Drug interactions
Hydrochlorothiazide-losartan + Primidone
Severity: Moderate
Hydrochlorothiazide-losartan and Primidone: moderate 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
Primidone and its metabolite phenobarbital induce CYP3A4 and CYP2C9, which may reduce conversion of losartan to its active metabolite and lower its plasma levels. This can weaken blood pressure control.
What this interaction means in plain words
Hydrochlorothiazide-losartan and Primidone can affect each other. The combination is often manageable, but it may need a change of dose, a change of timing, or extra checks while both are taken.
Hydrochlorothiazide-losartan belongs to Cardiovascular; Primidone belongs to Central Nervous System.
Why it happens
Hepatic enzyme induction by primidone and phenobarbital increases the clearance of losartan.
What to do
Monitor blood pressure when primidone is started, changed, or stopped, and increase the antihypertensive dose or add another agent if needed.
What to ask your pharmacist
- Should I take them at different times of day?
- Does the dose of either medicine need to change?
- Is there anything I should avoid, such as alcohol or certain foods, while on both?
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Other interactions of Hydrochlorothiazide-losartan
- Aliskiren + Hydrochlorothiazide-losartan Contraindicated
- Dofetilide + Hydrochlorothiazide-losartan Contraindicated
- Hydrochlorothiazide-losartan + Sparsentan Contraindicated
- Aceclofenac + Hydrochlorothiazide-losartan Major
- Aldesleukin + Hydrochlorothiazide-losartan Major
- Amifostine + Hydrochlorothiazide-losartan Major
Other interactions of Primidone
- Lorlatinib + Primidone Contraindicated
- Lurasidone + Primidone Contraindicated
- Primidone + Ranolazine Contraindicated
- Primidone + Sofosbuvir-velpatasvir-voxilaprevir Contraindicated
- Primidone + Voriconazole Contraindicated
- Abiraterone + Primidone Major
Frequently asked questions
Can I take Hydrochlorothiazide-losartan with Primidone?
MediHelp rates the interaction as moderate. Hydrochlorothiazide-losartan and Primidone can affect each other. The combination is often manageable, but it may need a change of dose, a change of timing, or extra checks while both are taken. Primidone and its metabolite phenobarbital induce CYP3A4 and CYP2C9, which may reduce conversion of losartan to its active metabolite and lower its plasma levels. This can weaken blood pressure control.
How serious is the interaction between Hydrochlorothiazide-losartan and Primidone?
MediHelp rates it moderate, on a four-level scale (minor, moderate, major, contraindicated) based on published labels and references. What to do, in brief: Monitor blood pressure when primidone is started, changed, or stopped, and increase the antihypertensive dose or add another agent if needed.
What other medicines interact with Hydrochlorothiazide-losartan?
MediHelp also lists interactions of Hydrochlorothiazide-losartan with, for example, Aliskiren, Dofetilide, Sparsentan. The full list is on the Hydrochlorothiazide-losartan page.
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