Vorinostat

Pronunciation: pronunciation varies by local usage.

Generic name
vorinostat
Brand names
ZOLINZA
Drug class
Histone deacetylase (HDAC) inhibitor
Form
Capsule
Route
Oral
Legal status
Prescription-only medicine

Availability and supply rules vary by country

Trade names by country: United States · Canada

Australia: · Full directory

What vorinostat is and how it works

Vorinostat is an oral histone deacetylase (HDAC) inhibitor that blocks Class I and Class II HDAC enzymes, promoting chromatin acetylation and altering gene transcription in cancer cells. It is used to treat cutaneous manifestations of cutaneous T-cell lymphoma (CTCL). (1)

Vorinostat is indicated for patients with CTCL whose disease is progressive, persistent, or recurrent on or following two systemic therapies. It is an oral oncology treatment that requires regular blood monitoring and specialist supervision. The information in this draft is based on the United States prescribing information; regulatory details for other regions have not been reviewed in this pass.

Mechanism of action: how vorinostat works

Vorinostat is a histone deacetylase (HDAC) inhibitor. It inhibits the enzymatic activity of Class I HDAC enzymes (HDAC1, HDAC2, and HDAC3) and the Class II enzyme HDAC6 at nanomolar concentrations, leading to increased histone acetylation, chromatin remodelling, and altered gene transcription that can induce cell-cycle arrest and apoptosis in cancer cells. (1)

What vorinostat is used for

Cutaneous T-cell lymphoma (CTCL)

Vorinostat is indicated for the treatment of cutaneous manifestations in patients with cutaneous T-cell lymphoma who have progressive, persistent, or recurrent disease on or following two systemic therapies. (1)

Before taking vorinostat

Do not take / not appropriate for

  • The current US prescribing information reviewed does not list specific contraindications. Treatment decisions must be made by the responsible oncologist based on the patient's full clinical picture. (all products) (1)

Tell your clinician about

  • Any personal history of thromboembolic disease (such as blood clots in the lung or deep veins).
  • History of anaemia, bleeding problems, or low platelet counts.
  • If you are taking valproic acid or any other HDAC inhibitor.
  • If you are taking warfarin or any other coumarin-derivative anticoagulant (blood thinner).
  • If you have liver problems, diabetes, or a history of high blood sugar.
  • If you have heart problems or a history of abnormal heart rhythms (QT prolongation).
  • If you are pregnant, planning pregnancy, or breastfeeding.
(1)

How to take vorinostat

  • Take vorinostat capsules orally once daily with food, exactly as prescribed by your oncologist.
  • The standard starting dose is 400 mg once daily. Your doctor may reduce the dose to 300 mg once daily or alter the schedule to 300 mg once daily for five days per week if you experience side effects.
  • Swallow capsules whole. Do not open, crush, or chew them.
  • If a capsule is accidentally opened, avoid direct contact of the powder with your skin or mucous membranes.
  • Do not change the dose, schedule, number of capsules, or stop treatment yourself without discussing with your oncology team first.
(1)

Procedures and treatment changes

Tell the treating team before surgery, procedures, or any medicine change. Do not alter treatment without the responsible clinician. (1)

Missed dose

If a dose is missed, contact your prescribing oncology team or pharmacist for advice rather than deciding on your own whether to take it, skip it, or adjust your schedule.

Overdose

There is no specific antidote for vorinostat overdose. Management involves supportive care and gastrointestinal decontamination if clinically appropriate. It is not known whether vorinostat can be removed by dialysis. Seek immediate emergency medical care or contact a poison-information service if you suspect an overdose. (1)

Side effects

Side effects are common during vorinostat treatment. Many are manageable with dose adjustments or supportive medications, but some can be serious and require close monitoring.

Diarrhoea

What to notice: Frequent, loose, or watery stools.

What to do: Report to your treatment team. They may recommend antidiarrheal medications and fluids to prevent dehydration. (1)

Fatigue and nausea

What to notice: Unusual tiredness, lack of energy, or feeling sick.

What to do: Discuss persistent or troublesome symptoms with your oncologist. Antiemetic treatment may be prescribed for nausea. (1)

Taste disturbance (dysgeusia) and loss of appetite (anorexia)

What to notice: Changes in the way food tastes or reduced appetite.

What to do: Discuss nutritional support strategies with your care team. (1)

Low platelet count (thrombocytopenia)

What to notice: Increased bruising, bleeding gums, or tiny red spots on the skin.

What to do: This is detected through routine blood tests. Report any unusual bleeding or bruising promptly. (1)

Signs of a blood clot (thromboembolism)

What to notice: Specific symptom detail was not established in the sources reviewed for this article; the sources support that pulmonary embolism and deep vein thrombosis have been reported.

