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Medical Disclaimer: This information is for educational purposes only and is not a substitute for professional medical advice.
Ganciclovir
Brand Name
Zirgan
Generic Name
Ganciclovir
Active Ingredient
GanciclovirCategory
Cytomegalovirus Nucleoside Analog DNA Polymerase Inhibitor [EPC]
Salt Form
Sodium
Variants
1
Different strengths and dosage forms
| Strength | Form | Route | NDC |
|---|---|---|---|
| 1.5 mg/g | GEL | OPHTHALMIC | 24208-535 |
Detailed information about Zirgan
This page is for informational purposes only and does not replace medical advice. Before using any prescription or over-the-counter medication for Zirgan, you must consult a qualified healthcare professional.
Ganciclovir is a potent nucleoside analog antiviral used to treat and prevent Cytomegalovirus (CMV) infections, particularly in immunocompromised patients and transplant recipients.
Dosage for ganciclovir is highly individualized and is often calculated based on the patient's body weight and renal function.
For patients with active CMV retinitis, the standard induction dose is typically 5 mg/kg administered intravenously over one hour, every 12 hours. This intensive phase usually lasts for 14 to 21 days to bring the viral replication under control.
Following the induction phase, patients are usually transitioned to a maintenance dose to prevent recurrence. The standard maintenance dose is 5 mg/kg administered intravenously once daily, seven days per week, or 6 mg/kg once daily, five days per week.
For the prevention of CMV disease in transplant patients, the typical dose is 5 mg/kg every 12 hours for 7 to 14 days, followed by 5 mg/kg once daily. The duration of this preventative therapy is determined by the transplant team based on the patient's risk profile.
The safety and efficacy of ganciclovir in pediatric patients have not been established through large-scale clinical trials. However, healthcare providers may use ganciclovir in children for the treatment of symptomatic congenital CMV or CMV disease in immunocompromised pediatric patients. Dosing is typically weight-based (e.g., 6 mg/kg every 12 hours for congenital CMV), but this must be managed by a specialist in pediatric infectious diseases. There is a significant concern regarding long-term carcinogenicity and reproductive toxicity in children.
Since ganciclovir is cleared almost entirely by the kidneys, dose adjustments are mandatory for patients with a Creatinine Clearance (CrCl) below 70 mL/min.
Because ganciclovir is not significantly metabolized by the liver, no specific dosage adjustments are generally required for patients with isolated hepatic impairment.
Older adults often have reduced glomerular filtration rates. Dosage should be selected cautiously, starting at the lower end of the dosing range, and renal function must be monitored closely.
Ganciclovir IV must be administered via a slow intravenous infusion over exactly one hour. It should never be given as a rapid or 'bolus' injection, as this increases the risk of toxicity and kidney damage. Patients should be well-hydrated during treatment to help the kidneys clear the drug.
For the ophthalmic gel, patients should wash their hands before and after application, avoid touching the dropper tip to any surface, and follow the specific frequency (usually five times daily until the ulcer heals, then three times daily for 7 days) as prescribed by their ophthalmologist.
In a hospital setting, healthcare providers will manage the schedule. If you are receiving ganciclovir at home and miss a dose, contact your healthcare provider immediately. Do not double the dose to catch up. Consistency is vital for suppressing viral replication.
Signs of ganciclovir overdose may include severe bone marrow suppression (leading to infections or bleeding), kidney failure, or seizures. In cases of overdose, hemodialysis may be used to reduce drug concentrations in the blood. If an overdose is suspected, seek emergency medical attention or contact a poison control center immediately.
> Important: Follow your healthcare provider's dosing instructions exactly. Do not adjust your dose or stop the medication without explicit medical guidance, as this can lead to viral resistance and treatment failure.
Ganciclovir is associated with significant systemic side effects, primarily affecting the blood and the gastrointestinal system.
> Warning: Stop taking Ganciclovir and call your doctor immediately if you experience any of these symptoms:
Prolonged use of ganciclovir carries risks that extend beyond the immediate treatment period.
The FDA has issued several boxed warnings for ganciclovir due to its high toxicity profile:
Report any unusual symptoms to your healthcare provider immediately to ensure safe management of your therapy.
