Generic Name: Cidofovir Brand Name(s): Cidofovir.

Uses

What is Cidofovir used for?

Cidofovir is commonly used with probenecid to treat a certain viral eye infection (retinitis due to cytomegalovirus-CMV) in people with AIDS. It lowers your risk of blindness and other vision problems. Cidofovir belongs to a class of drugs known as antivirals. It works by stopping the growth of the virus.

Cidofovir is not a cure for CMV retinitis, and your disease may still worsen during and after treatment.

How should I take Cidofovir?

This medication is given into a vein as directed by your doctor, usually over 1 hour. It is usually given every 1 to 2 weeks or as directed by your doctor. This medication should not be injected into the eyes. Permanent loss of vision may occur.

Dosage is based on your medical condition, body weight, and response to treatment. You will usually receive IV fluids before your dose of cidofovir. Your doctor will also direct you to take probenecid by mouth before and after you receive cidofovir. To prevent kidney problems, drink plenty of fluids unless otherwise directed by your doctor. This is especially important if you are vomiting or having diarrhea.

If you are giving this medication to yourself at home, learn all preparation and usage instructions from your health care professional. Before using, check this product visually for particles or discoloration. If either is present, do not use the liquid. Learn how to store and discard medical supplies safely.

It is very important to use the probenecid with this medication exactly as prescribed by your doctor. Nausea and vomiting due to probenecid may be prevented by taking it after meals. Your doctor may also prescribe another medication to prevent nausea, and may direct you to take antihistamines (e.g., diphenhydramine) and/or acetaminophen to prevent allergic reactions to probenecid.

This medication works best when it is used regularly. Keep all your medical appointments. You may want to mark a calendar to help you remember.

Do not use more or less of this drug than prescribed or stop using it (or your HIV medicines) even for a short time unless directed to do so by your doctor. Doing so may cause the amount of virus to increase, make the infection more difficult to treat (resistant), or worsen side effects.

Avoid direct contact of this medicine with the skin/eyes/mouth. If contact occurs, wash thoroughly with soap and water. For eyes, rinse with a steady stream of tap water for at least 5 minutes.

How do I store Cidofovir?

If you need to store cidofovir at home, talk with your doctor, nurse, or pharmacist about how to store it.

Precautions & warnings

What should I know before using Cidofovir?

Before using cidofovir, tell your doctor or pharmacist if you are allergic to it; or to other antivirals (e.g., ganciclovir); or to probenecid; or to other sulfa drugs (e.g., sulfamethoxazole); or if you have any other allergies. This product may contain inactive ingredients, which can cause allergic reactions or other problems. Talk to your pharmacist for more details.

This medication should not be used if you have certain medical conditions. Before using this medicine, consult your doctor or pharmacist if you have: severe kidney disease.

Before using this medication, tell your doctor or pharmacist your medical history, especially of: diabetes, ganciclovir eye implant, mild/moderate kidney disease.

This drug may cause vision changes. Do not drive, use machinery, or do any activity that requires clear vision until you are sure you can perform such activities safely. Limit alcoholic beverages.

Kidney function declines as you grow older. This medication is removed by the kidneys. Therefore, elderly people may be at a greater risk for kidney damage while using this drug.

During pregnancy, cidofovir should be used only when clearly needed. It may harm an unborn baby. Discuss the risks and benefits with your doctor. The manufacturer recommends avoiding pregnancy. To prevent pregnancy, men with female partners should use effective barrier protections (such as latex or polyurethane condoms) during all sexual activity during treatment and for at least 90 days after stopping the medication. Women should use effective forms of birth control (such as birth control pills and condoms) during treatment and for at least 1 month after stopping the medication.

It is not known if this medication passes into breast milk. Because of the possible risks to the infant and because breast milk can transmit HIV, do not breast-feed.

Is it safe during pregnancy or breast-feeding?

There are no adequate studies in women for determining risk when using this medication during pregnancy or while breastfeeding. Please always consult with your doctor to weigh the potential benefits and risks before taking this medication. This medication is pregnancy risk category C according to the US Food and Drug Administration (FDA).

FDA pregnancy risk category reference below:

  • A=No risk,
  • B=No risk in some studies,
  • C=There may be some risk,
  • D=Positive evidence of risk,
  • X=Contraindicated,
  • N=Unknown

Side effects

What side effects can occur from Cidofovir?