What to do: Report to your oncology team immediately or seek urgent medical assessment. (1)

Severe high blood sugar (hyperglycemia)

What to notice: Specific symptom detail was not established in the sources reviewed for this article; severe hyperglycemia has been reported in about 5% of patients in clinical trials.

What to do: Report any symptoms of concern to your care team. Blood sugar levels will be monitored regularly during treatment. (1)

Severe anaemia

What to notice: Specific symptom detail was not established in the sources reviewed for this article; anaemia is a documented adverse reaction (reported in about 2.3% of patients as a serious adverse reaction in clinical trials).

What to do: Contact your oncology team for assessment; blood counts are monitored regularly. (1)

Serious warnings

Thromboembolism (blood clots) — high_priority

Symptoms: Specific symptom detail was not established in the sources reviewed for this article; the sources support that pulmonary embolism and deep vein thrombosis have been reported.

Action: Seek emergency medical attention immediately. Pulmonary embolism was reported in about 5% of patients in clinical trials, and deep vein thrombosis has also been reported. (1)

Severe thrombocytopenia and gastrointestinal bleeding with concurrent HDAC inhibitor use — high_priority

Symptoms: Specific symptom detail was not established in the sources reviewed for this article; the sources support a general risk of severe thrombocytopenia and gastrointestinal bleeding, particularly with concurrent use of other HDAC inhibitors such as valproic acid.

Action: Seek urgent medical assessment if you notice unusual bleeding or bruising. Platelet counts must be monitored more frequently during concurrent use. (1)

Squamous cell carcinoma of the skin — high_priority

Symptoms: Specific symptom detail was not established in the sources reviewed for this article; squamous cell carcinoma of the skin was reported as a serious adverse reaction in about 3.5% of patients in clinical trials.

Action: Report any new or changing skin lesions to your oncology team for assessment. Whether and how this reported risk affects your individual treatment should be discussed with your treating clinician. (1)

Interactions

Medicine or testEffectAction
Other HDAC inhibitors (e.g., valproic acid)Concurrent use has been associated with severe thrombocytopenia and gastrointestinal bleeding.Inform your oncologist if you are taking valproic acid or any other HDAC inhibitor. Platelet counts should be monitored every 2 weeks with concurrent use. (1)
Coumarin-derivative anticoagulants (e.g., warfarin)Vorinostat may prolong prothrombin time and INR in patients taking warfarin or other coumarin anticoagulants.Prothrombin time and INR should be monitored more frequently. Ensure your oncologist and the clinician managing your anticoagulation are aware of all medicines. (1)

Pregnancy, breastfeeding, kidney/liver function, age

Hepatic impairment (liver problems)

For patients with mild-to-moderate hepatic impairment, the vorinostat dose is reduced to 300 mg once daily. There is insufficient data in the current US label to recommend a dose for patients with severe hepatic impairment. (1)

Renal impairment (kidney problems)

No specific dose adjustment for renal impairment was extracted from the reviewed US prescribing information. Your oncologist will make a treatment decision based on your individual circumstances. (1)

Pregnancy and reproductive potential

Vorinostat can cause fetal harm. Females of reproductive potential should use effective contraception during treatment and for 6 months after the final dose. Males with female partners of reproductive potential should use effective contraception during treatment and for 3 months after the final dose. (1)

Breastfeeding

Breastfeeding should be avoided during treatment and for 1 week after the final dose. (1)

Children

No pediatric dosing information was extracted from the reviewed US prescribing information. Treatment of pediatric patients must be managed by a specialist based on individual risk-benefit assessment. (1)

Monitoring

Before starting

  • Confirm the diagnosis of progressive, persistent, or recurrent cutaneous T-cell lymphoma on or following two systemic therapies.
  • Specific baseline (pre-treatment) laboratory testing and pregnancy-status confirmation requirements were not established in the sources reviewed for this article beyond the ongoing monitoring schedule described below; these should be confirmed with the treating oncology team.
  • Review personal history of thromboembolic disease and bleeding disorders.
  • Review all concurrent medications, specifically HDAC inhibitors (valproic acid) and coumarin anticoagulants (warfarin).

During treatment

  • Complete blood counts, serum chemistry panel (including electrolytes, creatinine, magnesium, and calcium), and blood glucose every 2 weeks for the first 2 months of treatment, then monthly.
  • Monitor platelet counts every 2 weeks if vorinostat is used concurrently with other HDAC inhibitors such as valproic acid.
  • Monitor prothrombin time and INR more frequently if vorinostat is co-administered with warfarin or other coumarin anticoagulants.
  • Assess patients with a prior history of thromboembolic disease for signs and symptoms of pulmonary embolism and deep vein thrombosis.
  • ECG monitoring as clinically indicated; the reviewed label does not provide a detailed routine ECG-monitoring protocol beyond this general recommendation.
  • Monitor for gastrointestinal toxicity (nausea, vomiting, diarrhoea) and intervene with supportive care to prevent dehydration.
(1)

Storage

Specific storage instructions for vorinostat capsules were not established in the sources reviewed for this article. Follow the instructions on the pharmacy packaging, and consult the dispensing pharmacy or prescriber if clarification is needed.

