GENERIC NAME: lamivudine and zidovudine
　

BRAND NAME: Combivir
DRUG CLASS AND MECHANISM: Combivir is a combination of lamivudine (Epivir) and zidovudine (Retrovir) that is used for the treatment of infections with the human immunodeficiency virus (HIV). Lamivudine and zidovudine are in a class of drugs called reverse transcriptase inhibitors which also includes zalcitabine (Hivid) and didanosine (Videx). During infection with HIV, the HIV virus multiplies within the body's cells. The newly-formed viruses then are released from the cells and spread throughout the body where they infect other cells. In this manner, the infection continually spreads to new, uninfected cells that the body is continually producing, and HIV infection is perpetuated. When producing new viruses, the HIV virus must manufacture new DNA for each virus. Reverse transcriptase is the enzyme that the virus uses to form this new DNA. Lamivudine and zidovudine inhibit the activity of reverse transcriptase and block the production of DNA and new viruses. Specifically, lamivudine is converted within the body to its active form, lamivudine triphosphate, and zidovudine is converted to its active form, zidovudine triphosphate. The active forms are similar to deoxycytidine triphosphate and thymidine triphosphate, respectively, chemicals that are used by reverse transcriptase to make new DNA. The reverse transcriptase uses lamivudine triphosphate and zidovudine triphosphate instead of deoxycytidine triphosphate and thymidine triphosphate for making DNA, and it is these active forms that interfere with the reverse transcriptase. The effectiveness of lamivudine or zidovudine when used alone may decrease as the HIV virus develops resistance to the drugs. By combining lamivudine and zidovudine, it is more difficult for the HIV virus to develop resistance to therapy. Therefore Combivir is more effective than lamivudine or zidovudine alone. Combivir does not kill existing HIV virus and it is not a cure for HIV. Combivir was approved by the FDA in September, 1997.

GENERIC AVAILABLE: No

PRESCRIPTION: Yes

PREPARATIONS: Tablets: 150 mg/300 mg (lamivudine/zidovudine)

STORAGE: Store at room temperature, 15-30癈 (59-86癋).

PRESCRIBED FOR: Combivir is used for the treatment of HIV infection.

DOSING: For the treatment of HIV infection the recommended oral dose for adults or children greater than 12 years of age is one tablet twice daily. Combivir is administered without regard to meals.

DRUG INTERACTIONS: Fluconazole (Diflucan), probenecid and trimethoprim (Trimpex) reduce the elimination of zidovudine and therefore increase the blood concentration of zidovudine. This can lead to increased side effects from zidovudine.

PREGNANCY: Use of Combivir during pregnancy has not been adequately evaluated.

NURSING MOTHERS: Use of Combivir by nursing mothers has not been studied. HIV infected mothers should not breast feed because of the potential risk of transmitting HIV to an infant that is not infected.

SIDE EFFECTS: The most severe side effects are a decrease in blood cells, muscle pain (myopathy), liver enlargement and metabolic disturbance (lactic acidosis). Other side effects are chills, rash, abdominal pain, nausea and vomiting, weight loss, headache and insomnia.