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Tuesday

 

Cyanocobalamin low viscosity aqueous formulations for intranasal delivery: STUDY































Abstract

A stable pharmaceutical mercury-free aqueous solution of cyanocobalamin comprised of cyanocobalamin and water wherein said solution of cyanocobalamin is suitable for intranasal administration, has a viscosity less than about 1000 cPs, and wherein said solution of cyanocobalamin has a bioavailability of cyanocobalamin when administered intranasally of at least about 7% relative to an intramuscular injection of cyanocobalamin with the proviso that the solution is essentially free of mercury and mercury-containing compounds. The present invention is also directed towards a method for elevating the vitamin B12 levels in the cerebral spinal fluid (CSF) comprising administering intranasally a sufficient amount of a mercury-free cyanocobalamin solution so as to increase the average ratio of vitamin B12 in the CSF to that in the blood serum (B12 CSF/B12 Serum.times.100) to at least about 1.1 comprising intranasally administering an aqueous solution of a cyanocobalamin, wherein said solution of cyanocobalamin has a bioavailability of at least 7% relative to an intramuscular injection of a cyanocobalamin.


Description of the Invention

BACKGROUND OF THE INVENTION

Vitamin B12 is a dietary essential, a deficiency of which results in defective synthesis of DNA in any cell in which chromosomal replication and division are taking place. Since tissues with the greatest rate of cell turnover show the most dramatic changes, the hematopoietic system is especially sensitive to vitamin B12 deficiencies. An early sign of B12 deficiency is a megaloblastic anemia. Dietary B12, in the presence of gastric acid and pancreatic proteases, is released from food and salivary binding protein and bound to gastric intrinsic factor. When the vitamin B12-intrinsic factor complex reaches the ileum, it interacts with a receptor on the mucosal cell surface and is actively transported into circulation. Adequate intrinsic factor, bile and sodium bicarbonate (suitable pH) all are required for ileal transport of vitamin B12. Vitamin B12 deficiency in adults is rarely the result of a deficient diet; rather, it usually reflects a defect in one or another aspect of this complex sequence of absorption. Achlorhydria and decreased secretion of intrinsic factor by parietal cells secondary to gastric atrophy or gastric surgery is a common cause of vitamin B12 deficiency in adults. Antibodies to parietal cells or intrinsic factor complex also can play a prominent role in producing deficiency. A number of intestinal diseases can interfere with absorption. Vitamin B12 malabsorption is seen with pancreatic disorders (loss of pancreatic protease secretion), bacterial overgrowth, intestinal parasites, sprue, and localized damage to ileal mucosal cells by disease or as a result of surgery. The recommended daily intake of vitamin B12 in adults is 2.4 .mu.g.

There are four main forms of vitamin B12: cyanocobalamin: hydroxocobalamin, methylcobalamin and adenosylcobalamin. Methylcobalamin and adenosylcobalamin are unstable and damaged by light. They are therefore unsuitable for use in dietary supplements or pharmaceuticals and are not essential since they can be formed from cyanocobalamin or hydroxocobalamin within the body. The main form of vitamin B12 found in food is hydroxocobalamin. The main form used therapeutically and in nutritional supplements is cyanocobalamin, chosen because it is the most stable form and therefore easiest to synthesize and formulate.

Because deficiencies of vitamin B12 are generally caused by the inability of the vitamin to be absorbed in the small intestine due to a breakdown in the vitamin B12-intrinsic factor complex transport mechanism, vitamin B12 must therefore be administered systemically. Currently, therapeutic amounts of cyanocobalamin are administered by intramuscular or deep subcutaneous injection of cyanocobalamin. However, patients must return to the physician's office periodically to receive additional injections to maintain their levels of vitamin B12. However, an intranasal gel cyanocobalamin preparation, NASCOBAL.RTM. is currently being marketed in which cyanocobalamin is administered intranasally as maintenance vitamin B12 therapy. However, many patients find the consistency of the intranasal gel unpleasant and would prefer to have administered intranasally a low viscosity spray containing cyanocobalamin.

