Cidofovir Macure
Cidofovir 75 mg/ml – Concentrate for Solution for Infusion
Quick Facts About Cidofovir Macure
Key Takeaways About Cidofovir Macure
- Hospital-only antiviral: Cidofovir Macure is given as an intravenous infusion in a clinical setting under medical supervision and is not suitable for home use
- Mandatory kidney protection: Must always be co-administered with oral probenecid and IV saline hydration to prevent serious kidney damage (nephrotoxicity)
- Specific indication: Approved for treatment of CMV retinitis in adult patients with AIDS when other antivirals are unsuitable or have failed
- Regular monitoring required: Kidney function (serum creatinine and urine protein) must be checked before every dose; treatment must be stopped if values deteriorate
- Not for pregnant women or children: Contraindicated in pregnancy due to teratogenic risk; safety in children has not been established
What Is Cidofovir Macure and What Is It Used For?
Cidofovir Macure is an antiviral medicine containing cidofovir, a nucleotide analogue that inhibits the replication of cytomegalovirus (CMV). It is indicated for the treatment of CMV retinitis in adult patients with AIDS who cannot be treated with, or have not responded to, other antiviral agents such as ganciclovir or foscarnet.
Cytomegalovirus (CMV) is a herpesvirus that infects a large proportion of the global population. In individuals with healthy immune systems, CMV typically remains dormant and causes no symptoms. However, in people with severely compromised immune function — particularly those with AIDS whose CD4+ T-cell counts fall below 50 cells/μL — CMV can reactivate and cause serious, potentially blinding eye disease known as CMV retinitis.
CMV retinitis remains one of the most common opportunistic infections in untreated or inadequately treated HIV/AIDS patients. Without treatment, it leads to progressive retinal destruction and irreversible vision loss within weeks to months. The condition affects approximately 20–40% of AIDS patients with very low CD4 counts in the absence of antiretroviral therapy, according to data published in the Journal of Infectious Diseases and endorsed by the World Health Organization (WHO).
Cidofovir belongs to the class of acyclic nucleoside phosphonates (nucleotide analogues). Unlike nucleoside analogues such as ganciclovir that require initial phosphorylation by a viral kinase, cidofovir is already a monophosphate and is converted to its active diphosphate form by host cell enzymes. This unique mechanism means cidofovir retains activity against many CMV strains that have become resistant to ganciclovir through mutations in the UL97 viral kinase gene.
The active metabolite, cidofovir diphosphate, competitively inhibits the CMV DNA polymerase (encoded by the UL54 gene), leading to disruption of viral DNA synthesis and chain termination. The intracellular half-life of cidofovir diphosphate is remarkably long (17–65 hours), which allows for the infrequent dosing schedule that characterises this medicine — once weekly during induction and once every two weeks during maintenance.
Although the introduction of highly active antiretroviral therapy (HAART) has dramatically reduced the incidence of CMV retinitis in HIV/AIDS patients, cidofovir remains an important therapeutic option for patients who do not respond to first-line antivirals, who develop resistance to ganciclovir, or who cannot tolerate alternative treatments. It is also used off-label in some cases for other viral infections, including adenovirus and BK virus infections in immunocompromised transplant recipients.
What Should You Know Before Taking Cidofovir Macure?
Before starting cidofovir, your doctor must confirm adequate kidney function and ensure there are no contraindications. Cidofovir carries significant risks, particularly to the kidneys, and requires careful patient selection, pre-treatment assessment, and ongoing monitoring throughout the course of therapy.
Contraindications
Cidofovir Macure must not be used in patients with any of the following conditions:
- Pre-existing renal impairment: Serum creatinine above 1.5 mg/dL (133 μmol/L), creatinine clearance below 55 mL/min, or urine protein ≥100 mg/dL (equivalent to ≥2+ proteinuria)
- Hypersensitivity: Known allergy to cidofovir, probenecid, or any of the excipients in the formulation
- Sulfonamide hypersensitivity: Probenecid is a sulfonamide derivative; patients with severe sulfonamide allergy should not receive cidofovir as probenecid is a mandatory co-treatment
- Concomitant nephrotoxic drugs: Use with other nephrotoxic agents such as aminoglycosides, amphotericin B, IV pentamidine, or non-steroidal anti-inflammatory drugs (NSAIDs) should be avoided. Nephrotoxic agents must be discontinued at least 7 days before starting cidofovir
- Direct intraocular administration: Cidofovir must never be injected directly into the eye due to risk of severe ocular toxicity
Warnings and Precautions
Cidofovir treatment requires a high level of clinical vigilance. The following warnings apply:
Cidofovir is associated with dose-dependent nephrotoxicity. Renal failure, sometimes requiring dialysis or resulting in death, has been reported. To minimise this risk, probenecid and intravenous saline pre-hydration must be administered with every dose. Serum creatinine and urine protein must be measured within 48 hours before each infusion. If serum creatinine increases by ≥0.3 mg/dL above baseline or proteinuria of ≥2+ develops, cidofovir must be temporarily withheld or permanently discontinued.
