PROCESS FOR INCREASING PHOSPHATIDYLCHOLINE IN VIVO

Abstract: Cytidine is administered to a patient in order to increase tissue levels of phosphatidylcholine (PC).

Description: PROCESS FOR INCREASING PHOSPHATIDYLCHOLINE IN VIVO BACKGROUND OF THE INVENTION This invention relates to a process for increasing the production of phosphatidylcholine (PC) by increasing a source of cytidine to a patient. Cell membranes contain large amounts of PC, and cells must synthesize additional PC in order to divide or to change their shape as happens when there is remodeling of the synapses made by nerve cells, or neurons. In neurolog¬ ical diseases, when parts of a neuron have been damaged, the ability of the neuron to survive and to resume its normal communications functions requires that it synthesize rela¬ tively large amounts of additional PC, in order to make additional cellular membranes. Examples of diseases associ¬ ated with damage to nerve cells include brain diseases like Alzheimer's Disease, Parkinson's Disease, strokes, the be¬ havioral and neurological syndrome seen after brain trauma and/or anoxia, and diseases of the peripheral nervous sys¬ tem, e.g., neuromuscular disorders such as myasthenia gra- vis, the post-polio syndrome, and the muscular dystrophies. Prior to the present invention, it has not been shown that purines or pyri idines which are substrates in normal metabolic pathways have been rate limiting factors in pro¬ ducing the characteristic products of these pathways. In addition, prior to the present invention, it has not been shown that supplementary cytidine in the blood can become available to the brain for use in metabolic pathways. Cytidine is an essential substrate in the formation of PC by the following normal metabolic pathway: Choline-^Phosphocholine + Cytidyl Triphosphate- Cytidyl Diphosphocholine + Diacyglycerol -- Phosphatidylcholine (PC) Since PC is the product of this metabolic pathway and since it is desirable to increase its production, particularly in those areas of the human body where nerve cell damage has occurred such as in the brain, it would be highly desirable to provide a means for increasing the activity of this path¬ way iri vivo. Prior to the present invention, it has been shown that cytidine-diphosphocholine is useful for providing choline to form acetyl choline ir__ vivo. This is shown, for example, in U.S. Patents 4,569,929; 4,609,647 and 4,624,852. Prior to the present invention, CDP choline has not been shown to be a useful source in_ vivo of a product other than choline. SUMMARY OF THE INVENTION This invention is based upon the discovery that when a source of cytidine is administered to a human patient, it can pass the brain-blood barrier and that the administered cytidine is capable of effecting an increase in the amount of PC which is produced by the normal metabolic pathway. ___ , _ P The source of cytidine can be administered orally such as in tablet, capsule or liquid form or parenterally by intravene- ous, intramuscular or subcutaneous injection. The process of this invention is useful for patients suffering from trauma or disease associated with malformed nerve cells in the brain or periphery. DETAILED DESCRIPTION OF SPECIFIC EMBODIMENTS In accordance with this invention, a pharmaceutically acceptable source of cytidine is administered to a patient either alone or with a pharmaceutically acceptable source of choline in order to increase brain levels of phosphatidyl- choline (PC) . It has been found that when cytidine is provided to neurons their production of PC can be increased, thus providing PC for forming nerve cell membranes. In addition, it has been found that the administered cytidine is converted to PC by the normal metabolic pathway which includes cytidine triphosphate and choline as substrates in the pathway. Accordingly, the source of cytidine can be administered alone to combine with endogenous choline in vivo, or can be administered together with a pharmaceuti¬ cally acceptable source of choline. Thus, the process of this invention is useful for repairing damaged brain nerve cells caused by either trauma, old age or a disease state. Representative brain disease states which can be improved in accordance with this invention are Alzheimer's Disease, Par¬ kinson's Disease, mania, ataxias including Friedreich'ε Ataxia, the post-stroke syndrome, the dyslexias, the behav¬ ioral and neurological syndrome seen after brain trauma and/ or anoxia and those involving the peripheral nervous sys¬ tems, e.g., neuromuscular disorders such as yasthenia gra- vis, the post-polio syndrome and the muscular dystrophies. Representative pharmaceutically acceptable sources of cytidine include cytidine, cytidine diphosphate, other cy¬ tidine phosphates, cytidyldisphosphocholine, and cytidine precursors like orotic acid, or uracil-containing compounds. The cytidine is administered so that a cytidine level of at least 4 to 200 nanomoles/ml and usually between about 6 and 50 n moles/ml is attained in the blood stream. For example, when administering cytidine in the form of cytidiphosphocholine (CDP choline) as capsules or tablets, suitable dosages of from about 20 mg and 10 g/day, prefer¬ ably between about 100 mg and 3 g/day taken in divided doses of 10 mg to 1 g/cap or tab. When the cytidine is adminis¬ tered in liquid form admixed with a conventional liquid carrier such as a sweetened elixer or the like from about 10 mg to 3 grams/15 ml, preferably between about 100 mg to 500 m grams/15 ml