Technical field:
This invention relates to the field of pharmaceutical co crystals. More particularly, the present invention relates to synergistic pharmaceutical co crystals comprising Metformin in combination with amino acids. The pharmaceutical co-crystals of Metformin-amino acid have unique physical properties and biological activity which differ from the active agent in pure form. The invention further relates to process for preparation of the same and also relates to pharmaceutical compositions comprising these synergistic co-crystals.
Background and prior art:
Pharmaceutical co crystals are defined as hydrogen bonded complexes between an active pharmaceutical ingredient (API) and a coformer (CCF, benign partner molecule), usually having a fixed API: CCF stoichiometry. The utility of pharmaceutical co-crystals in solving stability, solubility, bioavailability, filtration, hydration, tableting, etc. issues is highlighted in recent papers.
Even though co-crystals were known as early as 19th century, the pharmaceutical industry has recognized the potential for their applications only recently. Pharmaceutical co-crystals are crystalline molecular complexes containing therapeutic molecules. These co crystals represent emerging class of pharmaceutical materials offering the prospects of optimized physical properties as discussed.
These co-crystals have utility in imparting desirable physical properties and stability, which are otherwise not achievable for the pure active agent or in combination as a simple formulation using the excipients incorporated with the active agent. Pharmaceutical co-crystals are crystalline molecular complexes containing therapeutic molecules. These co-crystals represent emerging class of pharmaceutical materials offering the prospects of optimized physical as well as therapeutic properties.
Metformin is an oral anti-diabetic drug from the biguanide class. It is the first-line drug for the treatment of type 2 diabetes, particularly in overweight and obese people and those with normal kidney function. Evidence suggests it may be the best choice for people with heart failure. It is also used in the treatment of polycystic ovary syndrome. Though, Metformin causes few adverse effects, like gastrointestinal upset, however, unlike many
other anti-diabetic drugs, do not cause hypoglycemia if used alone. It also helps to reduce LDL cholesterol and triglyceride levels, and may aid weight loss.
Metformin is most widely used first line drug for diabetes type II. Its mechanism of action involves raising peripheral glucose uptake by increasing both the binding capacity of insulin to its receptor and the translocation and synthesis of glucose transporters.
Metformin has an oral bioavailability of 50-60% under fasting conditions, and is absorbed slowly. Peak plasma concentrations (Cmax) are reached within one to three hours of taking immediate-release Metformin and four to eight hours with extended-release formulations. The plasma protein binding of Metformin is negligible, as reflected by its very high apparent volume of distribution (300-1000 L after a single dose).
Protein binding can influence the drug's biological half-life in the body. The bound portion may act as a reservoir or depot from which the drug is slowly released as the unbound form. Since the unbound form is being metabolized and/or excreted from the body, the bound fraction will be released in order to maintain equilibrium.
As on today Metformin is available in the market as immediate release and sustained release tablet form. However, prior art failed to provide alternate synergistic bioavailable dosage forms of Metformin to enhance the residence time of Metformin in the blood.
a-amino acids are naturally occurring biomolecules. Apart from being essential building blocks for the proteins, alpha-aminoacids have a wide range of biological action.
Essential Amino Acids and their role in biological functions are given below:
L-Isoleucine - is needed in regulating sugar and the energy levels, as well as in the formation of hemoglobin. This amino acids is transformed and converted into muscle tissue. Lack of this AA produces a symptom similar to hypoglycemia or low blood sugar.
L-Leucine - an important amino acid, which is found in animal and vegetable proteins. It is important for controlling the blood sugar level.
L-Lysine - an important for the construction of proteins principally in muscles and bones. Helps the assimilation of calcium, to obtain greater mental concentration and helps to lessen the effects of colds, flu and the herpes virus. It helps in the production of hormones, antibodies, enzymes and also in the formation of collagen. The deficiency of this amino acid produces: fatigue, irritability, anemia, and hair loss.
L-Methionine - helps to remove poison wastes from the liver and take part in the formation of the liver and kidney tissues. Help the digestive system, weak muscles, fragile hair, and is beneficial for osteoporosis.
