Download Potential Radiopharmaceuticals: Sm-153 & Re-186-Labeled Hydroxyapatite for Synovectomy and more Study notes Nuclear medicine in PDF only on Docsity!
RadionudideHalf-life(days)DecayEnergy(MeV)Range
in
(m)lssSm1.95V0.70 tissue
0.082.5196Au2.7I0.
0.413.6ireRe3.75‘I, . 0.143.7nap14.3p-1.707.9166Ho1.12571.
0.088.5165Dy0.0958@-
I
0.095.7soy2.7$—2.211.
ablation of inflamed synovium by means of an intra-artic
ular injection of a beta-emitting radionuclide (Table 1) in
colloidal or particulate form (2—18).This technique has
been used extensively in Europe for more than 25 yr. A
major problem associated with use of radiocolloids has
been excessive leakage (5%-.25%)ofradionucides (4) pos
sibly due to the relatively small size of colloids used. This
problem was partly overcome by using radioactive parti
des or aggregates that were 1—20@min size (19). Ferric
hydroxide macroaggregates (FHMA) were known to be
taken up by synovial tissue and metabolized by synovial enzymes (20,21). Extra-articular leakage of radionuclides
when labeled to FHMA was variable (1%—13%)(6). We
have recently shown that although radiolabeled FHMA
particles have significant advantages when compared to
colloidal preparationsfor radiation synovectomy, FHMA
may not be the ideal carriersystem for long-lived radionu
cides with low specific activities (22).
Recently, a number of radiolabeled microspheres
TABLE 1
RadionudidesProposedfor Usein RadiatiOnSynovectomy
Hydroxyapatite(HA),a naturalconstituentof bone,wasstudied
asa particulatecarnerforbeta-emittingradionuclidesinradiabon
synovectomy.PartideswereradiOiabeledwfth153@or lesRe
andtheirin @in@osafetywas investigatedfollowingintra-articular
injectioninto knees of normal rabbits and rabbits withantigen
inducedarthritis(AlA).Radiolabelingefficiencywasgreaterthan
95%; invifrostudiesshowedminimal(1%) lossofactMtyfrom partldes over a 6-day period with leaSm@1abeIedHA and about 5% lossof activityover a 5-day penodwithlesRe@IabeIedHA.
The total cumulativeextra-articularleakageof maSmover 6
days was 0.28% in normalrabbitsand 0.09% in AlA rabbits.
Leakageof 186Refromthepnt was3.05%overa 4-dayperiod
with80%of extra-articularactivityfoundintheurine.Histopatho
logicalevaluationoftreatedkneesshowedthatHApartidesare
distributedthroughoutthe synovium,embeddedin the syrxMal
fat pad.The easeand effidencywith whichthis HA earneris
labeled,coupledv@thobservedextremelylow leakagerates
fromthejo@r*,makeradiolabeledHApartidesanattractivecan
didateas a radiationsynovectomyagentfor evaluationin rheu
matoidarthritispatients.
J NucI Med 1993; 34:1536-
proximately 1% of adults in the United States have
definite or probable rheumatoid arthritis by current diag
nostic criteria (1). The major cause of pain, as well as
physical disability in these patients, is destruction of diar
throdial or synovial joints. This inflammatory response is modulated by synoviocytes, lymphocytes and macro
phages in the synovium. Radiation synovectorny is the
ReceWedO@ 27. 1992;rev@n acceptedApr@I , 1993. Forcorrespondenceorreprintscont@ShankarVallabhajosula,PhD,Associ atePrc1eSSOrOfR@OIOgy.Div.ofNudearMethane,MountSin@Med@Center, One GustaveL LevyPlace,NewYork,NV10029.
1536 The Journalof Nudear Medicine•Vol. 34 •No. 9 •September
Chemistry and Biological Behavior of
S amarium- 153 and Rhenium- 186-Labeled
Hydroxyapatite Particles : Potential
Radiopharmaceuticals for Radiation
Synovectomy
Marco Chinol, Shankar Valiabhajosula, Stanley J. Goldsmith, Michael J. Klein, Karen F. Deutsch,
Lori K. Chinen, James W. Brodack, Edward A. Deutsch, Barbara A. Watson and Andrew J. Tofe
Division ofNuclear Medicine, Long Island Jewirh Medical Center, New Hyde Park, New York,@Department of
Radiolo@/Nuclear Medicine and Depamnent ofPatholo@, Mount Sinai Medical Center, New YorlçNew York,@
Mallinckrodt Medical Inc., St. Louir, Missouri; and CeraMed Corporation, Denver, Colorado
(hr)‘56ReO4-lmRe@HEDP‘@Sm-cftrateUrine0—24OrganTkne
24— 48—
0.6Blood0-
48—720.
