Drug interactions
Dolutegravir + Fosphenytoin
Severity: Major
Dolutegravir and Fosphenytoin: major interaction.
Last updated
For healthcare professionals — reference only. This page is a brief summary, not medical advice and not a substitute for official labeling or clinical judgement. Always verify before prescribing or dispensing.
Summary
Fosphenytoin is converted to phenytoin, which lowers dolutegravir concentrations considerably. This risks loss of virologic control and resistance.
What this interaction means in plain words
Dolutegravir and Fosphenytoin can interact in a way that may be serious. Using them together is sometimes necessary, but it needs a deliberate decision by the prescriber, a plan for monitoring, and clear advice on the warning signs to watch for.
Dolutegravir belongs to Anti Virals; Fosphenytoin belongs to Central Nervous System.
Why it happens
Phenytoin strongly induces UGT1A1 and CYP3A4, accelerating dolutegravir metabolism.
What to do
Avoid the combination and use a non-inducing anticonvulsant such as levetiracetam. If it cannot be avoided, consult HIV specialists and monitor viral load.
What to ask your pharmacist
- Does the benefit of taking both outweigh the risk in my case?
- Do I need any blood test, ECG or other check while on both?
- What early warning signs should I watch for, and what should I do if they appear?
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Other interactions of Dolutegravir
Other interactions of Fosphenytoin
- Dronedarone + Fosphenytoin Contraindicated
- Fosphenytoin + Ledipasvir-sofosbuvir Contraindicated
- Fosphenytoin + Lorlatinib Contraindicated
- Fosphenytoin + Lurasidone Contraindicated
- Fosphenytoin + Ranolazine Contraindicated
- Fosphenytoin + Sofosbuvir-velpatasvir-voxilaprevir Contraindicated
Frequently asked questions
Can I take Dolutegravir with Fosphenytoin?
MediHelp rates the interaction as major. Dolutegravir and Fosphenytoin can interact in a way that may be serious. Using them together is sometimes necessary, but it needs a deliberate decision by the prescriber, a plan for monitoring, and clear advice on the warning signs to watch for. Fosphenytoin is converted to phenytoin, which lowers dolutegravir concentrations considerably. This risks loss of virologic control and resistance.
How serious is the interaction between Dolutegravir and Fosphenytoin?
MediHelp rates it major, on a four-level scale (minor, moderate, major, contraindicated) based on published labels and references. What to do, in brief: Avoid the combination and use a non-inducing anticonvulsant such as levetiracetam. If it cannot be avoided, consult HIV specialists and monitor viral load.
What other medicines interact with Dolutegravir?
MediHelp also lists interactions of Dolutegravir with, for example, Dofetilide, Aluminum hydroxide, Atidarsagene autotemcel. The full list is on the Dolutegravir page.
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