Abstract:
The invention provides methods for treating or suppressing tobacco or nicotine usage or dependence involving administration of a therapeutically-effective amount of a cytosine-containing or cytidine-containing compound, creatine-containing compound, adenosine-containing, or adenosine-elevating compound to a mammal.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application claims benefit of U.S. Provisional Application No. 60/424,972, file Nov. 8, 2002, hereby incorporated by reference. 
    
    
     BACKGROUND OF THE INVENTION 
     This invention relates to methods for the treatment or suppression of tobacco or nicotine dependence or usage. 
     Substance abuse disorders present unique complications for patients, clinicians, and care givers. These disorders are difficult to diagnose unequivocally and fear of societal condemnation, as well as lack of simple and effective therapies, often results in patients who are reluctant to disclose their symptoms to health professionals, leading to adverse societal and health consequences. Substance abuse disorders, e.g., tobacco or nicotine usage or dependence, occur in people of all ages and backgrounds. 
     Use of substances such as tobacco or nicotine often leads to addiction and dependence on these substances, causing a variety of adverse consequences, including clinical toxicity, tissue damage, physical dependence and withdrawal symptoms, and an impaired ability to maintain social and professional relationships. The etiology of substance abuse or dependence is unknown, although factors such as the user&#39;s physical characteristics (e.g., genetic predisposition, age, weight), personality, or socioeconomic class have been postulated to be determinants. 
     Simple and effective pharmacological treatments for these disorders have proven scarce to date. It would be beneficial to provide pharmacotherapies suitable for administration to all populations, including the elderly and children, for the treatment of tobacco or nicotine dependence or usage. 
     SUMMARY OF THE INVENTION 
     In general, the invention features methods of treating or suppressing tobacco or nicotine dependence or usage by administering a therapeutically-effective amount of a cytidine-containing, cytosine-containing, creatine-containing, uridine-containing, adenosine-containing, or adenosine-elevating compound to a mammal. Any of the cytidine-containing, cytosine-containing, creatine-containing, uridine-containing, adenosine-containing, or adenosine-elevating compounds of the invention may be administered separately. 
     In preferred embodiments, the cytidine-containing compound is cytidine, CDP, or CDP-choline; the cytidine-containing compound includes choline; and the mammal is a human child, adolescent, adult, or older adult. In other preferred embodiments, the CDP-choline is administered orally and the administration is chronic, e.g., treatment occurring over a period of greater than 1, 2, 3, 4, 5, 6, 7, 14, 21, 30, 60, 90, or 180 days or even over a period of greater than one year. 
     In other preferred embodiments, a brain phospholipid (e.g., lecithin) or a brain phospholipid precursor (e.g., a fatty acid or a lipid), is also administered to the mammal. In other preferred embodiments, an antidepressant is also administered to the mammal. 
     By use of “tobacco” is meant use of any form of tobacco including cigarettes, cigars, and smokeless tobacco. 
     By “abuse” is meant excessive use of a substance, particularly one that may modify body functions. 
     By “dependence” or “dependency” is meant any form of behavior that indicates an altered or reduced ability to make decisions resulting, at least in part, from the use of tobacco or nicotine. Representative forms of dependency behavior may take the form of antisocial, or inappropriate behavior and include those behaviors directed at the desire, planning, acquiring, and use of tobacco or nicotine. This term also includes the psychic craving for tobacco or nicotine that may or may not be accompanied by a physiological dependency, as well as a state in which there is a compulsion to use tobacco or nicotine, either continuously or periodically, in order to experience its psychic effects or to avoid the discomfort of its absence. Forms of dependency include habituation, that is, an emotional or psychological dependence on tobacco or nicotine to obtain relief from tension and emotional discomfort; tolerance, that is, the progressive need for increasing doses to achieve and sustain a desired effect; addiction, that is, physical or physiological dependence which is beyond voluntary control; and use of tobacco or nicotine to prevent withdrawal symptoms. Dependency may be influenced by a number of factors, including physical characteristics of the user (e.g., genetic predisposition, age, gender, or weight), personality, or socioeconomic class. 
