Ibudilast

IBUDILAST

AV-411
KC-404
MN-166

2-methyl-1-(2-propan-2-ylpyrazolo[1,5-a]pyridin-3-yl)propan-1-one

KYORIN Kyorin Seiyaku Kk……….INNOVATOR

Ibudilast is an anti-inflammatory and neuroprotective oral agent which shows an excellent safety profile at 60 mg/day and provides significantly prolonged time-to-first relapse and attenuated brain volume shrinkage in patients with relapsing-remitting (RR) and/or secondary progressive (SP) multiple sclerosis (MS). Ibudilast is currently in development in the U.S. (codes: AV-411 or MN-166), but is approved for use as an antiinflammatory in Japan.

Molecular Formula:C₁₄H₁₈N₂O

Molecular Weight:230.30552 g/mol

 

Ibudilast is a leukotriene antagonist and phosphodiesterase inhibitor which has been commercialized in Japan and other parts of Asia for over 15 years as capsules for the treatment of bronchial asthma and cerebrovascular disturbances. In 2000, the product was launched for the topical treatment of allergic conjunctivitis. At present, the drug is undergoing phase II trials at MediciNova for the oral treatment of multiple sclerosis (MS), for the treatment of medication overuse headache (MOH), for the treatment of diabetic neuropathic pain, for the treatment of methamphetamine addiction and for the treatment of opioid withdrawal.

Early clinical trials are ongoing for the treatment of amyotrophic lateral sclerosis as an adjunt to riluzole.MediciNova and the University of Colorado had been evaluating the product in preclinical studies for the treatment of post-traumatic brain injury; however, no recent development has been reported for this research.Ibudilast exhibits antiplatelet properties mainly by inhibiting phosphodiesterase V (PDE V), which in turn potentiates antiplatelet function of endothelium-derived nitric oxide (NO). The compound has also been shown to suppress hippocampal apoptosis induced by amyloid beta hypoxia.

 

Ibudilast (development codes: AV-411 or MN-166) is an antiinflammatory drug used mainly in Japan, which acts as aphosphodiesterase inhibitor, inhibiting the PDE-4 subtype to the greatest extent,^[1] but also showing significant inhibition of other PDE subtypes.^[2][3]

Ibudilast has bronchodilator, vasodilator ^[4] and neuroprotective effects,^[5][6] and is mainly used in the treatment of asthma andstroke.^[7] It inhibits platelet aggregation,^[8] and may also be useful in the treatment of multiple sclerosis.^[9]

Ibudilast crosses the blood–brain barrier and suppresses glial cell activation. This activity has been shown to make ibudilast useful in the treatment of neuropathic pain and it not only enhances analgesia produced by opioid drugs, but also reduces the development oftolerance.^[10]

It may have some use reducing methamphetamine addiction.^[11]

Avigen has identified the potential of ibudilast (AV-411) for the treatment of neuropathic pain and other neurological indications, including opiate withdrawal. As an inhibitor of glial cells, ibudilast can deactivate these cells which produce various chemicals, including proinflammatory cytokines, in response to nerve damage or viral infection to amplify and maintain pain. Preclinical evaluation to date indicates that it reverses the painful sensory abnormality allodynia in chemotherapy- and trauma-induced neuropathic pain models.

Originator Kyorin and Banyu Pharmaceutical (now MSD KK following the merger of Banyu and Schering-Plough KK in 2010) have been developing ibudilast under a collaborative agreement. MediciNova obtained exclusive, worldwide rights outside of Japan, China, Taiwan and South Korea from Kyorin in October 2004 to develop and commercialize the compound for MS. In 2012, a codevelopment agreement was signed between MediciNova and the University of Colorado for the treatment of post-traumatic brain injury.

Sixteenth revised Japanese Pharmacopoeia chemicals, etc. IBUDILAST　 Ibudilast C14H18N2O: 230.31 [ 50847-11-5 ] that this product was dried when to quantify, including ibudilast (C14H18N2O) 98.5 ~ 101.0%.

