Pitolisant

Bioprojet INNOVATOR

Jean-Charles Schwartz, Jeanne-Marie Lecomte

Pitolisant (INN) or tiprolisant (USAN) is a histamine receptor inverse agonist/antagonist selective for the H₃ subtype.^[1] It hasstimulant and nootropic effects in animal studies,^[2] and may have several medical applications, having been researched for the treatment of narcolepsy, for which it has been granted orphan drug status in the EU and US.^[3][4] It is currently in clinical trials forschizophrenia and Parkinson’s disease.^[4][5][6]

Pitolisant hydrochloride was approved by European Medicine Agency (EMA) on Mar 31, 2016. It was developed and marketed as Wakix^® by Bioprojet in EU.

Pitolisant hydrochloride is an antagonist/inverse agonist of the histamine H3 receptor, which is indicated in adults for the treatment of narcolepsy with or without cataplexy.

Wakix^® is available as tablet for oral use, containing 4.5 mg and 18 mg of Pitolisant hydrochloride. The initial dose of 9 mg (two 4.5 mg, tablets) per day, and it should be used at the lowest effective dose, depending on individual patient response and tolerance, according to an up-titration scheme, without exceeding the dose of 36 mg/day.

Pitolisant was developed by Jean-Charles Schwartz, Walter Schunack and colleagues after the former discovered H₃ receptors.^[7]Pitolisant was the first clinically used H₃ receptor inverse agonist.

Pitolisant, also known as Tiprolisant, is a histamine receptor inverse agonist/antagonist selective for the H3 subtype. It has stimulant and nootropic effects in animal studies, and may have several medical applications, having been researched for the treatment of narcolepsy, for which it has been granted orphan drug status in the EU and US. It is currently in clinical trials for schizophrenia and Parkinson’s disease. Pitolisant was the first clinically used H3 receptor inverse agonist.

The European Medicines Agency (EMA) has recommended granting marketing authorization for pitolisant (Wakix, Bioprojet Pharma) for narcolepsy with or without cataplexy, the agency announced today.

Narcolepsy is a rare sleep disorder that affects the brain’s ability to regulate the normal sleep-wake cycle, leading to excessive daytime sleepiness, including the sudden urge to sleep, and disturbed night-time sleep. Some patients also experience sudden episodes of cataplexy, potentially causing dangerous falls and increasing the risks for accidents, including car accidents. Symptoms of narcolepsy can be severe and significantly reduce quality of life.

Pitolisant “will add to the available treatment options for narcolepsy. It is a first-in-class medicine that acts on histamine H3 receptors in the brain. This leads to increased histamine release in the brain, thereby enhancing wakefulness and alertness,” the EMA notes in a news release.

The EMA recommendation for approval of pitolisant is based on an evaluation of all available safety and efficacy data conducted by the Committee for Medicinal Products for Human Use (CHMP). The data include two pivotal placebo-controlled trials involving 259 patients, as well as one uncontrolled, open-label study involving 102 patients with narcolepsy and one supportive study in 105 patients.

The studies showed that pitolisant was effective in reducing excessive daytime sleepiness in patients with narcolepsy. The beneficial effect of the drug on cataplexy was demonstrated in one of the pivotal studies as well as in the supportive study.

No major safety concerns with pitolisant emerged in testing. Insomnia, headache, and nausea were among the most common adverse effects observed in the clinical trials, and the CHMP decided on measures to mitigate these risks, the EMA said. The CHMP also requested the company conduct a long-term safety study to further investigate the safety of the drug when used over long periods.

Pitolisant for narcolepsy received orphan designation from the Committee for Orphan Medicinal Products in 2007. Orphan designation provides medicine developers access to incentives, such as fee reductions for scientific advice, with the aim of encouraging the development of treatments for rare disorders.

The CHMP opinion will now be sent to the European Commission for the adoption of a decision on a European Union–wide marketing authorization. Once that has been granted, each member state will decide on price and reimbursement based on the potential role/use of this medicine in the context of its national health system.

