Oral fluid collection article

Abstract: The article (10), which fits in the mouth of a patient, includes a closed chamber (14) formed of a semi-permeable membrane (12) which allows saliva to pass therethrough but has pores (18) which filter out large particles or larger molecules, and a material (16) which creates an osmotic pressure inside the chamber (14), for drawing saliva from the buccal cavity of the patient into the chamber (14). The chamber (14) may itself be surrounded by an outer membrane (20) containing macroscopic pores (22).

Description: The present invention relates to the sampling of oral fluids from an individual. More particularly the present invention relates to a saliva and oral fluid collection article to be used in the buccal cavity of a patient. The sampling and testing of body fluids has long been used in the medical field to test and monitor the human body for various biochemical or physiological conditions or elements or just generally the state of health of a patient's body. Commonly, blood and urine samples are taken from patients for analysis to determine various levels of electrolytes, drugs, hormones, metabolites, or other physiologically revelant biochemicals of the body. Recently, it has been found that a person's oral fluids or saliva may also be analyzed to provide valuable information regarding various biochemicals. It has been found that for a large number of molecules, direct correlation exists between the concentrations of particular substances in blood with that contained in oral fluids or saliva and also the concentrations of substances in urine correlate with those contained in saliva. Therefore, recently saliva has become a more desirable medium for monitoring of hormones, drugs, metabolites, or other physiologically relevant biochemicals in clinical chemistry and related fields. The use of saliva as a testing medium is desirable since the saliva of a patient is readily available without the intrusive methods required in sampling of blood, by the use of syringes or other methods for instance, and without the undesirable nature of urine sampling which may cause other problems, such as monitoring of a patient while taking of a sample. Therefore use of saliva as a medium in biochemical and physiological analyses is desirable since it can be obtained by non-invasive methods. While it has been found that saliva can be advantageously used in the analysis of the body's biochemistry there remain problems in the collection of saliva and in the handling of saliva by laboratory technicians. For instance, saliva contains mucopolysaccharides which contribute to the highly viscous, stringy or sticky consistency which creates problems in pipetting and measuring of the saliva. There are also sampling and handling problems due to the presence of particulate matter in the form of oral squames which preferably must be removed before analysis. Additionally, food or other particulate matter in the mouth presents further undesirable handling problems in that the particles must be removed from the sample before analysis. In addition, the intake of food substances can drastically affect the consistency and the appearance of saliva for extended periods of time further increasing the variable consistency and requiring difficult processing prior to analysis. Moreover, conditions of food substances can interfere with the analysis of saliva for both qualitative and quantitive measurements. Variations in the consistency and contents of saliva also creates problems in its handling such that a centrifugal apparatus or other filtering or separation device must be used to separate and purify the sample from the undesirable particulate matter contained in the saliva prior to analysis. Additionally, the pipetting and measuring of saliva is difficult due to its stringy or viscous consistency. For these reasons, it is difficult for technicians to handle samples of saliva. The sampling of saliva from patients may create further problems in that it is hard to obtain the sample inconspicuously from a patient. For instance, in certain conditions if a patient knows that saliva is going to be collected this might have the adverse psychological effect of causing the patient's mouth bo become dry thus creating problems in taking of a saliva sample. Additionally, some patients may even be hesitant to agree to sampling of saliva in their mouth or to expectorate for various reasons. Saliva might contain large molecules or other components which might interfere with further analysis. For example, many hormones and drugs in saliva reflect the "free" component in blood, i.e. the fraction which is not bound to proteins. This fraction might constitute only a small percentage of the total amount ("bound" and "free") in blood. However, through small lacerations of the gum or the cheeks, blood, containing substances bound to protein(s), might enter the oral cavity and substantially increase the total concentration of substance to be analyzed. Thus, some "bound" substance