A recent letter to the editor of the Annals of Internal Medicine documented a single case of myopathy apparently due to an interaction between simvastatin (Zocor, and others) and green tea. Since it became available generically, simvastatin has surpassed atorvastatin (Lipitor) as the best selling statin. As such, it is probably the most common cause of statin-induced myopathy, which is often a result of drug interactions.

The FDA has approved Genvoya (Gilead), 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 alafenamide, for treatment of HIV-1 infection in patients ≥12 years old. This is the first approval for tenofovir alafenamide (TAF), a tenofovir prodrug. Stribild, a fixed-dose combination of elvitegravir, cobicistat, emtricitabine, and tenofovir disoproxil fumarate (TDF), was approved in 2012.

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.

The FDA has approved Viekira Pak (Abbvie), a fixed-dose combination of two new direct-acting antiviral agents (ombitasvir, paritaprevir) with the pharmacologic enhancer ritonavir in one tablet, co-packaged with a third new direct-acting antiviral agent (dasabuvir) in a second tablet, for oral treatment of chronic hepatitis C virus (HCV) genotype 1 infection. Genotype 1 is responsible for 70-80% of HCV infections in the US.

The FDA has approved Opill (Perrigo), a progestin-only oral contraceptive that contains norgestrel, for sale over the counter (OTC). Opill is the first oral contraceptive to be approved in the US for sale without a prescription. Approval of OTC Opill is intended to increase access to effective contraception and reduce the rate of unintended pregnancies.

Caspofungin acetate(Cancidas) is the first of a new class of antifungals, the echinocandins. It has been approved by the FDA for treatment of invasive aspergillosis in patients who fail to respond to or are unable to tolerate other antifungal drugs such as amphotericin B and itraconazole.

The FDA has approved daclatasvir (Daklinza – BMS), an oral direct-acting antiviral drug, for use with sofosbuvir (Sovaldi) for treatment of chronic hepatitis C virus (HCV) genotype 3 infection. Daclatasvir is the first drug approved for this indication that does not require the addition of interferon or ribavirin. It is approved in Japan and Europe in combination with other drugs for treatment of HCV genotypes 1-4.

About 2.5 million persons in the US had hepatitis C between 2017 and 2020. Guidelines from the American Association for the Study of Liver Diseases (AASLD) and the Infectious Diseases Society of America (IDSA) on management of hepatitis C virus (HCV) infection were updated in 2023.

Lopinavir/ritonavir is the first fixed-dose combination of protease inhibitors approved by the FDA for the treatment of HIV infection. It is being marketed for use with other drugs in adults and children more than six months old. Lopinavir is a new drug available only in this combination. Ritonavir is often used with other protease inhibitors to raise their plasma concentrations.

Many drugs can cause psychiatric symptoms, but a causal connection is often difficult to establish. Psychiatric symptoms that emerge during drug treatment could also be due to the underlying illness, previously unrecognized psychopathology, or psychosocial factors. The withdrawal of some drugs can cause symptoms such as anxiety, psychosis, delirium, agitation or depression.

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