WO2017125739A1

WO2017125739A1 - New use of pemirolast

Info

Publication number: WO2017125739A1
Application number: PCT/GB2017/050123
Authority: WO
Inventors: Johan Raud; Carl-Johan Dalsgaard; Göran TORNLING
Original assignee: Rspr Pharma Ab
Priority date: 2016-01-21
Filing date: 2017-01-19
Publication date: 2017-07-27
Also published as: GB201601138D0

Abstract

According to the invention there is provided pemirolast, or a pharmaceutically acceptable salt thereof, for use in the treatment of cough. Suitable lower doses of pemirolast are least about 110 mg per day.

Description

NEW USE OF PEMIROLAST

Field of the Invention This invention relates to a new pharmaceutical use. Background and Prior Art

Cough is an important defensive reflex action of the respiratory tract intended to clear upper airways (including the larynx, trachea and large bronchi) of secretions, such as mucous, and foreign bodies, such as particulates and other substances.

Cough is characterized by an inspiratory phase, followed by forced expiratory effort against a closed glottis and then opening of the glottis and rapid expiration, generating the characteristic cough sound.

The cough reflex can be triggered by stimulation of sensory nerve receptors responding to stimuli caused by changes in the airways, including bronchial congestion and/or by inhalation of irritants, such as cigarette smoke, dust or the like.

It has been estimated that up to about 40% of the population at any one time report a cough (see Janson et al, Eur. Respir. J., 18, 647 (2001 )). It is one of the most frequent reasons for consultations with general medical practitioners.

Cough can be characterized as acute, self-limiting cough, which is typically defined as coughing episodes lasting less than 3 weeks. Chronic cough, on the other hand, is defined as a persistent cough that usually lasts for more than 8 weeks. Coughs that last between 3 and 8 weeks are often referred to as "subacute" cough. (See the definitions provided in, for example, the review article by Chung and Pavord in The Lancet, 371, 1364 (2008).)

Acute cough is usually a consequence of an upper respiratory tract infection (URTI), which typically clears within 2 weeks. Other causes of acute cough include exposure to environmental pollutants and short-term exacerbations of existing conditions, such as asthma or chronic obstructive pulmonary disease (COPD). Chronic cough accounts for between 10 and 38% of respiratory outpatient practice in the US (see, for example, Irwin et al, Am. Rev. Respir. Dis., 141 , 640 (1990)). Many cigarette smokers have chronic cough but rarely seek medical attention unless they notice a change in the intensity of that cough. Other causes of chronic cough include eosinophilic bronchitis, chronic obstructive pulmonary disease, idiopathic pulmonary fibrosis, upper airway cough syndrome (UACS, or postnasal drip), asthma, lung cancer and gastro-esophageal reflux disease (GERD).

Patients with chronic cough have been found to be more sensitive to external stimuli, such as citric acid or capsaicin compared to those that do not have chronic cough (see, for example, Choudrey er a/, Eur. Respir. J., 5, 296 (1992)).

Chronic cough in particular is associated with impaired quality of life (see, for example, Birring ef al, Thorax, 58, 339 (2003)), due to sleep disturbance, nausea, chest pains, social embarrassment and depression (see, for example, Brignall er al, Lung, 186, S55 (2008)). There is a significant cost associated with lost productivity due to absence from work.

Many drugs have been labelled "antitussive". The most widely-employed antitussive agent, despite being regarded as being of somewhat modest benefit, is dextromethorphan, which has been available over-the-counter for many years in the US (see, for example, Cass et al, Am. J. Med. Sci., 227, 291 (1954)).

As noted in the recent review article by Dicpinigaitis ei al in Pharmacol. Rev., 66, 468 (2014), it is unclear whether dextromethorphan, or the many other drugs that have been labelled (at some point or other) "antitussive", are truly effective. Hence, the provision of new and/or effective treatments of cough, such as chronic cough, whether as a symptom of another condition or as a problem in its own right, remains a serious unmet clinical need. Pemirolast is an orally-active anti-allergic mast cell inhibitor that is used in the prevention of conditions such as asthma, allergic rhinitis and conjunctivitis. See, for example, US patent No. 4,122,274, European Patent Applications EP 316 174 and EP 1 285 921 and Drugs of Today, 28, 29 (1992). The drug is only known for the prophylaxis (i.e. preventative treatment) of asthma, and indeed has been marketed for over 20 years in e.g. Japan as the potassium salt in 5 and 10 mg doses (equating to 4.25 and 8.5 mg of the free acid, respectively) e.g. under the trademark ALEGYSAL™. Two doses are administered every day to provide an immediate mast cell stabilising effect and so the short-term prevention of asthma attacks resulting from subsequent challenge by normal asthma triggers.

