Highly concentrated liquid aqueous pyronaridine formulation

Abstract

NOT VISIBLE DUE TO STATUS OF PATENT

Description

[0001] HIGHLY CONCENTRATED LIQUID AQUEOUS PYRONARIDINE FORMULATION

[0002] TECHNICAL FIELD OF THE INVENTION

[0003] The invention relates to a highly concentrated liquid aqueous pyronaridine formulation that is particularly suited for e.g. intramuscular or intranasal administration.

[0004] The invention further relates to the use of the aforementioned pyronaridine formulation in medical treatment, such as the treatment of malaria.

[0005] BACKGROUND OF THE INVENTION

[0006] Malaria is a serious and sometimes fatal disease caused by a parasite that commonly infects a certain type of mosquito which feeds on humans. People who get malaria are typically very sick with high fevers, shaking chills, and flu-like illness. Four kinds of malaria parasites infect humans: Plasmodium falciparum, P. vivax, P. ovale, and P. malariae. In addition, P. knowlesi, a type of malaria that naturally infects macaques in Southeast Asia, also infects humans, causing malaria that is transmitted from animal to human (“zoonotic” malaria). P. falciparum is the type of malaria that is most likely to result in severe infections and if not promptly treated, may lead to death.

[0007] Globally, the World Health Organization estimates that in 2020, 241 million clinical cases of malaria occurred, and 627,000 people died of malaria, most of them children in Africa. Because malaria causes so much illness and death, the disease is a great drain on many national economies. Since many countries with malaria are already among the poorer nations, the disease maintains a vicious cycle of disease and poverty.

[0008] Pyronaridine is an antimalarial drug. It was first made in 1970 and has been in clinical use in China since the 1980s. In a small (n=88) malaria study in Cameroon, pyronaridine had a 100% cure rate, compared with 60% for chloroquine. It has also been studied as a potential anticancer drug, and treatment for Ebola.

[0009] Artesunate / pyronaridine, sold under the brand name Pyramax®, is a fixed-dose combination medication for the treatment of malaria that is taken by mouth. Each Pyramax tablet contains 180 mg pyronaridine tetraphosphate and 60 mg artesunate. Pyramax tablets should be taken orally as a single daily dose for three consecutive days (1-4 tablets daily, depending on bodyweight). The combination of pyronaridine and artesunate is being studied as a possible treatment for moderate to severe SARS-COV-2.

[0010] Shao (A review of antimalarial drug pyronaridine, Chin Med J (Engl) 1990, 103:428-434) reports that an intramuscular injection of pyronaridine 48 pmol / kg in 4% solution induced mild local irritant reaction in rabbits which completely disappeared within 2 weeks.

[0011] Adegoke et al. (Determination of the phyiscochemical properties of pyronaridine - a new antimalarial drug, Pak. J. Pharm. Sci. 2006, Vol. 19(1), 1-6) investigated the physicochemical properties of pyronaridine. Pyronaridine tetraphosphate was found to be sparingly soluble in water and very slightly soluble in other solvents. At the end of the article the authors conclude that their study points to the need to improve on the properties of pyronaridine to enhance its usefulness and they hypothesize that the choice of other salt forms with better solubility, partition and distribution properties may help in improving the already observed poor bioavailability of this drug.

[0012] Croft et al. (Review of pyronaridine anti-malarial properties and product characteristics, Malaria Journal 2012, 11 :270) report that pyronaridine has high potency against Plasmodium falciparum, including chloroquine-resistant strains. The authors report that pyronaridine is administered as pyronaridine tetraphosphate (56.89% base), a yellow, odourless powder with a bitter taste and that the drug was produced in China as tablets for oral use, as an injectable liquid for intramuscular administration and that it has also been administered intravenously. The authors further observe that pyronaridine free base is ‘very sparingly’ soluble in water, whereas the tetraphosphate salt is ‘sparingly’ soluble in water (1.46%), aiding oral absorption.

[0013] Chu et al., Pyronaridine: a review of its clinical pharmacology in the treatment of malaria, J Antimicrob Chemother 2023; 78: 2406-2418, provide a provide a comprehensive overview of the clinical pharmacology of pyronaridine in the treatment of malaria. In the paper it is stated that pyronaridine tetraphosphate as monotherapy is available for the Chinese market under the trade name Malaridine and that it is formulated as an enteric-coated tablet (100 mg pyronaridine base) for oral administration and as an injectable drip (80 mg pyronaridine base / 2 mL) for intramuscular administration.