0.03Otherorgans7231.5Tctal
Leakage;3 days84.365.135.
TABLE 2
Extra-artlcularLeakage (%ID) of Non-HA Partide-Bound
RadioactMty:ControlStudiesin NormalRabbits
mixture was purged with additional N2 and then stirred for 60 mm
at roomtemperature.Contentsof the vial were transferredto a
15-mi centrifuge tube using 4-mi N2-purged saline to rinse. Radi olabeled particles were separated from free PseRe activity via centrifugation (8 mm at 1000 rpm) to determine labeling efficiency.
LabeledHA particleswere then resuspendedin 1—5ml of saline.
Samatium-153-HA. Samarium-153 was supplied by the Univer
sity of Missouri-ColumbiaResearchReactor (MURR)as 153Sm
chloridein 0.1 N HG (5.55-10.36GBq (150-280mCi) ‘53S@/@ng
Sm203).Preparationof 1535m-labeledHA particleswas done in
two steps. Preparation of 1535m-citrate was followed by incuba tion of 153Sm-citrate with HA particles. Samarium-153-citrate was prepared by adding sufficient citric acid monohydrate to the above ‘53Sm-chloridesolution to give a concentration of 15 mg/mt citric acid in 0.1 N HQ. The mixture was allowed to stand at room temperature for 30 mm.
TheHAparticleswerelabeledby adding250 @1(0.555GBq(
mCi)) of the above ‘53Sm-citratesolution to a vial containing 40
mgHA in750 @lofwater.Thevialwas sealedandcontentswere
gently agitated via rotation for 30 mis at room temperature. Ra
diolabeledparticleswere transferred to a 15-micentrifugetube
using4-misalineto rinse. Radiolabeledparticleswere separated
fromfree ‘53Smactivityvia centrifugation(8 mis at 1000rpm)to
determinelabelingefficiency.LabeledHA particleswere then
resuspendedin5 mlof salineandautoclavedfor20mmat 121°C.
InVitro Stability of RadIOIabOISdHA Particles
The in vitro stabilitystudieswere performedby incubating
labeledparticlesin2 mlofeithersalineordilutedhumansynovial
fluidat roomtemperature.Frozensynovialfluidwas diluted1:
with saline (to reduce viscosity). At various times (up to three half-lives of the radionucide), radiolabeled particles in the inca bating fluid were centrifuged at 1000rpm for 8 mm and activity in
the pellet and supernatantwas measured.Stabilityof the HA
particlesradiolabeledwith 1535mor iseReis shown in Figure2.
Animal Model
Normalrabbitsandrabbitswithantigen-inducedarthritis(AlA)
wereusedas modelsto evaluatetheinvivo stabilityandsafetyof
a z
w
0 Ui U.
5 10 II 20 25 30 35 40 45 50 55 SO
PARTICLE SIZE (microns)
FiGURE 1. Frequency(%)distributionof hydroxyapatitepartides as a functionof particlesize (pn@).
(23—25)were introduced as potential carriers of beta-emit
ting radionucides. These agents all exhibit unacceptable
extra-articular leakage of radionucides. Although radia
tion synovectomy appears to be efficacious, its safety is
suspect and the challenge to find an appropriate radiophar
maceutical still remains. We have developed a new class of
agents (26—28)for radiation synovectomy using particles made from hydroxyapatite (HA), a natural constituentof
bone and biologically compatible. In this report, we eval
uate the safety of 153Smand @Re-labeledHA particles in
normal rabbits and rabbits with antigen-induced arthritis
(AlA).
