns, respectively] would

make these isotopes prime candidates for both dose enhancement with neutron therapy and melanoma detection withprompt y analysis. 164Dy [o(n,y) = 2600 barns; 165Dy tVz =

2.35 hr; y = 95 keV] might allow conventional imaging.

If one can accumulate boron in tumor, irradiation with neutrons releases charged particles in tumor via the 10B(n,a)7Li

reaction. In such a circumstance, NCT would provide optimalconditions for radiotherapy, because the short range and highlinear energy transfer of the reaction products allow selectiveirradiation of tumor cells and a greater effectiveness againsthypoxic cells as the oxygen enhancement ratio is =1. A reviewof various high linear energy transfer "particle" beam radio-

therapeutic modalities has concluded that potentially, NCToffers a uniquely powerful system for cancer therapy (8).However, the consensus is that previous efforts with NCT havesuffered from borated compounds which failed to clear theblood (34). The possible advantage afforded by a boratedanalog of CPZ is based on its specificity and high concentrationin melanoma and its essentially complete clearance from blood.It has been demonstrated that CPZ provides differential andabsolute concentrations in melanoma which are more adequatefor therapy, assuming borated analogs behave similarly. Whilea borated analog of CPZ has been reported in the literature(21, 23, 24), attempts to make such a compound available in

this country have so far been unsuccessful. The possibility ofa robust 10B concentration coupled with a nearly complete

clearance from blood and other tissues would make continuedefforts to synthesize a borated CPZ analog of prime importance.

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Fig. 1. WBAR of BALB/c mice carrying Harding-Passey melanoma. CPZ dose was 5 ^g/g with a specific activity of 6 /iCi/100 g (i.V. injection). A, distribution 6hr postinjection; B, distribution at 48 hr.

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1982;42:556-562. Cancer Res   Ralph G. Fairchild, Dennis Greenberg, Karen P. Watts, et al.   Transplantable MelanomaChlorpromazine Distribution in Hamsters and Mice Bearing

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