Dr. Ogbru received his Doctorate in Pharmacy from the University of the Pacific School of Pharmacy in 1995. He completed a Pharmacy Practice Residency at the University of Arizona/University Medical Center in 1996. He was a Professor of Pharmacy Practice and a Regional Clerkship Coordinator for the University of the Pacific School of Pharmacy from 1996-99.
Jay W. Marks, MD, is a board-certified internist and gastroenterologist. He graduated from Yale University School of Medicine and trained in internal medicine and gastroenterology at UCLA/Cedars-Sinai Medical Center in Los Angeles.
DRUG CLASS AND MECHANISM: Atazanavir is an oral medication that is used for treating infections caused by the human immunodeficiency virus (HIV). It is in a class of drugs called protease inhibitors that also includes ritonavir (Norvir), nelfinavir (Viracept), indinavir (Crixivan) and saquinavir (Invirase, Fortovase). During infection with HIV, the HIV virus multiplies within the body's cells. Viruses are released from the cells and spread throughout the body where they infect other cells. In this manner, HIV infection is perpetuated among new cells that the body produces continually. During the production of the viruses, new proteins must be made. Some of the proteins are structural proteins, that, is, proteins that form the body of the new viruses. Other proteins are enzymes that manufacture DNA and other components for the new viruses. Protease is the enzyme that forms the new structural proteins and enzymes. Atazanavir blocks the activity of protease and results in the formation of new viruses with defective proteins that are unable to infect the body's cells. As a result, the number of viruses in the body (the viral load) decreases. Nevertheless, atazanavir does not prevent the transmission of HIV among individuals, and it does not cure HIV infections or AIDS. Atazanavir was approved by the FDA in June, 2003.
PRESCRIPTION: Yes
GENERIC AVAILABLE: No
PREPARATIONS: Capsules: 100, 150, 200 mg
STORAGE: Store at room temperature between 15-30°C (59-86°F).
PRESCRIBED FOR: Atazanavir is used in combination with other drugs for the treatment of infections with HIV.
DOSING: The starting dose of atazanavir for adults is 400 mg once daily with food. Ritonavir (Norvir) increases the concentration of atazanavir in the blood. Therefore, when atazanavir is administered with ritonavir, the dose of atazanavir should be reduced to 300 mg daily. Efavirenz (Sustiva) decreases the concentration of atazanavir in the blood. Therefore, when patients are receiving both atazanavir and efavirenz, 100 mg of ritonavir also should be added in order to keep the levels of atazanavir in the blood at the desired levels.
DRUG INTERACTIONS: Atazanavir inhibits the enzymes that eliminate many drugs from the body. Administration of these drugs along with atazanavir may result in increased concentrations of these drugs and cause more side effects. Atazanavir also is eliminated by enzymes in the liver, and drugs that increase the activity of these enzymes may decrease the concentration of atazanavir in the blood and reduce the effect of atazanavir. Conversely, drugs that prevent the elimination of atazanavir may increase the concentration of atazanavir in the blood and cause increased atazanavir-related side effects. Some of the important potential or known interactions are mentioned below. Viewers should consult their healthcare provider before combining any drugs with atazanavir.
Rifampin (Rifadin), St. John's Wort and efavirenz (Sustiva) decrease the blood levels of atazanavir and this can reduce the effect of atazanavir.
Atazanavir decreases the elimination and, therefore, could increase the side effects of triazolam (Halcion), midazolam (Versed), bepridil (Vascor), verapamil (Isoptin) , diltiazem (Cardizem), sildenafil (Viagra), lovastatin (Mevacor) , simvastatin (Zocor), atorvastatin (Lipitor), pimozide (Orap), (irinotecan (Camptosar), cyclosporine (Sandimmune), rifabutin (Mycobutin), amiodarone (Cordarone), clarithromycin (Biaxin) and ergot drugs (Migranal, Cafergot).
Atazanavir is best absorbed under acidic conditions. Therefore, medications that decrease stomach acidity could reduce the absorption of atazanavir. Drugs that decrease stomach acidity include antacids, proton pump inhibitors such as omeprazole (Prilosec), lansoprazole
(Prevacid), pantoprazole (Protonix), rabeprazole (Aciphex) esomeprazole (Nexium): H2-receptor antagonists such as cimetidine (Tagamet), ranitidine (Zantac), famotidine (Pepcid) and nizatidine (Axid): and buffered drugs such as didanosine (Videx)). Individuals who are taking antacids or didanosine should take their atazanavir two hours before or one hour after the didanosine or antacid.
HIV (human immunodeficiency virus) is the cause of AIDS (acquired immunodeficiency syndrome). HIV is a type of virus called a retrovirus, which infects humans when it comes in contact with a break in the skin or tissues such as those that line the vagina, anal area, mouth, or eyes.
In 1981, homosexual men with
symptoms of a disease that now are considered typical of the acquired
immunodeficiency syndrome (AIDS) were first described in Los Angeles and New
York. The men had an unusual type of lung infection (pneumonia) called
Pneumocystis carinii (now known as
Pneumocystis jiroveci)
pneumonia (PCP) and rare skin tumors called Kaposi's sarcomas. The patients were
noted to have a severe reduction in a type of cell in the blood that is an
important part of the immune system, called CD4 cells. These cells, often referred to as
CD4 T cells, help
the body fight infections. Shortly thereafter, this disease was recognized
throughout the United States, Western Europe, and Africa. In 1983, researchers
in the United States and France described the virus that causes AIDS, now known
as the human immunodeficiency virus (HIV) and belonging to the group of viruses
called re...