GB2367242A

GB2367242A - Antiviral treatment

Info

Publication number: GB2367242A
Application number: GB0023199A
Authority: GB
Inventors: Christopher Edward Hartley
Original assignee: Henderson Morley Research and Development Ltd
Current assignee: Henderson Morley Research and Development Ltd
Priority date: 2000-09-21
Filing date: 2000-09-21
Publication date: 2002-04-03
Anticipated expiration: 2020-09-21
Also published as: GB0023199D0; GB2367242B

Abstract

The use of a loop diuretic to alter the ionic balance of a living cell to a level that will inhibit the replication of viral DNA without detrimentally affecting cellular metabolism. The loop diuretic used may be selected from frusemide (furosemide), bumetanide, ethacrynic acid or torasemide, and may be adapted for topical or systemic administration. A preferred embodiment provides contact lenses carrying such a loop diuretic, which may be used for the treatment of DNA virus infections of the eye.

Description

ANTIVIRAL TREATMENT The invention relates to anti-viral treatments and in particular to prophylactic and therapeutic treatments of DNA viral infections such as Herpes virus infections.

Herpes viruses are DNA viruses, having a central core of DNA within a proteinaceous structure. DNA carries the genetic code to reproduce the virus. Viruses must infect a living cell to reproduce. There are numerous viral proteins that are well characterised including important enzymes which act as ideal targets for antiviral chemotherapy. These include DNA polymerase and thymidine kinase which are needed for DNA replication. The replication of viral DNA is essential for virus infectivity. It is known that infecting viruses can alter the natural ionic balances of a living cell in the course of their replication. We have discovered that a loop diuretic can be used for an antiviral effect against DNA viruses. According to this invention in one aspect there is provided the use of a loop diuretic acting to alter the natural ionic balance of a living cell to a level less than that which will affect cellular metabolism detrimentally but sufficient to inhibit replication of viral DNA. In another aspect the invention provides a composition useful for the treatment of virus infections in subjects, comprising an effective anti-viral amount of a loop diuretic and a suitable carrier.

The loop diuretic may be selected from a wide range of available agents. Preferably the loop diuretic is any one or more of frusemide, bumetanide, ethacrynic acid or torasemide. According to our studies the loop diuretics mediate their antiviral effects through alteration to the cellular concentration of ions, cellular ionic balances, cellular ionic milieu and electrical potentials.

Frusemide is an anthrilic acid derivative, chemically 4-chloro-N-furfuryl-5- sulfamoylanthranilic acid. It is practically insoluble in water at neutral pH, however is freely soluble in alkali. Frusemide exerts its physiological effect by inhibition of the transport of chloride ions across cell members. Frusemide is a loop diuretic with a short duration of action. It is used for treating oedema due to hepatic, renal, or cardiac failure and treating hypertension. The bioavailability of frusemide is between 60% to 70% and it is primarily excreted by filtration and secretion as unchanged

drug. Frusemide acts on the Na+/K+/2Cl-cotransfonner. For its diuretic effect, its predominant action is in the ascending limb of the loop of Hennie in the kidney. Loop diuretics markedly promote K+ excretion, leaving cells depleted in intracellular potassium. This may lead to the most significant complication of long term systemic frusemide usage namely a lowered serum potassium. We postulate that it is this action however which makes frusemide a candidate for use as an agent against DNA viral infections. Recent evidence suggests that the major biotransformation product of frusemide is a glucuronide. Frusemide is extensively bound to plasma proteins, mainly albumin. Plasma concentrations ranging from 1 to 400 mcg/ml are 91-99% bound in healthy individuals. The unbound fraction ranges between 2.3-4. 1% at therapeutic concentrations. The terminal half life of frusemide is approximately 2 hours, and it is predominantly excreted in the urine. The invention is applicable to Herpes and other DNA viruses such as parvoviruses; papoviruses; adenoviruses; hepadnoviruses and poxviruses. The compositions of the invention may be adapted for external or internal administration. The formulations may be adapted for slow release. Topical and systemic applications are likely to be the most useful. Other ingredients may be present, provided that they do not compromise the anti-viral activity.

A preferred embodiment of this invention is the use of local concentrations of a loop diuretic as a highly effective treatment of virus infections of the eye. Recurrent Herpes infections of the cornea in man is the most common viral cause of blindness. The use of contact lenses carrying e. g. impregnated with a loop diuretic would be a safe and efficient method for creating high intracellular concentrations to prevent or treat the disease. A depot application of a loop diuretic applied intra-occularly would be a suitable method for the treatment of cytomegalovirus retinitis, a major cause of blindness in patients suffering with AIDS. In order that the invention may be well understood it will now be described by way of illustration only with reference to the following example: EXAMPLE In vitro bioassays were undertaken to follow the anti-viral activity of a diuretic compound.

The therapeutic compositions were applied to African green monkey kidney and BHK1 veros cells infected with type 2 herpes simplex virus (strains 3345 and 180) at low, intermediate, and high multiplicities of infection (MOI). Inhibition of virus replication was scored on the scale: no inhibition 20% inhibition + 40% inhibition ++ 60% inhibition +++ 80% inhibition ++++ 100% inhibition +++++ T denotes drug toxicity. The following results were obtained using African green monkey kidney cells and type 2 herpes simplex strain 3345: Inhibition of hsv2 Multiplicity of infection (Dose of virus) Effect of frusemide High Medium ++ Low ++ The experiment was repeated using BHK1 vero cells and type 2 herpes simplex strain 180. Similar results were obtained. These results show the antiviral effect of frusemide at Imgjml.

Claims

CLAIMS 1. Use of a loop diuretic acting to alter the natural ionic balance of a living cell to a level less than that which will affect cellular metabolism detrimentally but sufficient to inhibit replication of viral DNA.
2. Use according to Claim 1, wherein the loop diuretic is one or more of frusemide, bumetamide, ethacyrnic acid or torasemide.
3. A composition useful for the treatment of DNA virus infections in subjects, comprising an effective anti-viral amount of a loop diuretic and a suitable carrier.
4. A composition in accordance with Claim 3 adapted for topical application.
5. A composition in accordance with Claim 3 adapted for systemic application.
6. A composition according to Claim 3,4 or 5, wherein the loop diuretic is one or more of frusemide, bumetamide, ethacrynic acid or torasemide.
7. Contact lenses carrying e. g. impregnated with a loop diuretic.