L-Phenylalanine - helps against depression, obesity, and loss of memory. It is an important element in the production of collagen, the principal fibrous protein in the body. Due to its action in the central nervous system, these amino acids decrease the pain associated with migraines, menstruation, and arthritis. L-Phenylalanine should not be taken by pregnant women or those who suffer from high blood pressure.
L-Tryptophan - helps control hyperactivity in children, alleviate stress, is good for the heart. It helps in weight control and allows the growth of the hormones necessary for the production of Vitamin B6 and Niacin. The brain utilizes this amino acid to produce Seratonina and Melatonina, neurotransmitters necessary for transferring nervous impulses from one cell to another. Lack of them (viz. Serotonine and Melatonine) produces depression, loss of sleep and other mental disorders.
L-Threonine - found in the heart, central nervous system and muscles. It is beneficial in the formation of collagen and elastin. Helps the liver and maintain the body's proteins in balance.
L-Valine - has a stimulating effect. It maintains the metabolism of muscles, repairs tissues and balances nitrogen. Valine should be combined with Leucine and isoleucine.
Types of Non Essential A A
L-Alanine - acts as a producer of energy and it regulates blood sugar. Also, intervenes in the metabolism of glucose.
L-Asparagine - is important in the metabolic process of the nervous system.
L-Aspartic Acid - is essential for the transformation of carbohydrates into muscular energy.
L-Citruline - immune system stimulator helps in the production of body energy and helps to detoxify the liver from ammonia substance.
L-Cysteine - stimulates the growth of hair and protects against the damages that can be caused by alcohol and cigarettes.
L-Glutamine - helps the memory, concentration, and the correct functioning of mental activity.
L-Glutamic Acid - helps in the production of energy and brain function.
L-Glycine - slow the muscle degeneration by supplying addional creatine. Vital for structuring red blood cells and providing amino acids to the body. Glucose and creatine are 2 essential substances in the production of energy and require glycine in their synthesis process.
L-Histidine - important in the production of red and white blood cells, and is vital for the formation of body tissues.
L-Proline - is important ingredient in the formation of tissues.
L-Serine - aid the memory, the nervous system function, and is very important in the production of cell energy.
L-Tyrosine - helps in the treatment of insomnia, anxiety and depression, as well as allergies and is very important in the function of the thyroid and hypophysis glands. Deficiency of this amino acid is associated to hyperthyroidism (can cause fatigue).
L-Carnitine - helps control weight and body fat, as well as reduce the risk of heart problems. Lysine and vitamin Bl and B6 along with iron are needed for the body to produce this amino acid.
GABA (Gamma-Aminobutyric Acid) - helps stop anxiety and hyperactivity.
L-Taurine - important for the muscle and disorders of the heart, helps the digestion of fats (it is found in bile), and also helps in hypoglycemia and hypertension.
Amino acids are critical to life, and have a variety of roles in metabolism. One particularly important function is as the building blocks of proteins which are linear chains of amino acids. Amino acids are also important in many other biological molecules, such as forming parts of coenzymes, or as precursors for the biosynthesis of
molecules such as heme. Due to this central role in biochemistry, amino acids are very important in nutrition.
Many important a-amino acids are useful in regulating sugar and energy levels, moreover, these amino acids being lipophilic helps Metformin in binding with blood plasma protein thereby increasing the plasma protein binding effect of the drug which in turn helps slow release of the drug from the co-crystals in unbound form yet maintaining the equilibrium of the drug levels in the body.
Therefore, the objective of the present invention is to provide synergistic pharmaceutical co-crystals comprising Metformin composed of alpha-amino acids to provide effective treatment of polycystic ovary syndrome, metabolic syndrome, hypoglycemia, hypertension or diabetes Type II with reduced dosage of the active.
Summary of the invention:
In accordance with the above objective, the present invention discloses a novel synergistic pharmaceutical co-crystal composed of Metformin with at least one alpha amino acid(s). The inventive co-crystal of Metformin can be used in Metformin sustained release dosage forms.
The word 'Metformin' as described herein also encompasses Metformin salts including Metformin hydrochloride.
In one aspect, the invention provides novel synergistic Metformin co-crystals which comprise Metformin and at least one alpha amino acid(s). Alpha amino acids are selected from Leucine, isoleucine, lysine, methionine, phenyl alanine, threonine, tryptophan, valine, alanine, asparagines, aspartic acid, cystenine, glutamic acid, glutamine, glycine, proline, serine, tyrosine, arginine, and histidine.
