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• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61K—PREPARATIONS FOR MEDICAL, DENTAL OR TOILETRY PURPOSES
  • A61K31/00—Medicinal preparations containing organic active ingredients
  • A61K31/70—Carbohydrates; Sugars; Derivatives thereof
  • A61K31/7042—Compounds having saccharide radicals and heterocyclic rings
  • A61K31/7052—Compounds having saccharide radicals and heterocyclic rings having nitrogen as a ring hetero atom, e.g. nucleosides, nucleotides
  • A61K31/706—Compounds having saccharide radicals and heterocyclic rings having nitrogen as a ring hetero atom, e.g. nucleosides, nucleotides containing six-membered rings with nitrogen as a ring hetero atom
  • A61K31/7064—Compounds having saccharide radicals and heterocyclic rings having nitrogen as a ring hetero atom, e.g. nucleosides, nucleotides containing six-membered rings with nitrogen as a ring hetero atom containing condensed or non-condensed pyrimidines
  • A61K31/7076—Compounds having saccharide radicals and heterocyclic rings having nitrogen as a ring hetero atom, e.g. nucleosides, nucleotides containing six-membered rings with nitrogen as a ring hetero atom containing condensed or non-condensed pyrimidines containing purines, e.g. adenosine, adenylic acid
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61K—PREPARATIONS FOR MEDICAL, DENTAL OR TOILETRY PURPOSES
  • A61K31/00—Medicinal preparations containing organic active ingredients
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61K—PREPARATIONS FOR MEDICAL, DENTAL OR TOILETRY PURPOSES
  • A61K31/00—Medicinal preparations containing organic active ingredients
  • A61K31/66—Phosphorus compounds
  • A61K31/675—Phosphorus compounds having nitrogen as a ring hetero atom, e.g. pyridoxal phosphate
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61P—SPECIFIC THERAPEUTIC ACTIVITY OF CHEMICAL COMPOUNDS OR MEDICINAL PREPARATIONS
  • A61P11/00—Drugs for disorders of the respiratory system
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61P—SPECIFIC THERAPEUTIC ACTIVITY OF CHEMICAL COMPOUNDS OR MEDICINAL PREPARATIONS
  • A61P11/00—Drugs for disorders of the respiratory system
  • A61P11/06—Antiasthmatics
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61P—SPECIFIC THERAPEUTIC ACTIVITY OF CHEMICAL COMPOUNDS OR MEDICINAL PREPARATIONS
  • A61P25/00—Drugs for disorders of the nervous system
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61P—SPECIFIC THERAPEUTIC ACTIVITY OF CHEMICAL COMPOUNDS OR MEDICINAL PREPARATIONS
  • A61P43/00—Drugs for specific purposes, not provided for in groups A61P1/00-A61P41/00
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61P—SPECIFIC THERAPEUTIC ACTIVITY OF CHEMICAL COMPOUNDS OR MEDICINAL PREPARATIONS
  • A61P9/00—Drugs for disorders of the cardiovascular system
  • A61P9/06—Antiarrhythmics

Definitions

• the present invention relates to methods of regulating vagal tone in human patients.
• the parasympathetic limb i.e., the vagus nerve
• the parasympathetic limb is a major component of the autonomic nervous system which regulates the function of various organs and tissues throughout the body.
• Sensory stimuli elicit neural signals (i.e.,action potentials) traveling in the vagus nerve via afferent fibers to the central nervous system which in turn sends neural signals to effector organs via efferent vagal fibers; known as vagal reflexes.
• sensory stimuli can elicit localized release of biologically active compounds (i.e., neuropeptides) from afferent nerve terminals, independent of afferent traffic traveling to the central nervous system; known as axonal reflexes.
• vagus nerve maintains a basal level of activity, evidenced by the output of the efferent vagal fibers, or tone.
• Vagal tone is increased or decreased depending upon the body's needs, generally in response to internal or external sensory stimuli.
• the former can be either central or peripheral .
• the effects of the vagus nerve are mediated by the neurotransmitter acetylcholine, released from efferent nerve terminals, activating muscarinic cholinergic receptors on target cells .
