Therapeutic Paint of Cidofovir/Sucralfate Gel Combination Topically Administered by Spraying for treatment of Orf Virus Infections

A new therapeutic paint for the topical treatment of orf virus skin infection is presented in this study. The product combines the potent antiviral activity of the acyclic nucleoside phosphonate cidofovir (1-(S)-3-hydroxy-2-(phosphonomethoxy)propylcytosine, Vistide®) and the wound healing properties of sucralfate gel (sucrose octasulphate basic aluminum salt). The product administration was performed by topical spraying making it particularly suitable for veterinary applications. In vitro experiments, consisting of a physico-chemical characterization of formulation and of delivery device, demonstrated the necessity of including sodium dihydrogen phosphate in the formulation (16% w/w) in order to avoid an interaction between the two active substances (sucralfate 15% and ciofovir 1% w/w). For in vivo experiments, lambs infected with orf virus were treated with different cidofovir/sucralfate formulations and for comparison with sucralfate gel suspension alone. The treatment with formulations containing cidofovir for four consecutive days resulted in a rapid resolution of the lesions, with scabs containing significantly lower amounts of viable virus (Log TCID50/ml < 1) when compared with untreated lesions (Log TCID50/ml 5,31 ± 0,38) and lesions treated with sucralfate suspension alone (Log TCID50/ml 4,83 ± 0,7).