GB2176706A

GB2176706A - Pyrethroid-containing parasiticidal compositions

Info

Publication number: GB2176706A
Application number: GB08614989A
Authority: GB
Inventors: Andrew Rennie Galbraith
Original assignee: YOUNG ROBERT CO Ltd
Current assignee: YOUNG ROBERT CO Ltd
Priority date: 1985-06-19
Filing date: 1986-06-19
Publication date: 1987-01-07
Also published as: GB8515459D0; GB2176706B; AU595225B2; WO1986007525A1; AU6126386A; GB8614989D0; EP0259340A1

Abstract

Pour-on compositions for simultaneously controlling ecto- and endo-parasites on e.g. sheep and cattle comprise: (i) salt of levamisole and/or tetramisole; (ii) at least one pyrethroid, in a carrier system comprising (iii) water; (iv) at least one organic water-miscible cosolvent and optionally (v) at least one organic water-immiscible solvent. The presence of (ii) appears to synergistically improve the performance of (i) and by selection of (iv) and (v) skin damage or irritation can be minimised. (i) should be present in an anthelmintically effective amount and (ii) in an insecticidally effective amount.

Description

SPECIFICATION Pyrethroid-containing Parasiticidal Compositions This invention concerns pyrethroid-containing compositions for controlling ectoparasites such as lice, keds, mites, ticks, fleas and nuisance fly and endoparasites such as helminths including gut and lungworms which may infest non-human animals. More specifically the invention is concerned with aqueous compositions containing at least one synthetic (light-stable) pyrethroid insecticide and at least one anthelmintic agent.

The present compositions may be provided in a form suitable for subsequent pour-on or spot-on application to the skin or fleece of a non-human animal according to well known techniques. They may, most conveniently, comprise solutions of the active ingredients.

The principal use of the compositions is for simultaneously controlling endoparasites and ectoparasites in sheep and/or cattle. As such, pour-on compositions are provided which can confer dual control, rendering separate treatments for ecto-and endo-parasites unnecessary.

Tetramisole, 2,3,5,6-tetrahydro-6-phenylimidazo (2,1-b) thiazole and its (I-) laevo isomer levamisole are known to be effective anthelmintic agents. Tetraminsole is a racemic mixture of the D- and L-isomers and the activity against helminths has been shown to be derived mainly or almost entirely from levamisole.

Tetramisole and levamisole are described in GB-A-1 043489.

GB-A-1 464552 is concerned with a method of using tetramisole and/or levamisole by application to the skin of an animal. According to the teaching, the salts should be avoided due to reduced efficacy and water is stated to be an ineffective carrier for effecting passage of the active ingredient through the skin, a pre-requisite to helmintic control.

Anthelmintic compositions based on conventional organic solvents have caused skin irritation or damage in the treated animal. GB-A-2 095 107 discloses anthelmintic compositions having reduced skin irritation problems.

Synthetic pyrethroids as disclosed in GB-A-1 413491 are known to be powerful insecticides suitable for ectoparasite control on non-human animals.

The term "pyrethroid" as used througb the description and claims is meant to include one or more compounds including geometrical and stereochemical isomers according to the formula (I):

TABLE 1

No. X1 X2 X3 X4 X5 R1 trivial name 1 Cl Cl - - H H permethrin 2 CH3 CH3 - - H H phenothrin 3 Br Br - - H CN deltamethrin 4 Cl Cl - - H CN cypermethrin 5 Cl CF3 - - H CN cyhalothrin 6 Cl < }Cl - - F CN flumethrin 7 Cl Cl - - F CN cyfluthrin 8 CH3 CH3 - - H CN cyphenothrin TABLE 2

No. X1 X2 X3 X4 X5 R1 trivial name 9 Br Br Br Br H CN tralomethrin 10 Cl Cl Br Br H CN tralocythrin TABLE 3

there is a prejudice against using (i) salt(s) of levamisole and/or tetramisole and (iii) water as a carrier medium see GB-A-1 464552.