might constitute a substantial amount of the total substance measured and be erroneous interpreted as "free". Thus, it is desirable to exclude larger molecules such as binding proteins. In another example, some enzyme proteins metabolize saliva components to metabolites. Thus, for accurate measurement of substances subject to enzymatic degradation, rapid and complete separation of enzymes from remaining fluid is required. US 4756314 describes a fluid collection patch typically for use in the collection of sweat. The patch comprises an impermeable backing body, suitably of rigid water impermeable polycarbonate, and a semi-permeable membrane, the backing body and the membrane defining a receptacle for receiving an absorbent pad. The pad is impregnated with an osmotically active material for drawing fluid across the membrane into the receptacle. The patch of US 4756314 has the disadvantages that the impermeable backing body is rigid, and correct arrangement of the patch for the collection of fluid is needed. Furthermore US 4756314 teaches that the patch should be provided with a contact adhesive. The use of such an adhesive would be detrimental to use of the patch in a patient's buccal cavity, potentially leading to problematic insertion into the cavity and debilitating a patient from carrying out oral functions, such as speaking, while the patch is retained in the cavity. The above disadvantages make the patch particularly unsuitable for use in a patient's buccal cavity, and we have now developed an oral fluid collection article which helps to alleviate the problems associated with the prior art. The present invention is concerned with fluid collection article comprising: a container defining an enclosed chamber, the container comprising a semi-permeable membrane having pores which are of a size to allow desirable fluid molecules to pass through, the pores acting as a filter for filtering out of larger undesirable particulate or molecular matter from a fluid; and osmotic substance means being disposed in the enclosed chamber for creating an osmotic pressure system inside of the chamber and for drawing fluid through the membrane and into said chamber and retaining at least a portion of the fluid in the chamber. According to the present invention, the container consists of the semi-permeable membrane, such that the membrane wholly defines the chamber, whereby the article is suitable for placement wholly within the buccal cavity of an individual so as to draw oral fluid from the cavity through the membrane into the chamber. Other features of the present invention will be apparent from the following description, in which reference is made to the accompanying drawings wherein: Figure 1 is a perspective view of an exemplary oral fluid collection article according to the present invention; Figure 2 is a cross-sectional view along line 2-2 of Figure 1; Figure 3 is a chart showing the relation of testosterone analyzed in a saliva sample directly sampled and that collected with an oral fluid collection article of the present invention; and Figure 4 is a chart showing the time dependent collection of oral fluid by means of an article according to the invention. Referring to Figure 1 there is provided an oral fluid collection article generally shown at 10. Oral fluid collection article 10 is preferably an ovoid small disc or pillow shaped article which is adapted to fit conveniently in the mouth of a patient. As shown more particularly in Figure 2, the oral fluid collection article 10 includes a semi-permeable membrane 12 which defines an enclosed chamber 14. An osmotic substance means 16 is provided which is totally enclosed by semi-permeable membrane 12. The fluid collection article 10 of the present invention is adapted for placement entirely in the buccal cavity of an individual all allows for collection and filtering of an oral fluid/saliva sample. The semi-permeable membrane 12 is made of a substance which has a plurality of pores which are of a suitable size to allow salivary fluid to pass therethrough but which pores 18 also act as a filter for filtering out unwanted particulate matter or larger molecules such as binding proteins from the sample. Osmotic substance means 16 is included inside the chamber 14 and is soluble in saliva thereby providing an osmotic pressure inside chamber 14 for drawing saliva from the buccal cavity of the patient into the chamber 14. After which time the semi-permeable membrane 12 will retain at least a portion of the fluid in chamber 14 for later removal by a technician for analysis. The osmotic substance means 16 in a preferred embodiment includes a crystalline or amorphous material which is soluble in saliva and will allow interference-free analysis of the saliva sample for whatever particular analysis is being undertaken. Alternatively, the osmotic substance means could comprise a high molarity solution of a crystalline or amorphous material which is dissolved in water or some other non-interferring solute. Of course, since