Drug interactions
Clozapine + Hydroxycarbamide
Severity: Major
Clozapine and Hydroxycarbamide: major interaction.
Last updated Sources: UK SmPC
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
Both drugs can suppress bone marrow, and clozapine carries a risk of severe neutropenia and agranulocytosis. Hydroxyurea may amplify this risk and complicate attribution of falls in blood counts.
What this interaction means in plain words
Clozapine and Hydroxycarbamide 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.
Clozapine belongs to Central Nervous System; Hydroxycarbamide belongs to Oncology.
Why it happens
Additive myelosuppression.
What to do
Avoid the combination if possible, and otherwise monitor full blood counts including neutrophils frequently. Stop or interrupt treatment according to neutrophil thresholds in clozapine monitoring protocols.
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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References
- Clozapine Viatris 100 mg Orodispersible Tablets - SmPC sections 4.3/4.5 (class statement: cytotoxic agents; "Bone marrow suppressants (e.g. carbamazapine, chloramphenicol), sulphonamides (e.g. co-trimoxazole), pyrazolone analgesics (e.g. phenylbutazone), penicillamine,") — electronic medicines compendium (UK SmPC)
Other interactions of Clozapine
- Clozapine + Deferiprone Contraindicated
- Clozapine + Irinotecan Contraindicated
- Clozapine + Pimozide Contraindicated
- Clozapine + Thioridazine Contraindicated
- Acalabrutinib + Clozapine Major
- Adagrasib + Clozapine Major
Other interactions of Hydroxycarbamide
- Didanosine + Hydroxycarbamide Contraindicated
- Hydroxycarbamide + Stavudine Contraindicated
- Adenovirus types 4 and 7 live + Hydroxycarbamide Major
- Axicabtagene ciloleucel + Hydroxycarbamide Major
- Bcg intravesical live + Hydroxycarbamide Major
- Bcg vaccine live + Hydroxycarbamide Major
Frequently asked questions
Can I take Clozapine with Hydroxycarbamide?
MediHelp rates the interaction as major. Clozapine and Hydroxycarbamide 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. Both drugs can suppress bone marrow, and clozapine carries a risk of severe neutropenia and agranulocytosis. Hydroxyurea may amplify this risk and complicate attribution of falls in blood counts.
How serious is the interaction between Clozapine and Hydroxycarbamide?
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 if possible, and otherwise monitor full blood counts including neutrophils frequently. Stop or interrupt treatment according to neutrophil thresholds in clozapine monitoring protocols.
What other medicines interact with Clozapine?
MediHelp also lists interactions of Clozapine with, for example, Deferiprone, Irinotecan, Pimozide. The full list is on the Clozapine page.
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