Sildenafil (Viagra), tadalafil (Cialis) and vardenafil (Levitra, Staxyn) have become the standard treatment for erectile dysfunction. Head-to-head comparisons of these agents are still lacking, but some differences between them and new recommendations for their dosing (see Table 2) are worth noting.

The severity and rapid spread of COVID-19 (caused by SARS-CoV-2) have raised questions about the use of some drugs in patients with the disease and whether currently available drugs could be effective in treating it. Definitive answers are lacking, but some recommendations can be made. For additional information on specific drugs, see our table Some Drugs Being Considered for Treatment of COVID-19.

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.

The FDA has approved Zepatier (Merck), a fixed-dose combination of two direct-acting antiviral agents — elbasvir, an NS5A inhibitor, and grazoprevir, an NS3/4A protease inhibitor — for oral treatment of chronic hepatitis C virus (HCV) genotype 1 or 4 infection.

Serious adverse interactions between drugs continue to be reported. Many of these are due to inhibition or induction of cytochrome P450 (CYP) enzymes, particularly CYP3A4. CYP3A is thought to be involved in the metabolism of more than 50 percent of currently prescribed drugs.2 CYP3A4, which is more abundantly expressed than CYP3A5, accounts for most CYP3A activity in vivo.

Annovera (TherapeuticsMD), a contraceptive vaginal ring that releases segesterone acetate, a synthetic progestin, and ethinyl estradiol, was approved by the FDA in 2018 and is now available. It is the first product to contain segesterone and the second vaginal ring to become available in the US; NuvaRing, which delivers etonogestrel and ethinyl estradiol, was the first. Unlike NuvaRing, which requires use of a new ring each month, the Annovera ring can be used for an entire year, but it must be removed for one week each month.

The FDA has approved Twirla (Agile Therapeutics), a transdermal contraceptive patch containing the estrogen ethinyl estradiol and the progestin levonorgestrel, for use in women with a BMI <30 kg/m². It is the second contraceptive patch to become available in the US; Xulane, a patch that delivers ethinyl estradiol and the progestin norelgestromin, has been available since 2014.

Bupropion hydrochloride, currently available as an antidepressant (Wellbutrin - Medical Letter, 31:97, 1989; Wellbutrin SR), is now being marketed in a sustainedrelease formulation as Zyban (Glaxo Wellcome) for use as an aid in smoking cessation.

Amprenavir is the fifth protease inhibitor to become available for treatment of HIV infection. It was approved by the FDA for use with other drugs in the treatment of HIV-infected adults and children at least four years old.

The FDA has approved Mavyret (Abbvie) and Vosevi (Gilead), two new fixed-dose combinations of direct-acting antiviral (DAA) drugs, for treatment of chronic hepatitis C virus (HCV) infection caused by any of the six major HCV genotypes in patients without cirrhosis or with compensated cirrhosis. Both are approved for use in treatment-experienced patients. Mavyret is also approved for treatment-naive patients.