AU2002224699A1 - Regulation of organic nitrate tolerance - Google Patents

Description

REGULATION OF ORGANIC NITRATE TOLERANCE

TECHNICAL FIELD

In one of its aspects, the present invention relates to a pharmaceutical composition for regulation of organic nitrate tolerance. In another of its aspects, the present invention relates to a method for regulating organic nitrate tolerance.

BACKGROUND ART

Organic nitrates such as glyceryl trinitrate, isosorbide dinitrate, isosorbide-5-mononitrate, and the like are recognized as important pharmacologic agents used in the treatment of coronary artery disease and congestive heart failure - see Parker J, Nitrate Therapy for Stable Angina

Pectoris. N Engl J Med. 1998;338:520-531. Despite successful application, the use of nitroglycerin is limited by a number of its pharmacologic characteristics. One of the important limitations is loss of efficacy during continuous therapy, a phenomenon known as "tolerance". The etiology of tolerance is not clearly understood, however recent experimental data have improved the understanding of the mechanism(s) involved - see one or more of:

a. Mϋnzel T, Sayegh H, Freeman BA et al. Evidence for enhanced vascular superoxide anion production in nitrate tolerance. A novel mechanism underlying tolerance and cross-tolerance. J Clin Invest 1995; 95 (l):187-94;

b. Mϋnzel T, Li H, Mollnau H, Hink U et al. Effects of long-term nitroglycerin treatment on endothelial nitric oxide synthase (NOS III) gene expression, NOS Ill-mediated superoxide production, and vascular NO bioavailability. Circ Res 2000; 86 (1): E7-E12; and c. Mϋnzel T, Mollnau H, Hartmann M et al. Effects of a nitrate-free interval on tolerance, vasoconstrictor sensitivity and vascular superoxide production. J Am Coll Cardiol 2000; 36 (2): 628-34.

Thus it would desirable to have a pharmaceutical composition which obviates or mitigates tolerance to organic nitrate therapy.

DISCLOSURE OF THE INVENTION

It is an object of the present invention to provide a novel composition which is useful to obviate or mitigate tolerance to organic nitrate therapy.

It is another object of the present invention to provide a novel method for regulating tolerance to organic nitrate therapy.

Accordingly, in one of its aspects, the present invention provides an organic nitrate therapy ^' tolerance regulation pharmaceutical composition comprising a folate compound, a folate derivative compound, a hydrobiopterin compound, a hydrobiopterin derivative compound and mixtures thereof, together with a pharmaceutically acceptable carrier therefor.

In another of its aspects, the present invention provides a method for regulating tolerance during organic nitrate therapy, the method comprising the step of administering to a patient undergoing organic nitrate therapy a pharmaceutical composition comprising a folate compound, a folate derivative compound, a hydrobiopterin compound, a hydrobiopterin derivative compound and mixtures thereof, together with a pharmaceutically acceptable carrier therefor.

In yet another of its aspects, the present invention provides a pharmaceutical composition comprising:

(i) a first active ingredient comprising an organic nitrate; (ii) a second active ingredient comprising a folate compound, a folate derivative compound, a hydrobiopterin compound, a hydrobiopterin derivative compound and mixtures thereof; and

(iii) a pharmaceutically acceptable carrier therefor.

In yet another of its aspects, the present invention provides a kit for use in organic nitrate therapy, the kit comprising:

(i) a first pharmaceutical composition comprising an organic nitrate, together a pharmaceutically acceptable carrier therefor;

(ii) a second pharmaceutical composition comprising a folate compound, a folate derivative compound, a hydrobiopterin compound, a hydrobiopterin derivative compound and mixtures thereof, together with a pharmaceutically acceptable carrier therefor.

In yet another of its aspects, the present invention provides a method for regulating tolerance during organic nitrate therapy, the method comprising the step of administering to a patient:

(i) a first pharmaceutical composition comprising an organic nitrate, together a pharmaceutically acceptable carrier therefor; and

(ii) a second pharmaceutical composition comprising a folate compound, a folate derivative compound, a hydrobiopterin compound, a hydrobiopterin derivative compound and mixtures thereof, together with a pharmaceutically acceptable carrier therefor.

In yet another of its aspects, the present invention provides for the use of a compound selected from the group comprising a folate compound, a folate derivative compound, a hydrobiopterin compound, a hydrobiopterin derivative compound and mixtures thereof for the production of a pharmaceutical composition useful in regulated tolerance to organic nitrate therapy. BEST MODE FOR CARRYING OUT THE INVENTION

Thus, I have surprisingly and unexpectedly discovered that selected compounds are useful in obviating or mitigating tolerance during organic nitrate therapy.

