Tizanidine, a muscle relaxant, can interact with several substances, potentially altering its effectiveness or increasing the risk of side effects. The most significant interactions involve drugs that inhibit or induce the cytochrome P450 1A2 (CYP1A2) enzyme system, which is responsible for metabolizing tizanidine [1].
What medications should be avoided with tizanidine?
Certain medications can significantly increase tizanidine levels in the body, leading to enhanced sedative effects and a higher risk of hypotension. These include:
* Fluvoxamine: An antidepressant that strongly inhibits CYP1A2 [2].
* Ciprofloxacin: An antibiotic also known for its potent CYP1A2 inhibition [2].
* Oral contraceptives: Contain estrogen and progestins, which can inhibit CYP1A2 and potentially increase tizanidine concentrations [3].
* Other CYP1A2 inhibitors: This category includes certain antiarrhythmics (e.g., amiodarone), other antibiotics (e.g., enoxacin), and other antidepressants (e.g., clomipramine, duloxetine) [2].
Taking tizanidine with these substances is generally not recommended, as it can lead to marked increases in tizanidine plasma levels and a greater likelihood of adverse events such as marked hypotension, bradycardia, and somnolence [2].
Can you drink alcohol while taking tizanidine?
Alcohol should be avoided or used with extreme caution when taking tizanidine. Both tizanidine and alcohol can cause drowsiness and dizziness. Combining them can intensify these effects, impairing your ability to drive or operate machinery safely [4].
What other drugs interact with tizanidine?
Besides CYP1A2 inhibitors, other drug interactions can occur:
* Alpha-2 adrenergic agonists: Tizanidine itself is an alpha-2 adrenergic agonist. Concomitant use with other drugs in this class may amplify their pharmacologic effects and is not recommended [1].
* Antihypertensive drugs: Tizanidine can enhance the blood-pressure-lowering effects of antihypertensive medications, potentially leading to significant hypotension [1].
* Central nervous system (CNS) depressants: When tizanidine is taken with other CNS depressants, such as sedatives, hypnotics, or other muscle relaxants, there may be an additive effect on CNS depression [1].
What happens if you take too much tizanidine?
Overdosing on tizanidine can lead to pronounced hypotension, somnolence, dizziness, and bradycardia. In severe cases, hallucinations and gastrointestinal upset have also been reported [1].
Sources:
1. https://www.drugpatentwatch.com/drug-interactions/tizanidine
2. https://www.ncbi.nlm.nih.gov/books/NBK518712/
3. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3000526/
4. https://www.drugs.com/interactions-check.php?drug_list=2285-0,940-0