COMBINATIONS OF PARASYMPATHOMIMETIC AGENTS WITH MUSCARINIC ANTAGONISTS FOR TREATING NICOTINE CRAVING IN SMOKING CESSATION

Abstract: A method for relieving craving in a nicotine-habituated patient and a composition for treating the patient is provided. The composition administered has a non-specific acethylcholine agonist and a muscarinic antagonist. A particularly preferred composition for relieving craving takes the form of a tablet where the first component is a water soluble physostigmine and the second component is a water soluble scopolamine. Patients treated have reported a slight increase in alertness and a diminished craving for nicotine.

Description: TREATING NICOTINE CRAVING IN SMOKING CESSATION Field of the Invention The present invention generally relates to treating smoking withdrawal symptoms, and more particularly. to a composition useful in relieving craving in a nicotine- habituated patient abstaining from or reducing nicotine intake. This invention was made with government support under The Veterans Administration and Grant No. H-22149, awarded by the National Institutes of Health. .The government has certain rights in this invention. Background of the Invention The statistical risk of dying from lung cancer in the United States has doubled in the past thirty years for male cigarette smokers and has quadrupled for female cigarette smokers. Lung cancer has now displaced cardiovascular disease as the single most important cause of excess mortality among smokers. Yet, about 50 million Americans continue to smoke. The benefits for smoking cessation are many, and are summarized in a publication entitled "The Health Benefits of Smoking Cessation: A Report of the Surgeon General, 1990", available from the Office on Smoking and Health, Center for Disease Control, Rockville, Maryland. Among the benefits summarized are that within twenty-four hours the chance of a heart attack decreases, within about two weeks to three months lung function increases up to thirty percent, and in one year the excess risk of coronary heart disease becomes half that of a smoker. Glassman et al. in an article entitled, "Cigarette Craving, Smoking Withdrawal, and Clonidine, " Science, 226, pp. 864-866 (November 1984), describes the craving developed for the tension-reducing drug, nicotine, in the absence of the drug and attributes the craving to the habituated user's experience of a rebound dysphoria. The habituated user thus seeks the drug to eliminate that dysphoria in order to treat, or relieve, craving when the person is attempting to abstain from or is reducing nicotine intake. Smoking cessation programs often address both the physiological (biochemical) factor and the psychological factor. Recently, "nicotine-releasing patches" have been highly advertised, and are presumably useful by maintaining a nicotine-habituated patient on nicotine while addressing the psychological factor. Methods that maintain a patient on nicotine do not provide a- long term solution to the problem. For example, there are now a number of -patients addicted to nicotine containing gum, some of whom are seeking treatment for their new or substitute addiction. Glassman et al., Science, 226, pp. 864-866 (1984) describe use of clonidine or alprazolam in diminishing withdrawal symptoms when fifteen heavy smokers abstained from cigarettes. The authors suggest that noradrenergic activity may be a common feature in the pathophysiology of withdrawal and that a special relationship may exist between central noradrenergic activity and craving. The authors noted that previous studies of smoking withdrawal syndrome had shown that craving is the most consistently observed withdrawal symptom. U.S. Patent 4,788,189, issued November 29, 1988, inventor Glazer, suggests administering clonidine hydrochloride with an imipramine derivative in a method to treat smoking withdrawal symptoms. Clonidine is clinically used as an antihypertensive while imipramine is an antidepress nt. U.S. Patent 4,555,397, issued November 26, 1985, inventor Bachynsky, describes subcutaneously injecting a patient during an initial office visit with a composition containing atropine, scopolamine, and chlorpromazine. Following the initial office visit and treatment,* the patient is placed upon oral dosages of predominately centrally acting anticholinergic drugs (such as scopolamine by patch administration) . Atropine and scopolamine are alkoids that block the action of acetylcholine at muscarinic receptors to produce antispasmodic, antisecretory, and antiparkinsonism actions. Scopolamine (sometimes also called "hyoscine") -is a powerful suppressant of salivation (as is atropine), and. is effective in the prevention and control of motion sickness. Physostigmine (sometimes called "eserine") is an inhibitor of acetylcholine metabolism (by inhibiting the enzyme acetylcholinesterase) and is an antagonist of scopolamine. Since the action of acetylcholine . is terminated by its rapid hydrolysis into choline and acetic acid, acetylcholinesterase inhibitors prolong or mimic the action of the neurotransmitter, acetylcholine. Acetylcholine is released into synapses where it behaves as a neurotransmitter that associates with macromolecular receptors. The association of acetylcholine with its receptors initiates a physiological response, probably by opening membrane calcium channels. The acetylcholine