Ganciclovir is a potent medication that requires intensive medical supervision. Because of its potential for severe toxicity, it is typically reserved for serious infections where the benefit outweighs the significant risks. Patients must adhere to a strict schedule of laboratory monitoring to ensure the drug is not causing irreversible damage to the bone marrow or kidneys.
According to the FDA-approved labeling (2024), Ganciclovir carries the following Boxed Warnings:
Patients with a known hypersensitivity to ganciclovir, valganciclovir, acyclovir, or valacyclovir should not use this medication. Cross-sensitivity among these nucleoside analogs is common.
Because ganciclovir is eliminated by the kidneys, patients with pre-existing renal impairment are at a much higher risk for systemic toxicity. Adequate hydration is essential, and dosage must be adjusted based on creatinine clearance.
Ganciclovir has been associated with central nervous system (CNS) toxicities, including convulsions (seizures), sedation, dizziness, and ataxia (loss of muscle coordination). Use with caution in patients with a history of seizures or those taking other medications that lower the seizure threshold.
While on ganciclovir, patients must undergo frequent laboratory testing:
Ganciclovir may cause somnolence (sleepiness), dizziness, or confusion. Patients should not drive or operate heavy machinery until they know how the medication affects them.
While there is no direct chemical interaction between ganciclovir and alcohol, alcohol can dehydrate the body and stress the liver and kidneys. Given the potential for ganciclovir to cause kidney stress and CNS side effects, it is generally advised to avoid alcohol during treatment.
Stopping ganciclovir prematurely can lead to a rapid 'flare-up' of CMV retinitis or other CMV diseases. It can also encourage the development of viral resistance, making the infection much harder to treat in the future. Always consult your doctor before stopping the medication.
> Important: Discuss all your medical conditions, especially any history of blood disorders or kidney disease, with your healthcare provider before starting Ganciclovir.
Certain drugs should never be used alongside ganciclovir due to the extreme risk of toxic reactions.
For the intravenous form, food does not impact the drug's efficacy. For the older oral capsules (rarely used now), a high-fat meal increases absorption. However, since ganciclovir is a hazardous drug that can cause nausea, maintaining a bland diet and staying hydrated is often recommended.
Ganciclovir does not typically interfere with the chemical results of lab tests, but it does fundamentally change the blood counts (WBC, RBC, Platelets) and kidney markers (Creatinine), which are the primary indicators used to monitor its safety.
Most interactions with ganciclovir occur through pharmacodynamic synergism (where two drugs have the same toxic effect, like bone marrow suppression) or renal competition (where two drugs compete to be excreted by the kidneys). Because ganciclovir is not metabolized by the liver, it avoids many of the common CYP450-mediated drug interactions.
> Important: Tell your doctor about ALL medications, supplements, and herbal products you are taking, including over-the-counter pain relievers like ibuprofen, which can also affect kidney function.
There are specific circumstances where ganciclovir must not be used because the risk of harm is nearly certain.
These are conditions where the drug should be used only if no other options exist and the infection is life-threatening:
As noted, cross-sensitivity is a major concern. Ganciclovir, valganciclovir, acyclovir, valacyclovir, and famciclovir all share similar chemical structures. If a patient has experienced a skin rash, hives, or breathing difficulties with one of these, the healthcare provider must perform a thorough risk assessment before administering ganciclovir.
> Important: Your healthcare provider will evaluate your complete medical history, including all past allergic reactions, before prescribing Ganciclovir.
Ganciclovir is classified as a hazardous drug during pregnancy. According to the FDA, it should be avoided unless the potential benefit to the mother justifies the potential risk to the fetus. Animal studies have shown that ganciclovir causes cleft palate, stunted growth, and organ malformations. Women of childbearing potential must use effective contraception during treatment and for at least 30 days after the final dose. Men should use barrier contraception (condoms) during treatment and for at least 90 days after the final dose, as the drug can be present in sperm and may cause genetic damage to the embryo.
It is not known if ganciclovir is excreted in human milk. However, because of the drug's potential for serious adverse reactions in nursing infants—including carcinogenicity and bone marrow suppression—the CDC and the FDA recommend that mothers either discontinue nursing or discontinue the drug. In most cases involving CMV infection in an HIV-positive mother, breastfeeding is already discouraged to prevent the transmission of HIV to the infant.