The present invention is based on the discovery that water-containing pour-on compositions can be produced by incorporating at least one organic water-miscible cosolvent. Our experimentation has shown an unexpected improvement in anthelmintic skin penetration compared to levamisole or tetramisole free base alone. Furthermore, organic solvent content can be reduced whilst still maintaining acceptable or superior skin tolerance.

According to this invention there is provided a parasiticidal compositions, suitable for pour-on application to a non-human animal which comprises: (i) at least one salt of tetramisole and/or levamisole, (ii) at least one pyrethroid as herein defined, in carrier system comprising (iii) water, (iv) at least one organic water-miscible cosolvent.

The composition may include (v) a minor proportion (less than 50% by weight) of at least one organic water-immiscible solvent.

Included within the scope of this invention are pour-on or spot-on compositions for controlling endoand ectoparasites in a non-human animal and methods of controlling such parasites by use of the compositions. The term controlling is used to mean interfering with the development and/or reproduction of the parasite(s). Preferably, the compositions are solutions and they may be prepared by admixture of the relevant ingredients with (v), when present, being added to (iv) before or after addition of (iii).

It is preferred to use salt(s) of levamisole, such as acid addition salt(s). As examples thereof levamisole hydrochloride, levamisole phosphate and levamisole citrate and levamisole oleate may be mentioned. The most preferred salt is levamisole hydrochloride.

As examples of preferred pyrethroids one or more of permethrin, cypermethrin, cyholothrin or decamethrin may be employed. It is more preferred to use permethrin and most preferred to use permethrin in high-cis form. Permethrin contains cis- and trans-isomers and it has been found that the cis-isomer is the more effective in controlling lice, keds, mites, fleas or the like, but particularly nuisance fly on cattle.

Water may be present (by weight per unit volume of solution) in an amount of 530%, preferably 1025%, more preferably 1220% w/v.

Examples of organic water-miscible cosolvent include one or more of the following, separately or as a mixture of two or more thereof: alkanols, alkoxyalkanols, alkoxy-alkoxyalkanols, dipolar aprotic solvents such as dimethylsulphoxide (DMSO) or dimethylformamide (DMF) and the like.

It is preferred to use one or more alcohols of the formula (V): HO(CH2CH2O)rnR (V) wherein m=1, 2 or 3 and R=(C1-C6)-alkyl.

It is more preferred to use one or more alcohols wherein m-2 and most preferred to use 2-(2-butoxyethoxy)ethanol, also known as diethylene glycol monobutyl ether (DGBE), which we have found well tolerated by animal skins or hides. Component (iv) may comprise at least 50% by weight, preferably 80% or more of DGBE.

Provision is made for the optional presence of one or more water-immiscible organic solvents. The said solvent may itself be a mixture of solvents such as the commercial solvent comprised almost entirely of aromatic hydrocarbon fractions b.p. 186205"C sold as Shellsol AB. This commercial solvent is preferred and comprises 35% C,-fraction, 49% CrO-fraction,9% Ct1-fraction and 7% napthalene and methylnaphthalene. The inclusion of water-immiscible solvent, such as C9- or higher aromatic hydrocarbon(s) may enhance skin penetration of the salt(s) (i) whilst retaining the components in solution, avoiding precipitation. Alternatively or additionally a monoterpene solvent such as eucalyptus oil may be included in the formulation.

Component (v), when present, may be in a proportion of (by weight per unit volume of composition) 130%, preferably 530%, more preferably in the range 1 10-25% w/v of the carrier system.

Preferred compositions contain levamisole hydrochloride (and/or phosphate) high-cis permethrin, 2-(2-butoxyethoxy) ethanol, water with or without aromatic hydrocarbons.

We have surprisingly found that such compositions containing anthelmintically effective amount of (i) levamisole hydrochloride 11.8 g high-cis permethrin 4.0 g water 20 g DGBE 43 g Shellsol AB 20 g This was found to control at least nuisance fly and helminths in cattle applied as a pour-on along the backline of the animals.