The compounds may be selected from the group comprising a folate compound, a folate derivative compound, a hydrobiopterin compound, a hydrobiopterin derivative compound and mixtures thereof.

In certain cases, a precursor to the folate compound may have activity and thus, it is intended that such a precursor is encompassed by the term "folate compound". The term "folate derivative compound" will be readily understood by those of skill in the art to encompass compounds having a folate "backbone" which has been derivatized. Non-limiting examples of suitable such compounds may be selected from the group comprising tetrahydrofolate, 5-methyltetrahydrofolate and mixtures thereof.

The preferred hydrobiopterin compound for use herein is tetrahydrobiopterin. The term "hydrobiopterin derivativie" will be readily understood by those of skill in the art to encompass compounds derived from a hydrobiopterin compound. For example, tetrahydrobiopterin may be reduced to dihydrobiopterin, the latter being an example of hydrobiopterin compound. In this case, a precursor to tetrahydrobiopterin is 7,8-dihydroneopterin triphosphate. This precursor (an other precursors) are intended to be encompassed by the term "hydrobiopterin compound".

The dosage administered of the folate compound, the folate derivative compound, the hydrobiopterin compound and/or the hydrobiopterin derivative compound will vary depending on the use and known factors such as the pharmacodynamic characteristics of the particular substance, and its mode and route of administration; age, health, and weight of the individual recipient; nature and extent of symptoms, kind of concurrent treatment, frequency of treatment, and the effect desired. For use in co-administration with and organic nitrate for the treatment of coronary artery disease and/or congestive heart failure, by way of general guidance, a daily dosage of an active ingredient such as the folate compound, the folate derivative compound or the tetrahydrobiopterin can be in the range of from about 0.01 to about 80 mg/kg of body weight, preferably from about 0.1 to about 20, more preferably from about 0.2 to about 10 mg/kg of body weight. Ordinarily a dose of from about 0.5 to about 50 mg/kg per day of the folate compound, the folate derivative compound or the tetrahydrobiopterin in divided doses one to multiple times a day, preferably up to four times per day, or in sustained release form is effective to obtain the desired results.

In the treatment methods and compositions of the present invention, the folate compound, the folate derivative compound or the tetrahydrobiopterin described in detail herein is (are) the active ingredient(s), and are typically administered for oral, topical, rectal, parenteral, local, inhalant or intracerebral use. In an embodiment of the invention, the substances are administered in intranasal form via topical use of suitable intranasal vehicles, or via transdermal routes, using forms of transderaial skin patches known to those of ordinary skill in that art. To be administered in the form of a transdermal delivery system, the dosage administration will be continuous rather than intermittent throughout the dosage regimen. The substances can also be administered by way of controlled or slow release capsule system and other drug delivery technologies.

A preferred form of administration is oral. For example, for oral administration in the form of a tablet or capsule, the active substance(s) can be combined with an oral, non-toxic, pharmaceutically acceptable, inert carrier such as lactose, starch, sucrose, glucose, methyl cellulose, magnesium stearate, dicalcium phosphate, calcium sulfate, mannitol, sorbitol and the like; for oral administration in liquid form, the oral active substances can be combined with any oral, non-toxic, pharmaceutically acceptable inert carrier such as ethanol, glycerol, water, and the like. Suitable binders, lubricants, disintegrating agents, and colouring agents can also be incorporated into the dosage form if desired or necessary. Suitable binders include starch, gelatin, natural sugars such as glucose or beta-lactose, corn sweeteners, natural and synthetic gums such as acacia, tragacanth, or sodium alginate, carboxymethylcellulose, polyethylene glycol, waxes, and the like. Suitable lubricants used in these dosage forms include sodium oleate, sodium stearate, magnesium stearate, sodium benzoate, sodium acetate, sodium chloride, and the like. Examples of disintegrators include starch, methyl cellulose, agar, bentonite, xanthan gum, and the like.

Gelatin capsules may contain the active substance and powdered carriers, such as lactose, starch, cellulose derivatives, magnesium stearate, stearic acid, and the like. Similar carriers and diluents may be used to make compressed tablets. Tablets and capsules can be manufactured as sustained release products to provide for continuous release of active ingredients over a period of time. Compressed tablets can be sugar coated or film coated to mask any unpleasant taste and protect the tablet from the atmosphere, or enteric coated for selective disintegration in the gastrointestinal tract. Liquid dosage forms for oral administration may contain colouring and flavouring agents to increase patient acceptance.

