Is it safe for a patient taking baclofen (20 milligrams, four times a day) to also use tizanidine (2-4 milligrams) for persistent muscle spasms?

From the Guidelines

It is not recommended to combine baclofen 20 mg four times daily with tizanidine 2-4 mg without medical supervision due to the increased risk of central nervous system depression and other adverse effects. Both medications are muscle relaxants that work through different mechanisms but can cause additive sedation, dizziness, confusion, weakness, and potentially dangerous respiratory depression when used together [ 1 ]. The patient is already on a high dose of baclofen (80 mg daily), and adding tizanidine could create safety concerns, such as significant hypotension, bradycardia, and sedation, especially in patients with hepatic or renal dysfunction and in elderly patients [ 1 ].

Key Considerations

• The combination of baclofen and tizanidine can increase the risk of adverse effects, including excessive sedation, dizziness, and respiratory depression.
• Tizanidine clearance is significantly reduced when given concomitantly with certain medications, such as ciprofloxacin and fluvoxamine, and is contraindicated in these cases [ 1 ].
• Alternative approaches, such as physical therapy, heat/cold therapy, or other non-pharmacological interventions, might be beneficial for managing persistent muscle spasms without increasing medication risks [ 1 ].

Recommendations

• The patient should consult their healthcare provider about their continuing muscle spasms to discuss alternative treatment options.
• The provider might adjust the baclofen dosage, switch to a different medication entirely, or carefully supervise a combination therapy if deemed appropriate.
• Close monitoring of the patient's vital signs, sedation levels, and muscle spasm severity is necessary if combination therapy is initiated.

From the FDA Drug Label

DOSAGE AND ADMINISTRATION A single oral dose of 8 mg of tizanidine reduces muscle tone in patients with spasticity for a period of several hours. The effect peaks at approximately 1 to 2 hours and dissipates between 3 to 6 hours. Effects are dose-related Although single doses of less than 8 mg have not been demonstrated to be effective in controlled clinical studies, the dose-related nature of tizanidine’s common adverse events make it prudent to begin treatment with single oral doses of 4 mg. The patient is taking baclofen (20 milligrams, four times a day) and wants to use tizanidine (2-4 milligrams) for persistent muscle spasms.

• The tizanidine dose of 2-4 milligrams is within the recommended starting dose.
• However, there is no information about the interaction between baclofen and tizanidine in the provided drug label.
• The label does mention that tizanidine has dose-related common adverse events, and the dose should be increased gradually.
• Since there is no direct information about the safety of using tizanidine with baclofen, a conservative clinical decision would be to exercise caution and consider potential interactions or increased risk of adverse events.
• The FDA label for tizanidine 2 does not provide direct information to support the safety of this combination.

From the Research

Safety of Combining Baclofen and Tizanidine

• The safety of combining baclofen (20 milligrams, four times a day) with tizanidine (2-4 milligrams) for persistent muscle spasms is not directly addressed in the provided studies.
• However, studies have compared the efficacy and tolerability of baclofen and tizanidine as individual treatments for spasticity 3, 4.
• Baclofen and tizanidine have been found to have equivalent efficacy in reducing spasticity, but tizanidine has a more favorable tolerability profile, with less frequent reports of weakness 3, 4.
• The most common adverse effects associated with tizanidine are dry mouth and somnolence/drowsiness, while baclofen is associated with sedation, weakness, vertigo, and psychological disturbances 3, 4.

Potential Interactions and Risks

• There is limited information on the potential interactions between baclofen and tizanidine, but both drugs can cause sedation and somnolence, which may be additive when used together 3, 4.
• The risk of adverse effects, such as excessive weakness, vertigo, and psychological disturbances, may also be increased when combining these drugs 3.
• Patients with renal disease may be at increased risk of adverse effects from baclofen, and the use of tizanidine in these patients should be carefully considered 3.

Clinical Considerations

• The choice of skeletal muscle relaxant, including baclofen and tizanidine, should be based on its adverse-effect profile, tolerability, and cost 5.
• Pharmacotherapy for spasticity should be tailored to the individual patient, and both patient and caregiver should have realistic expectations 6.
• Treatment should be initiated at low dosages and gradually increased to avoid adverse effects, with the goal of finding the lowest effective dosage 6.