the article of the present invention is for use in the buccal cavity of a patient, these materials should be nontoxic in nature and is possible should be palatable and may even be of a material which produces a pleasurable taste which may further increase the patient's salivation process. The material used may be a carbohydrate of small molecular weight which is biologically inert and which will be readily soluble in water and more particularly soluble in saliva. In a preferred embodiment of the present invention the crystalline material is glucose, fructose, or sucrose, however, other materials may be used which have the desirable characteristics as stated above. In another embodiment, the material might be a nontoxic polymer which creates an osmotic pressure by accommodating water molecules. The osmotic substance chosen must also be compatible with the analysis which is to be performed on the final sample, such that the substance chosen will not interfere with any testing being undertaken on the final saliva sample collected, since the sample will generally contain some of the osmotic substance 16. Whatever the osmotic substance 16 used, the substance must be soluble in saliva or accommodate water molecules, whereby saliva passing through the semi-permeable membrane 12 will dissolve the material or be accommodated by the material and produce a high molarity solution with the saliva and the osmotic substance 16 inside semi-permeable membrane 12. This will then produce an osmotic pressure system whereby the saliva from the outer portion of the semi-permeable membrane, i.e. the buccal cavity, will be drawn into the chamber 14 through the membrane 12 due to the difference in osmotic pressure on the inner side of the membrane and the saliva outside of the membrane thereby setting up an osmotic pump for drawing a saliva sample into the chamber 14. In some embodiments of the invention the solution inside the chamber 14 will be exchanged to the mouth of the patient. However, this exchange is not necessary for operation of the present invention a long as saliva is "pumped" into the chamber 14. The semi-permeable membrane 12 may be of any of a variety of semi-permeable materials. Preferably the material used is a cellulose film material. The pores 18 may be of any size which are of use for selectively filtering out undesirable materials while allowing desirable saliva molecules to pass through into the chamber 14 and allowing free exchange of the inner solution containing the osmotic substance from inside the chamber 14 into the patient's mouth. Thus the size of pores 18 may be controlled and selected according to the pertinent application to exclude larger molecules. In a preferred embodiment of the invention the semi-permeable membrane 12 is a 40 millimeter length of tubing having a 14.3 millimeter radius which is sealed at both ends. The tubing used is a CUPROPHAN dialysis tubing material. CUPROPHAN is a trademark of Enka, A.G. of Wupptertal, West Germany. The tubing material is sealed at both ends by tying with string or other means, preferably the semi-permeable membrane is formed as an ovoid or pillow shaped integral unit. The inner chamber preferably contains approximately 1-2 grams of sucrose. Shown in Figure 4 is the amount of saliva collected by the above described embodiment over periods of time. The quantity of sample collected is set forth on the absissa of the graph and the time required for sampling in minutes is shown on the ordinate. For this embodiment, a 4 milliliter sample of clear saliva is usually obtained in approximately five minutes as is shown by Figure 4. Thus the article of the present invention provides a sufficient sample in a reasonable period of time, which is relatively pure and ready for direct analysis. The sample collected in the article of the present invention is easily removed from the chamber 14 by use of a needle attached to a syringe or by other methods. Thus the sample can be transferred to suitable analytic equipment for desirable tests to be run on the sample. If desirable, the semi-permeable membrane 12 may be enclosed by an outer protective membrane 20 which includes macroscopic pores and is disposed about and completely enclosing the semi-permeable membrane 12. Outer protective membrane 20 is made of any material which would be generally pliable, tasteless, and nontoxic. Preferably the silicon materials or other materials such have a substantial mechanical strength which could protect the inner membrane from damage due to biting by a patient and similar hazards which may be associated with the use of the article of the present invention in a patient's mouth. The outer membrane 20 may be made of many materials whereby saliva easily passes through the macroscopic pores 22. Additionally, the article of the present invention may be practiced without the use of the outer membrane 20 wherein the inner membrane 12 is made of a material of a sufficient mechanical strength which will stand up to any hazardous problems which