Lesson
Recognize the CMV Decision State
CMV establishes lifelong latency, but end-organ disease concentrates in severe cell-mediated immunosuppression and demands rapid compartment-specific triage.
- Latency
- Advanced HIV
- Transplant risk
- End-organ signal
- Immune recovery
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Separate infection from disease
CMV is a double-stranded DNA herpesvirus acquired through infected body fluids. Seropositivity is common and latency is lifelong. A positive antibody or blood test does not, by itself, establish tissue-invasive disease.
Identify high-risk hosts
In HIV, end-organ disease occurs mainly with advanced immune suppression, especially CD4 counts below 50 cells per cubic millimeter without effective ART. Allogeneic stem-cell and solid-organ transplant risks depend on donor and recipient serostatus, immunosuppression, time after transplant, and prior CMV.
Recognize organ danger
New floaters, field loss, or visual decline can signal retinitis. Odynophagia, bloody diarrhea, abdominal pain, neurologic decline, radicular pain, urinary retention, or progressive weakness can indicate gastrointestinal or central nervous system disease and require urgent evaluation.
Prevent through immune control
For people with HIV, effective ART that sustains CD4 counts at or above 100 is the main prevention strategy. NIH does not recommend valganciclovir primary prophylaxis or routine CMV-viremia monitoring for asymptomatic viremia in this setting.
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Lesson
Prove Disease in the Affected Compartment
Diagnosis joins a compatible syndrome to organ-specific examination, pathology, imaging, or fluid evidence while preserving competing diagnoses.
- Dilated eye exam
- Tissue pathology
- Compartment PCR
- Shedding
- Differential diagnosis
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Diagnose retinitis visually
An experienced ophthalmologist can usually diagnose CMV retinitis by characteristic full-thickness necrotizing retinal lesions on dilated examination. Ocular-fluid PCR helps when the appearance is uncertain, but a negative result does not exclude every case.
Confirm gastrointestinal invasion
CMV colitis or esophagitis generally requires compatible ulceration plus histopathologic evidence in tissue. PCR or culture from gastrointestinal material without tissue injury may reflect shedding rather than invasive disease.
Interpret blood carefully
Blood CMV detection has limited value for diagnosing end-organ disease in HIV. Viremia can occur without tissue disease, while a negative plasma result does not rule out retinitis, gastrointestinal disease, or neurologic disease.
Match neurologic evidence
CMV encephalitis, ventriculoencephalitis, or polyradiculomyelopathy requires a compatible clinical state and CMV detection in cerebrospinal fluid or tissue when obtainable. Imaging, CSF pattern, and competing pathogens remain part of the interpretation.
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Lesson
Activate Ganciclovir and Read Resistance
The acyclic guanine analogue depends on CMV pUL97 phosphorylation, then inhibits pUL54 DNA polymerase as an intracellular triphosphate.
- Guanine analogue
- pUL97 kinase
- Host kinases
- pUL54 polymerase
- Cross-resistance
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Build the active triphosphate
CMV pUL97 kinase begins phosphorylation of ganciclovir. Host cellular kinases complete formation of ganciclovir triphosphate, which competitively inhibits pUL54 DNA polymerase and impairs viral DNA elongation.
Connect structure to toxicity
Ganciclovir resembles an acyclic guanosine nucleoside and gains antiviral selectivity through intracellular activation and viral-target preference. The active nucleotide can also affect host proliferating cells, helping explain marrow and reproductive toxicity.
Interpret UL97 mutations
UL97 mutations commonly reduce initial ganciclovir phosphorylation. They can cause ganciclovir and valganciclovir resistance while leaving kinase-independent foscarnet or cidofovir activity possible, subject to the complete genotype and toxicity profile.
Interpret UL54 mutations
UL54 polymerase mutations can reduce susceptibility to ganciclovir and may cause cross-resistance to cidofovir or foscarnet. Resistance selection must use mutation-specific evidence, organ burden, prior exposure, and specialist interpretation.
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Lesson
Build a Safe Intravenous Ganciclovir System
Intravenous ganciclovir joins weight-based exposure, renal adjustment, hazardous preparation, one-hour infusion, marrow surveillance, and organ-specific response.
- Induction
- Maintenance
- Sterile water
- One-hour infusion
- CBC and kidneys
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Separate induction and maintenance
A common adult retinitis induction regimen is 5 mg per kg intravenously every 12 hours for 14 to 21 days before renal adjustment. Maintenance can use 5 mg per kg intravenously daily or oral valganciclovir after control when absorption and follow-up are reliable.
Reconstitute correctly
Reconstitute the vial with sterile water for injection without preservatives. Do not use bacteriostatic water containing parabens because precipitation can occur. Further dilute the calculated dose in a compatible infusion solution.
Infuse and handle safely
Administer at a constant rate over one hour. Do not give by rapid intravenous injection. Use gloves and the institution's hazardous-drug process for preparation, spills, skin or eye exposure, and disposal.
Monitor the whole exposure
Trend complete blood count with differential and platelets, creatinine clearance, urine output, infection, bleeding, neurologic state, and organ-specific response. Recalculate the regimen during acute kidney change rather than relying on an old baseline.