     By “treating” is meant the medical management of a patient with the intent that a cure, amelioration, or prevention of a disease, pathological condition, or disorder will result. This term includes active treatment, that is, treatment directed specifically toward improvement of a disease, pathological condition, or disorder, and also includes causal treatment, that is, treatment directed toward removal of the cause of the disease, pathological condition, or disorder. In addition, this term includes palliative treatment, that is, treatment designed for the relief of symptoms rather than the curing of the disease, pathological condition, or disorder; preventive treatment, that is, treatment directed to prevention of the disease, pathological condition, or disorder; and supportive treatment, that is, treatment employed to supplement another specific therapy directed toward the improvement of the disease, pathological condition, or disorder. The term “treating” also includes symptomatic treatment, that is, treatment directed toward constitutional symptoms of the disease, pathological condition, or disorder. 
     By “suppressing” is meant reducing the desire, need, or number of usages of tobacco or nicotine. 
     By “therapeutically-effective amount” is meant an amount of a cytidine-containing, cytosine-containing compound, a uridine-containing compound, a creatine-containing compound, an adenosine-containing compound, and an adenosine-elevating compound sufficient to produce a healing, curative, prophylactic, stabilizing, or ameliorative effect in the treatment or suppression of tobacco or nicotine usage or dependence. 
     By “cytidine-containing compound” is meant any compound that includes, as a component, cytidine, CMP, CDP, CTP, dCMP, dCDP, or dCTP. Cytidine-containing compounds can include analogs of cytidine. Preferred cytidine-containing compounds include, without limitation, CDP-choline and cytidine 5′-diphosphocholine, frequently prepared as cytidine 5′-diphosphocholine [sodium salt] and also known as citicoline. 
     By “cytosine-containing compound” is meant any compound that includes, as a component, cytosine. Cytosine-containing compounds can include analogs of cytosine. 
     By “adenosine-containing compound” is meant any compound that includes, as a component, adenosine. Adenosine-containing compounds can include analogs of adenosine. 
     By “adenosine-elevating compound” is meant any compound that elevates brain adenosine levels, for example, compounds which inhibit or alter adenosine transport or metabolism (e.g., dipyridamole or S-adenosylmethionine). 
     By “uridine-containing compound” is meant any compound that includes as a component, uridine or UTP. Uridine-containing compounds can include analogs of uridine, for example, triacetyl uridine. 
     By “creatine-containing compound” is meant any compound that includes as a component, creatine. Creatine-containing compounds can include analogs of creatine. 
     By “phospholipid” is meant a lipid containing phosphorus, e.g., phosphatidic acids (e.g., lecithin), phosphoglycerides, sphingomyelin, and plasmalogens. By “phospholipid precursor” is meant a substance that is built into a phospholipid during synthesis of the phospholipid, e.g., fatty acids, glycerol, or sphingosine. 
     By “child or adolescent” is meant an individual who has not attained complete growth and maturity. Generally, a child or adolescent is under twenty-one years of age. 
     By “older adult” is meant an individual who is in the later stage of life. Generally, an older adult is over sixty years of age. 
     The compounds utilized herein are relatively non-toxic, and CDP-choline, uridine, and triacetyl uridine, in particular, are pharmocokinetically understood and known to be well tolerated by mammals. The present invention, therefore, provides treatments that are likely to have few adverse effects and may be administered to children and adolescents, as well as the elderly, or those whose health is compromised due to existing physical conditions. 
     Other features and advantages will be apparent from the following description and the claims. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a graph of the effects of citicoline on tobacco use. 
         FIG. 2  is a schematic illustration of the molecular structure of CDP-choline. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     The invention described herein features methods for the treatment or suppression of tobacco or nicotine dependence or usage. 
     To this end, the invention features the use of cytidine-containing, cytosine-containing, uridine-containing, creatine-containing, adenosine-containing, and adenosine-elevating compounds to alleviate symptoms of these disorders. A preferred cytidine-containing compound is CDP-choline (also referred to as citicoline or CDP choline [sodium salt]), a preferred adenosine-containing compound is S-adenosylmethionine (SAMe), and a preferred uridine-containing compound is triacetyl uridine. 
