“Use of Metadoxine as hepatoprotector against hepatic toxicity induced in patients undergoing treatment with Methotrexate”

The object of the present invention is the use of Metadoxine as hepatoprotector against hepatic toxicity induced in patients undergoing treatment with Methotrexate, preferably in patients affected by rheumatoid arthritis. The invention further relates to the use of Metadoxine administered in combination with Methotrexate, in the treatment of rheumatoid arthritis.

STATE OF THE ART

Rheumatoid arthritis is an ankylosing and progressive chronic inflammatory polyarthritis with autoimmune pathogenesis and an unknown etiology, mainly affecting synovial joints.

It can cause deformation and pain that can lead to loss of joint function.

Rheumatoid arthritis differs from osteoporosis because it initially affects the synovial membrane and not the cartilage.

The disease affects about 1 % of the population and the number of cases increases with age, in particular, women are more affected by this pathology than men.

The causes of the onset are not completely known. There is an inflammatory response of the synovium with swelling of synovial cells, excess fluid, and development of fibrous tissue in the synovium.

Diagnosis is made on the basis of symptoms and using radiography. The course of the disease is very varied and characterized by phases of exacerbation and remission. There are milder forms that respond well to therapy, and more severe forms with no remission phases and with severe ankylosis.

The disease is serious, not because it endangers the life of the individual, but because it is invalidating for the proper use of hands and limbs.

The state of the disease can be identified on the basis of the patient’s injuries.

In the first stage, tumefactions without redness are observed; in the second stage, phlogosis and synovial proliferation are present, with bone alterations noticeable also in ultrasound. In the third stage bone deformations, luxations, and fibrosis are detected.

In the first stage of the disease, symptomatic systemic drugs such as non-steroidal anti inflammatories and corticosteroids are administered; in the second stage, when the disease is more severe, the recommended therapy in the more aggressive forms is mainly based on the Methotrexate molecule (Fig. 1 - structural formula), an antimetabolite, inhibitor of the folic acid synthesis which, at low doses, acts as an immunosuppressant, with a high degree of therapeutic efficacy.

Methotrexate is therefore considered the drug of choice in the therapy of rheumatoid arthritis

(1).

Fig. 1 -Methotrexate structural formula.

The mechanism of action of this drug is exerted in a competitive and reversible way on the dihydrofolate reductase enzyme (DHFR), whose inhibition results in a depletion of the endocellular folates.

Methotrexate inhibits the folate-dependent enzymes involved in the synthesis of purine bases of cellular DNA.

Even low doses of this drug have been shown to be effective against rheumatoid arthritis. During therapy based on the use of this drug, various adverse effects may occur, including diarrhea, urticaria, loss of libido, erectile dysfunction and hepatotoxicity, which is undoubtedly the most common and most important toxic effect (2).

For this reason, in patients treated with Methotrexate for long periods, the hepatic function, characterized by an asymptomatic increase in hepatic enzyme levels (AST, ALT) should be monitored.

It has been observed that prolonged use of Methotrexate may give rise to fibrosis and liver cirrhosis.

Adverse effects may not appear in patients with rheumatoid arthritis, but an increase in liver enzymes may occur.

For this reason, guidelines for monitoring liver toxicity are reported in the literature (3). Several attempts to reduce hepatic toxicity induced by Methotrexate have been made over the years.

In particular, pre-clinical studies were performed using ursodeoxycholic acid (UDCA), folic acid, Montelukast, cumin seeds, carvacrol, cyclosporine A, taurine, and omega 3 fatty acids. Flowever, none of these compounds, except folic acid, which is known to diminish the clinical efficacy of Methotrexate, has been able to significantly reduce this toxicity in the clinic, and improve conditions and risks for the patient.

Therefore, to date there is no therapy validated as an antidote to Methotrexate, except for that with folic acid which, on the other end, reduces its effectiveness.

Fig. 2 - Metadoxine structural formula.

Metadoxine (piridoxol L-2 pyrrolidon-5-carboxylate) is a drug that has been known for a long time (Figure 2), and used in acute and chronic alcoholism, it is on the market in several countries, with no significant side effects, even after prolonged administration, with the pharmacological profile shown below.