Neutropenia: Cidofovir has been associated with neutropenia (low neutrophil count). Complete blood counts should be monitored regularly during treatment. Granulocyte colony-stimulating factor (G-CSF) may be considered for neutrophil counts below 0.5 × 109/L.
Ocular hypotony: Decreased intraocular pressure has been reported in up to 12–24% of patients in clinical trials. Patients should undergo regular ophthalmic examinations, including intraocular pressure measurements. Clinically significant hypotony may necessitate treatment discontinuation.
Metabolic acidosis: Fanconi syndrome and other forms of proximal renal tubular dysfunction, including metabolic acidosis with decreased serum bicarbonate, have been reported with cidofovir use. Electrolytes should be monitored regularly.
Carcinogenicity and mutagenicity: Cidofovir was shown to be carcinogenic in rodent studies, causing mammary adenocarcinomas in rats at sub-therapeutic doses. It is also mutagenic in in vitro assays. Healthcare providers should consider this risk when prescribing cidofovir.
Pregnancy and Breastfeeding
Cidofovir is classified as contraindicated in pregnancy. Animal reproductive studies have demonstrated embryotoxicity and teratogenicity. Cidofovir caused external, soft tissue, and skeletal malformations in rabbits at doses that also produced maternal toxicity.
Women of childbearing potential must use effective contraception during treatment and for at least 1 month after the last dose. Male patients should use barrier contraception during treatment and for 3 months after the last dose, as cidofovir has been shown to cause impaired spermatogenesis in animal studies.
Breastfeeding: It is not known whether cidofovir is excreted in human breast milk. Due to the potential for serious adverse reactions in nursing infants, breastfeeding should be discontinued during cidofovir treatment. Given that HIV-positive women are generally advised not to breastfeed to avoid postnatal HIV transmission, this is typically consistent with standard HIV care guidelines.
How Does Cidofovir Macure Interact with Other Drugs?
Cidofovir has clinically significant interactions primarily with other nephrotoxic drugs and medicines that undergo renal tubular secretion. The most critical interaction is the mandatory co-administration with probenecid, which is required to reduce the renal toxicity of cidofovir. All other nephrotoxic medications must be stopped before and during cidofovir treatment.
Drug interactions involving cidofovir are largely related to its renal elimination and its potential for kidney damage. Because cidofovir is eliminated unchanged by the kidneys through a combination of glomerular filtration and active tubular secretion, drugs that affect these pathways can alter cidofovir exposure or compound renal toxicity.
Probenecid, which must be given with every cidofovir dose, also has its own interaction profile. Probenecid blocks the tubular secretion of many drugs, potentially increasing their plasma concentrations. Patients should be aware that probenecid can interact with paracetamol (acetaminophen), ACE inhibitors, aminosalicylic acid, barbiturates, benzodiazepines, bumetanide, clofibrate, dapsone, fluroquinolones, methotrexate, NSAIDs, theophylline, and zidovudine.
Major Interactions
| Drug / Class | Interaction | Clinical Advice |
|---|---|---|
| Aminoglycosides (gentamicin, tobramycin, amikacin) | Additive nephrotoxicity; both drugs cause renal tubular damage | Discontinue at least 7 days before cidofovir; avoid concurrent use |
| Amphotericin B | Severe additive nephrotoxicity; markedly increased risk of acute renal failure | Discontinue at least 7 days before cidofovir |
| Tenofovir (TDF and TAF) | Both drugs are eliminated by renal tubular transport; increased nephrotoxic risk | Avoid concurrent use; monitor renal function closely if unavoidable |
| IV Pentamidine | Additive nephrotoxicity and risk of hypoglycaemia | Discontinue at least 7 days before cidofovir |
| Foscarnet | Additive nephrotoxicity; both agents commonly used for CMV | Do not use concurrently; allow washout period |
| Vancomycin | Additive nephrotoxicity | Use with caution; monitor renal function closely |
Other Interactions to Consider
| Drug / Class | Interaction | Clinical Advice |
|---|---|---|
| NSAIDs (ibuprofen, diclofenac, naproxen) | May reduce renal blood flow and increase cidofovir nephrotoxicity | Avoid use on cidofovir dosing days; temporarily discontinue if possible |
| Zidovudine (AZT) | Probenecid inhibits glucuronidation of zidovudine, increasing AZT plasma levels | Temporarily withhold or reduce zidovudine dose on cidofovir/probenecid dosing days |
| ACE Inhibitors | Probenecid may increase ACE inhibitor levels; additive renal effects | Monitor blood pressure and renal function |
| Methotrexate | Probenecid reduces renal excretion of methotrexate; increased toxicity risk | Avoid concurrent use; if necessary, monitor methotrexate levels |
What Is the Correct Dosage of Cidofovir Macure?
