Cidofovir is an antiviral medicine that is used to treat an eye infection called cytomegalovirus retinitis (CMV) in people who have AIDS (acquired immunodeficiency syndrome). Cidofovir is for treating CMV only in people who have AIDS.

Cidofovir is not a cure for CMV and may not prevent vision changes.

Cidofovir may also be used for purposes not listed in this medication guide.

Cidofovir can harm your kidneys after only one or two doses. You should not receive cidofovir if you have used any of the following drugs within the past 7 days: certain medicines for infections, cancer, osteoporosis, organ transplant rejection, bowel disorders, high blood pressure, or pain or arthritis (including Advil, Motrin, and Aleve).

Cidofovir is given as an infusion into a vein. A healthcare provider will give you this injection.

Your doctor test your kidney function within 48 hours before each dose of cidofovir.

Make sure your doctor knows if you also take zidovudine to treat HIV. You may need to change your dose or stop taking it on the day you receive a cidofovir infusion.

Cidofovir can harm your kidneys after only one or two doses. You will be given intravenous (IV) fluids and oral probenecid while you are receiving cidofovir.

Cidofovir and IV fluids must be given slowly, and your entire treatment can take up to 6 hours to complete.

Take probenecid with food if it upsets your stomach. Keep taking the probenecid for the full prescribed length of time. Skipping doses may increase your risk of complications caused by cidofovir.

You will need frequent medical tests, and your next cidofovir infusion may be delayed based on the results.

Usual Adult Dose for CMV Retinitis:

Dose, Frequency, and Infusion Rate Must Not Be Exceeded; Probenecid and IV Saline Prehydration Must Be Administered with Each Dose

Induction dose: 5 mg/kg via IV infusion once a week for 2 consecutive weeks
Maintenance dose: Following induction dose, 5 mg/kg via IV infusion once every 2 weeks

Comments:
-Probenecid dose: 2 g orally 3 hours prior to infusion, then 1 g orally at 2 and 8 hours following completion of infusion (total probenecid dose equals 4 g)
-IV infusion should be given at a constant rate over 1 hour; consult preparation and administration section for important instructions on preparing and administering infusion.
-Serum creatinine and urine protein must be checked within 48 hours of each dose; because serum creatinine may not provide a complete picture of underlying renal status in patients with advanced AIDS and CMV retinitis, it is important to utilize the Cockcroft-Gault formula to more precisely estimate CrCl.
-The safety and efficacy of this drug has not been established for the treatment of other CMV infections such as pneumonitis or gastroenteritis, congenital or neonatal CMV disease, or CMV disease in non-HIV-infected individuals.

Usual Adult Dose for Smallpox Vaccine Reaction:

(Not approved by FDA)

5 mg/kg via IV infusion once

A second dose 1 week later may be considered if clinically indicated.

Cidofovir is available under an IND protocol from the CDC as a second-line treatment of severe smallpox vaccine complications that have not responded to vaccinia immune globulin (VIG) treatment.

You should not be treated with cidofovir if you are allergic to it, or if you have:

• moderate to severe kidney disease; or

• a history of severe allergic reaction to probenecid or sulfa drugs.

You should not receive cidofovir if you've used certain other medicines within 7 days before a cidofovir injection. Tell your doctor if you use any of the following:

• blood pressure medicine;

• cancer medicine;

• injectable medications to treat osteoporosis or Paget's disease of bone;

• medication to prevent organ transplant rejection;

• medicines for infections;

• medicines to treat a bowel disorder; or

• some pain or arthritis medicines (including Advil, Motrin, and Aleve).

Tell your doctor if you have ever had:

• kidney disease;

• diabetes; or

• pancreas problems.

Cidofovir can harm an unborn baby if the mother or the father is using cidofovir.

• If you are a woman, do not use cidofovir if you are pregnant. Use effective birth control to prevent pregnancy while you are using this medicine and for at least 1 month after your last dose.

• If you are a man, use effective birth control if your sex partner is able to get pregnant. Keep using birth control for at least 3 months after your last dose.

• Tell your doctor right away if a pregnancy occurs while either the mother or the father is using cidofovir.

Women with HIV or AIDS should not breastfeed a baby. Even if your baby is born without HIV, the virus may be passed to the baby in your breast milk.

Call your doctor for instructions if you miss an appointment for your cidofovir injection, or if you miss any dose of probenecid.

Since cidofovir is given in a medical setting, you will be watched closely to make sure you do not receive too much of cidofovir. Your caregivers will quickly treat you if you have overdose symptoms.

Follow your doctor's instructions about any restrictions on food, beverages, or activity.

Get emergency medical help if you have signs of an allergic reaction: hives; difficult breathing; swelling of your face, lips, tongue, or throat.

Cidofovir may cause serious side effects. Call your doctor at once if you have:

• vision changes, white or yellow patches on your eyes;

• kidney problems--swelling, rapid weight gain, little or no urinating, increased thirst, loss of appetite, constipation, pain in your side or lower back;

• low blood cell counts--fever, chills, tiredness, mouth sores, skin sores, easy bruising, unusual bleeding, pale skin, cold hands and feet, feeling light-headed or short of breath; or

• pancreatitis--severe pain in your upper stomach spreading to your back, nausea and vomiting.

Common side effects of cidofovir may include:

• nausea, vomiting, diarrhea;

• pain, weakness;

• rash;

• headache; or

• hair loss.

While taking probenecid, you may have side effects such as:

• nausea, vomiting;

• skin rash;

• fever, chills; or

• headache.

This is not a complete list of side effects and others may occur. Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088.

Many drugs can affect cidofovir, and some drugs should not be used within 7 days before you receive cidofovir. Tell your doctor about all your current medicines and any medicine you start or stop using. This includes prescription and over-the-counter medicines, vitamins, and herbal products. Not all possible interactions are listed here.