In 1991 , a pilot study was published, in which pemirolast was found to have no effect whatsoever on the alleviation of cough in patients with seasonal allergic rhinitis at 50 mg doses used twice daily in humans (see Tinkelman et al, Annals of Allergy, 66, 162 (1991 )).

We have previously found that pemirolast has a previously-undisclosed and unappreciated plasma concentration (exposure) profile which means that it can be employed safely in doses that are significantly higher than those presently employed in the prevention of asthma.

In a double-blind, randomised clinical trial with a primary objective to investigate the relative efficacy of high dose and low dose pemirolast versus placebo in the prevention of the severity of mannitol-induced asthma attacks in human asthmatic subjects, a highly surprising and unexpected effect was observed. Mannitol inhalation challenge is known to have a tussive effect that is independent of bronchoconstriction (i.e. in non-asthmatics), and is therefore a recognised assessment of cough, particularly chronic cough (see, for example, Spector, Lung, 188 (suppl. 1 ), S99 (2010) and Singapuri et al, Cough, 4:10 (2008)).

In particular, patients having received high doses of pemirolast were found to be protected from coughing during mannitol challenge, particularly at higher mannitol doses. Disclosure of the Invention

According to the invention, there is provided pemirolast, or a pharmaceutically acceptable salt thereof, for use in the treatment of cough.

The term "cough" will be understood by those skilled in the art to include any reflex action of the respiratory tract characterized by:

(i) an inspiratory phase;

(ii) a forced expiratory effort against a closed glottis;

(iii) an opening of the glottis; and

(iv) rapid expiration.

According to the invention, cough may be defined as acute, chronic or subacute (as defined hereinbefore); may be idiopathic in nature; may be provoked by a foreign body such as by inhalation of a chemical (noxious or otherwise), or by a particulate material, such as dust; may be a symptom of an underlying diagnosed disease, including acute infections, such as an URTI (e.g. a common cold or influenza), bronchitis (including tracheobronchitis, acute bronchitis, chronic bronchitis and acute-on-chronic bronchitis), bacterial or viral pneumonia, pertussis, chronic infections, such as tuberculosis and bronchiectasis, allergies (e.g. allergic and/or seasonal rhinitis and asthma), other chronic conditions, such as cystic fibrosis, COPD, asthma-COPD overlap syndrome (ACOS), UACS, chronic interstitial lung fibrosis, pulmonary fibrosis, including idiopathic pulmonary fibrosis (IPF), emphysema, sarcoidosis, cancers, including benign airway tumours, mediastinal tumours and lung cancers, such as bronchogenic carcinoma, alveolar cell carcinoma, and other diseases, such as GERD other reflux esophagitis-related conditions, recurrent aspiration, or cardiovascular diseases, such as pulmonary infarction, aortic aneurysm, or result as a side effect from the bodily insertion a mechanical device, such as an endobronchial suture; and/or may result as a side-effect of taking certain drugs in which cough is known to be a side-effect. Diagnosis and management of cough is well known to those skilled in the art is summarized in, for example, the review article by Irwin et a/, Chest, 129, 1S (2006)).

According to a second aspect of the invention there is provided pemirolast, or pharmaceutically acceptable salt thereof, for use as an antitussive medication. According to a third aspect of the invention there is provided a method of treatment of cough, which method comprises the administration of a pharmacologically-effective amount of pemirolast, or a pharmaceutically acceptable salt thereof, to a patient in need of such treatment.

In all of the above situations, cough is either idiopathic, that is, it is has no discernible or diagnosed cause; it is a known symptom of an underlying pre- diagnosed condition; or it is provoked by something external, such a taking a medication in which cough is known to be a side-effect, or e.g. by inhalation of e.g. a chemical in the form of a solid, a liquid (e.g. a vapour) or a gas, or of particulate matter, such a powder, dust, etc.

Accordingly, "treatments" of cough according to the invention are direct therapeutic treatment of the cough itself, that is the relief of a pre-existing cough, irrespective of the cause, rather than the treatment of an underlying disease or condition, whether mentioned hereinbefore (e.g. asthma) or otherwise, in which cough is a potential symptom. The treatments are thus unrelated to, and are independent of, any non-symptomatic, preventative, therapeutic, palliative and/or curative treatment of any underlying disease or condition, whether mentioned hereinbefore (e.g. asthma), or otherwise.

