Collection device for blood

Abstract: The present invention is a container assembly that includes a multi-layer coating composition and more particularly a multi-layer coating composition for rapid clotting of a blood sample. In addition, the present invention includes a barrier package for enclosing the container assembly.

Description: 1. Field of Invention The present invention relates to a method of promoting clotting of a blood sample in a container comprising a multi-layer coating composition, a container for promoting rapid clotting of a blood sample, a method for making said container and a receptacle comprising said container. 2. Description of Related Art Blood samples are routinely taken in evacuated collection tubes. One end of a double-ended needle is inserted into a patient's vein. The other end of the needle then punctures a septum covering the open end of the tube so that the vacuum in the tube draws the blood sample through the needle into the tube. Using this technique, a plurality of samples can be taken using a single needle puncture of the skin. Blood collected in evacuated tubes often must be clotted prior to clinical examination. It is desirable to form a dense clot as rapidly and completely as possible to facilitate clean separation of the clot from the serum layer by centrifugation. To achieve this, collection tubes frequently employ a clot activator. Typical activators are diatomaceous earth and particles of inorganic silicates, or biochemicals such as ellagic acid, thrombin and thromboplastin. Two types of activators, classified in the art according to the portion of the blood coagulation cascade stimulated, are conventionally employed. Particulate activators share a common biochemical mechanism of clot activation known as contact activation of the intrinsic pathway. Whole blood contains all of the necessary factors to cause clotting by the intrinsic pathway. Clot activation by the intrinsic pathway is surface area dependent, i.e. the time required to form a complete blood clot is dependent on the total number of activating surface sites per unit area on the activator surface relative to the volume of blood. Greater surface area, provided by finely divided particulate activators, leads to shorter clot times. Particulate activators are used in practically all commercial blood collection tubes and lead to dense, crosslinked clots that cleanly separate from the serum in a centrifuge. Clot formation, however, is relatively slow, and about 30-60 minutes are required prior to centrifugation. Typical particulate activators used commercially are silica impregnated in fabric, silica particles in small plastic cups or silicate particles applied to the tube wall in polyvinylpyrrolidone (PVP). The second type of clot activators induces clotting through a different part of the coagulation cascade known in the art as the extrinsic pathway. The extrinsic system relies on the presence of a substance not normally present in whole blood. Activation is biochemical in nature and is concentration dependent. Clot activation rates lead to clot formation in 10-20 minutes, but clots resulting from the extrinsic pathway are gelatinous in nature and do not cleanly separate from serum. EP-A-0628816 discloses a blood collection container containing a clotting enhancer which activated both the intrinsic and extrinsic pathways. The activators for intrinsic and extrinsic coagulation are applies to separate areas of the wall surface of the container. Alternatively, glass microspheres coated with an immobilized activator of the extrinsic coagulation pathway may be combined with unmodified microspheres as activators of the intrinsic pathway. Preferably the coated microspheres may be crushed whereby the native unmodified glass surface is exposed and the ratio of surface areas of intrinsic and extrinsic activating surfaces is 50/50. EP-A-0073551 discloses a blood collection container equipped with various reagents (e.g. coagulation activators) applied to pieces of substrate, e.g. paper. Potential disadvantages of the introduction of reagents into containers by coating of the internal surfaces are mentioned. There is a need for a blood collection tube with means for promoting clot acceleration of a blood sample which provides an enhanced rate of blood coagulation but which does not remain in the serum layer or become part of the clot or centrifugation, thus avoiding potential interference with clinical tests and which is impermeable to moisture ingress. SUMMARY OF THE INVENTION The present invention is a container with means for promoting clot acceleration of a blood sample. The container comprises a multi-layer coating of an intrinsic coagulation activator and an extrinsic activator. In particular the present invention relates to a container for promoting clotting of a blood sample obtainable by applying a layer of an intrinsic coagulation activator to an interior surface of the container, applying an extrinsic coagulation activator (36) onto the layer of the intrinsic coagulation activator. In a further embodiment the present invention relates to a method of promoting clotting of a blood sample in a container by activating the intrinsic and extrinsic pathways, comprising applying a layer of an intrinsic coagulation activator to an interior surface of the container, applying an extrinsic coagulation activator onto the layer of the intrinsic coagulation activator. Finally the present invention relates to a moisture impermeable receptacle comprising the container of the invention and a moisture absorbing material. Preferred embodiments of the invention become evident from the dependent claims. Preferably, the intrinsic coagulation