Pharmacologically active compounds and use

The peptides of the formula ##STR1## together with their pharmacologically acceptable salts, which have been described as exhibiting analgesic, antidiarrhoeal and antitussive activity, are effective in reversing neuronally-mediated bronchoconstriction in mammals. The said compounds have application in the palliation of conditions characterized by such a state, in particular asthma in human beings.

This invention relates to compounds useful in medicine, to pharmaceutical 
formulations containing such compounds and the preparation thereof, and to 
the use of the compounds in medicine. 
The present invention more particularly relates to the peptides of formula 
(I) 
##STR2## 
as hereinafter defined, together with pharmacologically acceptable salts 
thereof, which have been described as exhibiting analgesic, antidiarrhoeal 
and antitussive activity when investigated according to standard 
pharmacological procedures; see EP-A-0 127 154. 
It has now surprisingly been found that the said compounds have an 
effect--reversal of neuronally--mediated bronchoconstriction, i.e. 
bronchodilatation--unrelated to those apparent from their previously 
taught, opioid properties and are in consequence of value, in both human 
and veterinary medicine, in a yet further, entirely distinct clinical 
area. 
The compounds thus have application in the palliation of conditions 
characterised by such bronchoconstriction (bronchospasm), in particular 
asthma (including status asthmaticus) such as that induced by exercise, 
local irritation of the airways or stress, allergic asthma and intrinsic 
asthma. 
Whereas the prototype opioid, morphine, has been proposed for use in the 
sedation of human patients with asthma or status asthmaticus to facilitate 
artificially assisted (mechanical) ventilation procedures, such a view has 
not found general favour and has been criticized, inter alia on the ground 
that such agents themselves cause bronchoconstriction and thus have the 
potential to exacerbate the very condition being treated. The novel 
finding, as above set forth, in respect of the present compounds is thus 
completely against current teaching regarding the pharmacological profile 
of and utilities for morphine and the like. 
In formula (I), as set forth above, 
R.sup.1 is hydrogen, alkyl of 1 or 2 carbon atoms or an amidino group, 
R.sup.2 is alkyl of 1 or 2 carbon atoms, 
R.sup.3 is hydrogen or carbamyl, 
X.sup.2 is a D-radical having the structure: 
##STR3## 
Z.sup.1 and Z.sup.2 are the same or different and each is hydrogen, halo, 
nitro or trifluoromethyl and at least one is other than hydrogen, 
m is 2, 3 or 4 and 
n is 0, 1 or 2, 
provided that when R.sup.3 is carbamyl then n is always 1, together with 
pharmacologically acceptable salts thereof. 
Specific identities for X.sup.2 are the followign D-radicals: 
2--amino--4--guanidinobutyryl (m is 2), arginyl (m is 3) and homoarginyl 
(m is 4). 
The halo identities for Z.sup.1 and Z.sup.2 may be selected from fluoro, 
chloro, bromo and iodo. 
As subclasses of peptides within formula (I) may be mentioned those 
wherein: 
(i) R.sup.1 is an amidino group 
(ii) R.sup.2 is ethyl 
(iii) R.sup.3 is hydrogen 
(iv) X.sup.2 is D-arginyl 
(v) one of Z.sup.1 and Z.sup.2 is hydrogen and the other is fluoro in the 
2-position 
(vi) n is 0, 
together with pharmacologically acceptable salts thereof. 
A preferred peptide within formula (I) is 
##STR4## 
together with pharmacologically acceptable salts thereof; a preferred said 
salt is the diacetate. 
The abbreviations used herein for amino acids and their radicals are those 
conventional in the art and may be found in, for example, Biochem. J. 
(1972) 126, 773-780. In the above and throughout the following all 
references are to the L-configuration of chiral amino acids and their 
radicals unless otherwise stated. 
In the salts of the peptides the biological activity resides in the peptide 
moiety and the identity of the acid is of lesser importance although for 
use in medicine it should be pharamacologically acceptable to the 
recipient. Examples of pharmacologically acceptable acids include mineral 
acids such as hydrochloric, hydrobromic, phosphoric, metaphosphoric, 
nitric and sulphuric acids and organic acids such as tartaric, acetic, 
citric, malic, lactic, fumaric, benzoic, glycollic, gluconic, gulonic, 
succinic and arylsulphonic, for example p-toluenesulphonic, acids. 
The peptides of formula (I) and their salts may be prepared by methods 
known in the art, in particular those methods taught in the previously 
identified EP-A-0 127 154. 
All references identified hereinabove or in the following are hereby 
incorporated herein by reference thereto. 
The peptides of formula (I) and their salts may be used in both human and 
veterinary medicine in circumstances such as those previously identified 
where it is desirable to reverse (i.e. treat) neuronally--mediated 
bronchoconstriction, and may be administered either on a regular 
maintenance basis or for the relief or amelioration of acute crisis 
states. 