According to four further aspects of the invention, there is provided the treatment cough in a patient:

(i) which is idiopathic cough;

(ii) which is chronic cough;

(iii) who has a pre-existing condition in which cough is a known symptom, such as IPF, COPD, asthma, asthma-COPD overlap syndrome patients; and/or

(iv) that is taking a medicine in which cough is known to be a side-effect, which method comprises the administration of a pharmacologically-effective amount of pemirolast, or a pharmaceutically acceptable salt thereof, to that patient, and/or a patient who is in need of such treatment. "Patients" include mammalian (particularly human) patients. Human patients include both adult patients as well as paedeatric patients, the latter including patients up to about 24 months of age, patients between about 2 to about 12 years of age, and patients between about 12 to about 16 years of age. Patients older than about 16 years of age may be considered adults for purposes of the present invention. These different patient populations may be given different doses of pemirolast, as discussed infra.

Pharmaceutically-acceptable salts of pemirolast that may be mentioned include acid addition salts and base addition salts. Such salts may be formed by conventional means, for example by reaction of a free acid or a free base form of an active ingredient with one or more equivalents of an appropriate acid or base, optionally in a solvent, or in a medium in which the salt is insoluble, followed by removal of said solvent, or said medium, using standard techniques (e.g. in vacuo, by freeze-drying or by filtration). Salts may also be prepared by exchanging a counter-ion of an active ingredient in the form of a salt with another counter-ion, for example using a suitable ion exchange resin.

Preferred salts of pemirolast include alkaline earth, and more particularly alkali, metal salts, such as calcium, magnesium, preferably potassium salts (e.g. pemirolast potassium) and sodium salts (e.g. pemirolast sodium hemihydrate, as described in international patent application WO 2010/146348).

In the uses and methods described herein, pemirolast and salts thereof are preferably administered locally or systemically, for example orally, intravenously or intraarterially (including by intravascular or other perivascular devices/dosage forms (e.g. stents)), intramuscularly, cutaneously, subcutaneously, transmucosally (e.g. sublingually or buccally), rectally, transdermal^, nasally, pulmonarily (e.g. tracheally, bronchially or by inhalation), topically, or by any other parenteral route, in the form of a pharmaceutical preparation comprising the compound in a pharmaceutically acceptable dosage form. Preferred modes of delivery include oral, intravenous, cutaneous or subcutaneous, nasal, intramuscular, or intraperitoneal delivery. Pemirolast and salts thereof will generally be administered in the form of one or more pharmaceutical formulations in admixture with a pharmaceutically acceptable adjuvant, diluent or carrier, which may be selected with due regard to the intended route of administration and standard pharmaceutical practice. Such pharmaceutically acceptable carriers may be chemically inert to the active compounds and may have no detrimental side effects or toxicity under the conditions of use. Such pharmaceutically acceptable carriers may also impart an immediate, or a modified, release of pemirolast/salt thereof. Suitable pharmaceutical formulations may be commercially available or otherwise are described in the literature, for example, Remington The Science and Practice of Pharmacy, 19th ed., Mack Printing Company, Easton, Pennsylvania (1995) and Martindale - The Complete Drug Reference (35^th Edition) and the documents referred to therein, the relevant disclosures in all of which documents are hereby incorporated by reference. Otherwise, the preparation of suitable formulations may be achieved non-inventively by the skilled person using routine techniques.

Administration of pemirolast or salt thereof may be continuous or intermittent (e.g. by bolus injection). The mode of administration may also be determined by the timing and frequency of administration, but is also dependent on the severity of the cough. For example, pemirolast may be administered peroally, by inhalation or by bolus injection.

Similarly, the amount of pemirolast or salt thereof in the formulation will depend on the severity of the cough, and on the patient, to be treated, but may be determined by the skilled person.

However, as described hereinafter, we have found that pemirolast may be administered to humans at doses that are significantly higher than those presently employed in humans in the prevention of asthma, which doses are not only safe, but also give rise to the claimed positive effect on the direct treatment of cough (and are therefore effective to treat cough). Accordingly, suitable lower daily doses (calculated as the free acid), irrespective of the route of administration, in adult patients (average weight e.g. 70 kg), may be about 110 mg, such as about 120 mg, for example about 125 mg, or about 150 mg, per day. Preferred lower daily doses (calculated as the free acid), irrespective of the route of administration, may be about 175 mg, including about 200 mg, such as about 300 mg, for example about 350 mg, including about 400 mg, per day. Doses may be split into two or more individual doses per day.