[0014] At present there are no pyronaridine formulations available that are sufficiently concentrated to be administered intramuscularly or intranasally to humans. SUMMARY OF THE INVENTION

[0015] The inventors have developed a liquid aqueous pyronaridine formulation that is sufficiently concentrated and yet has a sufficiently low osmolality to be administered intramuscularly. The liquid aqueous pyronaridine formulation of the present invention comprises at least 40 pmol / ml of dissolved pyronaridine, has a pH in the range of 2.5 to 5.8 and a ratio of the osmolality of the formulation (in Osm / kg) to the pyronaridine concentration of the formulation (in mmol / mL) of less than 2.0.

[0016] Accordingly, one aspect of the invention relates to a liquid aqueous formulation of pyronaridine for use in medical treatment, said liquid aqueous formulation comprising at least 70 wt.% water and at least 40 pmol / ml of dissolved pyronaridine, having a pH in the range of 2.5 to 5.8 and being characterised in that the ratio of the osmolality of the formulation (in Osm / kg) to the pyronaridine concentration of the formulation (in mmol / mL) is less than 2.0.

[0017] The inventors have found that a highly concentrated liquid aqueous formulation of pyronaridine that can safely be administered intramuscularly can be obtained by dissolving the pyronaridine base together with a strong acid in water, such that the resulting formulation has a pH in the range of 2.5 and 5.8 and a ratio of osmolality to pyronaridine concentration of less than 2.0. By using pyronaridine base instead of e.g. pyronaridine tetraphosphate, the inventors have been able to prepare a highly concentrated pyronaridine solution that is also isotonic.

[0018] Thus, another aspect of the invention relates to a sterile liquid aqueous formulation comprising at least 70 wt.% water and at least 40 pmol / ml of dissolved pyronaridine, having an osmolality in the range of 0.15 to 0.60 Osm / kg, a pH in the range of 2.5 to 5.8 and being characterised in that the ratio of the osmolality of the formulation (in Osm / kg) to the pyronaridine concentration of the formulation (in mmol / mL) is less than 2.0.

[0019] The concentrated aqueous pyronaridine formulation of the present invention is perfectly suited for intramuscular administration, but can also suitably be administered intranasally, orally or intravenously. DETAILED DESCRIPTION OF THE INVENTION

[0020] A first aspect of the present invention relates to a liquid aqueous formulation of pyronaridine for use in medical treatment, said liquid aqueous formulation comprising at least 70 wt.% water and at least 40 pmol / ml of dissolved pyronaridine, having a pH in the range of 2.5 to 5.8 and being characterised in that the ratio of the osmolality of the formulation (in Osm / kg) to the pyronaridine concentration of the formulation (in mmol / mL) is less than 2.0.

[0021] The term “pyronaridine” as used herein refers to the substance 4-[(7-chloro-2-methoxy-1,5- dihydrobenzo[b][1 ,5]naphthyridin-10-yl)imino]-2,6-bis(pyrrolidin-1-ylmethyl)cyclohexa-2,5- dien-1-one (CAS Number: 74847-35-1). The molar mass of pyronaridine is 518.05 g / mol.

[0022] The term “malaria” as used herein refers to an infection with a malaria parasite selected from Plasmodium falciparum, Plasmodium vivax, Plasmodium ovale, Plasmodium, malariae and Plasmodium, knowlesi.

[0023] The medical treatment of the present invention preferably is a medical treatment of humans.

[0024] The treatment of the present invention preferably comprises administration of the liquid aqueous pyronaridine formulation to provide pyronaridine in a dose of at least 1 pmol / kg of bodyweight, more preferably in a dose of 2 to 100 pmol / kg of bodyweight and most preferably in a dose of 3 to 60 pmol / kg of bodyweight.

[0025] The treatment may suitably comprise administration of the aqueous pyronaridine formulation by different modes of administration, including intramuscular, subcutaneous, intravenous, intranasal, oral or intraperitoneal administration. More preferably, the treatment comprises intramuscular, intranasal or intravenous administration of the aqueous pyronaridine formulation.

[0026] In one preferred embodiment of the present invention the treatment comprises intramuscular administration of the aqueous pyronaridine formulation. According to a particularly preferred embodiment, the aqueous pyronaridine formulation is administered intramuscularly to provide pyronaridine in a dose of at least 1 pmol / kg of bodyweight, more preferably in a dose of 2 to 30 pmol / kg of bodyweight and most preferably in a dose of 3 to 20 pmol / kg of bodyweight . In another preferred embodiment of the present invention the treatment comprises intranasal administration of the aqueous pyronaridine formulation. According to a particularly preferred embodiment, the aqueous pyronaridine formulation is administered intranasally to provide pyronaridine in a dose of at least 0.5 pmol / kg of bodyweight / day, more preferably in a dose of1 to 30 pmol / kg of bodyweight / day and most preferably in a dose of 2 to 20 pmol / kg of bodyweight / day.