can be utilized. In a preferred form of this invention, the source of cytidine is CDP choline since it is also a source of choline which can be utilized in a normal metabolic pathway. When the cytidine is administered conco itantly with a source of choline, the choline can be administered as _- — choline salts or esters, such as the chloride bitartrate or stearate or the like, or as a compound that dissociates to choline, such as sphingomyelin, cytidine-diphospho-choline, an acylglycerophosphocholine, e.g., lecithin (PC) , lysoleci- thin, glycerophosphatidyl choline, mixtures thereof or the like. By the term acylgylcerophosphocholine as used herein is meant a compound of the formula: CH— FA 2 0 CH 2 - 0-P-OCH 2 CH 2 N(CH- j ) 3 0 wherein FA. and FA„ can be the same or different and are fatty acid residues having from 6-26 carbon atoms, usually 16-24 carbon atoms and can be saturated or unsaturated such as palmitic acid, stearic acid, oleic acid, linoleic acid, eicosapentaenoic acid, linolenic acid, mixtures thereof or the like. The fatty acid residues of the acylgylcerophospho¬ choline can be varied easily by reacting the acylgylcero¬ phosphocholine, e.g., a lecithin with phospholipase A. or A„ (to cleave one fatty acid residue) or then phospholipase B (when desired to cleave both fatty acid residues) and then reacting the cleaved compound with the fatty acid of choice. It is preferred to employ an acylglycerophosphocholine, e.g., lecithin as the choline source since it is not degraded in the gut in contrast to choline. The choline or compound that dissociates to choline is administered so that a choline level of at least about 2-30 nanomoles/ml and usually between about 10 and 50 n moles/ml is attained in the patient's blood stream. For example, when administering choline chloride in the form of capsules or tablets, suitable dosages are from about 1 to 30 g/day, preferably 3-20 g/day taken in divided doses 500 to 1000 mg/cap or tab. When choline chloride is administered in liquid form admixed with a conventional liquid carrier such as a sweetened elixer or the like, from about 1 to 10 grams/15 ml can be utilized. When utilizing lecithin in a liquid carrier, it is administered in amounts of between about 0.1 and 50 grams/-day. When lecithin is administered in granu¬ lar form, as a tab let or in a capsule, it employed in amounts of between about 0.1 and 100 g/day, usually between about 30 and 50 g/day. Normally, lecithin is not available as a pure compound and is available in admixture with other phospholipids wherein the lecithin (PC) comprises about 20-30 weight percent of the mixture. Thus, it is more accu¬ rate to specify phosphatidylcholine (PC) than "lecithin". The following example illustrates the present invention and is not intended to limit the same. _ -- EXAMPLE I To demonstrate that administering cytidine could in¬ crease brain levels of cytidine and cytidine- (5')-diphos- phate-choline (CDP-choline) , the immediate precursor for phosphatidylcholine synthesis, groups of six rats received cytidine (1 g/kg, ip) or placebo and were sacrificed after 1 hour. Brain cytidine levels in treated animals rose by more than 8-fold, and brain CDP-choline levels by about 50% (Figures 1 and 2) . To demonstrate directly that circulating cytidine is taken up into the brain, cytidine levels were measured in carotid arterial, and retroglenoid venous blood among rats receiving a peripheral infusion of cytidine at a constant rate of .018 ml/min in the first 5 minutes, .037 ml/min for the second 5 minutes and .052 ml/min for the third 5 minutes for a total of .536 ml/15 min. The concentration of cytidine in solution was 5 mg/ml and the total dose of cytidine was 2.5 mg. Cytidine levels were found in venous blood that had drained the brain to be about 60% of the levels in arterial blood about to enter the brain, regardless of absolute levels. (Figure 3) . To demonstrate that an increase in cytidine levels within blood or other extracellular fluid could enhance the production of membrane phosphatidylcholine, a stable line of neuroblastoma/glioma cells (NG 108-15) were incubated with tritiated choline, and with or without supplemental cytidine ___ ._, (25 μl-l) for 90 minutes, and then the newly-formed cellular tritiated CDP-choline was extracted and measured. CDP-cho¬ line is the immediate precursor for the phosphatidylcholine in membranes of neurons and other cells and its formation controls the production of phosphatidylcholine. Cells incu¬ bated with supplemental cytidine contained almost twice as much newly-formed CDP-choline as those incubated without cy¬ tidine (Figure 4) .

Claims: CLAIMS 1. The process for treating a human being afflicted with a condition associated with damaged brain nerve cells which comprises administering to the patient a pharmaceuti¬ cally acceptable source of cytidine to increase brain cyti¬ dine levels and blood levels of cytidine to between about 4 and about 200 n moles/ml. 2. The process of claim 1 wherein the source of cytidine is cytidyl diphosphocholine. 3. The process of claim 1 wherein the patient is administered a pharmaceutically accessible source of choline concomitantly with the administration of the cytidine.

Inventors: GROWDON JOHN H, LOPEZ G-COVIELLA IGNACIO, WURTMAN RICHARD J, GROWDON, JOHN, H., LOPEZ G.-COVIELLA, IGNACIO, WURTMAN, RICHARD, J.
Applicants: MASSACHUSETTS INST TECHNOLOGY, MASSACHUSETTS INSTITUTE OF TECHNOLOGY
Application year: 1988
Main classification: A61K31
IPC codes: A61K31, C07H19