The peptides and salts thereof may be administered to the human or nonhuman 
mammalian recipient by a route selected from oral, parenteral (including 
subcutaneous, intradermal, intramuscular and intravenous), rectal, topical 
(including dermal, buccal and sublingual), nasal and pulmonary. The size 
of an effective, bronchodilator dose will depend upon a number of factors 
including the identity of the recipient, the precise condition to be 
treated and its severity and the route of administration and will 
ultimately be at the discretion of the attending physician or 
veterinarian. 
An effective dose for a human being will generally be in the range 0.1 to 
50 mg., more generally in the range 0.2 to 25 mg. and most often in the 
range 0.5 to 12.5 mg., a particularly suitable dose being 1 mg. (all doses 
calculated as the peptide per se: for salts the figures would be adjusted 
proportionately). Administration of such doses may be repeated as required 
throughout the day, for example three or four times a day. For veterinary 
use, for example in the treatment of non-human mammals such as cats, dogs, 
cattle, sheep, pigs and horses, the above-recited doses would be increased 
or decreased at the discretion of the veterinarian having regard to the 
weight and identity of the recipient. 
While it is possible for the compounds to be administered as the raw 
chemical it is preferable to present them as a pharmaceutical formulation 
preparation comprising a peptide of formula (I), as above defined, or a 
pharmacologically acceptable salt thereof together with one or more 
acceptable carriers therefor and optionally other therapeutic ingredients. 
The carrier(s) must be `acceptable` in the sense of being compatible with 
the other ingredients of the formulation and not deleterious to the 
recipient thereof. 
The formulations include those suitable for oral, parenteral (including 
subcutaneous, intradermal, intramuscular and intravenous), rectal, topical 
(including dermal, buccal and sublingual), nasal and pulmonary 
administration although the most suitable route may depend upon for 
example the condition and identity of the recipient. The formulations may 
conveniently be presented in unit dosage form and may be prepared by any 
of the methods well known in the art of pharmacy. All methods include the 
step of bringing into association the peptide or salt (the active 
ingredient) with the carrier which constitutes one or more accessory 
ingredients. In general the formulations are prepared by uniformly and 
intimately bringing into association the active ingredient with liquid 
carriers or finely divided solid carriers or both and then, if necessary, 
shaping the product into the desired formulation. 
Formulations suitable for oral, parenteral, rectal and topical 
administration are taught in EP-A-0 127 154. 
Formulations suitable for pulmonary administration via the buccal cavity 
are presented such that particles containing the active ingredient and 
desirably having a diameter in the range 0.5 to 7 microns are delivered 
into the bronchial tree of the recipient. 
As one possibility such formulations are in the form of finely comminuted 
powders which may conveniently be presented either in a pierceable 
capsule, suitably of for example gelatin, for use in an inhalation device, 
or alternatively as a self-propelling formulation comprising active 
ingredient, a suitable liquid propellant and optionally other ingredients 
such as a surfactant and/or a solid diluent. Self-propelling formulations 
may also be employed wherein the active ingredient is dispensed in the 
form of droplets of a solution or suspension. 
Such self-propelling formulations are analogous to those known in the art 
and may be prepared by established procedures. Suitably they are presented 
in a container provided with either a manually-operable or automatically 
functioning valve having the desired spray characteristics; advantageously 
the valve is of a metered type delivering a fixed volume, for example 50 
to 100 microliters, upon each operation thereof. 
As a further possibility the active ingredient may be in the form of a 
solution for use in an atomizer or nebulizer whereby an accelerated 
airstream or ultrasonic agitation is employed to produce a fine droplet 
mist for inhalation. 
Formulations suitable for nasal administration include presentations 
generally similar to those described above for pulmonary administration. 
When dispensed such formulations should desirably have a particle diameter 
in the range 10 to 200 microns to enable retention in the nasal cavity 
this may be achieved by, as appropriate, use of a powder of a suitable 
particle size or choice of an appropriate valve. Other suitable 
formulations include coarse powders having a particle diameter in the 
range 20 to 500 microns, for administration by rapid inhalation through 
the nasal passage from a container held close up to the nose, and nasal 
drops comprising 0.2 to 5% w/v of the active ingredient in aqueous or oily 
solution. 
Preferred unit dosage formulations are those containing an effective dose, 
as hereinabove recited, or an appropriate fraction thereof, of the active 
ingredient. 
EP-A-0 127 154 contains no invitation to administer the present compounds 
by the nasal or pulmonary route nor any suggestion that the said 
compounds, if administered in such a manner, would be effective in the 
treatment of the conditions therein taught; the said disclosure likewise 
contains no description of any formulation suitable for administration by 
the nasal or pulmonary route. 