[0027] The present treatment preferably comprises at least once daily intranasal administration of the aqueous pyronaridine formulation during a period of 2-10 days, preferably during a period of 3-6 days.

[0028] In yet another preferred embodiment the treatment comprises oral administration of the aqueous pyronaridine formulation. According to a particularly preferred embodiment, the aqueous pyronaridine formulation is administered orally to provide pyronaridine in a dose of at least 2 pmol / kg of bodyweight / day, more preferably in a dose of 4 to 50 pmol / kg of bodyweight / day and most preferably in a dose of 5 to 20 pmol / kg of bodyweight / day.

[0029] The present treatment preferably comprises at least once daily oral administration of the aqueous pyronaridine formulation during a period of 2-10 days, preferably during a period of 3-6 days.

[0030] A preferred embodiment of the present invention relates to the treatment of a disease that is caused by a parasite or a virus, more preferably a disease caused by a parasite.

[0031] Examples of diseases caused by parasites that can be treated in accordance with the present invention include malaria and diseases caused by metazoan parasites, such as schistosomiasis and cystic echinococcosis. Preferably, the disease that is treated is malaria or cystic echinococcosis caused by Echinococcus granulosus.

[0032] Examples of viral diseases that can be treated in accordance with the invention include SARS-cov-1, SARS-cov-2, Ebola and Marburg virus disease.

[0033] According to a particularly preferred embodiment, the medical treatment according to the present invention comprises treatment of malaria, especially malaria caused by Plasmodium falciparum. The present treatment is particularly suitable for treating severe malaria. Severe malaria occurs when infections are complicated by serious organ failures or abnormalities in the patient’s blood or metabolism. The manifestations of severe malaria include the following:

[0034] • Cerebral malaria, with abnormal behavior, impairment of consciousness, seizures, coma, or other neurologic abnormalities

[0035] • Severe anemia due to hemolysis (destruction of the red blood cells)

[0036] • Hemoglobinuria (hemoglobin in the urine) due to hemolysis

[0037] • Acute respiratory distress syndrome (ARDS), an inflammatory reaction in the lungs that inhibits oxygen exchange, which may occur even after the parasite counts have decreased in response to treatment

[0038] • Abnormalities in blood coagulation

[0039] • Low blood pressure caused by cardiovascular collapse

[0040] • Acute kidney injury

[0041] • Hyperparasitemia, where more than 5% of the red blood cells are infected by malaria parasites

[0042] • Metabolic acidosis (excessive acidity in the blood and tissue fluids), often in association with hypoglycemia

[0043] Treatment of malaria in accordance with the present invention may comprise coadministration of one or more other drugs. According to a preferred embodiment, the treatment comprises co-administration of artesunate. The combination treatment using coadministration of artesunate is particularly suitable for treating severe malaria.

[0044] The aqueous pyronaridine formulation that is employed in the medical treatment of the present invention preferably is a sterile liquid aqueous pyronaridine formulation as specified below.

[0045] Another aspect of the present invention relates to a sterile liquid aqueous formulation comprising at least 70 wt.% water and at least 40 pmol / ml of dissolved pyronaridine, having an osmolality in the range of 0.15 to 0.60 Osm / kg, a pH in the range of 2.5 to 5.8 and being characterised in that the ratio of the osmolality of the formulation (in Osm / kg) to the pyronaridine concentration of the formulation (in mmol / mL) is less than 2.0.

[0046] The liquid aqueous formulation of the present invention preferably comprises 100-400 pmol / ml, more preferably 150-330 pmol / ml and most preferably 180-300 pmol / ml of dissolved pyronaridine. Together, pyronaridine and water preferably constitute at least 90 wt.%, more preferably at least 93 wt.% and most preferably 95-98 wt.% of the aqueous pyronaridine formulation.

[0047] The liquid aqueous formulation preferably does not contain undissolved pyronaridine.

[0048] The osmolality of the aqueous pyronaridine formulation is preferably in the range of 0.18 to 0.50 Osm / kg, most preferably in the range of 0.20 to 0.40 Osm / kg.

[0049] The ratio of the osmolality of the aqueous pyronaridine formulation (in Osm / kg) to the pyronaridine concentration of the same formulation (in mmol / mL) is preferably in the range of 1.2 to 1.9, more preferably in the range of 1.3 to 1.8 and most preferably in the range of 1.4 to 1.7.

