Excessive exposure to ultraviolet (UV) radiation is associated with sunburn, photoaging, and skin cancer.1,2 Sunscreens are widely used to reduce these risks, but some questions remain about their effectiveness and safety.

UVA and UVB — UV radiation capable of injuring the skin is classified based on wavelength as UVA1 (340-400 nm), UVA2 (320-340 nm), and UVB (290-320 nm). UVA, which makes up 95% of terrestrial UV radiation, penetrates the dermis and causes long-term damage. UVB, which is mostly absorbed in the epidermis, is largely responsible for the erythema of sunburn. Both UVA and UVB can cause photoaging and skin cancer. UVB is strongest at midday and is present primarily in late spring, summer, and early autumn in temperate climates. UVA is constant throughout the day and the year and, unlike UVB, is not filtered by clear glass.

SPF — Sun Protection Factor (SPF) is the ratio of...  Continue reading

The FDA has approved Biktarvy (Gilead), a once-daily, fixed-dose combination of bictegravir, a new integrase strand transfer inhibitor (INSTI), and the nucleoside reverse transcriptase inhibitors (NRTIs) emtricitabine and tenofovir alafenamide (TAF), for treatment of HIV-1 infection in adults. The new combination is indicated for use in patients who are antiretroviral-naive or who have been virologically suppressed on a stable antiretroviral regimen for ≥3 months with no history of treatment failure and no known substitutions associated with resistance to any component of the combination.

Bictegravir is the fourth INSTI to become available in the US. Emtricitabine and TAF are also available together as Descovy1 and in fixed-dose combinations with the non-nucleoside reverse transcriptase inhibitor (NNRTI) ... Continue reading