Ibudilast

Systematic (IUPAC) name
2-methyl-1-(2-propan-2-ylpyrazolo[1,5-a]pyridin-3-yl)propan-1-one
Clinical data
AHFS/Drugs.com	International Drug Names
Identifiers
CAS number	50847-11-5
ATC code	R03DC04
PubChem	CID 3671
DrugBank	DB05266
Chemical data
Formula	C14H18N2O
Mol. mass	230.31 g/mol

……………………………

http://www.google.co.in/patents/US3850941

EXAMPLE 1 Synthesis of 2-isopropyl-3-is0butyrylpyrazolo[1,5-a] pyridine (KC404) A mixture of 1-amino-Z-methylpyridinium iodide g.), isobutyric anhydride (500 g.) and K CO (81 g.) was refluxed for 8 hr. After cooling, the precipitated crystals were filtered off and water was added to the filtrate, The solution was made basic to pH 11 with K CO’ and extracted with ethyl acetate (1000 ml.). The extract’was washed with water (400 ml.), dried over Na SO and concentrated under reduced pressure. The residue was distilled to give 58 g. of colorless crystalline product, hp, 110- 175 (7.5 mm. Hg). Recrystallization from hexane gave colorless prisms, melting point 53.554.

Analysis- Calcd.: C, 73.01; H, 7.88; N, 12.17 Found: C, 72.86; H, 7.94; N, 12.09

………………………………………..

http://www.customsynthesis.com/ibud.html

………………………..

http://www.google.com/patents/US8119657

FIG. 6 is a synthetic reaction scheme illustrating one approach for preparing (S)-AV1013; the approach employs chiral chromatography of an N-protected form of the racemate as described in detail in Example 1.

FIG. 7 demonstrates additional reaction schemes for synthesizing (S)-AV1013.

Example 1Synthesis of (S)-2-amino-1-(2-isopropylpyrazolo[1,5-a]pyridin-3-yl)propan-1-one hydrochloride

(S)-2-Amino-1-(2-isopropylpyrazolo[1,5-a]pyridin-3-yl)propan-1-one hydrochloride (also referred to herein as S-AV1013.HCl) was prepared on a preparative scale using two different routes to obtain the intermediate isopropylpyrazolo[1,5-a]pyridine (IPPP). In the first approach (method 1), ibudilast was employed as the starting material to obtain IPPP; an alternate synthetic approach (method 2) employed ibudilast acid as the starting material.

Step 1Method 1Preparation of Isopropylpyrazolo[1,5-a]pyridine (IPPP) from ibudilast

A 5 L 3-neck round-bottom flask was equipped with a mechanical stirrer, thermocouple, heating mantle and a Y-adapter with a nitrogen inlet. The flask was charged with water (350 mL, USP), concentrated sulfuric acid (350 mL) and ibudilast (3-isobutyryl-2-isopropylpyrazolo[1,5-a]pyridine) (140 g, 0.608 mol). The flask was purged with nitrogen, and the mixture was stirred while it was heated to 135° C. An aliquot was removed for HPLC analysis, which showed that all starting material was consumed after 5 hours at 135° C., so the mixture was allowed to cool to room temperature overnight. The mixture was cooled in an ice bath, and water (1400 mL, USP) was added over 10 min, with the temperature maintained below 25° C. With continuous cooling in an ice bath, the mixture was neutralized by adding sodium hydroxide (50% w/w aq., 1150 mL) dropwise, with the temperature maintained below 25° C. Ethyl acetate (250 mL) was added, and the layers were separated. The aqueous layer was washed with ethyl acetate (2×300 mL). The combined ethyl acetate extracts were washed sequentially with 250 mL portions of saturated aqueous sodium bicarbonate and saturated aqueous sodium chloride, then dried over anhydrous sodium sulfate for 30 minutes. Activated carbon (20 g) and silica (60 g) were added and stirred before filtering over a pad of Celite. The filtrate was concentrated under reduced pressure to obtain 96.5 g of IPPP (2-isopropyl-pyrazolo[1,5-a]pyridine, 99% crude yield, 99.6 area % pure by HPLC) as an amber oil.

¹H-NMR (CDCl₃) δ 1.4 (d, 6H), 3.2 (m, 1H), 6.3 (s, 1H), 6.6 (t, 1H), 7.0 (m, 1H), 7.4 (d, 1H), 8.4 (d, 1H). HPLC: RT=9.1 min (99.6 area %).

………………………………………..