[0050] The pH of the aqueous pyronaridine formulation is preferably in the range of 3.0 to 5.7, more preferably in the range of 4.0 to 5.6 and most preferably in the range of 4.5 to 5.5.

[0051] The aqueous pyronaridine formulation preferably comprises at least 72 wt.% water, more preferably it comprises 75-95 wt.% water, most preferably it comprises 80-92 wt.% water.

[0052] Due to the buffering capacity of pyronaridine, it is advantageous to employ a strong acid to reduce pH as otherwise it will be difficult if not impossible to achieve the desired near- isotonic osmolality. Accordingly, in a preferred embodiment, the aqueous pyronaridine formulation comprises per mmol of pyronaridine at least 1 mmol, more preferably 1.5-5 mmol and most preferably 2-4 of one or more strong acids selected from hydrochloric acid, hydrobromic acid, hydroiodic acid, nitric acid and sulphuric acid.

[0053] According to a particularly preferred embodiment, the aqueous pyronaridine formulation comprises per mmol of pyronaridine at least 1 mmol, more preferably 1.5-5 mmol and most preferably 2-4 mmol of hydrochloric acid.

[0054] According to a particularly preferred embodiment, the combination of water, pyronaridine and strong acid constitutes at least 92 wt.%, more preferably at least 96 wt.% and most preferably at least 99 wt.% of the aqueous pyronaridine formulation.

[0055] The aqueous pyronaridine formulation of the present invention preferably contains no phosphate or the phosphate content is less than 2 mmol per mmol of pyronaridine, more preferably less than 1 mmol per mmol of pyronaridine, even more preferably less than 0.3 mmol per mmol of pyronaridine.

[0056] The liquid aqueous formulation of the present invention preferably comprises 100-400 pmol / ml, more preferably 150-330 pmol / ml and most preferably 180-300 pmol / ml of dissolved pyronaridine.

[0057] Preferably the aqueous pyronaridine formulation contains 0-200 pmol / ml phosphate, more preferably 0-100 pmol / ml phosphate and even more preferably 0-50 pmol / ml phosphate. Most preferably, the aqueous pyronaridine formulation does not contain phosphate.

[0058] The inventors have found that the stability of the aqueous pyronaridine formulation may be improved by incorporating L- methionine. Accordingly, in a preferred embodiment, the aqueous pyronaridine formulation comprises 0.2-10 mg / mL of L-methionine, more preferably 0.4-6 mg / mL of L-methionine and most preferably 0.8-4 mg / mL of L-methionine.

[0059] Yet another aspect of the invention relates to a method of preparing the liquid aqueous formulation described herein before, the method comprising combining pyronaridine base, water and acid.

[0060] The acid employed in the present method is preferably selected from hydrochloric acid, hydrobromic acid, hydroiodic acid, nitric acid and sulphuric acid. Most preferably, the acid employed in the method is hydrochloric acid.

[0061] The invention is further illustrated by the following non-limiting examples.

[0062] EXAMPLES

[0063] Comparative Example A

[0064] Aqueous solutions of pyronaridine tetraphosphate (molar weight equals 910.03 g) were prepared and the osmolality of the solutions was determined. The results are shown in Table 1.

[0065] Table 1 The solution of 200 mg / mL pyronaridine tetraphosphate had a pH of 2.60.

[0066] Comparative Example B

[0067] An experiment was conducted to determine physical appearance of pyronaridine base in different solvents at a concentration of 10 mg / mL. The results are summarised in Table 2.

[0068] Table 2

[0069] Example 1

[0070] An aqueous pyronaridine solution according to the invention was prepared on the basis of the recipe that is shown in Table 3.

[0071] Table 3

[0072] The solution was prepared by weighing in 1200 mg pyronaridine free base into a glass vial and then adding the required amount of prediluted 1M HCI to neutralize the base. To attain pH 5.0, a setpoint of 5650 mg 1M HCI was used. Finally, all contents were diluted to 10.0 ml with MilliQ water.

[0073] The pyronaridine solution so obtained had an intensely dark orange to black colour, did not contain undissolved matter and had a pH of 5.0. The osmolality of the solution was 0.342 Osm / kg.

[0074] The ratio of the osmolality (in Osm / kg) and the pyronaridine concentration (in mmol / mL) equals 0.342 / 0.232 = 1.48.

[0075] The pyronaridine solution was sterilized by passing it through a sterilizing 0.22pm polyethersulfone filter.

