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Pharmacology · Anti-herpesvirus agents

Valganciclovir !

The oral prodrug of ganciclovir. It prevents and treats cytomegalovirus (CMV) disease and can lower all blood cell counts.

Updated 2026-11-01

  • Class: Anti-herpesvirus agents
  • Enzyme: CMV DNA polymerase (through ganciclovir, activated by UL97)
  • ATC code: J05AB14
  • WHO Model List of Essential Medicines

The figure shows ganciclovir, the active form of valganciclovir, in herpes simplex virus 1 thymidine kinase; in CMV the activating kinase is UL97.

Target in 3D: CMV DNA polymerase (through ganciclovir, activated by UL97). PDB structure 1KI2 (RCSB PDB, public domain). View the structure at RCSB PDB

Mechanism of action

Valganciclovir is the L-valyl ester of ganciclovir. It is well absorbed and rapidly converted into ganciclovir, which is then phosphorylated by the CMV kinase UL97 and cellular kinases. Ganciclovir triphosphate inhibits the viral DNA polymerase and stops viral DNA synthesis.

  1. Absorbed and converted to ganciclovir
  2. CMV kinase UL97 adds the first phosphate
  3. Ganciclovir triphosphate inhibits the viral DNA polymerase
  4. CMV replication slows

Pharmacokinetics

Absorption
Well absorbed by mouth, better with food; it replaces intravenous ganciclovir in many patients
Metabolism
Rapidly hydrolysed to ganciclovir
Elimination
As ganciclovir, by the kidneys

Indications

Adverse effects

Common

  • Diarrhoea, nausea, vomiting and abdominal pain
  • Headache
  • Muscle or joint pain
  • Mouth ulcers

Contraindications

  • Hypersensitivity to valganciclovir or ganciclovir

Key interactions

Mycophenolate, zidovudine and other myelosuppressive drugs
Additive bone marrow suppression
Nephrotoxic drugs
Higher risk of kidney injury and higher ganciclovir levels

What is monitored

  • Complete blood count and platelets regularly
  • Serum creatinine
  • Regular eye examinations in CMV retinitis

Administration and safety

  • Oral, with food
  • Tablets are swallowed whole: never split, crushed or chewed
  • Broken tablets must not touch skin, eyes or mucous membranes; wash with soap and water if they do
  • Look-alike/sound-alike risk with valaciclovir, a much less toxic drug

Nursing care

  • Check the blood count before starting and as ordered
  • Teach to report fever, sore throat, bleeding or unusual tiredness
  • Handle tablets without crushing them
  • Teach contraception: women during and for 30 days after; men, condoms during and for 90 days after
  • Advise against breastfeeding during treatment

Pregnancy and breastfeeding

Avoided in pregnancy because of the risk of fetal harm; a pregnancy test is done before starting.

Test yourself

Think of the answer, then tap the question to see it.

What is valganciclovir converted into?

Ganciclovir.

Why must valganciclovir tablets not be crushed?

Ganciclovir is considered potentially carcinogenic and teratogenic; broken tablets must not contact skin or mucosa.

Which transplant patients receive valganciclovir to prevent CMV disease?

Heart, kidney and kidney-pancreas recipients at risk of CMV.

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Educational content on how drugs work; not a prescribing guide and no substitute for a health professional's advice. No doses are given.

Sources: Valganciclovir: MedlinePlus Drug Information (MedlinePlus (U.S. National Library of Medicine), 2026); ATCDDD - ATC/DDD Index (WHO Collaborating Centre for Drug Statistics Methodology, 2026); eEML - Electronic Essential Medicines List (World Health Organization, 2025); Goodman & Gilman's The Pharmacological Basis of Therapeutics, 14th ed., ch. 62 (McGraw Hill, 2023).

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Representative model, for educational purposes only.