     The cytidine-containing, cytosine-containing, uridine-containing, creatine-containing, adenosine-containing, or adenosine-elevating compounds may be co-administered with other compounds that are precursors for the synthesis of brain phospholipids, e.g., fatty acids, lipids, or lecithin. 
     Tobacco or Nicotine Usage or Dependence 
     Surprisingly, we have discovered that CDP-choline is useful for the treatment of tobacco or nicotine dependence or usage, and believe that other, related compounds may be similarly useful. Data in  FIG. 1  show that the administration of citicoline reduces the usage of tobacco (expressed as a number of cigarettes smoked per day) compared to usage by human subjects receiving a placebo. 
     Cytidine-Containing and Cytosine-Containing Compounds 
     Useful cytidine-containing or cytosine-containing compounds may include any compound comprising one of the following: cytosine, cytidine, CMP, CDP, CTP, dCMP, dCDP, and dCTP. Preferred cytidine-containing compounds include CDP-choline and cytidine 5′-diphosphocholine [sodium salt]. This list of cytidine-containing and cytosine-containing compounds is provided to illustrate, rather than to limit the invention, and the compounds described above are commercially available, for example, from Sigma Chemical Company (St. Louis, Mo.). 
     CDP-choline is a naturally occurring compound that is hydrolyzed into its components of cytidine and choline in vivo. CDP-choline is synthesized from cytidine-5′-triphosphate and phosphocholine with accompanying production of inorganic pyrophosphate in a reversible reaction catalyzed by the enzyme CTP:phosphocholine cytidylyltransferase (Weiss, Life Sciences 56:637–660, 1995). CDP-choline is available for oral administration in a 500 mg oblong tablet. Each tablet contains 522.5 mg CDP-choline sodium, equivalent to 500 mg of CDP-choline. Matching placebo tablets are also available. The excipients contained in both active and placebo tablets are talc, magnesium stearate, colloidal silicon dioxide, hydrogenated castor oil, sodium carboxy-methylcellulose, and microcrystalline cellulose. The molecular structure of CDP-choline [sodium salt] is provided in  FIG. 2 . 
     Other formulations for treatment or suppression of tobacco or nicotine usage or dependence may take the form of a cytosine-containing or cytidine-containing compound combined with a pharmaceutically-acceptable diluent, carrier, stabilizer, or excipient. 
     Adenosine-Containing and Adenosine-Elevating Compounds 
     Adenosine-containing or adenosine-elevating compounds also provide useful therapies. Useful adenosine-containing or adenosine-elevating compounds include, without limitation, any compound comprising one of the following adenosine, ATP, ADP, or AMP. One preferred adenosine-containing compound is S-adenosylmethionine (SAMe). 
     In addition, compounds are known that are capable of increasing adenosine levels by other mechanisms. For example, adenosine uptake can be inhibited by a number of known compounds, including propentofylline (described in U.S. Pat. No. 5,919,789). Another known compound that inhibits adenosine uptake is EHNA. 
     Other useful compounds that can be used to increase brain adenosine levels are those that inhibit enzymes that break down adenosine, (e.g., adenosine deaminase and adenosine kinase). Finally, administering compounds that contain adenosine or precursors of adenosine, which are released as adenosine in vivo, can also be used. 
     Uridine-Containing Compounds 
     Uridine and uridine-containing compounds provide useful therapies because these compounds can be converted to CTP, a rate-limiting factor in PC biosynthesis (Wurtman et al., Biochemical Pharmacology 60:989–992, 2000). Useful uridine-containing compounds include, without limitation, any compound comprising uridine, UTP, UDP, or UMP. A preferred uridine-containing compound is triacetyl uridine. Uridine and uridine-containing compounds and analogs are well tolerated in humans. 
     Creatine-Containing Compounds 
     Creatine and creatine-containing compounds provide useful therapies because these compounds, by virtue of increasing brain phospholipid levels, can raise the levels of ATP. Creatine and creatine-containing compounds are known to be well tolerated at relatively high doses in humans. 
