Acyclovir , anti-herpes drug

Some fatty acids, especially unsaturated fatty acids, are well-known skin penetration enhancers. It is also known that many fatty acids possess antimicrobial activity. The topical activity of the anti-viral drug acyclovir is hampered by its inadequate permeability through the skin barrier. Some reports have shown that fatty acid extract of cod liver oil as well as the extract in the form of an ointment show effective antiviral properties against herpes simplex virus (HSV-1) (37). 

Acyclovir 4,19) is undoubtedly the most interesting of the known anti-viral drugs because of its.high therapeutic index. It is, for example, 3000 times more toxic to herpes simplex virus than to mammalian cells. Somewhat like amino-idoxuridine 4,14b), acyclovir is monophosphorylated by a virus-specified thymidine kinase and then converted to the triphosphoryl derivative which injures the virus by competing, against deoxyguanosine triphosphate, for the virus-specified DNA polymerase in the infected cells (Fyfe et al, 1978). This inhibition puts an end to all DNA synthesis in these cells. Its phosphorylation does not take place in healthy cells, which are thereby spared, and this accounts for most of the selectivity. For the rest the DNA polymerase of infected cells is more sensitive to acyclovir triphosphate than is the DNA polymerase of healthy mammalian cells which, in any case, receive very little of this product (Elion, 1980). 

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