Nausea may occur. Headache, nausea, and vomiting may occur with probenecid use. If any of these effects persist or worsen, tell your doctor or pharmacist promptly.

Not everyone experiences these side effects. There may be some side effects not listed above. If you have any concerns about a side-effect, please consult your doctor or pharmacist.

Interactions

What drugs may interact with Cidofovir?

Some products that may interact with this drug include: acyclovir, angiotensin-converting enzyme inhibitors, aminosalicylic acid, barbiturates (e.g., phenobarbital), benzodiazepines (e.g., triazolam), bumetanide, clofibrate, methotrexate, furosemide, nonsteroidal anti-inflammatory drugs-NSAIDs (e.g., ibuprofen), zidovudine.

If you are taking probenecid and any of the medications listed above, ask your doctor if you should temporarily stop the other medication or decrease its dosage because probenecid may affect how well those medications are removed from your body. This is very important for zidovudine.

Tell your doctor if you have had previous use of foscarnet.

Avoid taking other medications that may damage your kidneys (e.g., amphotericin B, foscarnet, pentamidine, vancomycin, aminoglycosides including tobramycin, nonsteroidal anti-inflammatory drugs-NSAIDs including ibuprofen) within 7 days before and during treatment with this medication. In some cases, serious (possibly fatal) kidney damage may occur.

Check the labels on all your medicines because they may contain NSAIDs (e.g., ibuprofen, naproxen). Ask your pharmacist about using those products safely.

Cidofovir may interact with other drugs that you are currently taking, which can change how your drug works or increase your risk for serious side effects. To avoid any potential drug interactions, you should keep a list of all the drugs you are using (including prescription drugs, nonprescription drugs and herbal products) and share it with your doctor and pharmacist. For your safety, do not start, stop, or change the dosage of any drugs without your doctor’s approval.

Does food or alcohol interact with Cidofovir?

Cidofovir may interact with food or alcohol by altering the way the drug works or increase the risk for serious side effects. Please discuss with your doctor or pharmacist any potential food or alcohol interactions before using this drug.

What health conditions may interact with Cidofovir?

Cidofovir may interact with your health condition. This interaction may worsen your health condition or alter the way the drug works. It is important to always let your doctor and pharmacist know all the health conditions you currently have.

Dosage

The information provided is not a substitute for any medical advice. You should ALWAYS consult with your doctor or pharmacist before using this medication.

What is the dose of Cidofovir for an adult?

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.

Renal Dose Adjustments

Moderate to severe renal impairment (calculated CrCl 55 mL/min or less, serum creatinine greater than 1.5 mg/dL, or urine protein 100 mg/dL or greater [equivalent to 2+ proteinuria or greater]): Contraindicated

Changes in renal function during therapy:
For increase in serum creatinine of 0.3 to 0.4 mg/dL above baseline: Maintenance dose must be reduced to 3 mg/kg.
For increase in serum creatinine of 0.5 mg/dL or greater above baseline or development of 3+ proteinuria or greater: Therapy must be discontinued.

Liver Dose Adjustments

No adjustment recommended

Dose Adjustments

Elderly:
-Safety and effectiveness have not been studied in patients over the age of 60 years.
-Since elderly individuals frequently have reduced glomerular filtration, particular attention should be paid to assessing renal function before and during cidofovir administration.

Probenecid:
-Tolerability may be improved by administering with food; antiemetic therapy may reduce potential for nausea.
-In patients who develop allergic or hypersensitivity symptoms, an appropriate prophylactic or therapeutic antihistamine and/or acetaminophen should be considered.

Concomitant Zidovudine:
-Due to an interaction of zidovudine with probenecid, zidovudine dose should be held or decreased by 50% on days of cidofovir injection.