EXAMPLE 2 The following parasiticidal pour-on composition (solution) was prepared: levamisole hydrochloride 11.8 g high-cis permethrin 4.0 g water 15.0 g DGBE 69.0 g EXAMPLE 3 The following parasiticidal composition (solution) was prepared and effectively used on cattle: levamisole hydrochloride 11.8 g high-cis permethrin 4.0 g DGBE 48.g water 15.g Shellsol AB 20.g EXAMPLE 4 The following parasiticidal composition (solution) was prepared and effectively used te control helminths and sheep lice: Levamisole hydrochloride 8.0 g cypermethrin 4.0 g DGBE 44.g water 12. g Shellsol AB 30. g EXAMPLE 5 (Comparative) The following non-pyrethroid containing compositions were prepared and used as a pour-on for cattle:: (A) (B) levamisole hydrochloride 11.8 g 23.6 g helminths in and lice on sheep. The pour-on compositions of Comparative Examples 5(A) and 5(B) were not found effective in controlling helminths in cattle despite the presence of a levamisole salt. In the absence of a pyrethroid the effect against ectoparasites was not monitored. In all of the tests no significant skin irritation or damage to the animal skin, fleece or hide was observed.

The compositions of Examples 1 to 3 showed significant improvement in anthelmintic activity whilst Example 4 was not compared. The levamisole salt component penetrates cattle skin, in in vitro testing equipment, at a rate comparable to a commercial levamisole free base product consisting of 20% levamisole base in solvent DGBE. Comparative formulations of Example 5(a) and 5(b) demonstrated little, if any, anthelmintic activity. The pyrethroid component thus appears to synergise the activity and/or penetration of the levamisole salt. By incorporating water in the compositions there are advantages of economics, environmental considerations, reduced toxicity and flammability.

Claims

1. Parasiticidal composition, suitable for pour-on application to a non-human animal which comprises (i) at least one salt of tetramisole and/or levamisole (ii) at least one pyrethroid as herein defined in a carrier system comprising (iii) water, and (iv) at least one organic water-miscible cosolvent.

2. Composition as claimed in Claim 1, further including (v) a minor proportion of at least one organic water-immiscible solvent.

3. Composition as claimed in Claim 1 or 2 wherein (i) comprises levamisole acid addition salt.

4. Composition as claimed in Claim 3 wherein the acid addition salt is the hydrochloride.

5. Composition as claimed in any preceding claim wherein the pyrethroid comprises one or more of: permethrin, cypermethrin, cyhalothrin and decamethrin.

6. Composition as claimed in Claim 5 wherein the pyrethroid comprises high-cis permethrin.

7. Composition as claimed in any preceding claim wherein (iii) water is present in an amount of 5 to 30% by weight per unit volume.

8. Composition as claimed in any preceding claim wherein (iv) comprises one or more of: alkanols, alkoxyalkanols, alkoxy-alkoxyalkanols, dipolar aprotic solvents.

9. Composition as claimed in Claim 8 wherein (iv) comprises one or more alcohols of the formula (V): HO(CH2CH2O)rnR (V) wherein m=1, 2 or 3 and R=(C1-C6)-alkyl

10. Composition as claimed in Claim 9 wherein (iv) comprises 2-2(butoxyethoxy)ethanol.

11. Composition as claimed in any one of Claims 2 to 10 wherein (V) comprises aromatic hydrocarbon solvent(s) and/or monoterpene solvent.

12. Composition as claimed in any one of Claims 2 to 11 wherein (V) is present in an amount of 1 to 30% by weight per unit volume.

13. Method of controlling endo- and ecto-parasites simultaneously which comprises apply to a non-human animal a composition as claimed in any preceding claim.

14. Composition substantially as herein described in any one of Examples 1 to 4.

15. Method of controlling endo- and ecto-parasites substantially as herein described.