activator is diatomaceous earth or ground silica. Most preferably, the intrinsic coagulation activator is ground silica. Desirably, the extrinsic coagulation activator is ellagic acid or a protein. Preferably, the extrinsic coagulation activator is thrombin, heparinase or fibrinogen. Most preferably, the extrinsic coagulation activator is thrombin. Desirably, the means for promoting clot acceleration is applied inside a container as follows: (a) mixing polyvinylpyrrolidene (PVP) and an intrinsic coagulation activator in water to form a first mixture; (b) spraying the first mixture onto the inner surface of the container; (c) drying the first mixture; (d) mixing an extrinsic coagulation activator with water to form a second mixture; (e) spraying the second mixture onto the first mixture; and (f) drying the second mixture. Preferably, the means for promoting clot acceleration is applied inside a container as follows: (a) mixing a water soluble surfactant with water to form a first mixture; (b) spraying the first mixture onto the inner surface of the container; (c) drying the first mixture; (d) mixing polyvinylpyrrolidene (PVP) and an intrinsic coagulation activator in water to form a second mixture; (e) spraying the second mixture onto the first mixture; (f) drying the second mixture; (g) mixing an extrinsic coagulation activator with water to form a third mixture; (h) spraying the third mixture onto the second mixture; and (i) drying the third mixture. Most preferably, the means for promoting clot acceleration is applied inside a container as follows: (a) mixing a water soluble silicone surfactant with water to form a first mixture; (b) spraying the first mixture onto the inner surface of the container; (c) drying the first mixture; (d) mixing polyvinylpyrrolidiene (PVP) and ground silica in water to form a second mixture; (e) spraying the second mixture onto the first mixture; (f) drying the second mixture; (g) mixing thrombin with water to form a third mixture; (h) spraying the third mixture onto the second mixture; and (i) drying the third mixture. In addition, the container with the intrinsic and extrinsic activators is provided in a moisture impermeable receptacle with a moisture absorbing material. The moisture impermeable receptacle with a moisture absorbing material maintains the integrity of the thrombin in the container. Since thrombin may degrade when exposed to high external humidity, the integrity for promoting clot acceleration of a blood sample with thrombin is found to be maintained in a moisture impermeable receptacle. Most notably, the present invention provides the means for promoting clot acceleration of a blood sample at a faster rate than when only silica is used. In addition, the present invention provides the means for promoting clot acceleration of a blood sample even when exposed to high humidity. DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view of a collection assembly. FIG. 2 is a cross-sectional view of the assembly of FIG. 1 illustrating the multi-layer coatings of the present invention. FIG. 3 is a perspective view of the assembly of FIGS. 1 and 2 in a pouch assembly. DETAILED DESCRIPTION The present invention may be embodied in other specific forms and is not limited to any specific embodiment described in detail which is merely exemplary. Various other modifications will be apparent to and readily made by those skilled in the art without departing from the scope and spirit of the invention. The scope of the invention will be measured by the appended claims and their equivalents. Referring to the drawings in which like reference characters refer to like parts throughout the several views thereof in FIG. 1, shows a collection assembly 10 comprising a sidewall 12 extending from an open end 16 to a bottom closed end 18 and a closure 14 . Sidewall 12 further includes an inner wall surface 28 and an outer wall surface 30 . As shown in FIG. 2, the multi-layer coating of the present invention is located on inner wall surface 28 of the assembly 10 . The multi-layer coating comprises a first layer 32 of a surfactant, a second layer 34 of an intrinsic coagulation activator and a third layer 36 of an extrinsic activator. First layer 32 comprises a water soluble silicone surfactant. Second layer 34 comprises ground silica and third layer 36 comprises thrombin. FIG. 3 shows the collection assembly in a pouch 50 . Within pouch 50 is a moisture absorbing material 54 . Collection assembly 10 is preferably of plastic, but may be of glass. Suitable plastics are polyvinyl chloride, polypropylene (PP) and polyethylene terephthalate (PET). If the collection assembly is impermeable to moisture transmission, then a pouch assembly is not necessary. However, when moisture penetration is a concern, the collection assembly may be placed within pouch 50 . It was found during testing of the present plastic collection assembly that when thrombin was used as an extrinsic activator, high levels of humidity caused degradation of the thrombin. Moisture penetrating the plastic receptacle walls was determined to be the causative agent. Thus, the present plastic collection device is most preferably packaged within an impermeable pouch containing a moisture absorbing material. Pouch 50 is preferably of an aluminum foil laminated with LDPE/OPET/adhesive/sealant. LDPE/OPET is a low density polyethylene/oriented polyethylene terephthalate. The layering provides mechanical protection of the foil, heat sealing and opening features. Pouch 50 is preferably packaged with moisture absorbing material 54 (desiccant) which may be of silica dioxide (silica gel) or moisture absorbing beads, rods, sheets, or sachets and which may incorporate