by way of example only a procedure for the preparation of dysprosium - 165 hydroxide macroaggregates ( dy - 165 hma ) is given below . preparation of ( dy - 165 hma ) 1 . 35 mg of dysprosium oxide ( spectrographically standardised ) is neutron irradiated for 8 hours at a neutron flux of 5 × 10 12 n / s / cm 2 . 2 . the dysprosium oxide is transferred to a 10 ml wheaton vial containing a magnetic stirring bar . the oxide is dissolved in 5 . 8 ml of 0 . 1 n hcl with stirring and heating for 5 min to boiling . 3 . with rapid stirring , 1 . 2 ml of 0 . 5 n naoh is added as quickly as possible . 4 . the suspension is transferred to a 13 ml centrifuge tube , 2 ml of saline is added and the tube treated in an ultrasonic bath for 1 min . 5 . the suspension is subjected to 140 g in a centrifuge for 1 minute and the supernatent discarded . 6 . the dysprosium hydroxide is resuspended in 10 ml of saline and centrifuged for 1 min at 140 g . the supernatant is discarded . 8 . the dysprosium hydroxide is resuspended in 4 ml of saline and transferred to a 10 ml wheaton serum vial . 9 . after autoclaving at 132 ° c . for 6 min , the suspension is treated with ultrasonics for 1 min . the final preparation contains a dysprosium concentration in the range 6 - 7 mg / ml and a ph of 10 . 5 - 11 . 0 , resulting in a suspension having a dose rating of 4 . 5 - 5 . 5 gbq dy - 165 / ml at time of callibration . table 1 listes the distribution of particle sizes that have been measured for 10 batches of dy - hma prepared by the above method . the percent of activity on particle sizes was determined by counting the activity that would pass through nuclepore polycarbonate membrane filters . as can be seen from table 1 , dy - hma has the majority of particles in the 3 - 5 micrometer range . also listed in table 1 is the distribution of particle sizes when yttrium hydroxide macroaggregates ( y - hma ) are prepared by the same method . in this case 5 mg of yttrium oxide was used and was precipitated with 2 ml of 0 . 1 n naoh . with this method y - hma is prepared with the majority of particles in the 3 - 5 micrometer range ( table 1 ). table 1______________________________________percent of activity on particlesof dy - hma and y - hma % % % % & lt ; 12 um * & lt ; 5 um & lt ; 3 um & lt ; 0 . 45 um______________________________________dy - hma 97 - 99 65 - 89 0 . 7 - 1 . 5 & lt ; 0 . 01y - hma 98 - 99 90 - 98 1 . 0 - 2 . 0 & lt ; 0 . 01______________________________________ * micrometer a patient dose to the knee will require the injection of approximately 11 gbq of dy - 165 . to allow for decay time due to the handling and transport from the reactor to the patient , increasing volumes of the above formulation will need to be injected as the time increases . typical volumes for various transport times that are relevant for the australian situation ( for example ex sydney ) are listed in table 1 below . table 2______________________________________volume of injection correctedfor transport timetransport time volume ( hours ) ( ml ) ______________________________________5 16 . 3 1 . 57 1 . 810 5______________________________________ for an injection to the knee with a dose of 11 gbq of dy - 165 . biological studies in rats were performed in order to determine the leakage of radioactivity to other organs following an intra - articular injection of dy - hma in the knee joint . for these studies , natural dysprosium was used but spiked with a tracer level of the gamma emitting nuclide samarium - 153 . approximately 10 mbq / ml of sm - 153 was co - precipitated in the formulation . two groups of 3 healthy male rats about 300 gram were used in each experiment . after being anaesthetised with sodium pentabarbitone solution ( 30 mg / kg ) each rat was given an