Doxecitine-doxribtimine (dok-SEE-sih-teen – dok-RIB-tih-meen) is a potential treatment for thymidine kinase 2 deficiency (TK2D), a type of mitochondrial disease.
Doxecitine-doxribtimine
Pharmaceutical company: UCB Pharma
About the treatment
Mitochondria make energy to help our bodies do important things like move muscles and keep organs working. To work properly, mitochondria use their own DNA, called mitochondrial DNA (mtDNA). This DNA needs to make copies of itself to stay healthy – a process called replication. For replication to work, the body needs the right mix of DNA building blocks, called nucleotides.
In thymidine kinase 2 deficiency (TK2d), a change in a gene causes the body to make a faulty protein. This protein normally helps keep the right balance of DNA building blocks. Without it, mtDNA can’t copy itself properly, and mitochondria can’t make enough energy.
Doxecitine-doxribtimine provides the body with extra molecules (called nucleosides) that help make those DNA building blocks. This helps support how mtDNA copies itself, so mitochondria can make more energy. That may help muscles and other parts of the body work better.
Doxecitine-doxribtimine comes as a powder that can be mixed into a liquid and taken by mouth or through a feeding tube.
Can I (or my child) get access now?
The treatment is currently only available through clinical trials in the UK.
Current status
| Can it be prescribed in the UK? | No, doxecitine-doxribtimine is not currently licensed in the UK |
| Is it available through the NHS? | Not available through the NHS in the UK |
UCB began the process which determines if doxecitine-doxribtimine can be prescribed on the NHS in England in 2025. In November, they announced a temporary pause in this process. We are in contact with UCB and will update the community as soon as we have more information.
What happens next?
The Medicines and Healthcare products Regulatory Agency (MHRA) will review the submission for doxecitine-doxribtimine and decide whether it should be allowed to be prescribed by doctors in the UK.
The National Institute for Health and Care Excellence (NICE) will also assess the treatment. If recommended, doxecitine-doxribtimine will be available on the NHS in England, Wales and Northern Ireland.
There currently isn’t a timeline for the assessment by the Scottish Medicines Consortium for use on the NHS in Scotland.
Our involvement
We are working in partnership with the charities Metabolic Support UK and the Lily Foundation to make sure the experience and views of people affected by TK2D are heard throughout the NICE assessment process.
Clinical trial results
The company making the drug, UCB, is expecting to publish the clinical trial data at the end of 2025 or in early 2026.
Last updated: 26/11/2025
Support and information
Mitochondrial disease
Thymidine kinase 2 deficiency is a type of mitochondrial disease. These conditions are caused by genetic changes in the mitochondria, which produce energy needed to power cells.
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