receptors appear to be of two general subtypes. One subtype appears to have nicotine as an agonist (that is, the nicotine molecule appears to fit into the one subtype of acetylcholine receptor) . For example, the nicotinic effect of acetylcholine can be revealed when its degradation by acetylcholinerase is inhibited, as is discussed by Vidal and Changeux, Neuroscience, 29 (2) , pp. 261-270 (1989) . The other general subtype of acetylcholine receptors is muscarinic. Muscarine is an alkaloid that mimics the action of acetylcholine. Activation of cholinergic receptors results in bradycardia, increased secretion (e.g. salivary and sweat) , gastrointestinal contractions, and other symptoms. Hypotensive, cardiac inhibitory effects caused by low doses of acetylcholine are similar to those produced by muscarine and appear to be mediated via muscarinic acetylcholinase receptors at postganglionic parasympathetic terminals, whereas effects at autonomic ganglion and skeletal neuromuscular junctions result from nicotinic acetylcholine receptors. Summary of the Invention In one aspect of the present invention, a method for relieving craving in a nicotine-habituated person who is abstaining from or reducing nicotine ' intake is provided by administering an admixture of first and second components. The first component is a non-specific acetylcholine agonist, preferably having at least one determinable muscarinic effect, and the second component is a muscarinic antagonist having a determinable antimuscarinic effect. Administration of a balanced admixture of the first and second components relieves craving, yet surprisingly results in substantially no identifiable muscarinic or antimuscarinic changes. Instead, practice of the invention appears merely to increase alertness without tenseness, and yet to reduce craving in persons who are abstaining from nicotine intake. Aparticularlypreferred composition for relieving craving takes the form of a tablet suitable for oral administration wherein the first component is a water soluble physostigmine and the second component is a water soluble scopolamine. The combination of the first and second components is surprising because the two classes of drugs (non-specific acetylcholine agonist and muscarinic antagonist, respectively) have been viewed as mutual antagonists, with antimuscarinics being conventional antidotes for antichounerase poisoning. Detailed Description of the Preferred Embodiments Practice of the inventive method comprises administrating an admixture that must include two essential components. The first component is a non-specific acetylcholine agonist. The first component preferably has at least one determinable muscarinic effect and one determinable nicotinic effect were it administered by itself. By "non-specific" is meant that the actions of the first component are not limited to one class or type of acetylcholine receptors, but rather that the first component acts on both the muscarinic receptors and the nicotinic receptors. By a "determinable muscarinic effect" is meant that pharmacologically effective dosages- will produce one or more of the typical muscarinic effects* (e.g. sweating, salivation, increased gastrointestinal motility, and heightened alertness) . By a- "determinable nicotinic effect" is meant typical activation of nicotinic receptors when a physiologically effective dose is administered, such as one or more of increased skeletal and/or muscle excitability, adrenaline release (such as tachycardia) and so forth. The second component is a muscarinic antagonist that preferably has at least one determinable " antimuscarinic effect were it administered by itself. By a "determinable antimuscarinic effect" is meant dry mouth, dry skin, impaired attention or alertness, and decreased gastrointestinal motility. Inventive admixtures of the first and second components are in a balanced weight ratio of first and second components sufficient substantially to eliminate the determinable muscarinic and antimuscarinic effects (with the exception of some typical increased alertness) , yet to be in an amount effective substantially to relieve nicotine craving for a duration of time. The duration in which craving is relieved depends upon several factors, such as the duration of action for the particular first and second components chosen, the particular patient (degree of habituation, weight, etc.), but preferably is on an order of several hours. The balance of first and second components for the admixture will normally be readily determined empirically by the physician or health care professional treating the nicotine-habituated patient. Treatment normally begins with established, pharmaceutically effective doses of each component by itself, then by establishing through observation and discussion with the patient whether the balance has been established that is sufficient substantially to eliminate the determinable muscarinic and antimuscarinic effects yet while being in an amount effective substantially to relieve nicotine craving for some measurable period of time. Each of the first and second components must- be able to pass the blood-brain barrier (usually due to a lipophilic nature) so as to have central nervous system effects. As will be more fully described hereinafter, a particularly preferred first component is a water soluble physostigmine and a particularly preferred