• Alteration of vagal tone is used in humans in the acute management of pathophysiologic conditions and therapy of certain diseases. For example, certain cardiac pathologies are associated with vagally mediated slowing of the heart rate (i.e., bradyarrhythmias) .
• vagal reflexes and vagal afferent axonal reflexes contribute to the pathophysiology and symptomatology of asthma and other obstructive pulmonary diseases.
• vagal tone can be modulated by blockade of muscarinic cholinergic receptors as well as by the inhibition of acetylcholinesterase, an enzyme which degrades acetylcholine.
• anticholinergic drugs are very effective in the treatment of bradyarrhythmias associated with acute myocardial ischemia. These drugs are also effective bronchodilators in chronic obstructive pulmonary diseases.
• axonal reflexes which exacerbate certain pathophysiologic conditions such as asthmatic bronchoconstriction.
• vasovagal syncope The vagus nerve also mediates neurogenic human fainting (i.e., vasovagal syncope) .
• a vasovagal reaction is characterized by an inappropriate decrease in blood pressure and/or heart rate.
• Patients suspected of suffering from vasovagal syncope are subjected to a clinical test (i.e., tilt test) in which the induction of fainting is attempted by head- up tilt in the presence or absence of drugs (e.g., isoproterenol) . This is a tedious and expensive test.
• drugs e.g., isoproterenol
• Adenosine 5' -triphosphate is a purine nucleotide found in every cell of the human body where it plays a major role in cellular metabolism and energetics. Once outside of cells, however, ATP exerts different effects on various tissues and organs. The actions of extracellular ATP are known to be mediated by specific cell surface receptors, P 2 -purinoceptors. These receptors are subdivided into two families: P 2x and P 2y (Abbracchio and Burnstock, Pharmacol Ther.
• Classification is based upon certain aspects of the signal transduction initiated by the activation of these receptors as well as the relative agonist potencies of ATP and ATP analogues in different systems. For example,
• P 2x -purinoceptor-mediated responses are characterized by the order of agonist potencies of ⁇ , j8-methylene ATP which is greater than ⁇ , ⁇ -methylene ATP which is greater than ATP and 2methyl-thio ATP (those two being equal) .
• purinoceptors are unique and their stimulation activates specific mechanisms.
• Extracellular ATP is known to affect neural elements via the activation of a P 2x - purinoceptor.
• ATP has been employed as a therapeutic in human patients.
• ATP has been used for many years in the acute management of paroxysmal supraventricular tachycardia.
• the mechanism of ATP's action in this setting involves the degradation of ATP to adenosine and the action of adenosine on the specialized tissue of the heart (i.e., atrio-ventricular node) .
• adenosine in this setting is the subject of Belardinelli et al . , U.S. Patent No. 4,673,563.
• ATP has also been shown to be effective against cancer in animal models and in humans.
• the present invention provides a unique approach to modulating vagal tone and vagal axonal reflexes in humans through the activation and blockade of P 2 -purinoceptors on afferent vagal nerve terminals in vivo.
• methods of altering vagal tone in mammals suffering from conditions associated with undesirable vagal tone comprising administering a mediator of P 2x -purinoceptors on afferent nerve terminals .
• diagnostic methods of detecting undesirable propensity for acute increase in vagal tone by administering a mediator to a patient and measuring the patient's vagal reflex triggered by the said mediator as compared to a standard reflex.
• Figure 1 is a schematic representation of the pulmonary-pulmonary and axonal reflexes which is a subject of the invention.
• Figure 2 is a bronchogram of a control (baseline conditions) (Panel A) and a bronchogram (Panel B) showing the pronounced bronchoconstriction induced by administration of ATP (Panel B) .
• FIG 3 is shows an (A) electrocardiogram (ECG) of (B) systemic arterial blood pressure (BP, mmHg) , (C) pulmonary air flow (AF, l/min) and (D) tracheal pressure (TP, mmH 2 0) of a dog following administration of ATP (marked by the arrow, sec-0)
• ECG electrocardiogram
• a novel approach to modulating vagal tone of the autonomic nervous system Treatment of conditions associated with the parasympathetic limb of the autonomic nervous system generally has focused on the modulation of the efferent portion of the vagal system.