MATERIALSAND MEtHODS
Preparation of RadlopharmaceutPcals
HydroxyapatiteParticles. Spherical and porous hydmxyapatite
(HA) particlesvaiying in size between 15 @mand 40 @tmwere
suppliedby CeraMedCorporation(Denver,CO).Particleswere
prepared by initially forming a precipitate from the reaction of
Ca(NO3)@and(NH@)@PO@at highpH (29).Theprecipitatewas
suspended in aqueous solution and subjected to a spray-drying
process to produce HA particles of controlled size and range.
Relative size distribution of particles used in these studies is
showninFigure1.At least90%ofHA particleswereintherange
of2O-40 @m.
PJzenium-186-HEDP-HA. Radiolabeling of HA particles with two steps. Preparation of 1taRe@hydroxyethylidenediphosphonate
(HEDP)was followedby the incubationof lmRe@HEDPwith the
HA particles.
Rhenium-186-HEDPwas prepared by adding 1 ml containing
1.11GBq(30mQ) of aNa[1mRe]Re04solution(6.18—10.06GBq
(167-272mCi)‘@Re/mgNaReO4,(MallinckrodtMedical,Inc.,St.
Loins, MO) to a vial containing a @yophilizedmixture of
Na@HEDP(10mg),SnQ22H2O(3.5mg),andgentisicacid(3mg).
Theresultantsolutionwasautoclavedfor20mmat 121°C.Radio
chemical purity (labeling efficiency) of ltaRe@HEDPwas deter
minedby twodifferentITLC methods.Thefirstmethodused0.
M HEDPin salineon a silicagel ITLC to separatefree lseRe@
@ perrhenateand1@Re-HEDPfromreducedhydrolysediseRe
cies (Re02). The second method used methyl ethylketone (MEK)
on a silica gel ITLCto determinethe amountof free 1@Re
perrhenate in the preparation. Rhenium-186-labeled HA particles were prepared by sequential
additionof the followingmaterialsto a vialcontaining40 mgHA
particles: N2-purged saline (750 j.d), tmRe@HEDP (0.074—0.
GBq(2—3mCi), 100p1),20%Triton-X100in water(50 @d)and
SnCl,.@2H2O(100@LIofa 4 mg/mIsolution in N2-purged water). The
I
LabaledHydroxyapatitePartidesfor RadiatiOnSynovectomy•Chinolat al.^1537
3days(n=4)6days(n=6)Blood0.
0.0001Liver0.007 ±0.00020.0003 ±
0.0030.012±0.007Kidney0.004± 0.0010.002±0.001Lung0.001± 0.002Bone0.026 ±0.0010.010 ± 0.025Marrow0.001 ±0.0060.039 ±
0.004Muscle0.008 ±0.0010.006 ±
0.007Spleen0.0002 ±0.0140.008 ±
0.0001Lymph ±0.00010.0001 ± 0.0001Urine nodes0.0003 ±0.00010.0001 ± ±0.001Cumulative (total)0.004 ±0.0020.01 1 leakage0.05 ±0.020.09±0.
OrgansRe-HEDP
=4)2days4daysBlood0.020.03Liver0.010.02Kidney0.050.05Lung0.0030.00 HA (n
nodes0.00010.0003Urine .672.82Cumulative @totai) leakage1 .823.
TABLE 4
E@dra-ArticuiarLeakage (%ID) of 153O@In AlA Rabbits
TABLE 5
Extra-ArticularLeakage (%ID) of @Rein AlA Rabbits
pared to ‘53Sm-HA.At 5 days, there was 5% unbound
‘@Reactivity that increased to 20% by 9 days. In some
experiments (data not shown) it was observed that
‘53Sm-HAexhftited high stability in an initially acidic me
dium (pH 3) over a period of several days. The pH of the
medium, however, gradually increased during this period,
probably due to the natural buffering capacity of HA. Un
der extremely acidic conditions (pH 1-2), however, radio
labeled HA particles and HA itself, would not be stable.
Animal Studies and Control Studies
The extra-articularleakage of radionucides following
injection of radiochemicals (not bound to HA particles)
into kneejoints of normalrabbitsis summarizedin Table 2.
