Drug – bio-affecting and body treating compositions – Designated organic active ingredient containing – Ester doai
Reexamination Certificate
2000-12-08
2001-09-04
Henley, III, Raymond (Department: 1615)
Drug, bio-affecting and body treating compositions
Designated organic active ingredient containing
Ester doai
Reexamination Certificate
active
06284792
ABSTRACT:
NEW FORMULATION
The present invention relates to the preparation of an improved galenic delivery form of valnemulin, which is notable for its good tolerance and stability in storage. The new delivery form in question is a non-aqueous or oily injection formulation, which is obtainable by means of in-situ preparation and subsequent stabilisation of the free, relatively unstable base of the active ingredient. A further aspect of the present invention concerns the oily injection formulation as such and its usage in a method of treating infectious diseases in productive livestock or domestic animals.
In connection with the present invention, valnemulin is understood to be the compound shown in the following formula I
Valnemulin is known from EP-0.1 53.277 and is described specifically therein in example 12. Valnemulin is also known by the commercial name Econor®.
As is generally known, this compound has antibacterial properties, e.g. following oral or parenteral administration, and is used for the prevention or cure of a series of bacterial infections in the field of animal health. The broad spectrum of activity includes
Streptococcus aronson, Staphylococcus aureus, Mycoplasma arthritidis, Mycoplasma bovigenitalium, Mycoplasma bovimastitidis, Mycoplasma bovirhinis,
Mycoplasma sp.,
Mycoplasma canis, Mycoplasma felis, Mycoplasma fermentans, Mycoplasma gallinarum, Mycoplasma gallisepticum, A. granularum, Mycoplasma hominis, Mydoplasma hyorhinis, Actinobacillus laidlawii, Mycoplasma meleagridis, Mycoplasma neurolyticum, Mycoplasma pneumonia and Mycoplasma hyopneumoniae.
WO 98/01127 describes its excellent activity against an illness complex that can arise whenever animals are kept in a very restricted space (increased stocking density) e.g. for transport purposes, and are thus exposed to great stress. The most frequent pathogens that play a decisive role in this instance are
Mycoplasma hyopneumoniae, Serpulina
(formerly Treponema)
hyodysenteriae, Serpulina pilosicoli, Lawsonia intracellularis, Mycoplasma gamlisepticum, Pasteurella multocida, Actinobacilius
(Haemophilus)
pleuropneumoniae
and
Haemophilus parasuis,
whereby diseases of the respiratory tract and other infections often occur together and lead to a complex clinical picture. All herd animals are affected, e.g. cattle, sheep and pigs, but also poultry.
In its free form (valnemulin base), valnemulin is relatively unstable and is therefore primarily used in the form of its salts, particularly as the hydrochloride. A current method of administering antibiotics in the field of animal health is the injection, since it is suitable for administering a controlled single dose and thus a quantity tailored to individual needs. This is often crucial to successful control of many infectious diseases in the field of animal medicines. In contrast, oral administration cannot be controlled nearly so well, and is more customary in human medicine.
However, it has been shown that aqueous injection solutions and even oily injection suspensions of the salts of valnemulin are poorly tolerated by most domestic animals and in particular by pigs. Damage ranging from mild skin irritation to poorly healing necroses, has been observed. This is also one of the reasons that valnemulin has mainly been used orally until now. In addition, aqueous solutions usually do not show the desired depot action. A further problem is that valnemulin cannot be produced in technical quantities in the free form, as the so-called valnemulin base, but occurs as the salt, and has therefore been used for therapy as the salt.
However, for commercial usage, it would be extremely desirable to have stable, storable, oily and, in addition, tolerable injection preparations.
It has now surprisingly been found that chemically stable, non-aqueous injection preparations of valnemulin can be produced in situ and can be stabilised in non-aqueous or oily solvents.
Suitable non-aqueous or oily solvents (i) for the in situ production of the valnemulin free base in connection with the present invention are isopropyl myristate, semi-synthetic and synthetic esters of glycerol, or ethylene or propylene glycol with short-chained to medium-chained mono- or dicarboxylic acids, for example mono-, di- and triglycerides (e.g. neutral oils or miglyol).
In order to stabilise the free base, other solvents (ii) are added to these solvents (i), e.g. esters of medium-hained to long-chained carboxylic acids (e.g. lactic, lauric, myristic, palmitic, stearic and oleic acid etc.) with monovalent alcohols (e.g. ethanol, n-propanol, 2-propanol, etc.), 1,2-O-isopropylidene glycerol, glycerol, ethanol, N,N-dimethylacetamide, benzyl benzoate or tetraethylene glycol, so that mixtures (iii) of solvents (i) with solvents (ii) are present in the end product. The addition of solvents (ii) serves to improve the galenic properties. Especially preferred as solvent (i) is isopropyl myristate with the addition of solvent (ii) benzyl benzoate or ethanol.
A preferred embodiment of the present invention is notable for the fact that solvents (I) and (ii) are present in the end product in a ratio of ca. 70:15.
As already mentioned, the free base of valnemulin has until now not been obtainable on a large scale. Therefore, in the following, a new and surprising way is shown of preparing this free base in situ and formulating it in a stable form.
To this end, 0.5 to 30% by weight, preferably 5 to 10% by weight of a salt of valnemulin is suspended in a non-aqueous solvent (i) in a concentration range of 50 to 99% by weight. Appropriate alkaline excipients are added to the suspension whilst stirring and heating gently at a temperature ranging from ca. 50 to 80° C., in order to release the valnemulin base in situ, whereby the free base immediately dissolves in the solvent (i).
Suitable alkaline excipients for the in situ release of the free valnemulin base are, for example, alkali and alkaline earth carbonates, hydrogen carbonates and hydroxides, or organic amines, such as triethylamine.
After completion of this process, the two phases which are immiscible together, the aqueous and the non-aqueous phase, are separated from one another at a temperature of ca. 50 to ca. 80° C. This phase separation may be assisted by centrifuging. The separated non-aqueous phase, which now contains the free base of (I), is washed many times with water at room temperature and undergoes fresh phase separation at a temperature of ca. 50 to 80° C. The non-aqueous phase is subsequently dried e.g. using a vacuum, in order to remove residual water and volatile substances such as organic amines, and is mixed with a solvent or solvent mixture from group (ii) to stabilise it. This addition of (ii) improves the galenic properties of the formulations.
To stabilise against oxidising influences, physiologically acceptable antioxidants may be added to the solution obtained, e.g. esters of ascorbic acid, butyl hydroxy toluene, butyl hydroxy anisole, propyl gallate, tocopherols or tocopherol derivatives, etc., and to stabilise against microbial infestation, physiologically acceptable preservatives may be added, e.g. benzyl alcohol, chlorocresol, chlorobutanol, esters of parahydroxybenzoic acid, phenoxy-ethanol, phenol and phenol derivatives, sorbic acd, etc.
The finished solutions are sterile-filtered or sterilised in the final container, e.g. in ampoules.
The present invention thus comprises essentially the following preferred aspects:
A method of producing a non-aqueous injection formulation which contains as active ingredient the free valnemulin base, optionally a stabiliser to protect against oxidising influences, and likewise optionally a stabiliser to protect against microbial infestation, and which is characterised in that the free valnemulin base is produced in situ from a salt form in a physiologically acceptable non-aqueous solvent or solvent mixture from the above-mentioned category (i) and is stabilised by adding a further solvent from the above-mentioned category (ii).
A preferred embodiment is characterised in that 0.5 to 30% by weight of a salt o
Koller Kurt
Schwarz Franz
Henley III Raymond
Lee Michael U.
Novartis AG
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