• the present invention is based upon the novel approach of modulating afferent nerve traffic which in turn ultimately evokes a modulated response of efferent fibers.
• the modulated reflex may be cardio-cardiac or pulmonary-pulmonary.
• the cardio-cardiac reflex involves afferent traffic elicited in the left ventricle of the heart which travels to the brain where it is subjected to central processing.
• the outcome of the central processing is efferent neural traffic which reaches the heart to cause slowing of heart rate and reduced force of cardiac muscle contraction.
• the pulmonary- pulmonary reflex consists similarly of afferent and efferent traffics as well as central processing, however, the efferent traffic of this reflex reaches the lungs to cause bronchoconstriction.
• Figure 1 illustrates the pulmonary- pulmonary reflex. In both reflexes the efferent nerve terminals release acetylcholine which acts on target cells; i . e .
• the cardio-cardiac reflex reduces the work load of the heart and thereby reduces oxygen demand.
• the pulmonary- pulmonary reflex protects the lungs by limiting the amount of noxious material entering the lungs.
• a patient's vagal reflexes may be modulated and the extent of the response observed.
• efferent nerve traffic is observed and compared with standard efferent nerve traffic associated with normal vagal function. Deviation from standard, i.e., normal vagal response will serve to aid the clinician in determining the severity of a patients condition and indicate an appropriate treatment .
• a standard vagal response is that of a healthy human subjects. As would be appreciated by those skilled in the art, a standard response might be obtained by measuring vagal reflex of healthy patients in response to a selected mediator.
• vagus nerve has also been implicated in the pathophysiology of the acute phase of pulmonary embolism.
• the mechanism of enhanced vagal tone in this setting was not known.
• ATP released from activated platelets in the lungs activates P 2 -purinoceptors located on vagal afferent nerve terminals thereby triggering a pulmonary-pulmonary vagal reflex.
• This reflex causes bronchoconstriction and bronchial secretion.
• bronchoconstriction and mucous plug in bronchi commonly found in patients at the time of pulmonary embolism, contribute to the causes of death in this setting.
• vagal reflexes elicited during the acute phase of pulmonary embolism may be suppressed by an antagonist mediator administered to the patient .
• vagal tone is modulated by the administration of one or more mediators.
• Mediators effective for purposes of this invention act upon P 2 -purinoceptors on afferent nerve terminals.
• the purinoceptor is P 2x - purinoceptor.
• Administration of one or more mediator is preferably by specifically targeted administration. For instance, localized catheters may be used to effectively administer the mediator to the desired target.
• Agonists of the present invention include, but are not limited to agonists at P 2x -purinoceptors such as ATP and its analogues.
• P 2x -purinoceptors such as ATP
• an agonist such as
• ATP may be administered in accordance with the present invention.
• an antagonist may be administered when vagal tone is too high; and/or to suppress axonal reflexes.
• vagal tone is too high; and/or to suppress axonal reflexes.
• an antagonist of the P 2x - purinoceptor such as pyridoxalphosphate-6-azophenyl-2' ,4' -disulphonic acid may be administered to decrease vagal tone.
• mediators of the present invention may be administered in therapeutically effective amounts in accordance with methods appreciated by those skilled in the art.
• the mode of administration of mediators according to the method that is the invention includes any means that produces contact of the active ingredient with the agent's site of action in the body of a mammal or in a body fluid or tissue. These modes of administration include but not limited to oral, topical, hypodermal, intravenous, intramuscular and intraparenteral methods of administration.
• the mediator is administered by a catheter directed to the site of the afferent nerve terminals.
• the mediators may be administered singly or in combination with other compounds used in the method that is the invention, other pharmaceutical compounds are preferably administered with a pharmaceutically acceptable carrier selected on the basis of the selected route of administration and standard pharmaceutical practice.
• the method may include administration of compounds to mammals, preferably humans, in therapeutically effective amounts.
• the dosage administered in any particular instance will depend upon factors such as the pharmacodynamic characteristics of the compound of the invention, its mode and route of administration; age, health, and weight of the recipient; nature and extent of symptoms; kind of concurrent treatment, frequency of treatment, and the effect desired.