The Bioavailability / blood plasma binding of Metformin is poor, hence these co-crystals (specially the ones with lipophilic amino acids) will enhance the blood plasma binding ability of Metformin, thereby enhancing the 'time of residence' of Metformin in the blood. This would naturally translate to improving the efficacy, and hence lowering the dose of Metformin. Hence, the pharmaceutical co-crystal composed of Metformin with
alpha amino acids is useful to treat polycystic ovary syndrome, metabolic syndrome, hypoglycemia, hypertension or diabetes Type II.
In another aspect, the invention provides the metformin-amino acid co-crystals, wherein said method comprises neat grinding of Metformin free base and amino acid in 1:1 ratio.
In a further aspect, the invention provides novel pharmaceutical composition comprising Metformin-amino acid co-crystals of the current invention in association with one or more pharmaceutical carriers.
The invention also provides methods for the treatment of the disorder discussed above. Metformin co-crystals and pharmaceutical compositions containing them may, according to the invention, be administered using any amount, any form of pharmaceutical composition and any route of administration effective for the treatment. After formulation with an appropriate pharmaceutically acceptable carrier in a desired dosage, as known by those of skill in the art, the pharmaceutical compositions of this invention can be administered by any means that delivers the active pharmaceutical ingredient (s) to the site of the body whereby it can exert a therapeutic effect on the patient. Brief description of drawings:
g 1 shows the PXRD profile of Metformin
g 2 shows the PXRD profile of L- Leucine
g 3 shows the PXRD profile of co-crystal of Metformin-L- Leucine
g 4 shows the PXRD profile of L-Alanine
g 5 shows PXRD profile of co-crystal of Metformin and L-alanine
g 6 shows IR spectra of Metformin
g 7 depicts IR spectra of L-Leucine
g 8 depicts IR spectra of co-crystal of Metformin-L-Leucine.
g 9 depicts DSC of Metformin
g 10 depicts DSC of L-Leucine
g 11 depicts DSC of co-crystal of Metformin- L-Leucine
g 12 depicts TGA of Metformin
g 13 depicts TGA of L-Leucine
g 14 depicts TGA of co-crystal of Metformin-L-Leucine
Description of the invention:
The invention will now be described in detail in connection with certain preferred and optional embodiments, so that various aspects thereof may be more fully understood and appreciated.
The present invention discloses novel synergistic pharmaceutical co-crystals composed of Metformin with at least one alpha amino acid(s). The inventive co-crystal of Metformin can be used in Metformin sustained release dosage forms.
In one embodiment, the invention provides novel synergistic Metformin co-crystals which comprise metform and alpha amino acid. Alpha amino acids are selected from leucine, isoLeucine, lysine, methionine, phenyl alanine, threonine, tryptophan, valine, alanine, asparagines, aspartic acid, cystenine, glutamic acid, glutamine, glycine, proline, serine, tyrosine, arginine, and histidine.
The Bioavailability / blood plasma binding of Metformin is poor, hence these co-crystals (specially the ones with lipophilic amino acids) will enhance the blood plasma binding ability of Metformin, thereby enhancing the 'time of residence' of Metformin in the blood. This would naturally translate to improving the efficacy, and hence lowering the dose of Metformin. Hence, the pharmaceutical co-crystal composed of Metformin with alpha amino acids is useful to treat polycystic ovary syndrome, metabolic syndrome, hypoglycemia, hypertension or diabetes Type II.
In another embodiment, the invention provides the metformin-amino acid co-crystals, wherein said method comprises neat grinding of Metformin free base and amino acid in 1:1 ratio and isolating the co-crystals.
In another embodiment, the process involves solvent drop grinding method. Generally co-crystals appear in 2-3 days. The formation of these co-crystal or salt was confirmed by powder X-ray powder diffractometry, IR spectrometry, DSC and TGA.