Ganciclovir is not FDA-approved for use in children, but it is used 'off-label' for severe CMV infections. The primary concern in pediatric populations is the long-term risk of cancer and permanent infertility. Healthcare providers must weigh the immediate need to treat a life-threatening infection against these significant long-term risks. In neonates with congenital CMV, ganciclovir or valganciclovir may be used to prevent hearing loss and developmental delays, but this requires specialized monitoring.
Clinical studies of ganciclovir did not include sufficient numbers of subjects aged 65 and over to determine whether they respond differently than younger subjects. However, it is well-known that renal function declines with age. Since ganciclovir is cleared renally, elderly patients are at a higher risk of toxic accumulation. Frequent monitoring of the Glomerular Filtration Rate (GFR) is essential in this population.
Renal impairment is the most significant factor affecting ganciclovir safety. For patients on hemodialysis, ganciclovir is removed by approximately 50% during a single session. Therefore, the drug should be administered after the dialysis session on dialysis days. Failure to adjust the dose for renal impairment can lead to profound bone marrow failure and neurotoxicity (coma, seizures).
There are no specific studies of ganciclovir in patients with liver disease. However, since the liver plays a negligible role in the drug's clearance, hepatic impairment is not expected to significantly alter the drug's levels. Nevertheless, many patients with CMV also have liver involvement (CMV hepatitis), so liver enzymes should still be monitored as part of general care.
> Important: Special populations require individualized medical assessment and frequent laboratory monitoring to ensure safety.
Ganciclovir is a nucleoside analog that inhibits the replication of herpesviruses, most notably Cytomegalovirus (CMV). The molecular mechanism involves three phosphorylation steps. Inside a CMV-infected cell, the viral protein kinase pUL97 phosphorylates ganciclovir to ganciclovir monophosphate. Subsequently, cellular guanylate kinases convert it to the triphosphate form. Ganciclovir triphosphate then acts as a false building block. It competitively inhibits the incorporation of deoxyguanosine triphosphate into viral DNA by the viral DNA polymerase. Once incorporated, it prevents the DNA chain from elongating, thereby halting viral replication.
The antiviral activity of ganciclovir is dose-dependent. The concentration of the drug required to inhibit viral replication by 50% (IC50) varies by viral strain but typically ranges from 0.02 to 3.48 μg/mL for CMV. Resistance can develop during prolonged treatment, usually due to mutations in the viral UL97 gene (preventing phosphorylation) or the UL54 gene (altering the DNA polymerase).
| Parameter | Value |
|---|---|
| Bioavailability | 5-9% (Oral); 100% (IV) |
| Protein Binding | 1-2% |
| Half-life | 2.5 - 4.1 hours (Normal Renal) |
| Tmax | 0.5 - 1 hour (End of IV infusion) |
| Metabolism | Minimal (Non-CYP) |
| Excretion | Renal >90% (Unchanged) |
Ganciclovir is classified as a Cytomegalovirus Nucleoside Analog DNA Polymerase Inhibitor. It is closely related to acyclovir but has an additional hydroxymethyl group on the acyclic side chain, which provides it with significantly greater activity against CMV. Other drugs in this class or related classes include valganciclovir (the oral prodrug), foscarnet (a pyrophosphate analog), and cidofovir (a nucleotide analog).
Common questions about Zirgan
Ganciclovir is primarily used to treat and prevent infections caused by Cytomegalovirus (CMV), a member of the herpesvirus family. It is most commonly prescribed for CMV retinitis, an eye infection that can cause blindness in people with weakened immune systems, such as those with HIV/AIDS. Additionally, it is used to prevent CMV disease in patients who have received organ or bone marrow transplants. Because CMV can affect various organs, including the colon and lungs, ganciclovir helps protect these vital systems in immunocompromised individuals. It is also used topically as a gel for certain herpes infections of the eye.
The most common side effects of ganciclovir involve the blood and the digestive system. Many patients experience a significant drop in white blood cell counts (neutropenia), which increases the risk of infection, or a drop in red blood cells (anemia), leading to fatigue. Platelet counts may also decrease, causing easier bruising or bleeding. Gastrointestinal issues like nausea, vomiting, diarrhea, and abdominal pain are also frequently reported. Other common symptoms include fever, headache, and reactions at the site of the intravenous injection. Because these side effects can be severe, regular blood tests are required during treatment.
