Drug interactions
Isoniazid + Tranylcypromine
Severity: Major
Isoniazid and Tranylcypromine: 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
Isoniazid has weak monoamine oxidase inhibitory activity, and tranylcypromine is a potent nonselective MAO inhibitor. Combining them may add to MAO inhibition and increase the risk of hypertensive reactions and, theoretically, serotonin toxicity. Reports of serious events with isoniazid are limited, but the consequences could be severe.
What this interaction means in plain words
Isoniazid and Tranylcypromine 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.
Isoniazid belongs to Anti Bacterial; Tranylcypromine belongs to Central Nervous System.
Why it happens
Additive inhibition of monoamine oxidase by isoniazid and tranylcypromine.
What to do
Avoid the combination if an alternative is possible. If both are essential, monitor blood pressure and for signs of serotonin toxicity such as agitation, tremor, hyperthermia and clonus, and advise the patient to avoid tyramine-rich foods.
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
Other interactions of Isoniazid
Other interactions of Tranylcypromine
- 5-HTP + Tranylcypromine Contraindicated
- Amitriptyline + Tranylcypromine Contraindicated
- Amoxapine + Tranylcypromine Contraindicated
- Atomoxetine + Tranylcypromine Contraindicated
- Benzphetamine + Tranylcypromine Contraindicated
- Brimonidine + Tranylcypromine Contraindicated
Frequently asked questions
Can I take Isoniazid with Tranylcypromine?
MediHelp rates the interaction as major. Isoniazid and Tranylcypromine 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. Isoniazid has weak monoamine oxidase inhibitory activity, and tranylcypromine is a potent nonselective MAO inhibitor. Combining them may add to MAO inhibition and increase the risk of hypertensive reactions and, theoretically, serotonin toxicity. Reports of serious events with isoniazid are limited, but the consequences could be severe.
How serious is the interaction between Isoniazid and Tranylcypromine?
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 an alternative is possible. If both are essential, monitor blood pressure and for signs of serotonin toxicity such as agitation, tremor, hyperthermia and clonus, and advise the patient to avoid tyramine-rich foods.
What other medicines interact with Isoniazid?
MediHelp also lists interactions of Isoniazid with, for example, Bacillus calmette-guerin substrain tice, Benzhydrocodone / acetaminophen, Carbamazepine. The full list is on the Isoniazid page.
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