According to a further aspect of the invention there is provided pemirolast, or a pharmaceutically acceptable salt thereof, for use in the treatment of cough, wherein pemirolast is administered at a dose of at least about 110 mg per day (calculated as the free acid). This corresponds to doses of about 1.5 mg/kg of body weight per day in all subjects irrespective of size or age.

Suitable upper limits of peroral daily dose ranges may be about 1 ,000 mg, such as about 800 mg, including about 600 mg, such as about 500 mg, for example about 400 mg, such as about 300 mg. Suitable upper limits for inhalation may be about 200 mg. Suitable upper limits for injectable bolus administration (e.g. subcutaneous or intravenous administration) may be about 5 g, for example about 2 g, such as about 0.8 g per day. (All of the above doses are calculated as the free acid and, again, doses may be split into two or more individual doses per day.)

In any event, the medical practitioner, or other skilled person, will be able to determine routinely the actual dosage, which will be most suitable for an individual patient, depending on the severity of the cough and route of administration. The above-mentioned dosages are exemplary of the average case; there can, of course, be individual instances where higher or lower dosage ranges are merited, and such are within the scope of this invention.

For example, calculated as the free acid, suitable lower dose limits are about 1.5 mg/kg of body weight per day (calculated as the free acid), irrespective of the mode of administration. Again, calculated as the free acid, suitable upper limits of peroral daily dose ranges may be about 15 mg/kg of body weight, for inhalation may be up to about 3 mg/kg of body weight; and for injectable bolus administration may be up to about 75 mg/kg of body weight. For paediatric patients, calculated as the free acid, suitable peroral lower dose limits:

(a) for patients up to the age of about 24 months, are between about 25% and about 30%;

(b) for patients between the ages of about 2 years and about 12 years, are between about 30% and about 75%; and

(c) for patients between the ages of about 12 years and about 16 years, are between about 75% and about 80%,

of the equivalent adult doses noted herein.

Calculated as the free acid, suitable peroral lower dose limits for paediatric patients:

(a) up to the age of about 24 months, are between about 2.5 mg/kg and about 20 mg/kg of body weight per day, such as between about 4.5 mg/kg and about 15 mg/kg of body weight per day, preferably between about 5 mg/kg and about 14 mg/kg of body weight per day, and more preferably between about 6 mg/kg and about 12.5 mg/kg of body weight per day;

(b) between the ages of about 2 years and about 12 years, are between about 2 mg/kg and about 16 mg/kg of body weight per day, such as between about 3 mg/kg and about 12 mg/kg of body weight per day, preferably between about 4 mg/kg and about 1 mg/kg of body weight per day, and more preferably between about 4.5 mg/kg and about 10 mg/kg of body weight per day; and (c) between the ages of about 12 years and about 16 years, are between about 1.5 mg/kg and about 12 mg/kg of body weight per day, such as between about 2.5 mg/kg and about 9 mg/kg of body weight per day, preferably between about 3 mg/kg and about 8 mg/kg of body weight per day, and more preferably between about 3.5 mg/kg and about 7.5 mg/kg of body weight per day.

Suitable lowest peroral doses for the respective paediatric patients are thus as follows:

(a) for patients up to the age of about 24 months, at least about 25 mg/day, such as at least about 30 mg/day, preferably at least about 35 mg/day, more preferably at least about 40 mg/day, such as at least about 50 mg/day (equivalent minimum paediatric doses based upon current daily 20 mg adult doses would be about 4.5 mg/day for this age group);

(b) for patients between the ages of about 2 years and about 12 years, at least about 30 mg/day, such as at least about 50 mg/day, preferably at least about 60 mg/day, more preferably at least about 80 mg/day, such as at least about 100 mg/day (equivalent minimum paediatric doses based upon current daily 20 mg adult doses would be about 8.2 mg/day for this age group); and

(c) for patients between the ages of about 12 years and about 16 years, at least about 80 mg/day, such as at least about 1 10 mg/day, preferably at least about 125 mg/day, more preferably at least about 140 mg/day, such as at least about 150 mg/day (equivalent minimum paediatric doses based upon current daily 20 mg adult doses would be about 8.2 mg/day for this age group).