second component is a water soluble scopolamine, with the inventive admixture being an amount of each component (per each oral dose) of between about 0.3 mg to about 0.9 mg, with the first and second components being in about a 1:1 weight ratio such an admixture relieves craving for about four hours. Among the non-specific acetylcholine agonists suitable as the first component are physostigmine, methacholine, edrophonium, quaternary tetraalkylammonium salts, 9-amino-l,2,3,4-tetrahydracridine (also known as "tacrine") , diisopropyl fluorophosphate, paraoxon, and soman. The latter three are quite potent and long-acting. These non-specific acetylcholine agonists include both reversible and irreversible inhibitors of acetylcholinesterase and also direct agonists such as arecoline. Suitable first and second components are preferably in a water soluble form, such as being present as pharmaceutically acceptable salts, which is meant to include both acid and base addition salts. "Pharmaceutically acceptable acid addition salt" refers to those salts which retain the biological effectiveness and properties of the free bases and which are not biologically or otherwise undesirable, formed with inorganic acids such as hydrochloric acid, hydrobromic acid, sulfuric acid, nitric acid, phosphoric acid and the like, and organic acids such as acetic acid, propionic acid, glycolic acid, pyruvic acid, oxalic acid, .maleic acid, malonic acid, succinic acid, fumaric acid, tartaric acid, citric acid, benzoic acid, cinnamic acid, mandelic acid, methanesulfonic acid, ethanesulfonic acid, p-toluenesulfonic acid, salicylic acid and the like. "Pharmaceutically acceptable base addition salts" include those derived from inorganic bases such as sodium, potassium, lithium, ammonium, 5 calcium, magnesium, iron, zinc, copper, manganese, aluminum salts and the like. Particularly preferred are the ammonium, potassium, sodium, calcium and magnesium salts. Salts derived from pharmaceutically acceptable organic non-toxic bases include salts of primary, secondary, and 0 tertiary amines, substituted amines including naturally occurring substituted amines, cyclic amines and basic ion exchange resins, such as isopropylamine, trimethylamine, diethylamine, triethylamine, tripropylamine, and ethanolamine. 5 Physostigmine is generally ' regarded as an irreversible acetylcholinesterase inhibitor because it forms a covalent bond with the catalytic site of the enzyme. Physostigmine is preferred as the first component due to a duration of activity that is equivalent to -the 0 preferred second component, and due to its orally active forms. Particularly preferred forms of physostigmine are water soluble derivatives, and include physostigmine salicylate and physostigmine sulfate. Physostigmine crosses the blood-brain barrier and can be administered 5 subcutaneously, intramuscularly, by slow intravenous injection, and orally (when in the water soluble salicylate or sulfate forms) . Muscarinic antagonists suitable as the second component include scopolamine, atropine, benactyzine, 0 oxybutynin, quinuclidinyl benzilate, 3-quinuclidinyl- xanthene-9-carboxylate, and quinuclidinyl atrolactate. - ' However, not preferred are muscarinic antagonists that have limited or no central antimuscarinic effects, such as methoctramine. The water soluble scopolamine derivatives 5 are particularly preferred, such as scopolamine butylbromide, scopolamine hydrobromide, and scopolamine methobromide. The quaternary derivatives (butylbromide, methobromide, and methonitrate) do not readily cross the blood-brain barrier. Scopolamine ' hydrobromide is a particularly preferred water soluble scopolamine for use as the second component. Compositions for use in the inventive method for relieving craving preferably are formed as tablets or capsules suitable for oral administration and have the first and second components admixed therein. The quantities of first and second components so admixed are wherein a dose of one or more tablets, preferably several, is effective substantially to relieve nicotine craving for a duration of time, preferably several hours, most preferably about three hours or more. Where, for example, the first and second components are water soluble physostigmine and water soluble scopolamine, then each tablet preferably has the components in about a 1:1 weight ratio and each tablet delivers a dose of about 0.3 mg. Tablets of the invention optionally include one or more pharmacologically suitable component or. components such as buffering agent, preservative (e.g. antioxidants) , excipients and/or tabletting agents, flavoring agents, and the like. Suitable such components are well-known to the tabletting art. Composition embodiments of the ' invention were formulated and administered to patients by a treating physician as will now be described for purposes of illustrating the invention. The persons who participated in the study had consented to be research subjects, and the Committee on Human Research, Office of Research Affairs of the University of California, San Francisco Institutional Review Board had reviewed and approved the application to involve humans as research subjects in the study. Patients (subjects) were chosen who were unable to stop smoking and were able to verbally report their feelings of craving. Once every four or more days the patient met with a treating