Changes caused by one drug in the absorption, distribution, metabolism or excretion of another may lead to a pharmacokinetic adverse drug interaction (DN Juurlink et al, JAMA 2003; 289:1652). Additive drug interactions, such as vasodilation caused by both sildenafil (Viagra) and nitrates, can also have adverse effects.

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.

Tinidazole (Tindamax - Presutti Labs), an oral antiprotozoal drug similar to metronidazole (Flagyl, and others), has been approved by the FDA for treatment of trichomoniasis in adults and for treatment of giardiasis, intestinal amebiasis and amebic liver abcess in adults and children more than 3 years old. Tinidazole has been widely used outside of the US for decades under the trade name Fasigyn (Pfizer).

Micafungin sodium (Mycamine - Astellas), the second echinocandin antifungal to become available in the US, has been approved by the FDA for intravenous treatment of esophageal candidiasis and prophylaxis of invasive Candida infections in patients undergoing hematopoietic stem cell transplantation (HSCT).

Methicillin-resistant Staphylococcus aureus (MRSA) infections, which have been a concern for many years, previously occurred primarily in hospitalized patients and those recently treated with antibiotics. In the past few years, there has been an increasing incidence worldwide of community-associated (CA) MRSA infections in patients without recent antibiotic exposure or contact with the healthcare system.

Sunitinib (Sutent - Pfizer) and sorafenib (Nexavar - Bayer), two oral tyrosine kinase inhibitors, have been approved by the FDA for treatment of advanced renal cell carcinoma (RCC). Sunitinib is also approved for use in patients with gastrointestinal stromal tumor (GIST) who are not responding to or are intolerant of standard therapy with imatinib (Gleevec).

Clopidogrel (Plavix), which prevents arterial thrombosis by inhibiting platelet activation, is commonly prescribed (usually with aspirin) for months after acute coronary syndromes and stent implantation. It may also, however, increase the risk of bleeding. Therefore, a proton pump inhibitor (PPI) such as omeprazole (Prilosec, and others) is often given concurrently to decrease the risk of gastrointestinal (GI) bleeding. Some reports have suggested that omeprazole may interfere with the antiplatelet effect of clopidogrel.

The FDA has approved the proton-pump inhibitor (PPI) dexlansoprazole (Kapidex - Takeda), a delayed release formulation of the R-enantiomer of lansoprazole (Prevacid - Takeda), for treating and maintaining healing of erosive esophagitis and for treatment of heartburn associated with non-erosive gastroesophageal reflux disease (GERD).

The FDA has approved daclizumab (Zinbryta – Biogen/Abbvie), an interleukin-2 (IL-2) receptor blocking monoclonal antibody, for treatment of adults with relapsing forms of multiple sclerosis (MS). It is the first subcutaneously injected monoclonal antibody to be approved for treatment of MS.

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...