Narcolepsy-cataplexy.

Narcolepsy-cataplexy, or Gelineau syndrome, is a rare but serious disorder characterized by excessive daytime sleepiness which can be an extreme hindrance to normal professional and social activities, and which is accompanied by more or less frequent attacks of cataplexy (a sudden loss of muscle tone triggered by emotions as varied as laughter or fear) and erratic episodes of REM sleep (during wakefulness and during sleep), sometimes associated with hypnagogic hallucinations. Moreover, individuals with narcolepsy have various degrees of cognitive impairment and tend to be obese (reviewed by Dauvilliers et al., Clin. Neurophysiol., 2003, 114, 2000; Baumann and Bassetti, Sleep Med. Rev., 2005, 9, 253).

The disorder is caused by the loss of a group of neurons in the brain which produce two peptides, orexins, also known as hypocretins, located in the anterior hypothalamus and projecting to the main groups of aminergic neurons which regulate wakefulness and sleep. Patients with the disorder generally have very low levels of orexins in cerebrospinal fluid. Orexin knock-out mice display many of the symptoms seen in narcoleptic subjects, confirming the role of these peptides and thereby providing an excellent animal model of the disease (Chemelli et al., Cell, 1999, 98, 437).

Several types of treatments which can improve the symptoms of narcolepsy already exist, although they do not completely relieve symptoms and, furthermore, can cause significant side effects limiting their usefulness.

For instance, amphetamines or analogues such as methylphenidate which release catecholamines are used to treated daytime sleepiness, but these agents induce a state of excessive excitation as well as cardiovascular disturbances and also carry a potential for drug addiction.

Modafinil, a drug whose mechanism of action is unclear, also improves daytime sleepiness without causing as many side effects as amphetamines. Nonetheless, its efficacy is limited and it can cause headaches and nausea, particularly at high doses. Moreover amphetamines and/or modafinil do not appear to improve some of the most disabling symptoms of the disease, particularly cataplexy attacks, cognitive deficits and weight gain. With regard to cataplexy, treatments include antidepressants and oxybate. Effectiveness of the former has not been demonstrated (Cochrane Database Syst. Rev., 2005, 20, 3), and the latter is a drug of illegal abuse and its use is restricted.

It has also been shown that histamine H3 receptor antagonists induce the activation of histaminergic neurons in the brain which release histamine, a neurotransmitter with a crucial role in maintaining wakefulness (Schwartz et al., Physiol. Rev. 1991, 71, 1).

PATENT

https://patentscope.wipo.int/search/en/detail.jsf?docId=WO2006084833&recNum=1&maxRec=&office=&prevFilter=&sortOption=&queryString=&tab=PCTDescription

Pharmaceutical products with histamine H3 receptor ligand properties and 0 subsequent pharmacological activities thereof are described in EP-980300. An especially important product among those disclosed is 1-[3-[3-(4- chlorophenyl)propoxy] propyl]-piperidine. This compound is disclosed as the free base and as the oxalate salt.

5 The use of 1-[3-[3-(4-chlorophenyl)propoxy]propyl]-piperidine as the free base is limited because of its oily nature. On the contrary, 1-[3-[3-(4- chlorophenyl)propoxy]propyl]-piperidine oxalate is a crystalline substance but its low aqueous solubility (0.025 g/ml at 230C) also limits its use as a
pharmaceutical ingredient.
0
Subsequent patents EP-1100503 and EP-1428820 mention certain salts of 1- [3-[3-(4-chlorophenyl)propoxy]propyl]-piperidine. However, the only one specifically described is the oxalate salt. The crystalline monohydrochloride salt is not described.