     Administration 
     Conventional pharmaceutical practice is employed to provide suitable formulations or compositions for administration to patients. Oral administration is preferred, but any other appropriate route of administration may be employed, for example, parenteral, intravenous, subcutaneous, intramuscular, intracranial, intraorbital, ophthalmic, intraventricular, intracapsular, intraspinal, intracisternal, intraperitoneal, intranasal, or aerosol administration. Therapeutic formulations may be in the form of liquid solutions or suspensions (as, for example, for intravenous administration); for oral administration, formulations may be in the form of liquids, tablets, or capsules; and for intranasal formulations, in the form of powders, nasal drops, or aerosols. 
     Methods well known in the art for making formulations are described, for example, in “Remington: The Science and Practice of Pharmacy” (20th ed.) ed. A.R. Gennaro, 2000, Lippincott, Philadelphia, Pa. Formulations for parenteral administration may, for example, contain excipients, sterile water, saline, polyalkylene glycols such as polyethylene glycol, oils of vegetable origin, or hydrogenated napthalenes. 
     If desired, slow release or extended release delivery systems may be utilized. Biocompatible, biodegradable lactide polymer, lactide/glycolide copolymer, or polyoxyethylene-polyoxypropylene copolymers may be used to control the release of the compounds. Other potentially useful parenteral delivery systems include ethylene-vinyl acetate copolymer particles, osmotic pumps, implantable infusion systems, and liposomes. Formulations for inhalation may contain excipients, for example, lactose, or may be aqueous solutions containing, for example, polyoxyethylene-9-lauryl ether, glycocholate and deoxycholate, or may be oily solutions for administration in the form of nasal drops, or as a gel. 
     Preferably, the compounds of the invention, such as CDP-choline, are administered at a dosage of at least 500 mg twice daily by oral administration. Orally administered CDP-choline is bioavailable, with more than 99% of CDP-choline and/or its metabolites absorbed and less than 1% excreted in feces. CDP-choline, administered either orally or intravenously, is rapidly converted into the two major circulating metabolites, choline and cytidine. Major excretion routes are lung (12.9%) and urine (2.4%); the rest of the dose (83.9%) is apparently metabolized and retained in tissues. 
     In general, the compounds of the invention, such as CDP-choline, uridine, UTP, creatine, or SAMe, are administered at a dosage appropriate to the effect to be achieved and are typically administered in unit dosage form. The dosage preferably ranges from 50 mg per day to 2000 mg per day. The exact dosage of the compound may be dependent, for example, upon the age and weight of the recipient, the route of administration, and the severity and nature of the symptoms to be treated. In general, the dosage selected should be sufficient to treat or suppress tobacco or nicotine usage or dependence, or one or more symptoms thereof, without producing significant toxic or undesirable side effects. As noted above, the preferred route of administration for most indications is oral. 
     In the case of CDP-choline, there have been no reported cases of overdoses. CDP-choline toxicity is largely self-limiting, ingestion of large amounts in preclinical studies shows common cholinergic symptoms (salivation, lacrimation, urination, defecation, and vomiting). 
     Combination with Other Therapeutics 
     The cytidine-containing, cytosine-containing, uridine-containing, creatine-containing, adenosine-containing, and adenosine-elevating compounds of the invention may be administered as a monotherapy, in combination with each other, or in combination with other compounds for the treatment of substance abuse disorders, including compounds for the treatment or suppression of tobacco or nicotine usage or dependence, or other associated physiological or psychological conditions. 
     The compounds of the invention, may be administered in conjunction with lower doses of current treatments for these disorders, including stimulants and antidepressants. For example, the compounds of the invention may be administered with phospholipids, e.g., lecithin, or with brain phospholipid precursors, e.g., fatty acids or lipids, or may be administered as an adjunct to standard therapy for the treatment of substance abuse disorders. 