Results are expressed as the percent of injected dose (%ID)
in the total blood or total urine (collected during a 24-br
period). A larger amount of ‘@Reactivity (82%) was cx
creted in urine within 24 hr of administration of ‘@Re
perrhenate when compared to 53% of excreted activity
following the ‘@Re-HEDPinjection. In contrast, less than
5% of ‘53Smactivity was excreted in urine within 72 hr after ‘53Sm-citrateadministration. With ‘@Re,the total
leakage in urine and blood over a period of 3 days was
more than 65%of injected dose. Samarium-153-citrate,on
the other hand, exhibited a total ofonly 5%leakage in urine
and blood. Based on tissue distribution studiesand organ counting, 32% of the ‘53Smactivity was retained in the
body, of which a significant amount (25%)was found in
bone. These control studies show that more than 60% of
the ‘53Smactivity is retained within the joint spacewhile most of ‘@Reactivity leaks from the joint.
Joint Laakage Studies Samarium-153-HA Particles. The extra-articular leak
age of ‘53Smactivity following injection of ‘53Sm-HApar
tides into the knee joint is summarizedin Table 3 (normal
rabbits)and Table 4 (AlA rabbits). Total cumulative leak
ageinnormalrabbitsis0.16%in3 daysand0.28%in
days. In AlA rabbits, the extra-articularleakage is 0.05% in
3 daysand0.09%in 6 days.All organsshowedinsignificant
accumulation of ‘53Smactivity. The ‘53Smactivity that
leaked from the knee joint was mostly seen in liver and
bone.
PJzenium-186-HEDP-HA Particles. In a small pilot study
involving four AlA rabbits, the safety studies were per
formedwith ‘@Re-HEDP-HAparticles. Two animalswere
killed after 2 days and the other two after 4 days. The
results are shown in Table 5. The cumulative leakage in 2
days is 1.82%and in 4 days is 3.05%. Most ‘@Reactivity
that leaked from the knee joint (>80%) was excreted in
urine.
Histopathology
Histopathology of a normal rabbit knee is shown in
Figures 3A and 3B and that of an AlA rabbit is shown in
Figures 4A and 4B. The normal rabbit knee joint shows
(Fig. 3A) articular cartilage of normal thickness with
smooth surface and clean joint space. The ALA knee re
veals (Fig. 4A) a hypercellularsynovial pannus consisting
of vascularized fibroconnectivetissue, inflammatory cells and proliferative synoviocytesfilling the joint spaceover lying the articular cartilage and eroding it laterally.
@‘tA'r:‘@, g
FIGURE3. Hlstopathologyof a normal
rabbitkneejolnt (A) A sectionthroughthe distal femur showing articularcartlI@e of
normalthicknesswithsmoothsurtaceand
cleanjointspece(63x). (B)The detailof
normals@aI tuft at the marginof joint
capsuleshowk@ga fibrovascularcore that
hasan almostinapparentsynovialsurfece
lining.UnderneaththefreetuftIsa portionof
fibrousjoint capsulewith a similarthin layer of inapparentsynoviocytes(157x).
LabeledHydroxyapatitePartidesfor RadiatiOnSynovectomy•Chinolat al. 1539
@@ .@
FIGURE 4. Hlatopathologyof a rabbit kneewith AlA Infection.(A) A hypercellular s@aI pannuscon&stlngof vascularized
fibroconnectivetissue,Inflammatorycells
and proliferative syno@riocytesfining joint spsce @n9the articularcartilageand erod@gft laterally(63x). (B) Proliferationof fibrous tissue, blood vesselsand synovio cytes to cause Increasedthicknessof the s_ membrane. The synov@ vii also containan admixtureof acute and chronic Inflammatoryce@
The normal rabbit knee with HA particles is shown in
Figures 5A and 5B. The synovial fat pad (Fig. 5A) shows
deposits of HA particles. Figure 5B is a polarized photo
graph revealing moderately birefringent crystals of HA
particles lodged in the synovium. Figure 6A and 6B show
HA particles in the knee joint of a rabbit with ALA infec
tion. The patellar fat pad (Fig. 6A) has large, dark awe
gates of HA particles embedded throughout the synovium.
DISCUSSION
The HA particles used in this study appearto be a very
attractive carrier for use in radiation synovectomy. HA is
readily prepared from common chemicals and can be
formed into particles of the desired size range in a con
trolled process. HA is a natural substance known to be
biodegraded into calcium and phosphate ions. For many
years, it has been used successfully as a coating for im
plants in joint arthroplasty and for dental reconstruction.