• the daily dosage of a compound used in the method that is the invention will be in the range of from about 1 ⁇ g to about 100 mg per kg of body weight, preferable from about 10 ⁇ g to about 20 mg per kg per day.
• Pharmaceutical compositions may be administered in a single dosage, divided dosages or in sustained release. Persons of ordinary skill will be able to determine dosage forms and amounts with only routine experimentation based upon the considerations of this invention.
• the method of administering mediators include administration as a pharmaceutical composition parenterally in sterile liquid dosage forms or topically in a carrier.
• the mediators may be formulated into dosage forms according to standard practices in the field of pharmaceutical preparations. See Gennaro Alphonso, ed.
• mediators may be mixed with a suitable carrier or diluent such as water, a oil, saline solution, aqueous dextrose (glucose) , and related sugar solutions, and a glycol such as propylene glycol or polyethylene glycol.
• a suitable carrier or diluent such as water, a oil, saline solution, aqueous dextrose (glucose) , and related sugar solutions, and a glycol such as propylene glycol or polyethylene glycol.
• Solutions for parenteral administration contain preferably a water soluble salt of the compound.
• Stabilizing agents, antioxidizing agents and preservatives may also be added. Suitable sulfite, and ascorbic acid, citric acid and its salts, and sodium EDTA. Suitable preservatives include benzalkonium chloride, methyl- or propyl-paraben, and chlorbutanol .
• Body temperature was maintained with a heating mattress (rectal temperature range, 36.2-37.2 * C) .
• Systemic arterial blood pressure was determined with a Millar pressure transducer located in the descending aorta.
• a peripheral vein was cannulated for the administration of a physiological saline solution and maintenance doses of the anaesthetic.
• Catheters were introduced via the right femoral vein and left atrial appendage and positioned in the right atrium and left atrium, respectively, for the administration of test solutions.
• a Swan-Ganz catheter was introduced via a femoral vein and positioned in the distal portion of the right pulmonary artery. The chest was opened by a longitudinal sternotomy.
• the right cervical vagosympathetic trunk was exposed by a midcervical longitudinal section of the skin and careful dissection of neck muscles and connective tissues. The edges of the cut skin were elevated and secured to create a trough which was filled with warm (37'C) mineral oil. A section of the vagosympathetic trunk was placed on a small plate of black Perspex and fine branches were separated from the main bundle by careful dissection using microsurgical tools and a dissecting microscope (Model F212, Jenopik Jena, GmbH, Germany) .
• Extracellular neural action potentials were recorded using a custom-made bipolar electrode, which consisted of two platinum-iridium wires (1.25x0.0125cm) , connected to a high- impedance first-stage differential amplifier (model AC8331, CWE Inc., Ardmore, PA, USA) via a shielded cable. The output of the first-stage amplifier was fed into a second-stage differential amplifier (model BMA-831/C, CWE, Inc.) Isolated fibres were laid on the pair of platinum wires. Vagal C fibres with chemosensitive endings have a sparse irregular discharge which is never associated with cardiac or respiratory cycles.
• Confirmation of fibre type was obtained by: first, monitoring the response to capsaicin (10 ⁇ g kg "1 , intra-right atrial bolus) ; second, monitoring the response to mechanical stimulation of the lungs using gentle probing with forceps as well as inflation of the lungs to 2-3 times the tidal volume; and third, determining the speed of conduction using a stimulating electrode positioned distal to the initial recording site.
• PTX ⁇ g kg "1 , given into a peripheral vein of conscious animals
• PTX was donated by Dr. E. Hewlett, University of Virginia, Charlottesville, VA, USA.
• Animals did not show any signs of distress during that period.
• These animals were subjected to glucose tolerance tests prior to and 48 h after PTX administration to confirm PTX intoxication.
• the test consisted of the application of a bolus of dextrose (l.lg kg ' ⁇ I.V.) and subsequent withdrawal of blood samples (5ml, every 10 min) .
• Glucose and insulin levels in the blood samples withdrawn during these tests were determined by the Diagnostic Laboratory at Cornell University, New York State College of Veterinary Medicine, Ithaca, NY, USA.
