The FDA has approved tenofovir alafenamide (Vemlidy – Gilead) for treatment of chronic hepatitis B virus (HBV) infection in adults with compensated liver disease. It is the first single-drug product containing tenofovir alafenamide (TAF), a prodrug of the nucleotide reverse transcriptase inhibitor tenofovir, to become available; several combination products containing TAF are approved for treatment of HIV-1 infection. Tenofovir disoproxil fumarate (TDF; Viread – Gilead), another tenofovir prodrug, has been used for many years for treatment of chronic HBV infection; a generic formulation of TDF is expected to become available in December 2017.

Antiretroviral therapy is recommended for all HIV-infected patients, both to reduce the risk of disease progression and to prevent transmission of the virus to others. Various guidelines for treatment of HIV infection are available.

The FDA has approved dolutegravir (doll-you-TEG-rah-veer; Tivicay – Viiv Healthcare), an integrase strand transfer inhibitor (INSTI), for treatment of HIV-1 infection in adults and in children ≥12 years old who weigh at least 40 kg. It is the third INSTI to be approved by the FDA; raltegravir and elvitegravir were approved earlier.

The drugs of choice for treatment of viral infections (other than HIV) and their dosages are listed in Tables 1-6 on the pages that follow. Some of the indications and dosages recommended here have not been approved by the FDA. Vaccines used for the prevention of viral infections are discussed elsewhere.

The FDA has approved a fixed-dose combination of the integrase strand transfer inhibitor (INSTI) elvitegravir, the pharmacokinetic enhancer cobicistat, and the nucleoside/nucleotide reverse transcriptase inhibitors (NRTIs) emtricitabine and tenofovir disoproxil fumarate (Stribild – Gilead) for treatment of HIV-1 infection in antiretroviral treament-naïve adults. Elvitegravir is the second INSTI to be approved by the FDA for use in HIV treatment; raltegravir (Isentress) was the first.

Guidelines for use of antiretroviral agents continue to shift toward earlier and more continuous treatment, both to treat the patient and to prevent transmission of the disease to others. Resistance testing is now recommended when antiretroviral drugs are started. Increases in HIV RNA levels ("viral load") while on therapy may indicate development of drug resistance, requiring further testing and a change in the treatment regimen. Antiretroviral drugs interact with each other and with many other drugs; complete information on these interactions is available at www.aidsinfo.nih.gov.

The drugs of choice for treatment of non-HIV viral infections and their dosages are listed in Tables 1-6 on the pages that follow. Some of the indications and dosages recommended here have not been approved by the FDA. Vaccines used for the prevention of viral infections are discussed in another issue of Treatment Guidelines.

New guidelines for use of antiretroviral agents have been published, with a shift towards earlier and more continuous treatment. HIV infection is treated with combinations of antiretroviral drugs depending on the patientÆs HIV RNA levels ("viral load") and CD4 cell count. Increases in viral load while on therapy may indicate development of drug resistance, requiring further testing and a change in treatment regimen. Resistance testing is now recommended when a patient is first seen, regardless of when therapy will be started.

The approval of new drugs and continuing concerns about drug toxicity and resistance have prompted new antiretroviral treatment guidelines. Resistance testing is not recommended before starting antiretroviral therapy. HIV infection is treated with combinations of antiretroviral drugs while monitoring the patient's HIV RNA levels ("viral load") and CD4 cell count. Increases in viral load while on therapy may indicate development of drug resistance requiring further testing and a change in treatment regimen.

Atripla (Gilead/Bristol-Myers Squibb) is the first once daily, single-tablet combination of 3 antiretroviral drugs for treatment of HIV infection. Each tablet contains 600 mg of the non-nucleoside reverse transcriptase inhibitor (NNRTI) efavirenz (Sustiva), 200 mg of the nucleoside reverse transcriptase inhibitor (NRTI) emtricitabine (Emtriva), and 300 mg of the nucleotide reverse transcriptase inhibitor (NRTI) tenofovir DF (Viread). These drugs have been recommended for use together, if resistance testing confirms susceptibility, as an initial regimen of choice for treatment-na∩ve patients.

The FDA has approved emtricitabine/tenofovir (Truvada - Gilead) and abacavir/lamivudine (Epzicom - GSK), two new fixed-dose combinations of nucleoside/nucleotide reverse transcriptase inhibitors (NRTIs), for once-daily use in treatment of HIV infection. Two other fixed-dose NRTI combinations were previously approved for twice-daily dosing. Dual NRTI therapy is generally used in either an NNRTI (non-nucleoside reverse transcriptase inhibitor)-based or a PI (protease inhibitor)-based regimen.

New drug approvals as well as continuing concerns about drug toxicity and the development of resistance have prompted new antiretroviral treatment guidelines (Panel on Clinical Practices for Treatment of HIV Infection, November 10, 2003, www.aidsinfo.nih.gov).

Atazanavir (Reyataz - Bristol-Myers Squibb), a new protease inhibitor (PI), and emtricitabine (Emtriva - Gilead), a nucleoside analogue reverse transcriptase inhibitor (NRTI) chemically similar to lamivudine, have been approved by the FDA for treatment of HIV-1 infection. Both are taken once daily, unlike most anti-HIV drugs.

Since the last Medical Letter article on this subject, continuing concerns about drug toxicity and development of resistance have prompted new antiretroviral treatment guidelines. The dosage and cost of drugs for HIV infection are listed in the table in this article.