Metadoxine decreases blood alcohol level (4) and the duration of tissues exposure to damaging action of alcohol, by facilitating metabolism and increasing the urinary elimination of alcohol and its toxic metabolite: acetaldehyde. This drug performs a protective action on the cell, by preventing alterations resulting from redox imbalance, in fact it facilitates the oxidation of excess NADH, maintains high levels of glutathione thus contributing to the protection of membranes from lipoperoxidative damage, opposes the fall of ATP level in liver and brain by stimulating its“de novo” synthesis. Metadoxine also acts on neurotransmitters, thus increasing GABA and acetylcholine release.

Treatment with Metadoxine in acute alcoholism allowed to highlight efficacy and rapidity of action on the excitomotor component of acute alcohol intoxication. In chronic alcoholism (5), without alcohol withdrawal during treatment, a tendency to statistically significant normalization of serum biochemical parameters such as AST (the main marker that is impaired in chronic alcoholism), bilirubin and ALT is generated. Finally, in the alcohol load curves, in the healthy subject, a more rapid kinetics of elimination of alcohol from the blood, and an approach to ornithyl-carbamoyl-transferase (OCT) enzyme limit levels is observed, which denotes damage to the mitochondrial apparatus, a generator of chemical energy, especially in the liver.

The international application WO2010/100619 describes the use of Metadoxine in the treatment of hepatic fibrosis, a disease due to an excessive accumulation of extracellular matrix proteins, in the presence of a chronic inflammatory disease and a fibrosis process.

The therapeutic effect of Metadoxine in hepatic fibrosis was therefore related to the anti- fibrotic role of Metadoxine.

As discussed above, to date, the treatments used for the treatment of Methotrexate-induced liver toxicity have not allowed to obtain significant therapeutic advantages.

There is therefore a clear need for an improved therapeutic treatment that has the advantage of reducing the side effects induced by Methotrexate on the liver, and at the same time demonstrates a therapeutic efficacy in the treatment of rheumatoid arthritis.

DEFINITIONS

Unless otherwise defined, all terms of the art, notations, and other scientific terms used herein are intended to have the meanings commonly understood by those skilled in the art to which this description belongs. In some cases, terms with meanings that are commonly understood are defined herein for clarity and/or ready reference; therefore, the inclusion of such definitions herein should not be interpreted as being representative of a substantial difference with respect to what is generally understood in the art.

The term“simultaneous, separate or sequential use” refers to the simultaneous administration of the first and second compounds, or in such a way that the two compounds act in the patient’s body at the same time, or the administration of one compound after the other compound in such a way to provide a therapeutic effect.

In some embodiments, the compounds are taken with a meal. In other embodiments, the compounds are taken after a meal, such as 30 minutes or 60 minutes after a meal. In some embodiments, a compound is administered to a patient for a period of time, followed by administration of the other compound.

The terms“comprising”,“having”,“including” and“containing” are to be construed as open- ended terms (i.e., meaning“comprising, but not limited to”), and are to be considered as a support also for terms such as “consist essentially of’, “consisting essentially of’, or “consisting of. The term“hepatic cytotoxicity/hepatotoxicity” according to the present invention refers to the ability of a chemical substance to cause liver damage. Such liver damage can be evidenced by a significant alteration of serum biochemical parameters, such as AST (aspartate transaminase), bilirubin, and ALT (alanine aminotransferase).

DESCRIPTION OF THE INVENTION

It has surprisingly been found that the association of Methotrexate, the elective drug in the treatment of patients with rheumatoid arthritis, with Metadoxine, a drug generally used in acute or chronic alcoholism, results in a significant reduction in liver function indices, with a consequent effect of Metadoxine in increasing Methotrexate tolerability, and reduction of liver toxicity during the treatment.

An object of the present invention is therefore the use of Metadoxine in the prevention and/or treatment of hepatic cytotoxicity in patients undergoing treatment with Methotrexate.

Preferably, such patients are affected by rheumatoid arthritis.