This success is attributed to the biocompatibility of HA with soft tissue. Particles used in this study, however,
differ from those used in dental procedures in that these
particles are not subjected to a sinteringprocess that hard
ens and toughens material. Unsintered HA particles are
more susceptible to biological degradation.A recent study
in normal rabbits shows that HA particles are indeed to
tally biodegraded and are no longer present in rabbit knees
6 wk postadministration(18).
Radiolabeling of HA with ‘@Reand 153Smis simple to
perform and provides excellent yields of labeled particles.
The two-step procedure described herein (preparationof
an intermediate radiochemical, followed by labeling of the
hydroxyapatite particles) offers a fundamental advantage
over previous one-step reactions that have been used to
prepare radiocolloids. In the two-step procedure, the par
ticulate carrier can be carefully prepared and controlled to
FIGURE5. Normalrabbitkneewithhy
@ droxyapatite(HA)partides.(i@4The syncMal @ fat pad shows deposits of HA crystals (9.6x). (B) A polarizedphotographshows
moderatelybWeflingentcrystalsof HAparti
des lodgedin the syncMum(125x).
have desired properties(size, density, porosity, biodegrad
ability, etc.) before radiolabeling occurs; then the radiola
beling process can be independently optimized and con
trolled. In the one-step procedure, neither chemistry of the
particle formation or the radiolabelingprocess can be in
dependently controlled; the final product is always the
result of balancing and compromising conditions for parti
dc formation and radiolabeling.
The ‘53Sm-HAparticles demonstratehigh in vitro stabil
ity in either saline or synovial fluid up to several half-lives
of the radionucide. The ‘53Sm-HAparticles also exhibited
high stability at low pH (pH 3) over several days (unpub lished results). The 1@Re-HEDP-HA particles, however,
exhibit significantloss oflabel over time. The difference in
stability between the two labeled species can be attributed to the chemicalpropertiesof each radionucide. Samarium
is a basic oxide (i.e., it yields alkalinesolutions when added
to water) and such +3 elements tend to form insoluble hydroxides and phosphates at physiological pH. Since hy
droxyapatite itself is a natural buffer at around pH 7, sa
marium remains bound to the HA particle as insoluble
species and cannot be washed off the particle until the HA
particle itself dissolves. In vivo, any free ‘53Smbinds pre
dominantly and not to bone marrow.
Rhenium, on the other hand, is either an acidic or basic oxide depending on its oxidation state. Rhenium in the +41+5 oxidation state, as in Re-HEDP, is a basic oxide.
Therefore, as with samarium, rhenium remains bound to
the HA particle. Rhenium-HEDP, however, is only stable
in the presence of excess ligand and reducing agent. With
out these, rhenium is easily oxidized to the +7 oxidation
state, forming an acidic oxide. In aqueous media, these
elements tend to exist in anionic forms (e.g., perrhenate,
ReO@)which are soluble and mobile at physiological pH.
Thus, the ‘@Relabelwashes off the HA particleswith time
1540 The Journal of Nudear Medicine•Vol. 34 •No. 9 •September 1993
evaluationof two Yttrium-90particulateagents.JNuclMed 1989;30:1047-
9. WinstonMA,BluestoneR, CraccioloA III, BlahdWH.Radioisotope synovectornywith @P.chmmkphosphate, kinetic studies. I Nuci Med 1973;14:886—889. 10.OnettiCM,GuticrrezE, HiebaE, AguirreCR.Synovionhesiswith @P colloidalchroniicphosphatein rheumatoidarthritis.I Rheumatol 1982;9: 229-238. 11.HowsonMP,ShepardNL, MitchellNS. COllOidalChrolniCphosphate@P synovcctomyin antigen-inducedarthritis in the rabbit. Clin Otth Re! Res 1988;229@83-293. 12.SledgeCB,NobleJ,HnatowichDJ,KramerR,ShortkroffS.Experimental radiation synovectomyby ‘@‘Dyferric hydroxide macroaggregate.A@th Rheum19Th2th1334—1342. 13. SledgeCB,ZuckennanJD,ZatutskyMR.et al.Treatmentof rheumatoid synovitisof the knee with intraarticularh@ectionof dysprosium165-ferric hydroxidemacroawegates. Ajth Risewn1986;29:153—159. 14. SledgeCB,ZuckermanJD,ShOrtkrOffS, et at.Synovectomyoftherheu matoidknee usingintra-articularinjectionofdysprosium-165ferrichydrox ide macroaggregates.JBoneioint Swg 1987;69k970-975.