Suitable upper peroral doses for the respective paediatric patients are thus as follows:

(a) for patients up to the age of about 24 months, about 180 mg/day, such as about 150 mg/day, preferably about 140 mg/day, more preferably about 130 mg/day, such as about 120 mg/day;

(b) for patients between the ages of about 2 years and about 12 years, about 450 mg/day, such as about 400 mg/day, preferably about 350 mg/day, more preferably about 320 mg/day, such as about 300 mg/day; and

for patients between the ages of about 12 years and about 16 years, about 500 mg/day, such as about 450 mg/day, preferably about 400 mg/day, more preferably about 350 mg/day, such as at least about 320 mg/day.

Peroral and inhaled doses may be given between once and four times daily, preferably three times daily and more preferably twice daily. However, we have also found that high doses of pemirolast may be given less than once daily to treat cough, such as every other day, every third day, or even weekly, two-weekly or three-weekly. The dose administered to a mammal, particularly a human, in the context of the present invention should be sufficient to effect an appropriate response in the mammal (e.g. human) over a reasonable timeframe (as described hereinbefore). One skilled in the art will recognize that the selection of the exact dose and composition and the most appropriate delivery regimen will also be influenced by inter alia the pharmacological properties of the formulation, the nature and severity of the cough being treated, and the physical condition and mental acuity of the recipient, as well as the age, condition, body weight, sex and response of the patient to be treated, and the stage/severity of the cough, as well as genetic differences between patients.

In the uses and methods described herein, pemirolast and pharmaceutically acceptable salts thereof may also be combined with one or more active ingredients that are useful in the treatment of cough (see, for example, any of those mentioned in the review articles by Dicpinigaitis et al, supra, Pavord and Chung, supra and Irwin et al, supra), such as dextromethorphan. Such patients may thus also (and/or already) be receiving such therapy based upon administration of one or more of such active ingredients, by which we mean receiving a prescribed dose of one or more of those active ingredients, prior to, in addition to, and/or following, treatment with pemirolast or salt thereof.

Pharmaceutically-acceptable salts, and doses, of other active ingredients useful in the treatment of cough include those that are known in the art and described for the drugs in question to in the medical literature, such as Martindale - The Complete Drug Reference (35^th Edition) and the documents referred to therein, the relevant disclosures in all of which documents are hereby incorporated by reference. Wherever the word "about" is employed herein, for example in the context of amounts (e.g. doses or concentrations of active ingredients), or time periods, it will be appreciated that such variables are approximate and as such may vary by ± 10%, for example ± 5% and preferably ± 2% (e.g. ± 1 %) from the numbers specified herein. The uses/methods described herein may have the advantage that, in the treatment of cough, they may be more convenient for the physician and/or patient than, be more efficacious than, be less toxic than, have a broader range of activity than, be more potent than, produce fewer side effects than, or that it may have other useful pharmacological properties over, similar methods (treatments) known in the prior art.

The invention is illustrated, but in no way limited, by the following example, in which Figure 1 shows mean plasma pemirolast concentrations (semi-log) versus time on Day 5 during a multiple-dose, open safety and tolerability study; and Figure 2 shows prevalence of mannitol-induced cough at various mannitol doses, preceded by placebo, and 40 mg and 400 mg doses of pemirolast.

Examples

Example 1

Pharmacokinetics of Pemirolast in Humans

This study comprised 18 healthy male subjects, 18 - 45 years of age, and was a single and multiple-dose, open study assessing the safety and tolerability of pemirolast potassium tablets (10 mg, Ulgixal™ tablets) with the doses 10, 30 and 50 mg (containing 8.5, 25.5 and 42.5 mg pemirolast free acid, respectively) b.i.d. (6 subjects in each dose group). The subjects received a single dose on the first day, then b.i.d. for three days and a single dose on the fifth day. The study was performed at the Berzelius Clinical Research Center AB in Linkoping, Sweden. All laboratory pharmacokinetic analyses were performed by Quintiles AB, Uppsala, Sweden. Pharmacokinetic calculations were performed by Pharm Assist Sweden AB, Uppsala, Sweden.