• ATP adenosine 5' -diphosphate
• AMP adenosine 5' -monophosphate
• capsaicin 10 ⁇ g kg "1
• ATP adenosine 5' -diphosphate
• AMP adenosine 5' -monophosphate
• capsaicin 10 ⁇ g kg "1
• 0.5-3 ⁇ mol kg "1 for purine compounds and 1-5 ⁇ g kg "1 for capsaicin. ⁇ -Methylene ATP
• mice were killed using sodium pentobarbitone (100 mg kg "1 , I.V.) plus 3M KCl (10ml, I.V.)
• a burst of action potentials in the same fibres a transient prolongation of sinus cycle length and a drop in systemic arterial blood pressure (i.e., capsaicin and ATP maximally reduced blood pressure 20 ⁇ 4 and 58 ⁇ 3%, respectively) .
• the time-to-peak negative chronotropic effect of ATP was significantly shorter than the time-to-peak vasodilatory effect.
• the elapsed times from the moment of injection of capsaicin and ATP to the beginning of the neural bursts and the duration of the elicited bursts were similar.
• hexamethonium did not alter the transient reduction of blood pressure caused by ATP and the significantly larger time-to-peak effect of ATP on blood pressure versus that of capsaicin indicates that a non-neural factor, i.e. adenosine, the product of the enzymatic degradation of ATP, is mediating, to a large extent, the peripheral vasodilatory action of ATP.
• a non-neural factor i.e. adenosine
• Intra-right pulmonary administration of PPADS reduced the number of neural action potentials elicited by intra-right pulmonary administration of ATP in a time-dependent manner.
• PPADS did not affect the neural response to intra-right pulmonary-applied capsaicin.
• ATP and capsaicin stimlate the same afferent fibers
• the differential potency and the response of two compounds to the P2-purinoceptor antagonist PPADS suggest that different receptors mediate their actions.
• Examples 1-5 show that an intra-right atrial bolus of ATP elicited a transient burst of action potentials in cervical vagal fibers; similar activity was elicited by capsaicin, given in the same mode; neural activity was elicited in otherwise quiescent slow-conducting fibers; adenosine, AMP, or ADP did not elicit this activity; ⁇ , ⁇ -mATP was much more potent than ATP while /S, ⁇ -mATP was inactive; PPADS but not RB2 abolished this action of ATP; and neither PTX nor hexamethonium prevented this action of ATP.
• ATP stimulates pulmonary vagal afferent C fiber terminals by activating P 2x -purinoceptors.
• Example 1 The fact that adenosine, AMP and ADP, unlike ATP, did not elicit neural responses (Example 1) indicates that the action of ATP was mediated by a P2-purinoceptor. Furthermore, the structure-function cascade: ⁇ ,
• Example 5 Specifically, PPADS, a P 2x -purinoceptor antagonist, but not RB2, a P 2y -purinoceptor antagonist effectively blocked the action of ATP on the pulmonary vagal afferent C fiber nerve terminals.
• FIG. 1 is a bronchogram of a control (baseline conditions) (Panel A) and a bronchogram (Panel B) showing the pronounced bronchoconstriction induced by administration of ATP
• FIG. 3 shows the electrocardiogram (ECG) systemic arterial blood pressure (BP, mmHg) pulmonary air flow (AF, 1/min) and tracheal pressure (TP, mmH 2 0) of the dog following administration of ATP (marked by the arrow, sec-0) .
• ECG electrocardiogram
• BP systemic arterial blood pressure
• AF pulmonary air flow
• TP tracheal pressure
• Figure 3 ATP exerted pronounced negative chronotropic and dromotropic effects on sinus node automaticity and AV nodal conduction, reduced BP and AF and increased TP. All of the effects were transient and markedly attenuated by bilateral cervical vagotomy (not shown) .
• ATP Triggers a vagal reflex by stimulating vagal afferent nerve terminals in the left ventricle. This reflex mediates the negative chronotropic action of ATP and is independent of adenosine, the product of its enzymatic degradation.

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• 1996
  • 1996-12-23 US US08/771,518 patent/US5874420A/en not_active Expired - Lifetime
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