Inclusion Criteria

Concurrent Medication:

Allowed:

• Medication for concurrent conditions (e.g., insulin, antihypertensives, bronchodilators, digoxin) or antibacterials or antifungals to treat concurrent infections at other sites or superinfection of the zoster lesion.
• Anti-inflammatory, analgesic (including narcotic analgesic), or antipyretic agents.
• Antidepressants and antipsychotics such as amitriptyline and/or fluphenazine.
• Nerve blocks.
• AZT, ddI, ddC, and amantadine.
• Low-dose corticosteroids for treatment of an underlying (not zoster-related) disease.
• Immune modulators without varicella-zoster virus activity (e.g., GM-CSF, gp160 vaccine).

Patients must have:

• HIV infection.
• Localized, cutaneous herpes zoster (shingles).
• Zoster-associated rash present for 3 or fewer days prior to entry.

Prior Medication:

Allowed:

• Zidovudine.
• ddI.
• ddC.

Exclusion Criteria

Co-existing Condition:

Patients with the following conditions and symptoms are excluded:

• Chickenpox.
• Evidence of visceral dissemination (organ involvement, i.e., brain, liver, or lung) and/or cutaneous dissemination (more than 20 vesicles in dermatomes beyond contiguous dermatomes) of zoster.
• Zoster-like lesion caused by organism other than VZV (e.g., HSV, enterovirus, or Mycoplasma).
• Bacterial superinfection of zoster lesion.
• Zosteriform lesion previously treated with topical antiviral agents.
• Acute, life-threatening opportunistic infection requiring treatment (ongoing suppressive or prophylactic maintenance therapy other than ganciclovir or foscarnet is permitted).
• Concurrent severe disease that may either impair ability to take oral medication in capsule or tablet form or limit survival during the 10-day treatment period or during acute phase follow-up (28 days).
• Suspected acute deterioration of renal or hepatic function.
• Mental impairment that precludes ability to comply with protocol.
• Any condition that would render the patient unsuitable for treatment.

Concurrent Medication:

Excluded during acute phase of study:

• Antiviral medications other than AZT, ddI, ddC, or anti-Parkinson's drugs (i.e., amantadine).
• Interferon.
• Isoprinosine.
• Levamisole.
• Transfer factor.
• Topical virucidal agents, oxidizing agents, DMSO, cell division-stimulating/healing agents, or astringents.
• Topical anesthetics (such as capsaicin or xylocaine).
• Topical creams or ointments that may interfere with evaluation of zoster lesions.
• Cimetidine.
• Fluorouracil or its derivatives, flucytosine, or cyclophosphamide (during drug administration and for 2 weeks thereafter).
• High-dose corticosteroids.
• Anticoagulant therapy (heparin locks and low-dose warfarin sodium permitted).
• Probenecid or derivatives.
• Treatment for any acute, life-threatening opportunistic infection (suppressive or prophylactic maintenance therapy other than ganciclovir or foscarnet is permitted).

Use of the following drugs is discouraged during the long-term phase of the study:

• Antiviral agents with VZV activity.
• Immunomodulators with presumed VZV activity.
• VZV immune globulin.
• Capsaicin.
• Cimetidine.

Patients with the following prior conditions are excluded:

• History of immediate hypersensitivity or serum sickness reaction or idiosyncratic reaction (such as hepatic necrosis or Stevens-Johnson syndrome) to any nucleoside analog antiviral agent or to any anticancer therapy with cytolytic agents.

Prior Medication:

Excluded within 1 month prior to entry:

• Any investigational drugs or treatments not licensed for any indication (other than ddI or ddC).

Excluded within 2 weeks prior to entry:

• Any systemic antiviral therapy, including ganciclovir, foscarnet, vidarabine, acyclovir, or ribavirin.
• Any antiretroviral drug other than zidovudine, ddI, and ddC.
• Immune globulin (e.g., IgG, VZIG).

Excluded within 72 hours prior to entry:

• Cyclophosphamide.
• Flucytosine.
• Fluorouracil or its derivatives.

Alcohol or drug abuse.