The physical characteristics of the co-crystals of Metformin + alpha amino acids prepared according to the current invention are as tabulated below:
1. Metformin + L-Leucine co-crystal (1:1)
(Table Removed)
IR DATA:

(Table Removed)
PXRD DATA (2Theta):

(Table Removed)
1. Metformin + L-Alanine co-crystal (1:1)

(Table Removed)
PXRD DATA (2Theta):

(Table Removed)
Generally, the co-crystal melts in-between the melting points of co-crystal formers (more often) or below their melting points (less often). Here, Metformin co-crystal with L-Leucine (1:1) start to decompose at 167 °C which is higher than the melting point of Metformin free base and lower than the melting point of L-Leucine. In a further embodiment, the invention provides pharmaceutical compositions comprising a therapeutically effective amount of Metformin-amino acid co-crystals of the current invention in association with one or more pharmaceutical carriers. The co-crystals of the invention have the same pharmaceutical activity as its API. Further, the pharmaceutical composition of the invention may be any pharmaceutical form which maintains the crystalline form of a co-crystal of the invention. The pharmaceutical composition may be a solid form, a liquid suspension or an injectable composition.
In a further embodiment, the present invention provides a method of reducing symptoms associated with polycystic ovary syndrome, metabolic syndrome, hypoglycemia, hypertension or diabetes Type II, which method comprises administering 'an effective amount' of the 'Metformin and alpha amino acid co-crystals' to the subject suffering from polycystic ovary syndrome, metabolic syndrome, hypoglycemia, hypertension or diabetes Type II. The subject mentioned herein is human.
Metformin co-crystals and pharmaceutical compositions containing them may, according to the invention, be administered using any amount, any form of pharmaceutical composition and any route of administration effective for the treatment. After formulation with an appropriate pharmaceutically acceptable carrier in a desired dosage, as known by those of skill in the art, the pharmaceutical compositions of this invention can be administered by any means that delivers the active pharmaceutical ingredient (s) to the site of the body whereby it can exert a therapeutic effect on the patient.
The invention further discloses use of the 'composition of the invention comprising Metformin and alpha amino acid co-crystals' in preparing the medicament intended to
reduce symptoms associated with polycystic ovary syndrome, metabolic syndrome, hypoglycemia, hypertension or diabetes Type II.
The following examples, which include preferred embodiments, will serve to illustrate the practice of this invention, it being understood that the particulars shown are by way of example and for purpose of illustrative discussion of preferred embodiments of the invention.
Examples:
Example 1
Method of Preparation:
Metformin free base (synthesized from Metformin hydrochloride in house) and L-Leucine (Aldrich - Sigma) in 1: 1 ratio was neat grinded for 5 min to yield the new co-crystal of Metformin-)- L-Leucine.
Example 2:
Metformin free base (synthesized from Metformin hydrochloride in house) and L-alanine (Aldrich - Sigma) in 1: 1 ratio was neat grinded for 5 min to yield the new co-crystal of Metformin+ L-alanine.

We claim,
1. A Synergistic pharmaceutical co-crystal composition of Metformin and at least one alpha amino acid(s).
2. The pharmaceutical co-crystal composition according to claim 1, wherein alpha amino acid(s) is selected from Leucine, isoleucine, lysine, methionine, phenyl alanine, threonine, tryptophan, valine, alanine, asparagines, aspartic acid, cystenine, glutamic acid, glutamine, glycine, proline, serine, tyrosine, arginine, and histidine.
3. The pharmaceutical co-crystal composition according to claim 1, wherein the alpha amino acid is L-Alanine.
4. The pharmaceutical co-crystal composition according to claim 1, wherein the alpha amino acid is L-Leucine.
5. The pharmaceutical co-crystal composition according to claim 1, further comprises one or more pharmaceutical carrier.
6. A process for preparing pharmaceutical co-crystal compositions according to claim 1, comprising (a) neat grinding of Metformin free base and amino acid in 1:1 ratio; (b) isolating the co-crystals.
7. Method of reducing symptoms associated with spolycystic ovary syndrome, metabolic syndrome, hypoglycemia, hypertension or diabetes Type II, which method comprises administering 'an effective amount' of the 'Metformin-amino acid cocrystals' according to claim 1 to the subject suffering from said symptoms.
8. The method according to claim 5, wherein said subject is human.
9. Use of Metformin-amino acid crystals according to claim 1 in preparing the medicament intend to reduce symptoms associated with polycystic ovary syndrome, metabolic syndrome, hypoglycemia, hypertension or diabetes Type II.