the present invention concerns a method of entrapping an active material in a particulate support material which is itself suspended in a water - immiscible material such as an oil . this invention is particularly advantageous where two incompatible active materials are to be used . each active can be entrapped separately and then a blend is made of the entrapped actives in the water immiscible material . if the actives are not soluble in the water immiscible material , the actives cannot leach from the carriers . since each of these entrapped actives is kept separate from the other , no cross - reactivity or other interaction can occur . while this is particularly advantageous if the two actives are incompatible , it also could be used where the actives , although compatible , are to be kept separate until they are removed from the water immiscible material . for example , it might be possible to have two monomers of a polymeric material , delivered to the same location , and only upon removal of the external water immiscible material or breakdown of the support materials can they interact to form the polymer . while the present invention can be used for aqueous soluble materials , it is particularly advantageous if the active to be entrapped is dispersible , but not soluble , in aqueous solutions . in this circumstance , the active is kept dispersed with the particulate support material until entrapped by the addition of the cross - linking agent . cross - linking agents for this procedure are soluble in the external phase , the water immiscible carrier , but not in the aqueous phase . aggregate size can be controlled by modifying the emulsion conditions and the cross - linking takes place only at the boundary of the phases . in contrast , many prior entrapping vehicles require that the active be aqueous soluble , not dispersible . the following example will more clearly illustrate the efficacy of the invention . the example is merely illustrative and should not be deemed limiting in any way . in this example , levamisole and closantel , which are incompatible anthelmintics used for animal treatment , were entrapped in a single two - component system . this system is particularly well adapted for use in animals such as sheep . levamisole , in the form of levamisole - hcl , is water soluble , while closantel - na is not soluble but rather is dispersible in aqueous solutions . these materials react if brought in contact , losing the efficacy of both . the levamisole and closantel are available from janssen pharmaceutica nv . vehicles entrapping these materials are made as follows . three stock solutions for use in making both vehicles are prepared first : solution a has 175 . 8 ml of soybean oil with 1 . 87 g of span 60 ( sorbitan monostearate ) dissolved therein by heating the solution for approximately 50 ° c . until it becomes clear . this water immiscible carrier solution is approximately 1 % by weight span 60 , which acts as a stabilizer . solution b is 10 % acetic acid in water . about 0 . 625 ml is used in making each vehicle . solution c is a 10 % manalox 130 ( rhone poulenc ) solution in soybean oil . manalox 130 is itself a 10 % solution of aluminum isopropoxide , yielding a final concentration of 1 % aluminum isopropoxide in soybean oil . about 12 . 5 ml of solution c is used in making each vehicle . the solutions of the two active materials are made as follows : solution d is 50 ml of a 1 % carboxymethylcellulose ( 9h4f from aqualon company ) in normal saline ( approximately 0 . 9 % weight ) to which 18 . 75 g of levamisole - hcl is added . solution e is identical to solution d except 25 g of closantel - na is added instead of the levamisole . two different procedures can be used which yield substantially the same results . in the first procedure , solution d or e is added to solution a , under agitation sufficient for dispersion into small particles , followed by the dropwise addition of solution b . the preferred procedure has solution b added dropwise to solution a before the addition of solution d or e . the combined solutions are homogenized by an overhead stirrer or a magnetic stirrer for at least five minutes , then solution c , the cross - linking agent , is added drop - wise while stirring and homogenizing . the stirring and homogenizing is continued at approximately 7 , 500 rpm for an additional 20 minutes . each of the two vehicles ( those containing the levamisole and the closantel ) are made separately . these vehicles in soybean oil may be kept separate or a combined product may be made by mixing equal amounts of the two materials . the combination product will contain approximately 37 . 5 mg / ml of levamisole - hcl and 50 mg / ml closantel - na . the foregoing example has also been tested with different amounts of each active , additional concentrations of cmc , different cross - linking agents and different dispersion methods . substantially the same results have been obtained in all of these procedures . the following claims more clearly define the invention . those skilled in the art may discover other examples which are equivalent to those shown herein . such other examples and procedures and encompassed within the following claims .
this invention concerns delivery vehicles entrapping active materials suspended in a water immiscible carrier . methods of making these materials , preferably using a carboxymethylcellulose support martrix , are disclosed . the vehicles of the invention are especially well adapted to delivery of incompatible actives that can be entrapped separately and kept separately until release from the vehicle .