Mean C_max data after multiple dosing are shown in and Table 1 , and mean plasma concentrations over time on Day 5 are shown in Figure 1. Table 1

Multiple dose pharmacokinetics of orally administered pemirolast potassium; 10,

30 and 50 mg doses

Based on these clinical data, C_max predictions were made (assumption: Linear pharmacokinetics when extrapolating to higher dose levels) and are presented in Table 2.

Table 2

Predictions

Thus, multiple oral b.i.d. dosing with 125 mg pemirolast is predicted to result in plasma concentrations (C_max) of about 10 pg/ml. To the applicant's knowledge pharmacokinetics of multiple b.i.d. doses of 25.5 mg pemirolast (30 mg pemirolast potassium) or higher have not previously been studied in man.

Later pharmacokinetic studies in healthy volunteers (7 to 8 in each group) have shown that actual C_max values for various multiple doses (b.i.d. for three and a half days) are as follows:

80 mg - 8.84 Mg mL

200 mg - 32.55 Mg/mL

320 mg - 50.95 g/mL.

Pemirolast was found to be safe and well-tolerated at all of these doses. Example 2

Toxicokinetics of Pemirolast in the Dog

In a study in beagles, systemic pemirolast exposure was determined for orally administered pemirolast potassium at 75 mg/kg daily for 7 consecutive days in male and female dogs (75 mg/kg daily having been found to be a safe chronic dose in dogs). The study, including all analyses and calculations, were performed by WIL Research, France, in compliance with Good Laboratory Practices (GLP).

There were no major differences in kinetics between males and females. Mean Cmax is shown in Table 3.

Table 3

Example 3

Effect of Pemirolast of hERG Channels This study was performed by PhysioStim, France, a GLP compliant facility.

The effects of pemirolast on hERG currents in HEK-293 cells stably expressing the hERG potassium channel were studied using patch-clamp technique. In these experiments, 2.7, 8.0, 26.6 and 79.9 pg/mL of pemirolast potassium concentration-dependently decreased hERG tail current amplitude by 5.4%, 10.2%, 14.1 % and 19.0%, respectively.

The reference compound E-4031 (0.1 μιτιοΙ/L), a selective hERG inhibitor, reduced hERG tail current amplitude by 82.0%, thus confirming the pharmacological sensitivity of the hERG potassium channel in these experiments. In conclusion, IC₅o for pemirolast could not be calculated because the inhibition was less than 20% at the highest concentration tested. These results show that pemirolast lacks potential to inhibit hERG channel (an important human "anti-target" that must be avoided during drug development to reduce the risk of certain potentially fatal cardiac adverse effects) at concentrations up to about 80 pg/mL.

Example 4

Clinical Trial This study comprised male and female asthma patients (18 to 46 years of age) with a positive asthma test (as determined by a mannitol challenge test (vide infra) performed within 4 weeks prior to randomization, Visit 2).

At entry, about 20% of the patients had ongoing asthma treatment with long- acting beta2-agonists (LABA), and about 30% of the patients had ongoing asthma treatment with inhaled glucocorticosteroids (ICS).

It was a double-blind, randomized, placebo-controlled, cross-over trial assessing the efficacy of orally administered single doses of placebo and 40 mg and 400 mg of pemirolast (immediate release tablets containing pemirolast sodium hemihydrate, as well as microcrystalline cellulose, mannitol, copovidone fine, croscarmellose sodium, anhydrous colloidal silica and magnesium stearate) in patients challenged with mannitol inhalation as described below. The patients were exposed to the different treatments at three separate hospital visits at least 2 (mean 6.8, median 6) days apart. The data reported in Figures 2 and 3 below represent the patients that received placebo treatment at the first visit (n=8) or placebo at the second visit (after 40 mg at the first visit (n=4) or after 400 mg at the first visit (n=4)).

All doses were administered 3 hours before initiation of the mannitol challenge test to ensure peak plasma concentrations of pemirolast when the mannitol challenge was performed (blood samples for analysing plasma concentrations of pemirolast were collected 3 hours after drug administration). There were 5 visits during the trial: A screening visit (Visit 1 , within 15 days before Visit 2), three visits for treatment with Investigational Medicinal Products (IMP; pemirolast 40 or 400 mg, or placebo) (Visit 2-4, spaced at least 2 days apart), and a final follow-up visit by telephone (Visit 5, at least 2, but less than 4 days after Visit 4 and within 30 days of Visit 2).