It is generally recommended to avoid alcohol while taking ganciclovir. Although there is no specific chemical interaction that makes the combination immediately toxic, both substances can place stress on the body's filtration systems. Ganciclovir is cleared by the kidneys, and alcohol can lead to dehydration, which may impair the kidneys' ability to process the drug effectively. Furthermore, ganciclovir can cause side effects like dizziness, confusion, and headaches, which can be worsened by alcohol consumption. To ensure your body is in the best condition to fight the infection and process the medication, abstaining from alcohol is the safest choice.
Ganciclovir is not considered safe during pregnancy and is classified as having significant fetal toxicity. Animal studies have shown that the drug can cause severe birth defects, including skeletal malformations and organ damage, as well as fetal death. Because it interferes with DNA synthesis, it poses a high risk to a developing embryo. Women of childbearing age must use effective birth control during treatment and for a month afterward. Men taking the drug should also use condoms for at least 90 days after treatment to avoid the risk of genetic damage to a potential fetus.
The time it takes for ganciclovir to work depends on the severity of the infection, but improvements are typically seen within the first 1 to 2 weeks of the induction phase. In the case of CMV retinitis, a healthcare provider will look for signs that the viral lesions in the eye are stabilizing or shrinking during an eye exam. For systemic infections, a reduction in fever and a decrease in the 'viral load' (the amount of virus in the blood) usually occur within the first 7 to 14 days. However, even if you feel better quickly, it is essential to complete the full course of induction and maintenance therapy as prescribed to prevent the virus from returning.
You should never stop taking ganciclovir suddenly without consulting your healthcare provider. CMV is a persistent virus that can quickly begin replicating again if the medication is withdrawn prematurely. Stopping the drug before the virus is adequately suppressed can lead to a rapid worsening of the infection, which may result in permanent organ damage or blindness. Furthermore, inconsistent use or early discontinuation can lead to the development of drug-resistant CMV strains, making future treatments much less effective. Your doctor will determine the appropriate time to transition from intensive induction therapy to maintenance therapy or to stop the drug entirely.
If you miss a dose of ganciclovir, you should contact your healthcare provider or pharmacist immediately for guidance. If it is almost time for your next scheduled dose, you will likely be told to skip the missed dose and continue with your regular schedule. You should never double the dose to make up for a missed one, as this can significantly increase the risk of bone marrow toxicity and kidney damage. Since maintaining a consistent level of the drug in your system is crucial for stopping the virus, try to use reminders or a schedule to ensure you receive every dose on time.
Weight gain is not a typical side effect of ganciclovir; in fact, weight loss is more commonly reported. Many patients taking ganciclovir experience gastrointestinal side effects such as nausea, vomiting, and a loss of appetite, which can lead to unintended weight loss. Additionally, the underlying infections that ganciclovir treats, such as CMV or HIV, often cause the body to burn more energy, leading to further weight reduction. If you notice rapid weight gain or swelling in your feet and ankles, you should contact your doctor immediately, as this could be a sign of kidney problems rather than actual fat gain.
Ganciclovir has several serious drug interactions, so it must be used cautiously with other medications. It should not be taken with zidovudine (AZT) or imipenem-cilastatin due to the risk of severe blood toxicity or seizures. Other drugs that can damage the kidneys, like certain antibiotics or anti-rejection medications, can increase the levels of ganciclovir in your blood to dangerous levels. Always provide your doctor with a complete list of all prescriptions, over-the-counter drugs, and herbal supplements you are taking. Your healthcare provider will monitor your blood work closely to manage any potential interactions.
Yes, ganciclovir is available as a generic medication. The brand name for the intravenous version was Cytovene, and the ophthalmic gel is known as Zirgan. Generic versions of the intravenous powder for injection are widely available and are typically much more cost-effective than the original brand-name product. Regardless of whether you receive the brand or the generic, the active ingredient and the safety profile remain the same. Your pharmacist or healthcare provider can confirm which version is being administered to you and ensure it meets the necessary quality standards.
Other drugs with the same active ingredient (Ganciclovir)