Cidofovir Macure is given as an intravenous infusion at 5 mg/kg body weight. The induction regimen is once weekly for two consecutive weeks, followed by a maintenance dose of 5 mg/kg every two weeks. Each dose must be accompanied by oral probenecid and intravenous saline pre-hydration.
Cidofovir is a hospital-only medicine that requires careful dosing based on body weight and strict adherence to the co-medication protocol. The infusion is prepared by diluting the concentrated solution in 100 mL of 0.9% sodium chloride (normal saline) and administering it over a period of 1 hour using a constant-rate infusion pump.
Adults
Induction Phase
Dose: 5 mg/kg body weight administered as an IV infusion over 1 hour
Frequency: Once weekly for 2 consecutive weeks
Pre-medication: Probenecid 2 g orally, 3 hours before the infusion. Then 1 g at 2 hours and 1 g at 8 hours after the infusion ends (total: 4 g per treatment day).
Hydration: 1 litre of 0.9% sodium chloride infused over 1–2 hours immediately before cidofovir. An additional 1 litre may be infused over 1–3 hours starting at the beginning of, or immediately after, the cidofovir infusion if tolerated.
Maintenance Phase
Dose: 5 mg/kg body weight administered as an IV infusion over 1 hour
Frequency: Once every 2 weeks (every 14 days)
Pre-medication and hydration: Same probenecid and saline pre-hydration protocol as induction
| Phase | Dose | Frequency | Duration |
|---|---|---|---|
| Induction | 5 mg/kg IV over 1 hour | Once weekly | 2 consecutive weeks |
| Maintenance | 5 mg/kg IV over 1 hour | Every 2 weeks | Continued as long as clinically indicated |
Dose Adjustments for Renal Function
Renal monitoring before every dose is mandatory. The following dose adjustments must be observed:
- Serum creatinine increase of 0.3–0.4 mg/dL above baseline: Reduce dose to 3 mg/kg and continue monitoring
- Serum creatinine increase of ≥0.5 mg/dL above baseline: Discontinue cidofovir treatment
- Development of ≥3+ proteinuria: Discontinue cidofovir treatment
- Development of 2+ proteinuria: Monitor closely; consider dose reduction or discontinuation
Children
The safety and efficacy of cidofovir in children and adolescents under 18 years of age have not been established. Cidofovir Macure is not recommended for paediatric use. No dosage recommendations can be made for this age group. The potential for long-term carcinogenic and reproductive effects is of particular concern in paediatric patients.
Elderly Patients
There are no specific dosage recommendations for elderly patients beyond the standard dose adjustments based on renal function. However, since age-related decline in kidney function is common, elderly patients may be at increased risk of nephrotoxicity. Renal function should be assessed with particular care in this population, and the creatinine clearance should be calculated using an appropriate formula (e.g. Cockcroft-Gault) to avoid overestimation of kidney function based on serum creatinine alone.
Missed Dose
If a scheduled dose of cidofovir is missed, contact your healthcare provider immediately. Do not double the dose to make up for a missed infusion. Your doctor will advise on the appropriate timing for the next dose based on your individual treatment schedule and clinical status.
Overdose
There is limited clinical experience with cidofovir overdose. Based on its known pharmacological profile, overdose would be expected to cause severe nephrotoxicity. In the event of an overdose, supportive care with careful monitoring of renal function, serum electrolytes, and fluid balance is essential. Haemodialysis may reduce plasma cidofovir concentrations — a single 4-hour session has been shown to remove approximately 75% of the drug from the systemic circulation. Probenecid may reduce renal tubular uptake and should be considered as part of overdose management.
What Are the Side Effects of Cidofovir Macure?