physician at an agreed-upon time when the patient expected to experience craving for nicotine to a degree that would ordinarily cause the patient to smoke a cigarette. For example, the subject will have refrained from using nicotine just before his or her appointment so that the subject was expected to be experiencing strong, but tolerable, craving within an hour after coming to the laboratory. The patient's heart rate,* blood pressure, and temperature were recorded and a questionnaire about the patient's moods was filled out and the degree of craving was rated on a simple scale. . A composition of the invention was then administered and over the following two hours the patient rated his or her craving on the scale at fifteen minute intervals and, with the help of the treating physician, made a record of various reactions (happy, anxious, tense, and so forth) . At the first few interviews balanced amounts of physostigmine and scopolamine were established for each patient (where substantially no sweating, increased GI activity, and bowel cramping, one hand, and no dry mouth, trouble concentrating, and a "spacey" feeling, on the other hand, were experienced) , but where craving for nicotine was diminished. In broader use of the inventive composition, persons attempting to abstain from nicotine intake will probably self-medicate. A recommended dose for self- medication is likely a maximum of about six capsules per day (each preferably with 0.3 mg of water soluble scopolamine and water soluble physostigmine for one preferred embodiment) at the rate of about one capsule per hour to one per three hours. EXAMPLE 1 Smokers (some of whom were nicorette-users) attempting to abstain from nicotine intake were initially administered small, equal doses of scopolamine (HBr, 0.3 mg) and physostigmine (S0 4 , 0.3 mg) tabletted with 0.5 g ascorbic acid as a stabilizing (antioxidant) agent. Pulse, blood pressure (systolic/diastolic) and orally taken temperature were recorded. Each patient rated him or herself on a sliding scale between happy/sad, extra alert/sleepy, clear or sharp/dull, anxious/calm, tense/relaxed, energetic/lazy, and on the degree of craving (worst ever/thought of nicotine is repulsive) . Table 1 summarizes data from six persons participating in the study. Subjects were given the selected dose and then were monitored and tested with a variety of scales and for vital signs (including temperature) . Of the vital signs, only pulse rate changed. There were no significant reports of autonomic side effects. The craving scale was from "0" (meaning "worst craving for a cigarette ever") to "100" (meaning "the thought of smoking is disgusting") . A value of "50" was generally interpreted as the craving felt about one-half hour after a usual cigarette had been smoked. With specific reference to the data for Subject 1 for illustration, this subject was smoking an average of 20 cigarettes a day plus was using nicotine containing gum. The patient was initially treated with a dose containing 0.3 mg of each scopolamine and physostigmine. Immediately after receiving this dose, the subject's pulse rate began to be monitored. The "pulse drop" category was the maximum drop in beats per minute that occurred. The "pulse time occur" category means the number of minutes following administration of the dose when the maximum ' pulse • drop occurred. In "craving relief" the 50% craving relief was not considered evidence of reduced craving. Only ratings of 60% or more were considered -as evidence of reduced craving. The "craving time occur" was the time that had elapsed from taking the dose when the craving relief (if present) was rated, whereas the "duration" was the additional amount of time that the patient spent in the laboratory and felt there had been craving relief. For example, when Subject 1 (who was still experiencing craving with 0.3 mg of each component) subsequently received an increased dose of 0.6 mg of each component, then the subject did experience craving relief (rated as 75%) , which was experienced 70 minutes after receiving the dose, and which craving relief lasted at least two hours after the initial 70 minute period (while the patient was yet in the laboratory) . Patients did report to the investigating physician that they had various degrees of continued craving relief after leaving the laboratory. As seen by Table 1, at doses of 0.6 mg (of each drug) , all subjects but one experienced a relief of craving for two or more hours. The onset of reduced craving and pulse rate minimum usually coincided. We conclude that relief from craving is obtained * for at least some patients when as little as 0.3 mg of each drug in the combination was administered with the craving relief lasting from three to six hours. The only side effect we have observed has been bradycardia at the lowest dose, which is less marked at the higher doses, but this has not been troublesome. A definite subjective effect has been noted. Neither dry mouth nor increased gastrointestinal activity has been noted. Pupil size has not shown a measurable change in the either direction. It is to be understood-that while the invention- has been described above in conjunction with preferred specific embodiments, the description and examples are intended to illustrate and not limit the scope of the invention, which is defined by the scope of the appended claims.