warning colors and/or wording which appear when the moisture content exceeds a certain level. Pouch 50 may accommodate one or more collection assemblies. Example 1 This example demonstrates the improved clotting activity when the present invention is utilized. Fifteen (15) plastic tubes coated with a soluble silicone surfactant, PVP and ground silica and thrombin were used in this example as compared to glass control tubes that are untreated to show the comparative clotting efficacy of the present invention versus glass tubes. Blood was drawn into the tubes and the glass control tube and the plastic tubes of the present invention were mixed using 10 complete inversions and allowed to clot upright in a rack at room temperature. A stopwatch started as soon as mixing was completed, which was used to document the individual clotting time for each tube. Each tube was checked for clotting every 30 seconds by picking the tube up out of the rack and tilting slightly to assess the status of the blood sample. A blood sample is considered clotted when there is no more liquid movement of the blood sample noted. At this point for each tube evaluated, the stopwatch was stopped and the time noted in seconds was considered into clotting time of that individual sample. Acceptable clotting time in seconds for the glass control tube is less than 300 seconds (5 minutes). The results of this Example are reported in Table 1. Clotting Time in Seconds: Donor Glass Plastic 1 307 76 2 161 115 3 156 68 4 286 76 5 319 86 6 259 118 7 317 71 8 198 118 9 146 57 10 183 140 11 212 119 12 161 118 13 300 198 14 190 157 15 152 86

Claims: A method of promoting clotting of a blood sample in a container by activating the intrinsic and extrinsic pathways, comprising applying a layer of an intrinsic coagulation activator to an interior surface of the container, applying an extrinsic coagulation activator onto the layer of the intrinsic coagulation activator. The method of claim 1, further comprising the step of applying a layer of surfactant prior to applying the layer of the intrinsic coagulation activator. The method of claim 1, wherein the extrinsic activator is selected from the group consisting of thrombin, heparinese and fibrinogen. The method of claim 1, wherein the intrinsic activator is silica. The method of claim 2, wherein the surfactant is a water-soluble silicone surfactant. The method of claim 1, wherein the step of applying the layer of the intrinsic coagulation activator comprises mixing the intrinsic coagulation activator with polyvinylpyrrolidene, and spraying the mixture onto the inner surface, and wherein the step of applying the extrinsic coagulation activator comprises mixing the extrinsic coagulation activator with water, and spraying the mixture onto the layer of the intrinsic coagulation activator. A container (10) for promoting clotting of a blood sample obtainable by applying a layer of an intrinsic coagulation activator (34) to an interior surface of the container (10), applying an extrinsic coagulation activator (36) onto the layer of the intrinsic coagulation activator (34). The container of claim 7 obtainable by the further step of applying a layer of surfactant (32) prior to applying the layer of the intrinsic coagulation activator (34). The container of claim 7, wherein the extrinsic activator is selected from the group consisting of thrombin, heparinese and fibrinogen. The container of claim 7, wherein the intrinsic activator is silica. The container of claim 8, wherein the surfactant is a water-soluble silicone surfactant. The container of claim 7, wherein the step of applying the layer of the intrinsic coagulation activator (34) comprises mixing the intrinsic coagulation activator with polyvinylpyrrolidene, and spraying the mixture onto the inner surface, and wherein the step of applying the extrinsic coagulation activator comprises mixing the extrinsic coagulation activator with water, and spraying the mixture onto the layer of the intrinsic coagulation activator (34). The container of claim 7 being of plastic or glass. A method for making the container (10) of claim 7 comprising the steps of applying a layer of an intrinsic coagulation activator (34) to an interior surface of the container (10), applying an extrinsic coagulation activator (36) onto the layer of the intrinsic coagulation activator (34). The method of claim 14, further comprising the step of applying a layer of surfactant (32) prior to applying the layer of the intrinsic coagulation activator (34). The method of claim 14, wherein the extrinsic activator is selected from the group consisting of thrombin, heparinese and fibrinogen. The method of claim 14, wherein the intrinsic activator is silica. The method of claim 15, wherein the surfactant is a water-soluble silicone surfactant. The method of claim 14, wherein the step of applying the layer of the intrinsic coagulation activator (34) comprises mixing the intrinsic coagulation activator with polyvinylpyrrolidene, and spraying the mixture onto the inner surface, and wherein the step of applying the extrinsic coagulation activator comprises mixing the extrinsic coagulation activator with water, and spraying the mixture onto the layer of the intrinsic coagulation activator (34). The method of claim 14, wherein the container is of plastic or glass. A moisture impermeable receptacle (50) comprising the container (10) of any one of claims 7 - 13, and a moisture absorbing material (54).

Inventors: DUBROWNY NANCY, HARROP ANDREW JOHN, DUBROWNY, NANCY, HARROP, ANDREW JOHN
Applicants: BECTON DICKINSON CO, BECTON, DICKINSON AND COMPANY
Application year: 2001
Main classification: G01N33
IPC codes: G01N33, G01N1, B01L3