Drug interactions
Calcitriol + Primidone
Severity: Moderate
Calcitriol 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, through its active metabolite phenobarbital, induces hepatic enzymes and can accelerate the breakdown of vitamin D compounds. This may reduce calcitriol exposure and its effect on calcium homeostasis, with a risk of hypocalcemia or bone loss over time.
What this interaction means in plain words
Calcitriol 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.
Calcitriol belongs to Musculoskeletal; Primidone belongs to Central Nervous System.
Why it happens
Enzyme induction (CYP3A4 and related pathways) by primidone/phenobarbital increases calcitriol catabolism.
What to do
Monitor serum calcium, phosphate and PTH after starting or stopping primidone. Increase the calcitriol dose if hypocalcemia or inadequate response occurs.
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 Calcitriol
- Amlodipine-hydrochlorothiazide-valsartan + Calcitriol Moderate
- Amlodipine-olmesartan-hydrochlorothiazide + Calcitriol Moderate
- Amobarbital + Calcitriol Moderate
- Apalutamide + Calcitriol Moderate
- Atazanavir + Calcitriol Moderate
- Atenolol-chlorthalidone + Calcitriol Moderate
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 Calcitriol with Primidone?
MediHelp rates the interaction as moderate. Calcitriol 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, through its active metabolite phenobarbital, induces hepatic enzymes and can accelerate the breakdown of vitamin D compounds. This may reduce calcitriol exposure and its effect on calcium homeostasis, with a risk of hypocalcemia or bone loss over time.
How serious is the interaction between Calcitriol 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 serum calcium, phosphate and PTH after starting or stopping primidone. Increase the calcitriol dose if hypocalcemia or inadequate response occurs.
What other medicines interact with Calcitriol?
MediHelp also lists interactions of Calcitriol with, for example, Amlodipine-hydrochlorothiazide-valsartan, Amlodipine-olmesartan-hydrochlorothiazide, Amobarbital. The full list is on the Calcitriol page.
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