Water, a suitable oil, saline, aqueous dextrose, and related sugar solutions and glycols such as propylene glycol or polyethylene glycols, may be used as carriers for parenteral solutions. Such solutions also preferably contain a water soluble salt of the active ingredient, suitable stabilizing agents, and if necessary, buffer substances. Suitable stabilizing agents include antioxidizing agents such as sodium bisulfate, sodium sulfite, or ascorbic acid, either alone or combined, citric acid and its salts and sodium EDTA. Parenteral solutions may also contain preservatives, such as benzalkonium chloride, methyl- or propyl-paraben, and chlorobutanol.

The active ingredient substances described in detail herein can also be administered in the form of liposome delivery systems, such as small unilamellar vesicles, large unilamellar vesicles, and multilamellar vesicles. Liposomes can be formed from a variety of phospholipids, such as cholesterol, stearylamine, or phosphatidylcholines.

The active ingredient substances described in detail herein may also be coupled with soluble polymers which are targetable drug carriers. Examples of such polymers include polyvinylpyrrolidone, pyran copolymer, polyhydroxypropylmethacrylamide-phenol, polyhydroxyethylaspartamide- phenol, or polyethyleneoxide-polylysine substituted with palmitoyl residues. The active ingredient substances may also be coupled to biodegradable polymers useful in achieving controlled release of a drug. Suitable polymers include polylactic acid, polyglycolic acid, copolymers of polylactic and polyglycolic acid, polyepsilon caprolactone, polyhydroxy butyric acid, polyorthoesters, polyacetals, polydihydropyrans, polycyanoacylates, and crosslinked or amphipathic block copolymers of hydrogels. The substances can also be affixed to rigid polymers and other structures such as fullerenes or Buckeyballs.

Pharmaceutical compositions suitable for administration contain about

1 milligram to 1500 milligrams of active substance per unit. In these pharmaceutical compositions, the active ingredient will ordinarily be present in an amount of about 0.5-95% by weight based on the total weight of the composition.

Suitable pharmaceutical carriers and methods of preparing pharmaceutical dosage forms are described in Remington's Pharmaceutical Sciences, Mack Publishing Company, a standard reference text in this field.

As will be developed hereinbelow, it has been surprisingly and unexpectedly discovered that supplemental oral folate is effective in minimizing or preventing the development of tolerance to the vascular effects of nitroglycerin.

Normal volunteers (n=-20) were randomized in a double bind, placebo- controlled fashion to either oral folate (5 mg per day) or placebo. After 1 week of this double-blind therapy, subjects returned to the laboratory. At that time, measures of standing systolic blood pressure and heart rate were recorded. Subsequently, measurements of forearm blood flow were made at rest and in response to sublingual nitroglycerin (0.6 mg). Forearm blood flow was measured using strain gauge plethysmography as described in Milone et al., The Angiotensin II Receptor Antagonist Losartan Does Not Prevent Tolerance to Nitroglycerin. A Randomized Double-blind, Placebo-controlled Study, J Cardiovasc Pharm. 1999;34:645-659.

Subsequently all subjects all received transdermal GTN (0.6 mg/hr). Standing heart rate and blood pressure responses were repeated 3 hours after initial patch application. Subjects were discharged from the laboratory with instructions to take transdermal GTN continuously for the next 5 to 7 days, changing the. patch each day at 0800 hours. After 5 to 7 days, subjects returned to the laboratory where measures of standing systolic blood pressure and heart rate as well as forearm blood flow were repeated.