Without being limited by theory, the peptides of formula (I) and their 
pharmacologically acceptable salts may in addition reverse the airway 
inflammation found in asthma (including status asthmaticus) and postulated 
also to be neuronal in origin.

The following Examples are provided in illustration of the present 
invention and should not be construed as in any way constituting a 
limitation thereof. All temperatures are in degrees Celsius. 
Pharmaceutical Formulations 
In the following the "Compound" is a pharmacologically acceptable salt of a 
peptide of formula (I) as hereinbefore defined, the weight thereof being 
calculated as the peptide per se. 
______________________________________ 
Capsule 
______________________________________ 
Compound 1.0 mg 
Magnesium stearate 0.75 mg 
Lactose BP to 200.0 mg 
______________________________________ 
Mix the ingredients and fill into hard gelatin capsules, each to contain 
1.0mg of compound. 
______________________________________ 
Tablet 
______________________________________ 
Compound 1.0 mg 
Avicel PH 101 22.5 mg 
Low-substituted hydroxypropylcellulose 
9.0 mg 
Polyvinylpyrrolidone K30 6.0 mg 
Magnesium stearate 0.75 mg 
Lactose BP to 150.0 mg 
______________________________________ 
______________________________________ 
Freeze-Dried Injection 
______________________________________ 
Compound 1.0 mg 
Mannitol 62.5 mg 
Water for Injections to 
2.5 ml 
______________________________________ 
Dissolve the mannitol and compound in 9/10 the total quantity of water and 
make to volume when solution is complete. Under sterile conditions, 
sterilise the solution by filtration through a suitable, sterile, 
sterilising grade filter and pack into clean, sterile vials using a fill 
of 2.5ml per vial. Partially insert freeze drying stoppers into the necks 
of the vials and freeze dry. Close the vials under an inert gas and secure 
with aluminium collars. 
______________________________________ 
Suppository 
______________________________________ 
Compound 1.0 mg 
Hard Fat BP to 1000.0 mg 
______________________________________ 
______________________________________ 
Dermal Lotion 
______________________________________ 
Compound 0.1 g 
Sorbitan monolaurate 0.6 g 
Polysorbate 20 0.6 g 
Cetostearyl alcohol 1.2 g 
Glycerin 6.0 g 
Methyl -p-hydroxybenzoate 
0.2 g 
Purified Water BP to 100.0 ml 
______________________________________ 
Dissolve the methyl p-hydroxybenzoate and glycerin in 70ml of the water at 
75.degree. C.; melt together the sorbitan monolaurate, polysorbate 20 and 
cetostearyl alcohol at 75.degree. C. and add to the aqueous solution. 
Homogenise the resulting emulsion, allow to cool with continuous stirring 
and add the compound as a solution in the remaining water; stir the 
product until homogeneous. 
______________________________________ 
Solution for nebulisation 
______________________________________ 
Compound of formula (I) 1.0 mg 
(calculated as peptide per se) 
Water for injections to 10.0 ml 
______________________________________ 
Dissolve the compound of formula (I) in the water for injections. Sterilize 
the solution by passage through a membrane filter, 0.2 .mu.m pore size, 
collecting the filtrate in a sterile receiver. Fill into sterile glass 
ampoules, 10 ml/ampoule, under aseptic conditions and seal each ampoule by 
fusion of the glass. 
______________________________________ 
Self-propelling formulation 
______________________________________ 
Compound of formula (I), micronised 
1.0 mg 
(calculated as peptide per se) 
Propellant to 5.0 ml 
______________________________________ 
Suspend the micronised compound of formula (I) in the propellant. Fill this 
suspension under pressure into preformed, valved aerosol canisters, 5 
ml/canister, through the valve orifice. 
The propellant is a commercially available mixture of 
trichloromonofluoromethane, dichlorodifluoromethane and 
dichlorotetrafluoroethane. 
______________________________________ 
Powder for inhalation 
______________________________________ 
Compound of formula (I), micronised 
1.0 mg 
(calculated as peptide per se) 
Lactose 29.0 mg 
______________________________________ 
Triturate and blend the micronised compound of formula (I) with the 
lactose. Fill the resulting powder blend into hard gelatin capsule shells, 
30 mg per capsule. 
______________________________________ 
Nasal drops 
______________________________________ 
Compound of formula (I) 100 mg 
(calculated as peptide per se) 
Methyl -p-hydroxybenzoate 
10 mg 
Water for injections to 10 ml 
______________________________________ 
Dissolve the compound of formula (I) and the methyl p-hydroxybenzoate in 
the water for injections. Fill this solution into suitable dropper 
bottles, 10 ml/bottle, and close by securing the dropper nozzle and bottle 
cap.