What muscle relaxers are better for a patient with hypotension?

From the Guidelines

For patients with hypotension, benzodiazepines are a better choice as a muscle relaxer due to their minimal reductions in blood pressure and safer hemodynamic profile compared to other agents like propofol and dexmedetomidine. When considering muscle relaxants for patients with hypotension, it is crucial to prioritize agents that have minimal effects on blood pressure and cardiac output. According to a study published in the European Heart Journal in 2019 1, benzodiazepines cause minimal reductions in blood pressure due to direct vasodilatation and autonomic nervous system modulation, making them a safer choice.

Some key points to consider when using benzodiazepines in hypotensive patients include:

• They may suppress arterial baroreceptors, yet no consensus exists on their chronotropic effects 1
• Benzodiazepines cause reductions in cardiac filling pressures without compromising coronary blood flow in a so-called nitroglycerine-like effect 1
• They have direct negative inotropic effects in vitro and in vivo studies incorporating the autonomic system, but such effects are clinically insignificant 1

In contrast, other agents like propofol and dexmedetomidine are associated with more notorious hemodynamic effects and potential deleterious reduction in cardiac output, making them less ideal for patients with hypotension 1. Therefore, benzodiazepines should be considered the first-line choice for muscle relaxation in patients with hypotension, with careful titration and close monitoring of vital signs to prevent further hemodynamic compromise.

From the FDA Drug Label

Tizanidine is an α2-adrenergic agonist (like clonidine) and can produce hypotension In a single dose study where blood pressure was monitored closely after dosing, two-thirds of patients treated with 8 mg of tizanidine had a 20% reduction in either the diastolic or systolic BP. The reduction was seen within 1 hour after dosing, peaked 2 to 3 hours after dosing and was associated, at times, with bradycardia, orthostatic hypotension, lightheadedness/dizziness and rarely syncope The hypotensive effect is dose related and has been measured following single doses of ≥ 2 mg.

Tizanidine is not suitable for patients with hypotension, as it can produce hypotension and exacerbate the condition.

• The drug can cause a significant reduction in blood pressure, which can lead to adverse effects such as bradycardia, orthostatic hypotension, lightheadedness, dizziness, and syncope.
• The hypotensive effect of tizanidine is dose-related, and the risk of significant hypotension may be increased in patients with pre-existing hypotension.
• Therefore, alternative muscle relaxers should be considered for patients with hypotension 2.

From the Research

Muscle Relaxers for Patients with Hypotension

• When considering muscle relaxers for patients with hypotension, it is essential to evaluate the potential effects of these medications on blood pressure.
• Tizanidine, a widely used muscle relaxant, can lower blood pressure and may not be suitable for patients with hypotension 3, 4, 5.
• Studies have shown that tizanidine can cause severe hypotension, especially when co-prescribed with strong CYP1A2 inhibitors or other medications that lower blood pressure 3.
• Cyclobenzaprine, another muscle relaxant, may be a safer alternative for patients with hypotension, as it has been shown to have a lower risk of hypotensive episodes compared to tizanidine 3.
• It is crucial to monitor patients closely when prescribing muscle relaxers, especially those with a history of hypotension or concomitant use of medications that affect blood pressure 4, 5.

Considerations for Specific Medications

• Tizanidine should be used with caution in patients with hypotension, and alternative medications should be considered when possible 3, 4, 5.
• Cyclobenzaprine may be a suitable alternative for patients with hypotension, but its use should still be monitored closely 3.
• Other medications, such as antidepressants, can also affect blood pressure and should be considered when evaluating the risk of hypotension in patients 6.

Key Findings

• Tizanidine can cause severe hypotension, especially when co-prescribed with other medications that lower blood pressure 3, 4, 5.
• Cyclobenzaprine may be a safer alternative for patients with hypotension, but its use should still be monitored closely 3.
• Close monitoring of patients is essential when prescribing muscle relaxers, especially those with a history of hypotension or concomitant use of medications that affect blood pressure 4, 5.