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Lesson
Convert Oral Valganciclovir to Ganciclovir Exposure
Valganciclovir is the L-valyl prodrug of ganciclovir, designed for useful oral exposure when food, absorption, renal function, and adherence are dependable.
- L-valyl prodrug
- Food
- Induction
- Maintenance
- Pediatric formula
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Use the prodrug intentionally
Valganciclovir is rapidly converted to ganciclovir. Oral ganciclovir bioavailability after valganciclovir is about 60 percent, and administration with food improves exposure. Oral convenience does not remove marrow or renal toxicity.
Dose active retinitis
A common adult regimen is 900 mg with food twice daily for 14 to 21 days, followed by 900 mg daily maintenance before renal adjustment. Intravenous ganciclovir is often preferred for central sight-threatening disease or unreliable gastrointestinal absorption.
Choose the dosage form
Adults generally use intact 450 mg tablets. The 50 mg per mL oral solution supports pediatric or swallowing needs and must be prepared and measured according to labeling. Do not crush or break hazardous tablets for routine administration.
Calculate pediatric prophylaxis
Labeled pediatric transplant prophylaxis uses 7 times body surface area times modified Schwartz creatinine clearance, with current caps and transplant-specific duration. Recalculate from current height, weight, and serum creatinine rather than extrapolating an adult dose.
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Lesson
Control Ganciclovir Exposure Toxicity
Ganciclovir exposure can injure marrow, kidney, reproductive systems, and developing tissue, while hazardous handling extends safety beyond the patient.
- Cytopenia
- Renal adjustment
- Fetal risk
- Fertility
- Hazardous handling
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Protect the marrow
Severe neutropenia, anemia, thrombocytopenia, and pancytopenia can occur. Trend counts frequently and review other myelosuppressants, active infection, renal accumulation, dose, and feasible alternatives before cytopenia becomes catastrophic.
Protect the kidney
Both products require current renal-function assessment and product-specific dose or interval adjustment. Hydration, dialysis, acute kidney injury, nephrotoxins, age, and rapidly changing creatinine can alter exposure.
Use current reproductive evidence
Current labeling warns of fetal toxicity, impaired fertility, mutagenesis, and carcinogenesis. Counsel pregnancy-capable patients and exposed partners using current contraception durations, fertility goals, pregnancy, and lactation evidence rather than obsolete letter categories.
Handle as hazardous
Avoid direct contact with broken tablets, powder, or oral solution. Use gloves and an appropriate measuring device, wash exposed skin or eyes promptly, and follow hazardous-waste procedures for spills and unused material.
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Lesson
Use Foscarnet Without Viral Activation
Foscarnet directly occupies the pyrophosphate site of viral DNA polymerase, bypassing UL97 while imposing major renal, electrolyte, neurologic, and cardiac risk.
- Pyrophosphate analogue
- No phosphorylation
- Hydration
- Electrolytes
- QT and seizure
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Bypass UL97
Foscarnet is a phosphonoformic-acid analogue that does not require intracellular phosphorylation. It directly blocks pyrophosphate exchange at viral DNA polymerase, which can preserve activity when UL97 activation is lost.
Deliver by renal function
Use the current weight and renal-function table, provide compatible hydration, and administer through an infusion pump no faster than the labeled maximum rate of 1 mg per kg per minute. Reassess as kidney function changes.
Control electrolyte injury
Foscarnet chelates divalent ions and can disturb ionized calcium, magnesium, potassium, and phosphate. Monitor symptoms, renal function, ECG, QT interval, and interacting medications, and correct abnormalities promptly.
Prevent additional harm
Seizure, torsades, sodium burden, infusion reactions, and genital ulceration can occur. Hygiene after urination reduces local exposure, while neurologic or cardiac symptoms require urgent evaluation.
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Lesson
Build the Complete Cidofovir Protection System
Cidofovir bypasses viral kinase but can cause acute proximal tubular injury after very limited exposure, making eligibility, probenecid, saline, and surveillance inseparable from the dose.
- Nucleotide phosphonate
- Weekly induction
- Probenecid
- Normal saline
- Renal exclusion
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Activate through host enzymes
Cidofovir is an acyclic nucleotide phosphonate converted by host enzymes to cidofovir diphosphate. It does not require pUL97 activation, but pUL54 polymerase mutations can still reduce activity.
Use the labeled sequence
For CMV retinitis, induction is 5 mg per kg intravenously once weekly for two weeks, followed by 5 mg per kg every other week before any required adjustment or exclusion. It is not a daily antiviral.
Block tubular uptake
Give probenecid 2 grams three hours before cidofovir, then 1 gram two hours and 1 gram eight hours after the infusion, for 4 grams total. Review sulfonamide hypersensitivity, oral tolerance, food, antiemetic support, and interactions.
Hydrate and verify eligibility
Give at least 1 liter of normal saline before each dose and consider a second liter after treatment when tolerated. Check creatinine, calculated clearance, urine protein, recent nephrotoxins, and fluid tolerance. Protective measures do not override labeled renal contraindications.