would be encountered within the mouth of the patient. The substance 16 may also include an amount of a citric acid or ascorbic acid as a gustatory stimulus. This amount may be approximately 1-2% of the weight of the glucose material used within the chamber 14. This will increase the salivary flow from an individual but will not increase the volume of the saliva within the chamber 14 which is totally dependent on the osmotic pressure created therein. The present invention is preferably formed in a ovoid shape or pillow shape, as shown in Figure 1, such that it will readily fit in the cheek of an individual. However, the shape may be varied according to the particular application to which it will be used. Thus, in the present invention an oral fluid collection device is provided which is easily sterilizable and can be formed to fit desirably in the cavities of the mouth, allowing patients to talk and carry on normally while fluid is being sampled from their mouths. In addition, use of the materials stated such as glucose, fructose, or sucrose would not interfere with assays for steroid hormones or drugs as two examples. Additionally, in the article of the present invention the saliva sample is filtered as it is collected wherein the undesirable material including oral squames and bound proteins are filtered out of the sample prior to entering the chamber 14. Figure 3 is a chart showing the correlation of levels of testosterone analyzed in a saliva sample directly sampled as shown on the ordinate and that collected with the oral fluid collection article of the present invention represented on the absissa showing a 90% confidence interval in the results obtained with the samples taken with the article of the present invention. Thus, as shown in Figure 3 the results of testosterone measurements in fluid obtained from the subject invention as disclosed herein are highly accurate as compared to the results obtained by commonly used procedures at the present time.

Claims: A fluid collection article (10) comprising: a container defining an enclosed chamber (14), the container comprising a semi-permeable membrane (12) having pores (18) which are of a size to allow desirable fluid molecules to pass through, said pores (18) acting as a filter for filtering out of larger undesirable particulate or molecular matter from a fluid; and osmotic substance means (16) disposed in said enclosed chamber (14) for creating an osmotic pressure system inside of said chamber (14) and for drawing fluid through said membrane (12) and into said chamber (14) and retaining at least a portion of said fluid in said chamber (14), characterised in that said container consists of said semi-permeable membrane (12), such that said semi-permeable membrane (12) wholly defines said chamber (14), whereby said article (10) is suitable for placement wholly within the buccal cavity of an individual so as to draw oral fluid from said buccal cavity through said membrane (12) into said chamber (14). An article (10) according to claim 1, further comprising an outer protective membrane (20), for protecting said semi-permeable membrane (12), said outer protective membrane (20) being disposed about and enclosing said semi-permeable membrane (12), said outer protective membrane (20) having macroscopic pores (22) for allowing said oral fluid to pass therethrough. An article (10) according to claim 1 or 2, wherein said osmotic substance means (16) comprises a crystalline material which is soluble in saliva, or an amorphous material which accommodates water, said osmotic substance means being such that it will allow interference-free analysis of the saliva sample. An article (10) according to claim 1 or 2, wherein said osmotic substance means (16) comprises a high-molarity solution of a crystalline or amorphous material, dissolved in water. An article (10) according to claims 1 or 2, wherein said osmotic substance means (16) comprises a low molecular weight carbohydrate. An article (10) according to claim 5, wherein said carbohydrate is crystalline. An article (10) according to claim 5 or 6, wherein said carbohydrate comprises one or more of glucose, fructose or sucrose. An article (10) according to claim 1 or 2, wherein said osmotic substance means (16) comprises a water-soluble non-toxic polymer, or a non-toxic material which accommodates water. An article according to any of claims 1 to 8, wherein said pores (18) are of a size which will filter out particles having a mass of about 23.34 · 10⁻²¹g (25,000 daltons) or greater, or of a mass which allows osmotic pressure to be created in said chamber. An article according to any of claims 1 to 9, which is adapted to conform to the contours of a patient's buccal cavity. An article according to any of claims 1 to 10, wherein said semi-permeable membrane comprises a cellulose film material.

Inventors: SCHRAMM WILLFRIED, SCHRAMM, WILLFRIED
Applicants: BIOQUANT INC, BIOQUANT INC.
Application year: 1989
Main classification: A61B10
IPC codes: A61F13, G01N33, A61B5, A61B10