Precautions

US BOXED WARNINGS: NEPHROTOXICITY; NEUTROPENIA; CARCINOGENICITY, TERATOGENICITY; and HYPOSPERMIA:
-Renal impairment is the major toxicity of therapy. Cases of acute renal failure resulting in dialysis and/or contributing to death have occurred with as few as 1 or 2 doses. To reduce possible nephrotoxicity, IV prehydration with normal saline and administration of probenecid must be used with each dose. Renal function (serum creatinine and urine protein) must be monitored within 48 hours prior to each dose and the dose must be modified for changes in renal function. This drug is contraindicated in patients who are receiving other nephrotoxic agents.
-Neutropenia has been observed in association with this drug; therefore, neutrophil counts should be monitored during therapy.
-This drug is indicated only for the treatment of CMV retinitis in patients with Acquired Immunodeficiency Syndrome (AIDS).
-In animal studies, this drug was carcinogenic, teratogenic, and caused hypospermia.

Safety and efficacy have not been established in patients younger than 18 years.

Consult WARNINGS section for additional precautions.

Dialysis

Contraindicated

-High-flux hemodialysis reduces serum levels of cidofovir by about 75%.

Other Comments

Administration advice:
-For IV infusion only; dilute in 100 mL of normal saline prior to administration
-Administer as IV infusion at a constant rate over 1 hour; use of a standard infusion pump is recommended

Prior to infusion:
-Begin course of probenecid 3 hours prior to infusion; administer orally with food to reduce drug-related nausea and vomiting
-Begin hydration with at least 1 L of normal saline 1 to 2 hours prior to infusion; patients who can tolerate additional fluid should receive a second liter either at the start of the cidofovir infusion or immediately following and infused over a 1 to 3-hour period

Reconstitution/preparation techniques:
-Prepare infusion by extracting the appropriate volume of drug from vial and transferring to an infusion bag containing 100 mL normal saline.
-Due to mutagenic properties, use of appropriate safety equipment for preparation, administration, and disposal is recommended.

IV compatibility:
-Addition of other drugs or supplements is not recommended
-Compatibility with Ringer’s solution, Lactated Ringer’s solution or bacteriostatic infusion fluid has not been evaluated

Storage requirements:
-Chemical stability has been demonstrated in polyvinyl chloride and ethylene/propylene copolymer composition commercial infusion bags, and in glass bottles.
-Prepared admixtures should be used promptly, however, may store under refrigeration (2C to 8C) for up to 24 hours.

General:
-Concomitant use with other drugs with potential nephrotoxicity is contraindicated; potentially nephrotoxic drugs should be stopped at least 7 days before this drug is initiated.
-Direct intraocular injection is contraindicated as it has been associated with iritis, ocular hypotony, and permanent vision impairment.
-As a full course of probenecid must be administered with each dose of this drug, it is important to consider potential drug interactions and potential adverse events associated with this drug; administering after a meal or with antiemetics may decrease the nausea and prophylactic or therapeutic antihistamines and/or acetaminophen can be used to lessen hypersensitivity reactions.

Monitoring:
-Serum creatinine and urine protein must be checked within 48 hours of each dose; calculate CrCl using Cockcroft-Gault formula
-If proteinuria is present, start IV hydration and retest
-Monitor white blood counts with differential prior to each dose
-Intraocular pressure, visual acuity, and ocular symptoms should be monitored periodically

Patient advice:
-Patients should understand the importance of completing a full course of probenecid with each dose of this drug, they should be warned of potential adverse effects of probenecid and what they may be able to do to minimize them.
-Patients should be advised that this drug has caused embryotoxic and impaired fertility in animals and these effects may occur in humans; contraceptive measures are advised for men and women of childbearing potential.

What is the dose of Cidofovir for a child?

The dosage has not been established in pediatric patients. It may be unsafe for your child. It is always important to fully understand the safety of the drug before using. Please consult with your doctor or pharmacist for more information.

How is Cidofovir available?

Cidofovir is available in the following dosage forms and strengths:

  • Intravenous solution

What should I do in case of an emergency or overdose?

In case of an emergency or an overdose, call your local emergency services or go to your nearest emergency room.

What should I do if I miss a dose?

If you miss a dose of Cidofovir, take it as soon as possible. However, if it is almost time for your next dose, skip the missed dose and take your regular dose as scheduled. Do not take a double dose.

Hello Health Group does not provide medical advice, diagnosis or treatment.

Sources

Review Date: January 16, 2018 | Last Modified: January 16, 2018

Want to live your best life?
Get the Hello Doktor Daily newsletter for health tips, wellness updates and more.