intra - articular injection in both hind knee joints of 10 microliter . the animals were replaced in their cages unrestrained and allowed to regain consciousness . at 6 and 24 hours post injection the groups were sacrificed for tissues samples by an overdose of a sodium pentabarbitone injection . the results of the biodistributions are given in table 3 ( 6 hours ) and table 4 ( 24 hours ). in both tables the average values for the 3 rats are also given . at 6 hours , 99 % of the injected dose still remains in the knee joint and the total skin value has the highest uptake of the activity that has leaked from the joint ( 0 . 83 %). the majority of remaining leaked activity is then observed in the lungs ( 10 . 1 × 10 - 3 %/ gram ) spleen ( 4 . 98 × 10 - 3 %/ gram ) and liver ( 2 . 48 × 10 - 3 %/ gram ). at 24 hours , 98 . 5 % of the injected dose remains in the knee joint with the total gastrointestinal tract ( git ) having the highest uptake of leaked activity ( 6 . 72 × 10 - 3 % / gram ). the majority of the remaining leaked activity is observed in the liver ( 3 . 39 × 10 - 3 %/ gram ) spleen ( 1 . 25 × 10 - 3 %/ gram ) 10 - 3 %/ gram ) and heart ( 1 . 12 × 10 - %/ gram ). experiment 2 : comparison of biodistributions in rabbits between dy - hma , dy - fhma and yttrium - 90 silicate colloid rabbits wer chosen for these studies since the large regional lymph nodes in the legs could be obtained and counted . the rabbits were injected in one knee joint according to the procedure described in experiment 1 . healthy rabbits of approximately 3 kg were used . the results of the biodistributions at 6 and 24 hours are listed in table 5 together with a comparison with literature results for dysprosium - 165 ferric hydroxide macroaggregates ( dy - fhma - hnatowich et al ., j . nucl ., med ., 19 , 303 - 308 , 1978 ). also in table 5 are given the biodistributions obtained when yttrium - 90 silicate colloid ( amersham : y - sc ) is used . for these strudies , tissue samples were dried in a hot air oven at 65 degrees c . for 1 day , 95 degrees c . for 1 day and then ashed at 250 degrees c . for two days . the ash was dissolved in 1 n hcl , diluted to 250 ml and aliquots taken , mixed with instagel and counted in a packard liquid scintillation counter suitable windows . at 6 hours , leakage to the lymph nodes with dy - hma is approximately the same as obtained with dy - fhma but less than half the leakage with y - sc . for the liver , dy - fhma gives the lowest leakage with dy - hma and y - sc being approximately 6 times higher . for the kidney , leakages with dy - fhma and y - sc are 30 and 170 higher than with dy - hma at 24 hours dy - hma produces significantly less leakage to all the organs studied . compared to dy - hma , dy - fhma and y - sc produce 2 and 6 times higher leakage to the lymph nodes ; 90 and 1100 times higher to the liver ; 500 and 1200 higher to the kidney and 3000 and 19 times higher to the blood , respectively . at 72 hours leakage with y - sc remains high in the lymph nodes and kidney . these experiments demonstrate that dy - hma produces significantly less leakage compared with both dy - fhma and y - sc . dysprosium - 165 hydroxide macroaggregates ( dy - hma ) can be readily prepared as a suspension in saline . typically , the product has a dy concentration of 6 mg / ml and a ph in the range 10 . 0 - 11 . 5 . the majority of particles are in the 3 - 5 micrometer range and there is a negligible amount of particles less than 0 . 