Professional information

Clinician-facing context only. This draft reflects the US FDA-approved ZOLINZA label accessed via DailyMed in August 2026. Regional labels outside the United States have not been reviewed for this pass. Always use the current local prescribing information and applicable clinical guidelines for CTCL.

United States (FDA)

Indication: Cutaneous T-cell lymphoma (progressive, persistent, or recurrent disease on or following two systemic therapies)

Dose summary: Standard dose: 400 mg orally once daily with food. Reduced/intolerance dosing: 300 mg orally once daily with food. Alternative reduced schedule: 300 mg once daily for 5 consecutive days each week. Mild-to-moderate hepatic impairment: reduce to 300 mg once daily. Severe hepatic impairment: insufficient data for dose recommendation.

Renal context: No renal-impairment-specific dose adjustment was described in the reviewed US label. Treatment decisions in renal impairment require individual clinician assessment. (1)

European Union, United Kingdom, Australia, Canada

Indication: Cutaneous T-cell lymphoma

Dose summary: Regulatory labels for these regions were not reviewed in this research pass. A gap remains for EU/UK (SmPC), Australian (TGA), and Canadian dosing information.

Renal context: A gap remains; labels for these regions were not reviewed.

Mechanism of action

Hepatic guidance

For mild-to-moderate hepatic impairment, the dose is reduced to 300 mg once daily per the US label. No dosing recommendation is available for severe hepatic impairment.

Overdose note

No specific antidote is described. Management consists of supportive care and gastrointestinal decontamination where clinically appropriate. The dialyzability of vorinostat is unknown. Medication errors require product identification, dose reconstruction, and specialist oncology advice. (1)

Frequently asked questions

Can I open the vorinostat capsule and sprinkle it on food if I have trouble swallowing?

No. Vorinostat capsules must be swallowed whole and should not be opened, crushed, or chewed. If a capsule is accidentally opened, avoid direct contact of the powder with your skin or mucous membranes. (1)

What should I do if I miss a dose?

Contact your prescribing oncology team or pharmacist for advice. Do not decide on your own whether to take, skip, or double up a missed dose. (1)

Can vorinostat cause blood clots?

Yes. Pulmonary embolism (a blood clot in the lung) was reported in about 5% of patients in clinical studies, and deep vein thrombosis has also been reported. Inform your oncologist if you have a personal history of blood clots. Specific symptom detail was not established in the sources reviewed for this article; seek emergency care promptly for any symptoms that concern you. (1)

What is the mechanism of action of vorinostat?

Vorinostat is a histone deacetylase (HDAC) inhibitor. It inhibits the enzymatic activity of Class I HDAC enzymes (HDAC1, HDAC2, and HDAC3) and the Class II enzyme HDAC6 at nanomolar concentrations, leading to increased histone acetylation, chromatin remodelling, and altered gene transcription that can induce cell-cycle arrest and apoptosis in cancer cells. (1)

What is the generic name of Vorinostat?

The generic name is vorinostat. It is sold under brand names including ZOLINZA. (1)

What class of drug is vorinostat?

Vorinostat is classed as: Histone deacetylase (HDAC) inhibitor. (1)

References

  1. ZOLINZA - vorinostat capsule (prescribing information)U.S. National Library of Medicine, DailyMed · United States · dated not extracted in this pass · accessed 2026-08-05 · source 1
  2. ZOLINZA (VORINOSTAT) CAPSULE [MERCK SHARP & DOHME LLC] — US prescribing information (DailyMed SPL)U.S. National Library of Medicine (DailyMed) · US · accessed 2026-08-14 · source 2
  3. Vorinostat — patient drug information (MedlinePlus)U.S. National Library of Medicine (MedlinePlus) · US · accessed 2026-08-14 · source 3
  4. ZOLINZA — FDA approval record (Drugs@FDA NDA021991)U.S. Food and Drug Administration · US · accessed 2026-08-14 · source 4
  5. vorinostat — RxNorm normalized drug concept (RXCUI 194337)U.S. National Library of Medicine (RxNorm) · US · accessed 2026-08-14 · source 5

Brand names by country

Single-ingredient vorinostat names are shown separately by country. Product availability, strengths, and supply rules can change; combination products are not included here.

Priority countries

United States

  • ZOLINZA100 mg · merck sharp & dohme llc

Canada

  • ZOLINZA
View brands in additional countries.