Ibudilast (3-isobutyryl-2-isopropylpyrazolo[l,5-α]pyridine) is a small molecule drug that has been used for many years in Japan and Korea for the treatment of bronchial asthma as well as for treatment of cerebrovascular disorders such as post-stroke dizziness. It is sold in these countries under the tradename, Ketas®. Marketed indications for ibudilast in Japan include its use as a vasodilator, for treating allergy, eye tissue regeneration, ocular disease, and treatment of allergic ophthalmic disease (Thompson Current Drug Reports). Its use in the treatment of both chronic brain infarction (ClinicalTrials.gov) and multiple sclerosis (News.Medical.Net; Pharmaceutical News, 2 Aug 2005) is currently being explored in separate, ongoing clinical trials.

The mechanisms of action of ibudilast have been widely explored. Its role as a non-selective inhibitor of cyclic nucleotide phosphodiesterase (PDE) has been described

(Fujimoto, T., et al., J. of Neuroimmunology, 95 (1999) 35-92). Additionally, ibudilast has been reported to act as an LTD4 antagonist, an anti-inflammatory, a PAF antagonist, and a vasodilatator agent (Thompson Current Drug Reports). Ibudilast is also thought to exert a neuroprotective role in the central nervous system of mammals, presumably via suppression of the activation of glial cells (Mizuno et al. (2004) Neuropharmacology 46: 404-411). New uses for ibudilast continue to be explored.http://www.google.com/patents/WO2007146087A2?cl=en

…………………………

http://www.google.com/patents/WO2007142924A1?cl=en

IBUDILAST

Ibudilast is a small molecule drug (molecular weight of 230.3) having the structure shown below.

Ibudilast is also found under ChemBank ID 3227, CAS # 50847-1 1-5, and Beilstein Handbook Reference No. 5-24-03-00396. Its molecular formula corresponds to [Ci₄H_IgN₂O]. Ibudilast is also known by various chemical names which include 2- methyl-l-(2-(l-methylethyI)pyrazolo(l,5-a)pyridin-3-yl)l-propanone; 3-isobutyryl-2- isopropylpyrazolo(l,5-a)pyridine]; and l-(2-isopropyl-pyrazolo[l,5-a]pyridin-3-yl)-2- methyl-propan-1-one. Other synonyms for ibudilast include Ibudilastum (Latin), BRN 0656579, KC-404, and the brand name Ketas^®. Ibudilast, as referred to herein, is meant to include any and all pharmaceutically acceptable salt forms thereof, prodrug forms (e.g., the corresponding ketal), and the like, as appropriate for use in its intended formulation for administration.

Ibudilast is a non-selective nucleotide phosphodiesterase (PDE) inhibitor (most active against PDE-3 and PDE-4), and has also been reported to have LTD4 and PAF antagonistic activities. Its profile appears effectively anti-inflammatory and unique in comparison to other PDE inhibitors and anti-inflammatory agents. PDEs catalyze the hydrolysis of the phosphoester bond on the 3 ^‘-carbon to yield the corresponding 5′- nucleotide monophosphate. Thus, they regulate the cellular concentrations of cyclic nucleotides. Since extracellular receptors for many hormones and neurotransmitters utilize cyclic nucleotides as second messengers, the PDEs also regulate cellular responses to these extracellular signals. There are at least eight classes of PDEs: Ca²⁺/calmodul in-dependent PDEs (PDEl); cGMP-stimulated PDEs (PDE2); cGMP- inhibited PDEs (PDE3); cAMP-specific PDEs (PDE4); cGMP-binding PDEs (PDE5); photoreceptor PDEs (PDE6); high affinity, cAMP-specific PDEs (PDE7); and high affinity cGMP-specific PDEs (PDE9).

References

Literature References:

Leukotriene D4 antagonist. Prepn: T. Irikura et al., DE 2315801; eidem, US 3850941 (1973, 1974 both to Kyorin).

Pharmacology and antiallergic activity: K. Nishino et al., Jpn. J. Pharmacol. 33, 267 (1983); H. Nagai et al., ibid. 1215.

In vitro cerebral vasodilating activity: M. Ohashi et al., Arch. Int. Pharmacodyn. 280, 216 (1986);

in vivo activity: W. M. Armstead et al., J. Pharmacol. Exp. Ther. 244, 138 (1988).

Bronchodilating activity in animals: S. Mue et al., Arch. Int. Pharmacodyn. 283,153 (1986).

Antiplatelet activity in animals: M. Ohashi et al., ibid. 321; M. Ohashi et al., Gen. Pharmacol. 17, 385 (1986).

Keywords: Antiallergic; Antiasthmatic (Nonbronchodilator); Leukotriene Antagonist; Vasodilator (Cerebral).