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Lesson
Prevent CMV with Letermovir
Letermovir inhibits the CMV terminase complex and is a prophylaxis agent for defined transplant populations, not a treatment for established end-organ disease.
- Terminase
- HSCT prophylaxis
- Kidney transplant
- Cyclosporine
- Interaction review
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Target DNA packaging
Letermovir inhibits the terminase complex involving pUL51, pUL56, and pUL89. The result is defective viral-DNA processing and packaging, a mechanism distinct from polymerase inhibition.
Use current indications
Current labeling includes prophylaxis for CMV-seropositive allogeneic stem-cell transplant recipients and high-risk donor-positive recipient-negative kidney-transplant recipients. Older RxPrep teaching that limited approval to HSCT is outdated.
Dose with cyclosporine
The usual adult dose is 480 mg once daily orally or intravenously. Reduce to 240 mg once daily with cyclosporine. Follow current age, weight, transplant-day, route, and duration instructions for pediatric and adult care.
Reconcile interactions
Review pimozide, ergot products, cyclosporine, tacrolimus, sirolimus, statins, and other CYP or transporter substrates. Some combinations are contraindicated, and immunosuppressant concentrations may require active monitoring.
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Lesson
Treat Refractory Post-Transplant CMV with Maribavir
Maribavir directly inhibits pUL97 and provides an oral option for eligible post-transplant CMV that is refractory to prior treatment, with or without genotypic resistance.
- pUL97 inhibitor
- Refractory CMV
- 400 mg twice daily
- Antagonism
- Drug interactions
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Inhibit pUL97 directly
Maribavir is a benzimidazole riboside that inhibits pUL97 kinase, disrupting viral DNA replication, encapsidation, and nuclear egress. This is distinct from ganciclovir, which needs pUL97 for activation.
Confirm eligibility
Current labeling covers post-transplant CMV infection or disease refractory to prior therapy in adults and adolescents age 12 or older who weigh at least 35 kg, with or without genotypic resistance.
Administer accurately
Give 400 mg orally twice daily with or without food before interaction modification. Tablets can be dispersed or crushed in water according to the label and delivered through an appropriate enteral tube. Review strong enzyme inducers before dosing.
Avoid antagonism
Do not combine maribavir with ganciclovir or valganciclovir because UL97 inhibition can impair ganciclovir phosphorylation. Monitor tacrolimus, cyclosporine, sirolimus, everolimus, digoxin, rosuvastatin, virologic response, relapse, and dysgeusia.
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Lesson
Match Therapy to CMV End-Organ Disease
Retinal, gastrointestinal, pulmonary, and neurologic CMV share antivirals but differ in urgency, route, local therapy, duration, maintenance, and evidence strength.
- Retinitis
- Sight threat
- GI disease
- Pneumonia
- Neurologic disease
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Protect vision
Peripheral retinitis can use systemic valganciclovir when absorption is reliable. Central sight-threatening lesions often favor intravenous ganciclovir plus weekly intravitreal ganciclovir or foscarnet during induction under ophthalmology care. Intravitreal cidofovir is contraindicated.
Treat the whole patient
Systemic therapy protects the other eye and reduces visceral disease, so intravitreal treatment does not replace it. Induction generally lasts 14 to 21 days until retinal activity is controlled, then maintenance begins.
Treat gastrointestinal disease
CMV colitis or esophagitis generally starts with intravenous ganciclovir. Mild disease or improving absorption can support oral valganciclovir. Treat for 21 to 42 days or until signs and symptoms resolve. Maintenance is not routine after uncomplicated resolution.
Escalate neurologic disease
NIH recommends intravenous ganciclovir plus foscarnet for CMV neurologic disease for at least 21 days based on response. The role of oral valganciclovir is not established. Proven pneumonia also requires prolonged systemic therapy and exclusion of more likely pulmonary pathogens.
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Lesson
Close the CMV Care Loop
Safe CMV care connects host, compartment, proof, treatment or prevention role, molecular target, exposure, toxicity, response, immune recovery, resistance, and follow-up ownership.
- Complete order
- Response
- Resistance
- Immune recovery
- Follow-up
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Verify the complete order
Confirm host, compartment, diagnostic evidence, treatment or prophylaxis goal, product, route, dose, interval, duration, weight, renal function, blood counts, electrolytes, interactions, pregnancy or lactation, administration, response target, and accountable follow-up.
Audit treatment failure
Review diagnosis, tissue compartment, viral kinetics, adherence, absorption, preparation, renal underexposure, immune status, source control, drug antagonism, resistance, and alternative disease before labeling failure as genetic resistance.
Stop maintenance safely
For CMV retinitis in HIV, consider stopping maintenance only after at least three months of treatment, inactive lesions, CD4 at least 100 for at least three months on ART, and ophthalmology agreement. Continue eye surveillance and restart if immune control is lost.
Use current evidence
This module supports education and structured verification. It does not replace patient-specific diagnosis, current labeling, current NIH guidance, transplant protocols, ophthalmology, infectious-disease consultation, or qualified prescribing.
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References
Current clinical foundation.
Lecture material was synthesized with the following contemporary guidance. Verify local policy and current guidance before applying clinical information.