The most common side effects of cidofovir are nephrotoxicity (kidney damage), proteinuria, neutropenia, nausea, vomiting, fever, and asthenia. Many side effects are related to the co-administered probenecid. Regular monitoring of kidney function and blood counts is essential throughout treatment.
Like all medicines, cidofovir can cause side effects, although not everyone experiences them. The side effect profile of cidofovir reflects both the direct toxicity of the drug and the effects of mandatory probenecid co-administration. In clinical trials, the most frequently reported adverse reactions included nephrotoxicity (occurring in up to 50–60% of patients based on laboratory criteria), proteinuria, neutropenia, metabolic acidosis, asthenia, nausea, and vomiting.
It is important to note that many patients receiving cidofovir have advanced AIDS with multiple concurrent conditions and medications, making it difficult to attribute all adverse events solely to cidofovir. The following frequency classification is based on data from clinical trials and post-marketing surveillance.
Very Common (affects more than 1 in 10 patients)
- Nephrotoxicity (elevated serum creatinine, proteinuria)
- Neutropenia (low white blood cell count)
- Nausea and vomiting (often related to probenecid)
- Fever (pyrexia)
- Asthenia (weakness, fatigue)
- Headache
- Rash
- Alopecia (hair loss)
- Decreased intraocular pressure
- Diarrhoea
Common (affects 1 in 10 to 1 in 100 patients)
- Metabolic acidosis (Fanconi syndrome)
- Decreased serum bicarbonate
- Anorexia (loss of appetite)
- Dyspnoea (shortness of breath)
- Pneumonia
- Iritis or uveitis (eye inflammation)
- Anaemia
- Elevated liver enzymes
- Chills
- Infection (opportunistic)
Uncommon (affects 1 in 100 to 1 in 1,000 patients)
- Acute renal failure requiring dialysis
- Pancreatitis
- Hepatotoxicity (liver damage)
- Hearing impairment
- Peripheral neuropathy
- Hypotension
Rare (affects fewer than 1 in 1,000 patients)
- Severe hypersensitivity reactions (anaphylaxis)
- Stevens-Johnson syndrome
- Complete renal failure (irreversible)
- Diabetes insipidus (nephrogenic)
Contact your healthcare provider or seek emergency care if you experience: significantly reduced urine output; swelling of ankles, feet, or face; severe nausea, vomiting, or abdominal pain; chest pain or difficulty breathing; unusual bruising or bleeding; sudden vision changes; or signs of severe allergic reaction such as skin rash, swelling of the face or throat, or difficulty breathing.
How Should You Store Cidofovir Macure?
Cidofovir Macure concentrate for solution for infusion should be stored at 2–8°C (refrigerator temperature) in the original packaging to protect from light. Do not freeze. Once diluted for infusion, the solution should be used within 24 hours when stored at 2–8°C.
Proper storage of cidofovir is essential to maintain the chemical stability and therapeutic efficacy of the medicine. As a hospital-administered product, storage is typically managed by the pharmacy or healthcare facility, but the following information is important for all healthcare professionals involved in handling the product.
- Unopened vials: Store at 2°C to 8°C (in a refrigerator). Do not freeze. Keep the vial in the outer carton to protect from light.
- Diluted solution: After dilution in 0.9% sodium chloride for infusion, the solution should be administered within 24 hours if stored at 2–8°C. Chemical and physical in-use stability has been demonstrated for 24 hours at 2–8°C.
- Room temperature: If stored at room temperature (15–30°C), the diluted solution should be used within 6 hours of preparation.
- Disposal: Any unused product or waste material should be disposed of in accordance with local requirements for cytotoxic/antiviral agents. Cidofovir is potentially mutagenic and carcinogenic — appropriate personal protective equipment should be used when handling.
Do not use Cidofovir Macure after the expiry date stated on the vial and outer carton. The expiry date refers to the last day of that month. Do not use if the solution is discoloured or contains visible particles.
Cidofovir is classified as a hazardous drug. Healthcare workers should wear gloves, protective eyewear, and a closed-front gown when preparing and handling cidofovir solutions. If cidofovir comes into contact with skin or mucous membranes, the area should be washed immediately and thoroughly with water. Preparation should ideally be carried out in a biological safety cabinet or using a closed-system drug transfer device.
What Does Cidofovir Macure Contain?
Each millilitre of Cidofovir Macure concentrate contains 75 mg of cidofovir (as cidofovir dihydrate) as the active substance. The solution also contains sodium hydroxide and hydrochloric acid for pH adjustment, and water for injections.