The prior art suggests that for vitamin B12 to be absorbed intranasally in therapeutically beneficial amounts, the concentration of the B12 in solution must either be greater that 1% by weight, see Merkus, U.S. Pat. No. 5,801,161 or be administered intranasally in a viscous gel, Wenig, U.S. Pat. No. 4,724,231 so that the gel remains in the nostril for an extended period of time. In fact Wenig states that B12 administered intranasally in a low viscosity solution is not in contact with the nasal mucosa long enough for a sufficient period of time to permit useful absorption. Wenig claims that most of the B12 is wasted if the solution has a low viscosity. Merkus developed intranasal formulations of hydroxocobalamin having a concentration of hydroxocobalamin greater than 1%, however hydroxocobalamin is not very stable and thus has a short shelve-life. Merkus chose hydroxocobalamin because cyanocobalamin is not soluble in an aqueous solution at concentrations greater than 1%.

U.S. Pat. No. 4,525,341, Deihl, discloses a method of administering vitamins intranasally but do not enable a specific formulation containing only cyanocobalamin. International Patent Application No. PCT/US86/00665, publication no. WO 86/05987, discloses nasal spray composition containing vitamin B12 as cyanocobalamin. However, the specific spray formulations all contained a mercury compound as a preservative, however the disclosure did require the presence of mercury compounds. Other preservatives were also mentioned including benzalkonium chloride and chlorobutanol. As was stated above, an intranasal gel containing cyanocobalamin, NASCOBAL.RTM., is currently being produced and marketed by Nastech Pharmaceutical Company Inc. of Bothell, Wash. It is very effective in maintaining levels of vitamin B12 for patients who have been deficient in the past but have recovered their levels of B12 through intramuscular injections. However, a number of patients find the consistency of the gel unpleasant in their nose, and would prefer an intranasal formulation that has a lower viscosity and is free of mercury compounds. Thus, there is a need to produce a pharmaceutically stable aqueous solution of cyanocobalamin that has a low viscosity, is free of mercury compounds and has sufficient bioavailability to be used as a maintenance therapy for vitamin B12.

SUMMARY OF THE INVENTION

The present invention fills this need by providing for a stable pharmaceutical solution of cyanocobalamin suitable for intranasal administration, having a viscosity less than about 1000 cPs, wherein said intranasal solution of cyanocobalamin has a bioavailability of at least 7% of the bioavailability of an intramuscular injection of cyanocobalamin and is free of mercury compounds.

A preferred formulation is comprised of cyanocobalamin, citric acid, sodium citrate, and water wherein the viscosity is less than 1000 cPs, and wherein the solution of cyanocobalamin has a bioavailability of at least 8%, more preferably at least about 9, 10, 11, or 12% of the bioavailability of an intramuscular injection of cyanocobalamin.

Preferred compositions within the scope of this invention will contain a humectant to inhibit drying of the mucous membranes and to prevent irritation. Any of a variety of humectants can be used including but not limited to sorbitol, propylene glycol or glycerol. A preferred humectant is glycerin.

A preservative is generally employed to increase the shelf life of the compositions. Examples of preservative include but are not limited to benzyl alcohol, chlorobutanol and benzalkonium chloride. A preferred preservative is benzalkonium chloride. A suitable concentration of the preservative will be from 0.002% to 2.0% based upon the total weight, although there may be appreciable variation depending upon the agent selected.

A most preferred formulation has the concentration of cyanocobalamin at 0.5% (percent of total weight), citric acid 0.12%, sodium citrate 0.32%, glycerin 2.23%, benzalkonium chloride 0.02% and 96.79% water.

Another embodiment of the present invention is a method for administering cyanocobalamin comprised of infusing the nose with an aqueous solution of cyanocobalamin, wherein the solution of cyanocobalamin has a viscosity of less than 1000 cPs, and wherein said solution of cyanocobalamin has a bioavailability of at least about 7% relative to an intramuscular injection of cyanocobalamin. Preferably, the bioavailability is at least 8%, 9%, 11% or 12%.

The present invention is further directed towards a method for elevating the vitamin B12 levels in the cerebral spinal fluid (CSF) comprising intranasally administering a solution of cyanocobalamin so as to increase the average ratio of vitamin B12 in the CSF to that in the blood serum (B12 CSF/B12 Serum.times.100) to at least about 1.1, wherein said solution of cyanocobalamin has a bioavailability of at least 7% relative to an intramuscular injection of cyanocobalamin. In a more preferred embodiment the B12 CSF levels are increased so that the ratio of B12 in the CSF to the levels in the blood serum is at least 1.9.

