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# Histone deacetylase (HDAC) inhibitors

Epigenetic drugs that block histone deacetylases, reopening silenced genes; vorinostat and romidepsin treat cutaneous T-cell lymphoma.

Updated Nov 1, 2026

## What they are

Histone deacetylases remove acetyl groups from histones and other proteins, compacting chromatin and silencing genes, including tumour suppressors. HDAC inhibitors reverse this. Vorinostat (oral) and romidepsin (intravenous) are used in cutaneous T-cell lymphoma; panobinostat and belinostat in other blood cancers.

## Mechanism of action

They bind the zinc ion in the active site of HDACs. Acetylated histones and transcription factors accumulate, chromatin opens and genes that stop the cell cycle or trigger differentiation and apoptosis are expressed again.

Target: Histone deacetylases (zinc-dependent enzymes)

## Key points

- Main indication to remember: cutaneous T-cell lymphoma (mycosis fungoides, Sézary syndrome).
- Common: nausea, vomiting, diarrhoea, fatigue, thrombocytopenia.
- ECG changes and QT prolongation: potassium and magnesium are checked before and during treatment.
- Vorinostat: dehydration, hyperglycaemia and blood clots; romidepsin: metabolised by CYP3A4 and can make oestrogen contraceptives fail.

## Drugs in this class

- [**Vorinostat** Oral histone deacetylase inhibitor for cutaneous T-cell lymphoma. Watch for dehydration, high blood sugar, low… Histone deacetylases (class I HDAC1, 2 and 3, and HDAC6)](https://durgical.com/en/pharmacology/vorinostat/)
- [**Romidepsin** Intravenous HDAC inhibitor, a natural prodrug from a bacterium, for cutaneous T-cell lymphoma. Watch ECG… Histone deacetylases (zinc-dependent enzymes)](https://durgical.com/en/pharmacology/romidepsin/)

## Others in the class

- panobinostat
- belinostat

## Test yourself

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

## What does an HDAC inhibitor do to chromatin?

It keeps histones acetylated, so chromatin stays open and silenced genes can be expressed.

## Which lymphoma do vorinostat and romidepsin treat?

Cutaneous T-cell lymphoma.

## Which electrolytes are checked before an HDAC inhibitor and why?

Potassium and magnesium, because these drugs can cause ECG changes and QT prolongation.

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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: [Vorinostat: MedlinePlus Drug Information](https://medlineplus.gov/druginfo/meds/a607050.html) (MedlinePlus (U.S. National Library of Medicine), 2026); [Romidepsin Injection: MedlinePlus Drug Information](https://medlineplus.gov/druginfo/meds/a610005.html) (MedlinePlus (U.S. National Library of Medicine), 2026); [ATCDDD - ATC/DDD Index](https://atcddd.fhi.no/atc_ddd_index/?code=L01XH) (WHO Collaborating Centre for Drug Statistics Methodology, 2026).

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Representative model, for educational purposes only.

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Source: https://durgical.com/en/pharmacology/classes/histone-deacetylase-inhibitors/
License: CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/). Cite as: DurgiPedia (durgical.com), https://durgical.com/en/pharmacology/classes/histone-deacetylase-inhibitors/