If Smokers melanosis is destroyed by excessive smoking, as in the hard palate of reverse smokers, who smoke with the glowing part of the cigarette inside the mouth for different reasons, a pale depigmented surface is first seen, indicating the loss of the protecting melanin. Then a red inflammation sometimes occurs and cancer development may follow. In reverse smokers it is important to regularly inspect the  areas with Smokers melanosis to detect any melanin destruction, in order to stop smoking in time and thus prevent a cancer to develop. Epidemiology
A study in Sweden showed that 21.5% of smokers and 3% of nonsmokers (genetic pigmentation or unknown cause) had lesions that could be classified as an oral melanin pigmentation. A gingival melanin index in 4 degrees was established. Already with a consumption of 1-3 cigarettes a day 9.3% of all 20.333 examined showed a smokers melanosis. Pipe smokers had smokers melanosis in 16.8%. One year after the start of cigarette smoking a clinically visible smokers melanosis could be seen in 12.3% of women, and 17% among men. In cigarette smokers who quit smoking, the number of individuals with smokers melanosis becomes slowly less frequent after 2–3 months, but can still be seen in a few former smokers three years after smoking stop. Although clinically visible genetic melanin pigmentations in the mouth are present in several ethnic groups all over the world, more mucosal areas will be melanin-pigmentet if tobacco products are used.
Foscarnet (phosphonomethanoic acid), known by its brand name Foscavir, is an antiviral medication which is primarily used to treat viral infections involving the Herpesviridae family. It is classified as a pyrophosphate analog DNA polymerase inhibitor. Foscarnet is the conjugate base of a chemical compound with the formula HO2CPO3H2 (Trisodium phosphonoformate).Foscarnet was approved for medical use in 1991. Medical use
This phosphonic acid derivative (marketed by Clinigen as foscarnet sodium under the trade name Foscavir) is an antiviral medication used to treat herpes viruses, including drug-resistant cytomegalovirus (CMV) and herpes simplex viruses types 1 and 2 (HSV-1 and HSV-2). It is particularly used to treat CMV retinitis. Foscarnet can be used to treat highly treatment-experienced patients with HIV as part of salvage therapy. Mechanism of action
Foscarnet is a structural mimic of the anion pyrophosphate that selectively inhibits the pyrophosphate binding site on viral DNA polymerases at concentrations that do not affect human DNA polymerases.In individuals treated with the DNA polymerase inhibitors acyclovir or ganciclovir, HSV or CMV particles can develop mutant protein kinases (thymidine kinase or UL97 protein kinase, respectively) that make them resistant to these antiviral drugs. However, unlike acyclovir and ganciclovir, foscarnet is not activated by viral protein kinases, making it useful in acyclovir- or ganciclovir-resistant HSV and CMV infections.However, acyclovir- or ganciclovir-resistant mutants with alterations in viral DNA polymerase may also be resistant to foscarnet. Administration
Foscarnet is administered by intravenous infusion or intravitreous injection. Side effects
Nephrotoxicity — increase in serum creatinine levels and renal injury can occur in patients receiving foscarnet.