The methods of present invention are further comprised of the cyanocobalamin solutions being administered into a nose of an individual through an actuator tip as a spray, wherein the spray preferably has one or more of the following properties: a spray pattern ellipticity ratio of from about 1.0 to about 1.4 when measured at a height of 3.0 cm from the actuator tip; or the spray produces droplets, less than about 5% of the droplets are less than 10 .mu.m in size; the spray has a spray pattern major axis of about 35.3 mm and a minor axis of about 30.8 mm; 50% of the droplets produced by the spray are 26.9 .mu.m or less in size; 90% of the droplets produced by the spray are 55.3 .mu.m or less in size; or 10% of the droplets produced by the spray are 12.5 .mu.m or less in size.

DETAILED DESCRIPTION OF THE INVENTION

Nasal Administration of Cyanocobalamin

Cyanocobalamin is administered intranasally using a nasal spray according to the present invention. In this area the following definitions are useful. 1. Aerosol--A product that is packaged under pressure and contains therapeutically active ingredients that are released upon activation of an appropriate valve system. 2. Metered aerosol--A pressurized dosage form comprised of metered dose valves, which allow for the delivery of a uniform quantity of spray upon each activation. 3. Powder aerosol--A product that is packaged under pressure and contains therapeutically active ingredients in the form of a powder, which are released upon activation of an appropriate valve system. 4. Spray aerosol--An aerosol product that utilizes a compressed gas as the propellant to provide the force necessary to expel the product as a wet spray; it generally applicable to solutions of medicinal agents in aqueous solvents. 5. Spray--A liquid minutely divided as by a jet of air or steam. 6. Metered spray--A non-pressurized dosage form consisting of valves that allow the dispensing of a specified quantity of spray upon each activation. 7. Suspension spray--A liquid preparation containing solid particles dispersed in a liquid vehicle and in the foam of course droplets or as finely divided solids.

The fluid dynamic characterization of the aerosol spray emitted by metered nasal spray pumps as a drug delivery device ("DDD"). Spray characterization is an integral part of the regulatory submissions necessary for Food and Drug Administration ("FDA") approval of research and development, quality assurance and stability testing procedures for new and existing nasal spray pumps.

Thorough characterization of the spray's geometry has been found to be the best indicator of the overall performance of nasal spray pumps. In particular, measurements of the spray's divergence angle (plume geometry) as it exits the device; the spray's cross-sectional ellipticity, uniformity and particle/droplet distribution (spray pattern); and the time evolution of the developing spray have been found to be the most representative performance quantities in the characterization of a nasal spray pump. During quality assurance and stability testing, plume geometry and spray pattern measurements are key identifiers for verifying consistency and conformity with the approved data criteria for the nasal spray pumps.

DEFINITIONS

Plume Height--the measurement from the actuator tip to the point at which the plume angle becomes non-linear because of the breakdown of linear flow. Based on a visual examination of digital images, and to establish a measurement point for width that is consistent with the farthest measurement point of spray pattern, a height of 30 mm is defined for this study

Major Axis--the largest chord that can be drawn within the fitted spray pattern that crosses the COMw in base units (mm)

Minor Axis--the smallest chord that can be drawn within the fitted spray pattern that crosses the COMw in base units (mm)

Ellipticity Ratio--the ratio of the major axis to the minor axis

D.sub.10--the diameter of droplet for which 10% of the total liquid volume of sample consists of droplets of a smaller diameter (.mu.m)

D.sub.50--the diameter of droplet for which 50% of the total liquid volume of sample consists of droplets of a smaller diameter (.mu.m), also known as the mass median diameter

D.sub.90--the diameter of droplet for which 90% of the total liquid volume of sample consists of droplets of a smaller diameter (.mu.m)

Span--measurement of the width of the distribution. The smaller the value, the narrower the distribution. Span is calculated as -- see Original Patent.

Cyanocobalamin Nasal Spray Kit.

The present invention is further comprised of a cyanocobalamin nasal spray kit and method of administering the cyanocobalamin solution using the nasal spray kit.