Claims: It is Claimed : 1. A method for relieving• craving in a nicotine-habituated person abstaining from or reducing nicotine intake comprising: administering an admixture consisting essentially of first and second components to a nicotine-habituated person, said person having endogenous acetylcholine, the first component being a non-specific acetylcholine agonist, the second component being a muscarinic antagonist . 2. The method as in claim 1 wherein the first component has at least one determinable muscarinic effect and one nicotine effect by itself, the second component has at least one determinable antimuscarinic effect by itself, and the admixture has a balanced weight ratio of the first and second components sufficient substantially to eliminate the determinable muscarinic and antimuscarinic effects while the admixture is in an amount effective substantially to relieve nicotine craving in the person to whom the admixture is administered for a period of time. 3. The method as in claim 1 wherein the admixture optionally includes a pharmacologically suitable component selected from the group consisting of a solvent, a buffering agent, a preservative, an excipient, a flavoring agent, a tabletting agent, and mixtures thereof. 4. The method as in claim 1 wherein the administration is an oral dose and includes providing a water soluble amount of each component in each dose of between about 0.3 mg to about 0.9 mg. 5. The method as in claim 2 wherein the first component is selected from the group consisting of physostigmine, tacrine, methacholine, edrophonium, and water soluble derivatives thereof. 6. The method as in claim ' 2 wherein the second component is selected from the group consisting of scopolamine, atropine, and water soluble derivatives thereof. 7. A composition for relieving craving in a nicotine-habituated person abstaining from or reducing nicotine intake comprising: a tablet suitable for oral administration to a nicotine-habituated person, said person having endogenous acetylcholine, said tablet having first and second components admixed therein, the first component being a non-specific acetylcholine agonist, the second component being a muscarinic antagonist, a dose of one or more tablets being effective substantially to relieve nicotine craving for a period of time in a nicotine-habituated person to whom said dose is administered. 8. . The composition as in claim 7 wherein the first component is a water soluble physostigmine. 9. The composition as in claim 7•wherein the second component is a water soluble scopolamine. 10. The composition as in claim 7 wherein the first component is physostigmine sulfate, the second component is scopolamine hydrobromide, and the first and second components are in about a 1:1 weight ratio. 11. The composition as in claim 7 wherein the tablet optionally includes a pharmacologically suitable component selected from the group consisting of a buffering agent, a preservative, an excipient, a flavoring agent, a tabletting agent, and mixtures thereof. 12. The composition as in claim 7 wherein the first component is physostigmine sulfate, the second component is a scopolamine salt, and a dose is wherein each of the first and second components is in an amount of between about 0.3 mg to about 0.9 mg. 13. The composition as in claim 12 wherein the first and second components are in about a 1:1 weight ratio.

Inventors: CALLAWAY ENOCH, CALLAWAY, ENOCH
Applicants: UNIV CALIFORNIA, THE REGENTS OF THE UNIVERSITY OF CALIFORNIA
Application year: 1993
Main classification: A61K31
IPC codes: A61K31, A61K45, A61P43