45 micrometer . dy - hma can be autoclaved and is stable for at least twice the time it takes for the dy - 165 to decay to unusable levels . the formulation for dy - hma has significant advantages over the use of both dy - fhma and y - sc . the preparation is simpler and the absence of iron avoids any possibility of &# 34 ; iron shock &# 34 ; leakages to other organs are considerably reduced . y - hma can be prepared with the same formulation as dy - hma ( e . g . paricles size range , ph ) and is therefore expected to produce considerably reduced leakages similar to dy - hma . table 3______________________________________biodistribution in rats at 6 hours post injectionwith dy - hmaorgan average______________________________________ % injected dose ( l + r ) knees 98 . 1 98 . 9 99 . 7 99 . 0 ( l + r ) legs 0 . 20 0 . 01 0 . 02 0 . 04total carcass 0 . 06 0 . 06 0 . 03 0 . 05skin 1 . 55 0 . 90 0 . 05 0 . 83 % injected dose × 10 . sup .- 3 / grambrain 0 . 41 0 . 0 0 . 0 0 . 14total git 2 . 80 1 . 84 0 . 63 1 . 76urine + bladder 0 . 47 0 . 38 0 . 25 0 . 37blood 0 . 03 1 . 07 0 . 04 0 . 38heart 0 . 48 3 . 00 0 . 0 1 . 16lung 0 . 03 2 . 92 27 . 4 10 . 1kidney 0 . 18 2 . 91 0 . 83 1 . 31spleen 0 . 07 5 . 52 9 . 36 4 . 98liver 0 . 56 1 . 14 5 . 76 2 . 48______________________________________ table 4______________________________________biodistribution in rats at 24 hours post injectionwith dy - hmaorgan average______________________________________ % injected dose ( l + r ) knees 98 . 0 98 . 5 98 . 8 98 . 5 ( l + r ) legs 0 . 51 0 . 08 0 . 06 0 . 10total carcass 1 . 23 1 . 25 1 . 04 1 . 17skin 0 . 01 0 . 01 0 . 0 0 . 03 % injected dose × 10 . sup .- 3 / grambrain 0 . 02 0 . 58 0 . 98 0 . 53total git 12 . 08 3 . 98 4 . 17 6 . 72urine + bladder 0 . 69 1 . 67 0 . 37 0 . 91blood 0 . 03 0 . 04 1 . 18 0 . 42heart 1 . 03 0 . 49 1 . 85 1 . 12lung 0 . 53 0 . 10 0 . 02 0 . 22kidney 0 . 69 0 . 62 1 . 35 0 . 89spleen 0 . 07 0 . 92 2 . 75 1 . 25liver 4 . 08 4 . 49 1 . 61 3 . 39______________________________________ table 5__________________________________________________________________________comparison of biodistributions in rabbits betweendy - hma , dy - fhma and yttrium silicate colloid ( y -- sc ) time rab . lymph liver kidney blood__________________________________________________________________________dy - hma 6 3 0 . 83 4 . 3 0 . 9 0 . 024 ( 0 . 0 - 1 . 5 ) ( 0 . 0 - 12 . 9 ) ( 0 . 0 - 2 . 2 ) ( 0 . 0 - 0 . 63 ) dy - fhma 5 7 1 . 0 0 . 7 27 17 ( 0 . 0 - 3 . 3 ) ( 0 . 2 - 1 . 3 ) ( 5 - 83 ) ( 4 - 49 ) y -- sc 6 3 1 . 9 5 . 4 160 0 . 23 ( 1 . 0 - 1 . 5 ) ( 3 . 5 - 7 . 0 ) ( 123 - 209 ) ( 0 . 0 - 0 . 44 ) dy - hma 24 3 1 . 5 0 . 04 0 . 27 0 . 01 ( 0 . 0 - 3 . 5 ) ( 0 . 01 - 0 . 07 ) ( 0 . 0 - 0 . 50 ) ( 0 . 0 - 0 . 015 ) dy - fhma 24 5 3 . 0 3 . 7 140 34 ( 0 . 7 - 12 ) ( 1 . 7 - 6 . 3 ) ( 21 - 326 ) ( 4 - 77 ) y -- sc 24 3 8 . 9 44 332 0 . 19 ( 6 - 10 ) ( 5 . 117 ) ( 256 - 487 ) ( 0 . 02 - 0 . 45 ) y -- sc 72 3 11 . 3 2 . 7 70 0 . 31 ( 0 - 21 ) ( 1 . 6 - 3 . 3 ) ( 45 - 90 ) ( 0 . 0 - 0 . 93 ) __________________________________________________________________________ time : hours rab . : number of rabbits lymph : % injected dose × 10 . sup .- 3 liver : % injected dose × 10 . sup .- 3 / gram kidney : % injected dose × 10 . sup .- 3 for one kidney blood : % injected dose × 10 . sup .- 3 / ml dy - fhma : literature results , hnatowich , d . j ., kramer , r . i ., sledge , c . b ., noble j ., and shortkroff , s . journal nuclear medicine , 19 ( 3 ), 303 - 308 , 1978 .
a formulation is provided for the treatment of synovial inflammation , the formulation consisting of dysprosium - 165 hydroxide macroaggregates or yttrium - 90 hydroxide macroaggregates , wherein the formulation is substantially devoid of other co - precipitating agents in particular , ferric hydroxide . a method of treatment of synovial inflammation is also provided in which the method comprises adminstering an intra - articular injection of the above formulation . preferably the above formulation is in the form of a isotonic apyrogenic injectable solution .