The nasal spray kit is exemplified by FIGS. 1A, 1B and FIG. 2. FIGS. 1A and 1B show a nasal spray device 10 before engagement (FIG. 1A) and after engagement (FIG. 1B). The cyanocobalamin nasal spray kit, 10, is comprised of a container, in this case a bottle 12 into which the cyanocobalamin formulation is placed, and an actuator 14, attached to bottle 12 and in fluid connection with the solution of cyanocobalamin in bottle 12. When the actuator, 14 is actuated or engaged, it forces a spray plume, 16 of cyanocobalamin through tip 15 of the actuator. The spray plume is comprised of droplets of the solution of cyanocobalamin. A spray pattern is determined by taking a photograph of a cross-section of the spray plume 16 above a predetermined height, of the plume. The spray plume also has angle of ejection, 20, as it leaves actuator, 14. A spray pattern of spray plume 16 is shown on FIG. 2. The Spray pattern of FIG. 2, is elliptical and has a major axis, 24, and a minor axis 26.

In a preferred embodiment, the actuator produces spray of the cyanocobalamin solution having a spray pattern ellipticity ratio of from about 1.0 to about 1.4 when measured at a height of 3.0 cm from the actuator tip. In a preferred embodiment less than 5% of the droplets of the cyanocobalamin solution are less than 10 .mu.m in size, the spray pattern has a major axis and minor axis of 25 and 40 mm, respectively, 50% of the droplets are 26.9 .mu.m or less in size, 90% of the droplets are 55.3 .mu.m or less in size, and 10% of the droplets are 12.5 .mu.m or less in size.

As noted above, the present invention provides improved methods and compositions for intranasal delivery cyanocobalamin to mammalian subjects for treatment or prevention of a variety of diseases, disorders and conditions. Examples of appropriate mammalian subjects for treatment and prophylaxis according to the methods of the invention include, but are not restricted to, humans and non-human primates, livestock species, such as horses, cattle, sheep, and goats, and research and domestic species, including dogs, cats, mice, rats, guinea pigs, and rabbits.

An initial therapy, the patient should receive daily intramuscular injections of 100 .mu.g of cyanocobalamin for about 1 to 2 weeks, together with 1 to 5 mg of folic acid. Intramuscular injections of cyanocobalamin should not be greater than 100 .mu.g as doses in excess of 100 .mu.g are rapidly cleared from the plasma into the urine, and administration of larger amounts of vitamin B12 will not result in greater retention of larger amounts of the vitamin.

The cyanocobalamin nasal spray of the present invention is directed towards the maintenance of the hematological status of patients who are in remission following intramuscular vitamin B12 therapy. So instead of a once a month injection of 100 .mu.g of cyanocobalamin, using the cyanocobalamin spray, the patient self-administers a dose of the nasal spray of the present invention containing 500 .mu.g of cyanocobalamin once or twice a week. The maintenance therapy of the intranasal cyanocobalamin is for any patient that had been diagnosed with a vitamin B12 deficiency, but especially for those treated for pernicious anemia and dietary deficiency of vitamin B12 occurring in strict vegetarians, the so-called vegans who eat no animal products. Maintenance cyanocobalamin therapy using the cyanocobalamin solution of the present invention is also indicated for those afflicted with malabsorption of vitamin B12 resulting from structural or functional damage to the stomach, where intrinsic factor is secreted or to the ileum, where intrinsic factor facilitates B12 absorption. These conditions include tropical sprue and nontropical sprue (Idiopathic steatorrhea, gluten-induced enteropathy).

Maintenance cyanocobalamin therapy using the cyanocobalamin solution of the present invention is also indicated for those afflicted with malabsorption of vitamin B12 resulting from inadequate secretion of intrinsic factor, resulting from lesion that destroys the gastric mucosa (ingestion of corrosives, extensive neoplasia), and a number of conditions associated with a variable degree of gastric atrophy (such as multiple sclerosis, human immunodeficiency viral (HIV) infection certain endocrine disorders, iron deficiency, and subtotal gastrectomy). Structural lesions that lead to B12 deficiency include ileitis, ileal resections, Crohn's disease and malignancies. Vitamin B12 deficiencies may also be the result of competition by intestinal parasites, and inadequate utilization of vitamin B12 occurring if antimetabolites for the vitamin are employed in the treatment of neoplasia.

The intranasal cyanocobalamin solution of the present invention can also be used for individual who require above normal levels of vitamin B12, due to for example pregnancy, thyrotoxicosis, hemolytic anemia, hemorrhage, malignancy, hepatic and renal disease.

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