White : Diseases of the Skin - Systemic Therapies

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Gary M. White & Neil H. Cox

Diseases of the Skin

4	Systemic Therapies

ANTIVIRAL DRUGS

Herpes simplex and varicella zoster infections are usually treated with the nucleoside analogs. These include aciclovir, its prodrug valaciclovir, or famciclovir (prodrug of penciclovir). Treatment must be started early, and at higher dose for varicella zoster (Fig.4.6). Treatment is usually oral, but intravenous administration is used in immunosuppressed patients or those with severe infections, associated viral meningoencephalitis, chickenpox, pneumonia, etc. Patients with recurrent herpes simplex (or herpes simplex-associated erythema multiforme) may require prophylactic therapy.

Figure 4.6 Chickenpox (varicella). Initially, there are typically small, clear blisters on an erythematous base. These subsequently become gray or pustular and then crust.

Other systemic (intravenous) antiviral agents, such as foscarnet or cidofovir, may be used for herpes infections, especially in the context of HIV infection, hematologic malignancy, or other immunosuppression states; they may be useful for some other infections also. Ganciclovir is used to treat cytomegalovirus.

Antiretroviral drugs for HIV infection fall into the following groups.

•	Nucleoside analogs—for example zidovudine, lamivudine, didanosine, zalcitabine, and abacavir.
•	Non-nucleoside reverse transcriptase inhibitors—for example nevirapine, delavirdine, and efavirenz.
•	Protease inhibitors—for example indinavir, saquinavir, nelfinavir, and ritonavir.

Combination therapy with drugs from different groups is used; the accepted regimens vary according to factors such as viral load and are updated at intervals. Most antiretroviral drugs have significant side effects, which vary according to the class of drug as well as the specific agent; for example, several of the nucleosides may cause gastrointestinal disturbance, pancreatitis, peripheral neuropathy, or marrow suppression, while lipodystrophy is more typically seen in relation to protease inhibitors.