[0076] The sterile solution so obtained can suitably be administered intramuscularly (e.g. in gluteal muscle) in a dose of 5 mL to deliver 600 mg pyronaridine. Example 2

[0077] Aqueous pyronaridine solutions according to the invention were prepared on the basis of the recipes shown in Table 4. Table 4

[0078] The solutions were prepared by weighing in the pyronaridine free base and, if applicable, the L-methionine into a glass vial. Next the required amount of prediluted 1M HCI was added to neutralize the base. To attain pH 5.0, 5,650 mg 1M HCI was used. Finally, all contents were diluted to 10.0 ml with MilliQ water.

[0079] The solutions so obtained were filled into separate clear glass HPLC vials with crimp cap tops. The stability of the solutions was investigated by storing the solutions for up to 6 months at 40, 25 and 5 °C. The pyronaridine concentration was monitored by analysing the solutions after 2, 3,6 and 14 months and comparing the pyronaridine concentration with the initial pyronaridine concentration. The results are shown in Table 5.

[0080] Table 5

Claims

CLAIMS1. A liquid aqueous formulation of pyronaridine for use in medical treatment, said liquid aqueous formulation comprising at least 70 wt.% water and at least 40 pmol / ml of dissolved pyronaridine, having a pH in the range of 2.5 to 5.8 and being characterised in that the ratio of the osmolality of the formulation (in Osm / kg) to the pyronaridine concentration of the formulation (in mmol / mL) is less than 2.0.

2. Liquid aqueous formulation of pyronaridine for use in medical treatment according to claim 1, wherein the liquid aqueous formulation has an osmolality in the range of 0.15 to 0.60 Osm / kg.

3. Liquid aqueous formulation of pyronaridine for use in medical treatment according to claim 1 or 2, wherein the liquid aqueous formulation comprises 100-400 pmol / mL of dissolved pyronaridine.

4. Liquid aqueous formulation of pyronaridine for use in medical treatment according to any one of the preceding claims, wherein the liquid aqueous formulation is administered intramuscularly.

5. Liquid aqueous formulation of pyronaridine for use in medical treatment according to claim 4, wherein the liquid aqueous formulation is administered intramuscularly to provide pyronaridine in a dose of at least 1 pmol / kg / day.

6. Liquid aqueous formulation of pyronaridine for use in medical treatment according to any one of claims 1-3, wherein the liquid aqueous formulation is administered intranasally.

7. Liquid aqueous formulation of pyronaridine for use in medical treatment according to claim 6 wherein the liquid aqueous formulation is administered intranasally to provide pyronaridine in a dose of at least 0.5 pmol / kg / day.

8. Liquid aqueous formulation of pyronaridine for use in medical treatment according to any one of claims 1-3, wherein the liquid aqueous formulation is administered orally to provide pyronaridine in a dose of at least 2 pmol / kg / day .

9. Liquid aqueous formulation of pyronaridine for use in medical treatment according to any one of the preceding claims, wherein the liquid aqueous formulation comprises per mmol of pyronaridine at least 1 mmol of hydrochloric acid.

10. Liquid aqueous formulation of pyronaridine for use in medical treatment according to any one of the preceding claims, wherein the liquid aqueous formulation is used in the treatment of a disease that is caused by a parasite or a virus.

11. A sterile liquid aqueous formulation comprising at least 70 wt.% water and at least 40 pmol / ml of dissolved pyronaridine, having an osmolality in the range of 0.15 to 0.60 Osm / kg and a pH in the range of 2.5 to 5.8 and being characterised in that the ratio of the osmolality of the formulation (in Osm / kg) to the pyronaridine concentration of the formulation (in mmol / mL) is less than 2.0.

12. Liquid aqueous formulation according to claim 11 , wherein the liquid aqueous formulation comprises 100-400 pmol / mL of dissolved pyronaridine.

13. Liquid aqueous formulation according to claim 11 or 12, wherein the liquid aqueous formulation has an osmolality in the range of 0.20 to 0.40 Osm / kg.

14. Liquid aqueous formulation according to any one of claims 11-13, wherein the liquid aqueous formulation contains no phosphate or wherein the phosphate content is less than 2 mmol per mmol of pyronaridine.

15. Liquid aqueous formulation according to any one of claims 11-14, wherein the liquid aqueous formulation comprises per mmol of pyronaridine at least 1 mmol of hydrochloric acid.

16. A method of preparing the liquid aqueous formulation according to any one of claims 11- 15, the method comprising combining pyronaridine base, water and acid.

17. Method according to claim 16, wherein the acid is selected from hydrochloric acid, hydrobromic acid, hydroiodic acid, nitric acid and sulphuric acid.

18. Method according to claim 17, wherein the acid is hydrochloric acid.