All laboratory pharmacokinetic analyses were performed by Clinical Pharmacology, Karolinska University Hospital , Stockholm, Sweden. Briefly, the concentration of pemirolast in human plasma was determined by solid phase extraction and liquid chromatography followed by tandem mass spectrometric detection (LC-MS/MS). The analytical method, utilizing a 200 μΙ_ sample aliquot, has a calibration range of 4.00-4000 ng/mL, with a lower limit of quantification (LLOQ) set at 4.00 ng/mL. At Clinical Pharmacology the method has earlier been partially validated prior to sample analysis.

The trial was performed in compliance with Good Clinical Practice (GCP). Inclusion Criteria were:

• Written informed consent before the trial

• Age≥18 and <50 years

• Diagnosis of asthma according to Global Initiative for Asthma (GINA) Guidelines

· Fractional exhaled nitric oxide (FENO) ≥20 ppb (calculated average of 2 independent FENO measurements)

• Baseline FEV1 >80% of the predicted normal value at Visit 1

• Demonstration of PD15 at≤315 mg mannitol Exclusion Criteria were:

• Lower respiratory tract infection <6 weeks prior to the trial

• Influenza vaccination <4 weeks prior to the trial

• Current smokers • Ex-smokers with a smoking history of >10 pack years (e.g. 10 pack years = 1 pack/day x 10 years, or ½ pack/day x 20 years). An ex-smoker may be defined as a subject who has not smoked for >6 months prior to the trial

• Treatment with any of the medications listed below <3 weeks prior to the trial:

-Inhaled steroids in a dose equivalent to≥2 x 400 μg budesonide /day (dose must not be changed <4 weeks prior to and during the trial)

- Oral corticosteroids

- Any systemic immunomodulatory therapy

- Any systemic anti-rheumatic therapy

- Anti-IL-4 therapy

Clinically significant comorbidities that may be compromised by induced bronchospasm or repeated spirometry as judged by Investigator

. BMI >30

• Known HIV positive

· Known active hepatitis B or C

• Significant concurrent, uncontrolled medical condition including, but not limited to, renal, hepatic, cardiac, haematological, gastrointestinal, endocrine, inflammatory, autoimmune, pulmonary, neurological, cerebral or psychiatric disease evaluated by the Investigator to interfere with effect of the trial drug · Subjects who have a clinically significant abnormal laboratory value and would be at potential risk if enrolled in the trial as evaluated by the Investigator

• Known uncontrolled allergic conditions or allergy/hypersensitivity to any component of the trial drug or placebo excipients

· Known uncontrolled allergic conditions or allergy/hypersensitivity to mannitol or gelatine used to make capsules

• Breast-feeding female subjects

• Female subjects of childbearing potential not willing to use adequate contraceptive methods (adequate contraceptive measures as required by local requirements or practice) during participation in the trial until at least 3 days after last intake of investigational drug

• Male subjects not surgically sterilized, who or whose partner is not using adequate contraceptive methods (adequate contraceptive measures as required by local requirements or practice) during participation in the trial until at least 3 days after last intake of investigational drug • Receipt of any experimental agents within 30 days prior to the trial

• Participation in any other interventional clinical trial during the trial period

• Subjects known or suspected of not being able to comply with the trial protocol (e.g. due to alcoholism, drug dependency or psychological disorder)

The primary endpoint in the study was the Provocation Dose (PD) of mannitol resulting in a 15% fall in Forced Expiratory Volume during 1 second (FEV1 ; values given in Litres (L)) (PD15 for mannitol), which is recognised by regulatory authorities as an acceptable method to evaluate potential efficacy of asthma drugs (European Medicines Agency. Note for Guidance on Clinical Investigation of Medicinal Products for Treatment of Asthma, 2013).

The mannitol challenge test (Aridol®, Pharmaxis Ltd, Frenchs Forest, Sydney Australia) was performed as follows: Application of nose clip and challenge with 0 (empty capsule acting as placebo), 5, 10, 20, 40, 80, 160, 160, 160 and 160 mg of mannitol via the Halermatic (the 80 and 160 mg doses were given as multiple doses of 40 mg capsules). After inhalation, subjects were instructed to hold their breath for 5 seconds. At least 2 repeatable FEV1 manoeuvres were performed 60 seconds after each dose and the highest FEV1 was used in the calculation. The FEV1 value taken after the 0 mg capsule was taken as pre-challenge FEV1 and used to calculate the percentage decrease in FEV1 in response to the mannitol challenge. The test was ended when the FEV1 had fallen by 15% or more. The mannitol PD15 in the trial participants ≤15 days before the first drug treatment was 133 mg (Geometric mean, n=24).