- Zuckerman3D, SledgeCB, ShortkroffS, VenkatesanP. Treatmentof antigen-inducedarthritis in rabbits with dysprosium-165-ferrichydroxide macroaweptee. I 0,11*Res 1989;7:50-60. 16. chinolM,VallabhajosulaS, GordonRE,KleinMi, GoldsmithSi. Hol mium-166-F1@IMA.@a newagent in radiationsynovectomy[Abstractl.JNucI Med 19893@h856. 17.aiinol M,VallabhajosulaS, ZuckermanJD,GordonRE,KleinMi,Gold smith SJ. Radiation synovectomy using Ho-166-FHMA in rabbits with antigen-inducedarthritis[Abstractj.JNucl Med 199031:780. 18. ShortkroffS, MahmoodA, SledgeCB,et al. Studieson Ho-166-labeled hydroxyapatite:a new agentfor radiationsynovectomy[Abstracti.INuci Med 199233:937. 19. NobleJ,JonesAG,DavisMA,SledgeCB,KramerRI, LivniE. Leakageof radioactiveparticle systems from a synovialjoint studied with a gamma camera: its applicationto radiationsynovectomy.I Boneloint Siug 1983; 65k381-389.
- Ball 3, ChapmanJA, MuirdenKD. The uptake of iron in rabbit synovial tissue following intra-articular injection ofiron dextran.JCeIIBIOZ 1964;22: 351—364.
- Muirden1W, Peace G, RogersK. aca@an@of ‘@Fe-1abeledeiythmcytes fromnormalandinflamedrabbitkneejointsAnnRheumDir 1%928:630-
- Qiinol M, Vallabhajosula S, Zuckerman 3D, Goldsmith SJ. Invivo stability of ferrichydroxidemacroaggregates(FHMA).Is it a suitablecarrierfor radionuclidesused in synovectomy?NuciMed Bid 199@,17:479-485.
- Mumper Ri, Mills BJA, Ryo UY, Jay M. Polymericmicrospheresfor radionucide synovectomy containingneutron-activatedHolmium-166.I NuciMed 199233:398-402.
- Ehrhardt GJ, LattimerJC, Day DE, StapletonJ. Evaluationof activable, degradable glass “Smmicrospheres for radiation synovectomy[Abstract@. INuciMed 199132:945.
- EhrhardtGJ, ZinnK, Jia W, Ctat. Microspheresof humanserum albumin labeled by a specific linker tecimok*j@ for use in radiation synovectomy [Abstract].INuci Med 199132:964.
- Qiinol M, VallabhajosulaS, GoldsmithSJ, Deutsth K, ChinenL, Deutsch E.Evaluationofnewradiopharmaceuticalsforradiationsynovectomy(RS) [Abstract].JNuclMed 1991;32:963.
- DeutschK, ChinenL, DeutschE, ChinolM, VallabhajosulaS, GOldsmith Si. The chemistiyof two new classesof agentsfor radiationsynovectomy [Abstracti.INuciMed 1991;32:945.
- BrodackJW, ChinenLK, DeutschE, DeutschKF. Studieson the radiola belingof hydrOxyapatiteparticlesfor use as radiationsynovectomyagents [Abstractj.JNUClMed 199233:980.
- Hayek E, Newesely H. Pentacalciummonohydroxyorthophosphate(by droxyapatite).Inoig Synth 1963;7:17.
- Dumonde DC, G@ynnLE. The production of arthritis in rabbits by an immunolo@ reactionto fibrin.Bri E*perPath 1982;43:373-380. 31. Steinberg ME, McCrae CR, Berselli PA, Cram B. Intra-articular5-fluorou racilin antigen-inducedarthritis.JBOneJOIU Suig 1@153A514-522.
- MaxonHR, ThomasSR, HertzbergVS. et aL Rhenium-186hydrwcyethyli dene diphosphonate for the treatment of painful osseous metastases. Semin NuciMed 199222:33—40.
1542 TheJournalof NuclearMedicine•Vol.34 •No.9 •September 1993
