From the Guidelines
Tizanidine should be avoided in older patients due to its significant sedative and hypotensive effects, as well as the potential for adverse interactions with other medications commonly used in this population. The use of tizanidine in older patients is complicated by its pharmacokinetics and potential for drug interactions, including significant reductions in clearance when given concomitantly with ciprofloxacin and fluvoxamine 1. Key considerations for older patients include:
- Increased susceptibility to sedation, dizziness, hypotension, and dry mouth
- Higher risk of falls when combined with other CNS depressants such as benzodiazepines, opioids, or alcohol
- Need for dose adjustments in patients with renal or hepatic impairment, which are more common in the elderly
- Potential for significant hypotension, bradycardia, and sedation when given with other CYP1A2 inhibitors, such as oral contraceptives, acyclovir, amiodarone, verapamil, mexiletine, propafenone, cimetidine, and famotidine, among others 1. Given these concerns, alternative treatments for muscle relaxation and spasticity should be considered in older patients to minimize the risk of adverse effects and improve overall quality of life.
From the FDA Drug Label
Tizanidine should be used with caution in elderly patients because clearance is decreased four-fold. Tizanidine clearance is reduced by more than 50% in elderly patients with renal insufficiency (creatinine clearance < 25 mL/min) compared to healthy elderly subjects; this would be expected to lead to a longer duration of clinical effect.
Considerations for using tizanidine in older patients:
- Decreased clearance: Tizanidine clearance is decreased four-fold in elderly patients, which may lead to increased drug concentrations and a higher risk of adverse effects.
- Renal insufficiency: Elderly patients with renal insufficiency (creatinine clearance < 25 mL/min) may experience a reduction in tizanidine clearance of more than 50%, leading to a longer duration of clinical effect.
- Caution is advised when using tizanidine in older patients, especially those with renal insufficiency, due to the potential for increased adverse effects 2, 3.
From the Research
Considerations for Using Tizanidine in Older Patients
- Tizanidine is a muscle relaxant that can be used to treat musculoskeletal pain in older adults, but its use requires caution due to potential adverse effects 4, 5.
- Older adults taking tizanidine may be at risk for hypotension, bradycardia, and falls, particularly when used in combination with other medications such as lisinopril or angiotensin-converting enzyme inhibitors 6, 7.
- The risk of hypotension associated with tizanidine may be increased in patients taking strong CYP1A2 inhibitors, which can decrease the metabolism of tizanidine and lead to higher plasma concentrations 8.
- Studies have shown that tizanidine may be associated with a lower risk of injury and delirium compared to baclofen, another muscle relaxant, in older adults with musculoskeletal pain 5.
- However, tizanidine can still cause significant adverse effects, including hypotension, bradycardia, and drowsiness, particularly in older adults with comorbidities such as hypertension, diabetes, and seizure disorders 4, 7.
- Close monitoring of patients receiving tizanidine, particularly when used in combination with other medications, is necessary to minimize the risk of adverse effects 6, 7.
- Alternative agents or lower doses of tizanidine may be considered in older adults to reduce the risk of adverse effects 4.