Ritonavir

Ritonavir, sold under the trade name Norvir, is an antiretroviral medication used along with other medications to treat HIV/AIDS. This combination treatment is known as highly active antiretroviral therapy (HAART). Often a low dose is used with other protease inhibitors. It may also be used in combination with other medications for hepatitis C. It is taken by mouth. The capsules of the medication do not work the same as the tablets. Ritonavir, sold under the trade name Norvir, is an antiretroviral medication used along with other medications to treat HIV/AIDS. This combination treatment is known as highly active antiretroviral therapy (HAART). Often a low dose is used with other protease inhibitors. It may also be used in combination with other medications for hepatitis C. It is taken by mouth. The capsules of the medication do not work the same as the tablets. Common side effects include nausea, vomiting, loss of appetite, diarrhea, and numbness of the hands and feet. Serious side effects include liver problems, pancreatitis, allergic reactions, and arrythmias. Serious interactions may occur with a number of other medications including amiodarone and simvastatin. At low doses it is considered to be acceptable for use during pregnancy. Ritonavir is of the protease inhibitor class. Typically, however, it is used to inhibit the enzyme that metabolizes other protease inhibitors. This inhibition allows lower doses of these latter medication to be used. Ritonavir was patented in 1989 and came into medical use in 1996. It is on the World Health Organization's List of Essential Medicines, the most effective and safe medicines needed in a health system. Globally the wholesale cost in the developing world is between US$0.07 and $2.20 per day. In the United States it costs about $9.20–55 per day depending on the dose. Ritonavir is used along with other medications to treat HIV/AIDS. When administered at doses effective for anti-HIV therapy, the side effects of ritonavir are those shown below. It is currently (2015) much more widely used at lower doses as a pharmacokinetic inhibitor. The adverse effects of these lower doses of ritonavir do not appear to have been extensively characterized. One of ritonavir's side effects is hyperglycemia. It appears that ritonavir directly inhibits the GLUT4 insulin-regulated transporter, keeping glucose from entering fat and muscle cells. This can lead to insulin resistance and cause problems for people with type Ⅱ diabetes. The capsules of the medication do not have the same bioavailability as the tablets. Concomitant therapy of ritonavir with a variety of medications may result in serious and sometimes fatal drug interactions. Ritonavir induces CYP 1A2 and inhibits the major P450 isoforms (3A4 and 2D6).