In both the placebo and folate therapy group, the acute administration of transdermal GTN caused a significant fall in systolic blood pressure as well as a significant increase in heart rate. The administration of sublingual GTN also caused a similar, significant increase in forearm blood flow in both groups. When subjects returned, 5 to 7 days later, standing systolic blood pressure had returned to baseline values in the placebo group and their forearm blood flow response to sublingual GTN was markedly blunted. Both of these hemodynamic observations indicate the development of tolerance to GTN in the placebo group. In contrast, in the folate group, standing systolic blood pressure remained significantly decreased as compared to baseline values following 5 to 7 days of transdermal GTN therapy. Further, their forearm blood flow responses to sublingual GTN remained unchanged as compared to responses prior to GTN therapy. These findings demonstrate that supplemental folate therapy prevents the development of tolerance during continuous therapy with GTN. The above observations have been confirmed in another study. In this case normal volunteers received folate or placebo in a double-blind fashion for 1 week. Subsequently both groups were treated with transdermal nitroglycerin (0.6 mg/hr) given continuously. They continued taking oral study medication and transdermal nitroglycerin for 1 week. At the end of this treatment period the forearm blood flow responses to brachial artery infusions of acetylcholine and L-monomethyl-L-argine and nitroglycerin. This study confirmed that supplemental folate completely prevented the development of endothelial dysfunction and tolerance during the continuous administration of nitroglycerin. This paper has been published (Circulation 2001 ; 104: 1114- 1123).

These findings provide evidence that tolerance to organic nitrates is caused by abnormalities in the function of NOS (nitric oxide synthase). While not wishing to be bound by any particular theory or mode of action, these abnormalities in the function of the enzyme appear to be caused by an uncoupling of the dimer, mediated by a reduction in tetrahydrobiopterin (BH4). Therefore, tolerance can be obviated or mitigated by the co- administration of supplemental BH4, or, alternatively, by the administration of supplemental folate which facilitates the regeneration of BH4 from its oxidized form dihydrobiopterin (BH2).

While this invention has been described with reference to illustrative embodiments and examples, the description is not intended to be construed in a limiting sense. Thus, various modifications of the illustrative embodiments, as well as other embodiments of the invention, will be apparent to persons skilled in the art upon reference to this description. It is therefore contemplated that the appended claims will cover any such modifications or embodiments.

All publications, patents and patent applications referred to herein are incorporated by reference in their entirety to the same extent as if each individual publication, patent or patent application was specifically and individually indicated to be incorporated by reference in its entirety.

Claims (10)

What is claimed is:

1. An organic nitrate therapy tolerance regulation pharmaceutical composition comprising a folate compound, a folate derivative compound, a hydrobiopterin compound, a hydrobiopterin derivative compound and mixtures thereof, together with a pharmaceutically acceptable carrier therefor.

2. The composition defined in claim 1, wherein the folate derivative compound is selected from the group comprising tetrahydrofolate, 5- methyltetrahydrofolate and mixtures thereof.

3. A method for regulating tolerance during organic nitrate therapy, the method comprising the step of administering to a patient undergoing organic nitrate therapy a pharmaceutical composition comprising a folate compound, a folate derivative compound, a hydrobiopterin compound, a hydrobiopterin derivative compound and mixtures thereof, together with a pharmaceutically acceptable carrier therefor.

4. The method defined in claim 3, wherein the folate derivative compound is selected from the group comprising tetrahydrofolate, 5- methyltetrahydrofolate and mixtures thereof.

5. A pharmaceutical composition comprising:

(i) a first active ingredient comprising an organic nitrate;

(ii) a second active ingredient comprising a folate compound, a folate derivative compound, a hydrobiopterin compound, a hydrobiopterin derivative compound and mixtures thereof; and

(iii) a pharmaceutically acceptable carrier therefor.

6. The composition defined in claim 5, wherein the folate derivative compound is selected from the group comprising tetrahydrofolate, 5- methyltetrahydrofolate and mixtures thereof.

7. A kit for use in organic nitrate therapy, the kit comprising:

(i) a first pharmaceutical composition comprising an organic nitrate, together a pharmaceutically acceptable carrier therefor;

(ii) a second pharmaceutical composition comprising a folate compound, a folate derivative compound, a hydrobiopterin compound, a hydrobiopterin derivative compound and mixtures thereof, together with a pharmaceutically acceptable carrier therefor.

8. The kit defined in claim 7, wherein the folate derivative compound is selected from the group comprising tetrahydrofolate, 5-methyltetrahydrofolate and mixtures thereof.

9. A method for regulating tolerance during organic nitrate therapy, the method comprising the step of administering to a patient:

(i) a first pharmaceutical composition comprising an organic nitrate, together a pharmaceutically acceptable carrier therefor; and

(ii) a second pharmaceutical composition comprising a folate compound, a folate derivative compound, a hydrobiopterin compound, a hydrobiopterin derivative compound and mixtures thereof, together with a pharmaceutically acceptable carrier therefor.

10. The method defined in claim 9, wherein the folate derivative compound is selected from the group comprising tetrahydrofolate, 5- methyltetrahydrofolate and mixtures thereof.