Occurrence of cough (yes/no) after each dose of mannitol was assessed by the investigators.

At the days of treatment with IMP (pemirolast 40 or 400 mg, or placebo), and mannitol testing (Visit 2-4), the following procedure was followed:

1 ) Before IMP administration testing:

a) Withdrawal from trial visit criteria to be checked

b) Urine sampling c) Blood sampling for haematology and blood biochemistry d) Vital signs, physical examination, adverse events and concomitant medication

2) Administration of IMP 3 hours (+/- 10 min) before the mannitol challenge 3) Before mannitol challenge:

a) <10 min before: Urine sampling

b) <10 min before: Blood sampling for analysis of plasma pemirolast concentration

4) Mannitol test 3 hours (+/- 10 min) after IMP administration

5) After mannitol challenge:

a) Urine sampling, 30 minutes after mannitol challenge

b) Pregnancy test (Visit 4 only, in addition to prior to enrolment)

e) Recording of concomitant medication just before sending the patient home f) Reporting of AEs just before sending the subject home

The following treatments were not allowed from <3 weeks prior to the screening visit (Visit 1 ) and during the trial period:

• Inhaled steroids in a dose equivalent to >2 x 400 pg budesonide per day (dose must not be changed <6 weeks prior to Visit 1 and during the study)

· Oral corticosteroids

• Any systemic immunomodulatory therapy

• Any systemic anti-rheumatic therapy

• Anti-IL-4 therapy The following treatments were not allowed within the indicated time-frames:

Time to withhold before Medication

mannitol challenge test was

performed

6-8 hours Inhaled non-steroidal anti-inflammatory agents

8 hours Short acting beta2 agonists

12 hours Short-acting anticholinergic

24 hours Inhaled corticosteroids plus long-acting beta2 agonists

24 hours Long acting beta2 agonists 72 hours Antihistamines

72 hours Long-acting anticholinergic

4 days Leukotriene receptor antagonists

Results

The results of the study showed that 3 hour pre-treatment with pemirolast increased the mannitol PDi₅.

As shown in Figure 2, an unexpected and surprising finding in this study was that, compared to placebo, 400 mg of pemirolast p.o., but not 40 mg of pemirolast p.o., decreased the proportion of patients coughing in response to mannitol challenge. As can be seen from Figure 2, this effect was found to be more pronounced at higher mannitol doses.

The mean peak plasma concentrations of pemirolast 3 hours after the 40 and 400 mg doses have been found to be about 3,000 ng/mL and 35,000 ng/mL (with ti/₂ being about 4 to 7 hours), respectively (geometric mean values, n=23-24).

In this study, there were no serious adverse events or clinically significant changes in vital signs, findings at physical examination or in haematological or blood biochemistry laboratory tests.

Taken together, a dose of pemirolast higher than ever previously tested in asthmatics, causes an unexpected reduction in cough (caused by inhalation of mannitol).

Claims

1. Pemirolast, or a pharmaceutically acceptable salt thereof, for use in the treatment of cough.

2. Pemirolast, or a pharmaceutically acceptable salt thereof, for use as an antitussive medication.

3. The use of pemirolast, or a pharmaceutically acceptable salt thereof, for the manufacture of a medicament for the treatment of cough.

4. A method of treatment of cough, which comprises the administration of a pharmacologically-effective amount of pemirolast, or a pharmaceutically acceptable salt thereof, to a patient in need of such treatment.

5. A compound for use, use or method as claimed in any one of Claims 1 to 4 (as appropriate), wherein the cough is idiopathic cough.

6. A compound for use, use or method as claimed in any one of Claims 1 to 4 (as appropriate), wherein the cough is in a patient that has a pre-existing disease or condition in which cough is a symptom.

7. A compound for use, use or method as claimed in any one of Claims 1 to 4 or 6 (as appropriate), wherein the cough is in a patient that is taking a medicine in which cough is known to be a side-effect.

8. A compound for use, use or method as claimed in any one of Claims 1 to 7 (as appropriate), wherein the cough is chronic cough.

9. A compound for use, use or method as claimed in any one of Claims 1 to 8 (as appropriate), wherein the dose of pemirolast (calculated as the free acid) is at least about 110 mg per day.

10. A compound for use, use or method as claimed in Claim 9, wherein the dose is at least about 350 mg per day.