Cidofovir Macure is supplied as a sterile, preservative-free, clear, colourless to slightly yellow concentrated solution. Each glass vial contains 375 mg of cidofovir in 5 mL of solution (75 mg/mL).
Active Substance
- Cidofovir (as cidofovir dihydrate) — 75 mg per mL
Inactive Ingredients (Excipients)
- Sodium hydroxide (for pH adjustment)
- Hydrochloric acid (for pH adjustment)
- Water for injections
The pH of the concentrated solution is approximately 7.4. The solution is a clear, colourless to slightly yellow liquid. Each vial is for single use only. Any unused solution must be discarded.
Cidofovir Macure does not contain preservatives, antimicrobial agents, latex, or any common allergens (gluten, lactose, peanut, soy). However, due to the mandatory co-administration of probenecid (a sulfonamide derivative), patients with sulfonamide allergy should not receive this treatment regimen.
Frequently Asked Questions About Cidofovir Macure
Cidofovir Macure is an antiviral medicine used to treat cytomegalovirus (CMV) retinitis in adult patients with AIDS. CMV retinitis is a serious viral infection of the eye that can cause blindness if untreated. Cidofovir is typically reserved for cases where first-line treatments such as ganciclovir or foscarnet are ineffective, poorly tolerated, or contraindicated. It works by blocking the virus from replicating its DNA, thereby halting the progression of the infection.
Cidofovir is given as an intravenous (IV) infusion over 1 hour in a hospital or clinic. During the induction phase, it is given once a week for two consecutive weeks. After that, the maintenance phase involves an infusion once every two weeks. Each treatment session also requires oral probenecid tablets (taken before and after the infusion) and intravenous saline to protect the kidneys. A full treatment day typically takes several hours due to the hydration and monitoring requirements.
Probenecid is a mandatory co-medication because it protects the kidneys from cidofovir's toxic effects. Without probenecid, cidofovir concentrates in the kidney tubule cells at levels that cause severe damage. Probenecid works by blocking the organic anion transporter in the kidneys, reducing the amount of cidofovir that enters kidney cells. The regimen is 2 g taken orally 3 hours before the infusion, followed by 1 g at 2 hours and 1 g at 8 hours after the infusion.
The most significant risk is nephrotoxicity (kidney damage), which can range from mild elevation of creatinine to complete renal failure requiring dialysis. This is why kidney function tests are mandatory before every single dose. Other important risks include neutropenia (low white blood cell count, which increases infection risk), decreased intraocular pressure, metabolic acidosis, and gastrointestinal side effects. In preclinical studies, cidofovir was also found to be carcinogenic and teratogenic, though these effects have not been confirmed in humans at therapeutic doses.
While cidofovir is formally approved only for CMV retinitis in AIDS patients, it has been used off-label for several other viral infections in immunocompromised patients. These include adenovirus infections (particularly in transplant recipients), BK virus-associated nephropathy after kidney transplantation, progressive multifocal leukoencephalopathy (PML) caused by JC virus, and severe molluscum contagiosum. However, evidence for these off-label uses is limited and based primarily on case reports and small case series rather than randomised controlled trials.
Yes, cidofovir is often effective against CMV strains that are resistant to ganciclovir. Ganciclovir resistance typically arises from mutations in the UL97 viral kinase gene, which is responsible for the first phosphorylation step of ganciclovir. Because cidofovir does not require this initial viral kinase activation (it is already a monophosphate), it retains activity against UL97-mutant CMV. However, some CMV strains develop resistance through mutations in the UL54 DNA polymerase gene, which can confer cross-resistance to both ganciclovir and cidofovir.
References
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About the Medical Editorial Team
This article has been written and medically reviewed by the iMedic Medical Editorial Team, comprising licensed physicians specialising in infectious diseases, clinical pharmacology, and HIV medicine.
Content developed by iMedic medical writers with expertise in antiviral pharmacology and infectious disease therapeutics, based on EMA SmPC data, FDA prescribing information, WHO guidelines, and peer-reviewed clinical literature.
Independently reviewed by the iMedic Medical Review Board in accordance with international clinical guidelines (NIH, ECIL, BNF) and the GRADE evidence framework to ensure accuracy, completeness, and clinical relevance.
Evidence level: This article follows Evidence Level 1A, based on systematic reviews, randomised controlled trials, and authoritative clinical guidelines. Last fact-checked: .
Conflict of interest: None. iMedic receives no funding from pharmaceutical companies and publishes no pharmaceutical advertising.