Drug – bio-affecting and body treating compositions – Preparations characterized by special physical form – Particulate form
Reexamination Certificate
2000-02-18
2003-01-14
Page, Thurman K. (Department: 1615)
Drug, bio-affecting and body treating compositions
Preparations characterized by special physical form
Particulate form
C424S400000, C424S439000, C424S464000, C424S468000, C514S937000, C514S951000, C514S952000, C514S960000
Reexamination Certificate
active
06506409
ABSTRACT:
THIS INVENTION relates to a dosage device. It relates also to a method of forming a dosage device, and to a method of treating an article or locus.
EP 0 777 964 A discloses a method of making a dosage device which comprises admixing at least one active ingredient which is a pesticide which is in solid form at 25° C., is sparingly soluble in water, and which has an average particle size of less than 5 microns, with a disintegrating agent, to provide a compressible mix; and compressing the compressible mix into a unitary dosage device capable of disintegrating in water to form a suspension of said active ingredient in the water. Neither suspension preparation techniques nor drying agents are used.
DE 25 12 247 A describes making stabilized tablets containing moisture-sensitive ingredients but in which the particle size is relatively large.
U.S. Pat. No. 4,172,714 A discloses the preparation of a herbicide composition in which the particle size is also relatively large, the herbicide being applied in the form of relatively large pellets so that the herbicide is applied in concentrated form at relatively few loci.
WO 93 13658 A describes pesticide tablets with an internal dessicant.
DE 41 09 921 C1 discloses the preparation of a solid product but without a compaction step and particle sizes of the components are relatively large.
According to a first aspect of the invention, there is provided a method of making a dosage device, which method comprises
mixing a suspension concentrate comprising at least one active ingredient which is in solid form at 25° C., and which has an average particle size of less than 10 microns, in a carrier liquid in which the active ingredient is non-soluble or sparingly soluble, and a drying agent for the carrier liquid, such that the drying agent takes up at least some of the carrier liquid of the suspension concentrate, thereby to dry the active ingredient at least partly and to obtain a mixture comprising the active ingredient and the drying agent; and
compressing the mixture into at least one unitary dosage device.
The method may include forming the suspension concentrate by mixing the active ingredient and the carrier liquid. The method may include communiting the active ingredient in solid form and having an average particle size greater than 10 microns, to have an average particle size of less than 10 microns. The active ingredient may be comminuted sufficiently to have an average particle size less than 5 microns, and even less than 3 microns, e.g. less than 1 micron. The comminution may be effected by wet milling the suspension concentrate, eg in a bead mill, to obtain the desired active ingredient particle size.
While, at least in principle, any carrier liquid in which the active ingredient is insoluble or sparingly soluble, can be used, the carrier liquid is preferably water.
The drying agent or dessicant may be an at least partially anhydrous substance. The at least partially anhydrous substance may be an anhydrous salt which takes up the carrier water as water of hydration. The anhydrous salt may be selected from the group comprising anhydrous magnesium sulphate, anhydrous sodium sulphate, anhydrous sodium acetate, and anhydrous calcium chloride. A molar excess of the anhydrous salt over the carrier water present in the suspension concentrate, may be used. For example, the molar proportion of anhydrous salt to carrier water may be about 2:1 to 2.5:1. However, it is envisaged that in some instances the proportion of anhydrous salt used need not necessarily be a molar excess over the carrier water present. For example, certain anhydrous salts can take up more than an equimolar quantity of water of hydration.
The method may include adding to the suspension concentrate and/or to the mixture a further substance capable of reaction with some of the water present in the suspension concentrate, thereby also to dry the active ingredient The further substance may be an oxide which is capable of reacting with water to form a hydroxide. The further substance may be magnesium oxide and/or calcium oxide. The magnesium oxide and/or calcium oxide may thus replace some of the anhydrous substance which is used. For example, when used, it may typically replace in the order of 25% to 50% by mass of the anhydrous substance which is used.
The method may include adding a dispersing agent for the active ingredient and/or an anti-foaming agent and/or an anti-settling agent to the suspension concentrate before and/or after comminution thereof.
Thus, the suspension concentrate may comprise the active ingredient, the dispersing agent, the anti-foaming agent, the anti-settling agent, and water as carrier for the other components. More preferably, the suspension concentrate may comprise
Component
% (m/m)
active ingredient
about 40 to 50
dispersing agent
about 7
anti-foaming agent
<1
anti-settling agent
<1
water
balance
The dispersing agent may be a surfactant such as that conventionally used in a wettable powder or suspension concentrate formulation, for example a lignosulphonate such as sodium lignosulphonate or that available from Borregaard under the trade name Borresperse CA; sodium naphthalene sulphonic acid/formaldehyde condensate; sodium alkyl aryl sulphonate; a nonyl phenol alkylene oxide, such as nonyl phenol ethylene oxide condensate or nonyl phenol ethylene/propylene oxide such as SYNPERONIC NPE 1800 (trade name), available from ICI; alcohol ethylene/propylene oxide condensate; a sodium lauryl sulphate which also acts as wetting agent, such as that available under the trade name EMPICOL LZ from Lankro; a sodium diisopropyl naphthalene sulfonate which also acts as wetting agent, such as that available under the trade name AEROSOL OS from Cyanamid; a sodium salt of naphthalene sulfonic acid formaldehyde condensate, such as that available under the trade name TAMOL NNO or TAMOL DN from BASF; oxyethylated polyarylphenol phosphate, which is a dispersing agent in aqueous media, and an example of which is obtainable under the trade name SOPROPHOR FL from Rhone-Poulenc; or the like.
While the active ingredient can be any suitable active ingredient, such as a therapeutic agent, anthelmintic, a pigment or dye, or the like, the Applicant believes that the method will find particular, but thus not necessarily exclusive, application in making dosage devices in which the active ingredient is a pesticide, eg an insecticide, herbicide, fungicide, acaricide, or the like.
The active ingredient may thus be a pesticide which is sparingly soluble in water, with water hence being the carrier liquid for use in forming the suspension concentrate, as hereinbefore described. The pesticide may have a water solubility of less than 1000 mg/l at 25° C., preferably less than 50 mg/l at 25° C. Preferably, the pesticide should have a melting point exceeding 70° C.
The pesticide may be a herbicide such as atrazine, simazine, cyanazine, terbuthylazine, diuron, chlorsulphuron, metsulfuron, tralkoxydin, or 2-(2-chloro-4-mesylbenzoyl)cyclohexane-1,3-dione; an insecticide such as deltamethrin, lindane, carbaryl, endosulfan, or carbofuran; a fungicide such as thiophanate methyl, carbendazim, flutriafol, hexaconazole, chlorothalonil, copper oxychloride, captan or thiram; or an acaricide such as hexythiazox, cyhexatin, amitraz or acrinathrin.
The method may include adding a disintegrating agent to the mixture before compressing it into the unitary dosage device.
The disintegrating agent may be capable of disintegrating by effervescing or swelling on contact with water. When it is capable of swelling on contact with water, it may be a cross-linked polyvinyl pyrrolidone which also acts as a binder. For example, the cross-linked polyvinylpyrrolidone may then be that available under the trade name POLYPLASDONE XL from GAF Corp., or that available under the trade name KOLLIDON CL from BASF. However, it can instead be any other suitable disintegrating agent capable of swelling on contact with water such as a modified cellulose gum, for example that available under the trade name AC-DI-SOL from FMC Co
Hoy John
Van Rensburg Phillipus Jansen
Evans Charesse
Manelli Denison & Selter PLLC
Melcher Jeffrey S.
Page Thurman K.
Plaaskem (Pty) Limited
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