     In one particular example, the compound of the invention may be administered in combination with an antidepressant, anticonvulsant, antianxiety, antimanic, antipyschotic, antiobsessional, sedative-hypnotic, stimulant, or anti-hypertensive medication. Examples of these medications include, but are not limited to, the antianxiety medications, alprazolam, buspirone hydrochloride, chlordiazepoxide, chlordiazepoxide hydrochloride, clorazepate dipotassium, desipramine hydrochloride, diazepam, halazepam, hydroxyzine hydrochloride, hydroxyzine pamoate, lorazepam, meprobamate, oxazepam, prazepam, prochlorperazine maleate, prochlorperazine, prochlorperazine edisylate, and trimipramine maleate; the anticonvulsants, amobarbital, amobarbital sodium, carbamazepine, chlordiazepoxide, chlordiazepoxide hydrochloride, clorazepate dipotassium, diazepam, divalproex sodium, ethosuximide, ethotoin, gabapentin, lamotrigine, magnesium sulfate, mephenytoin, mephobarbital, methsuximide, paramethadione, pentobarbital sodium, phenacemide, phenobarbital, phenobarbital sodium, phensuximide, phenytoin, phenytoin sodium, primidone, secobarbital sodium, trimethadione, valproic acid, and clonazepam; the antidepressants, amitriptyline hydrochloride, amoxapine, bupropion hydrochloride, clomipramine hydrochloride, desipramine hydrochloride, doxepin hydrochloride, fluoxetine, fluvoxamine, imipramine hydrochloride, imipramine pamoate, isocarboxazid, lamotrigine, maprotoline hydrochloride, nortriptyline hydrochloride, paroxetine hydrochloride, phenelzine sulfate, protriptyline hydrochloride, sertraline hydrochloride, tranylcypromine sulfate, trazodone hydrochloride, trimipramine maleate, and venlafaxine hydrochloride; the antimanic medications, lithium carbonate and lithium citrate; the antiobsessional medications, fluvoxamine, and clomipramine hydrochloride; the antipsychotic medications, acetophenazine maleate, chlorpromazine hydrochloride, chlorprothixene, chlorprothixene hydrochloride, clozapine, fluphenazine decanoate, fluphenazine enathrate, fluphenazine hydrochloride, haloperidol decanoate, haloperidol, haloperidol lactate, lithium carbonate, lithium citrate, loxapine hydrochloride, loxapine succinate, mesoridazine besylate, molindone hydrochloride, perphenazine, pimozide, prochlorperazine maleate, prochlorperazine, prochlorperazine edisylate, promazine hydrochloride, risperidone, thioridazine, thioridazine hydrochloride, thiothixene, thiothixene hydrochloride, and trifluoperzine hydrochloride; the sedative-hypnotic medications, amobarbital, amobarbital sodium, aprobarbital, butabarbital, chloral hydrate, chlordiazepoxide, chlordiazepoxide hydrochloride, clorazepate dipotassium, diazepam, diphenhydramine, estazolam, ethchlorvynol, flurazepam hydrochloride, glutethimide, hydroxyzine hydrochloride, hydroxyzine pamoate, lorazepam, methotrimeprazine hydrochloride, midazolam hydrochloride, non prescription, oxazepam, pentobarbital sodium, phenobarbital, phenobarbital sodium, quazepam, secobarbital sodium, temazepam, triazolam, and zolpidem tartrate; the stimulants, dextroamphetamine sulfate, methamphetamine hydrochloride, methylphenidate hydrochloride, and pemoline; and the anti-hypertensive, clonidine. 
     OTHER EMBODIMENTS 
     All publications, patents, and patent applications mentioned in this specification are herein incorporated by reference to the same extent as if each independent publication or patent application was specifically and individually indicated to be incorporated by reference. 
     While the invention has been described in connection with specific embodiments thereof, it will be understood that it is capable of further modifications and this application is intended to cover any variations, uses, or adaptations of the invention following, in general, the principles of the invention and including such departures from the present disclosure that come within known or customary practice within the art to which the invention pertains and may be applied to the essential features hereinbefore set forth, and follows in the scope of the appended claims. 
     Other embodiments are within the claims.