According to a preferred aspect of the present invention, Metadoxine is administered orally in a formulation comprising a content of Metadoxine of between 50 and 1500 mg per dose, preferably between 500 and 1000 mg per dose, more preferably of 500 mg per dose.

Preferably, Metadoxine is administered in the form of a tablet, capsule, granules, granulate, powder, pill, gel capsule, solution, suspension, emulsion, drops, syrup, powder for solution, granules for solution, powder for suspension or granulate for suspension.

In a further preferred aspect, Metadoxine according to the present invention is administered two to four times a day, preferably two or three times a day.

In a further aspect of the present invention, Metadoxine is administered in combination or temporal proximity with Methotrexate

Preferably, Metadoxine is administered before or during therapy with Methotrexate.

According to the present invention, when Metadoxine is administered before Methotrexate, it is administered two to eight weeks before, preferably four to six weeks before Methotrexate. More preferably, Metadoxine is administered following a therapy with Methotrexate.

In a further aspect, Metadoxine is administered after four or six weeks of treatment with Methotrexate, preferably after five weeks.

Preferably, according to the present invention, Metadoxine is administered for a period ranging between four and twelve weeks after the treatment with Methotrexate, preferably between four and eight weeks, more preferably for four weeks

More preferably, according to the present invention, Metadoxine is administered for a period ranging between two and twenty- four weeks after the treatment with Methotrexate, preferably between four and twelve weeks, more preferably between four and eight weeks, even more preferably for four weeks.

In a further preferred aspect of the present invention, Metadoxine is used in the treatment of rheumatoid arthritis, and it is administered in combination or temporal proximity with Methotrexate.

Preferably, Metadoxine is administered daily two to four times a day, preferably daily two to three times a day.

In a further preferred aspect, Methotrexate is administered one to two times a week, preferably one time a week.

Preferably, Methotrexate is administered parenterally at a dosage ranging between 10 and 20 mg, preferably between 12 and 16 mg.

In a further preferred aspect, Metadoxine is administered orally at a daily dosage ranging between 50 and 1500 mg, preferably between 500 and 1000 mg, more preferably of 500 mg. Preferably, Metadoxine is administered after at least four weeks of treatment with Methotrexate and for further 4-12 weeks, preferably 4-8 weeks, more preferably 4 weeks. More preferably, Metadoxine is administered at least between 4 and 24 weeks after the treatment with Methotrexate, preferably between 4 and 12 weeks, more preferably between 4 and 8 weeks, even more preferably for four weeks

EXAMPLES

Example 1. Evaluation of the efficacy of Metadoxine in contrasting hepatic toxicity resulting from Methotrexate therapy in patients with rheumatoid arthritis.

We treated 24 patients with rheumatoid arthritis (AR) with average age of 51.3 years (± 14.1), who started treatment with Methotrexate at the average dose of 12.3 mg subcutaneously, once a week.

Of these 24 patients, 13 patients were selected who received Metadoxine therapy (500 mg twice a day). This treatment with Metadoxine started at the fifth week of monitoring, up to the eighth week (4 weeks of treatment).

Patients treated with the combination of Methotrexate + Metadoxine showed a significant reduction in liver function indices (see Table 1) after 12 weeks of monitoring. This reduction is present even after 4 weeks of follow-up.

Table 1 - Liver function comparison between the two patient groups

Conclusions

This study showed the possible effect of MTDX in increasing tolerability to MTX. Its role, therefore, could have useful implications in patients, for example, who start therapy with MTX to improve its tolerability, or develop hepatotoxicity during treatment.

References

1. Martindale - The complete drug reference. Thirtythird ed. 2002. Pag. 554.

2. West SG, et al: Methotrexate hepatotoxicity. Rheum Dis Clin North Am, 1997, 23: 883-915.

3. Kemer JM. Arthritis Rheumatism, 1994, 37 (3): 316.

4. Shpilenya LS, et al: Metadoxine in acute alcohol intoxication: a double blind, randomized, placebo controlled study. Alcoholism: Clinical and Experimental Research, 2002, 26: 340.

5. Feher J, et al: A new approach to drug therapy in non-alcoholic steatohepatitis (NASH). J Int Med Res, 2003, 31 : 537-551.