Example 1 : 1-[3-[3-(4-chlorophenyl)propoxy]propyl]-piperidine

According to the method disclosed in EP-982300, Example 78, sodium 3-piperidinopropanolate (2.127 kg; 12.88 mol), 3-(4-chlorophenyl)propyl mesylate (1.121 kg; 4.51 mol) and 0.322 mol of 15-crown-5 in 4.5 kg of dry toluene were refluxed for 4 hours. The solvent was evaporated and the residue purified by column chromatography on silica gel (eluent: methylene chloride/methanol (90/10)). The obtained oil was distilled in a fractionating equipment at reduced pressure (0.3-0.7 mmHg) and with a heating jacket at 207-210⁰C. The head fractions and the distilled fraction at 0.001-0.010 mmHg with a jacket temperature of 180-200⁰C were collected. The obtained oil (1.0 kg; 3.38 mol) corresponds to 1-[3-[3-(4-chlorophenyl)propoxy] propyl]-piperidine. Yield 75%.

Example 2: 1-[3-[3-(4-chlorophenyl)propoxy]propyl]-piperidine
monohydrochloride

Preparation

Distilled 1-[3-[3-(4-chlorophenyl)propoxy]propyl]-piperidine (1.0 kg) and anhydrous ethyl acetate (4.5 kg) are transferred to a 10-L glass vessel fitted with a cooling bath and a gas inlet. A stream of gaseous hydrogen chloride is bubbled in the reaction mixture at 20-25⁰C.

The pH of the solution is checked by taking a 0.5 mL sample of the reaction mixture and diluting it with 5 mL of deionized water. The final pH must be about 3-4.

The mixture is cooled to -10°C-(-12°C) and stirred at this temperature for 1 h. The precipitate is filtered by using a sintered glass filter and washed with 0.5 L of anhydrous ethyl acetate previously cooled to 0-5⁰C. The product is dried in a vacuum oven at 5O⁰C for a minimum period of 12 hours. The resulting crude 1 -[3-[3-(4-chlorophenyl)propoxy]propyl]-piperidine monohydrochloride weighs 1.10 kg.

Purification

A mixture of the above-described crude, 3.98 kg of anhydrous ethyl acetate and 0.35 kg of /-propanol is heated slowly at 55-6O⁰C in a 10-L glass vessel fitted with a heating and cooling system. When the solution has been completed, it is filtered through a heat-isolated sintered glass filter, keeping the temperature at 55-6O⁰C. The solution is transferred to a 10 L glass vessel and the mass is slowly cooled to 0-5⁰C for about 1 hour. The mixture is stirred at this temperature for 1 hour and the precipitate is filtered through a sintered glass filter. The solid is washed with a mixture of 1.6 kg of anhydrous ethyl acetate and 0.14 kg of /-propanol cooled at 0-5⁰C. The solid is dried in a vacuum oven at 5O⁰C for a minimum period of 12 hours. M. p. 117-119⁰C. Yield 80%.
IR spectrum (KBr): bands at 1112 and 1101 (C-O Ether/ St. asym), 2936 and 2868 (Alkane CH(CH₂)) / St.), 1455 (Alkane CH(CH₂)) / Deform.), 2647 and 2551 (Amine Salt / St.), 1492 (Amine / St.), 802 (Aromatic / Deform.) cm^“1.

SEE

Eur. J. Pharm. Sci. 2001, 13, 249–259.

US2004220225A1.

CN101155793A

CN101171009A

References

Pitolisant

Names
IUPAC name 1-{3-[3-(4-Chlorophenyl)propoxy]propyl}piperidine
Other names BF2.649
Identifiers
CAS Number	903576-44-3
ChEMBL	ChEMBL462605
ChemSpider	8123714
Jmol 3D model	Interactive image
PubChem	9948102
InChI[show]
SMILES[show]
Properties
Chemical formula	C17H26ClNO
Molar mass	295.846 g/mol
Pharmacology
ATC code	N07XX11 (WHO)

//////////Pitolisant Hydrochloride, Wakix, histamine H3 receptor antagonist/inverse agonist, narcolepsy, orphan drug, tiprolisant

ClC1=CC=C(CCCOCCCN2CCCCC2)C=C1