From the Guidelines
Withdrawal from muscle relaxants, such as cyclobenzaprine, can cause systolic hypertension primarily through rebound sympathetic hyperactivity and norepinephrine potentiation. When muscle relaxants are discontinued abruptly, the body experiences a sudden removal of their inhibitory effects on the central nervous system, triggering an excessive release of catecholamines (adrenaline and noradrenaline), causing vasoconstriction and increased peripheral vascular resistance, which directly elevates systolic blood pressure 1.
Key Points to Consider
- The severity of hypertension depends on the specific medication, dosage, and duration of use, with longer-term use of higher doses creating more pronounced withdrawal effects.
- Cyclobenzaprine, in particular, has peripheral and central anticholinergic activity and can cause norepinephrine potentiation, which may contribute to the development of systolic hypertension during withdrawal 1.
- To prevent these complications, muscle relaxants should be tapered gradually over weeks rather than stopped abruptly, with cyclobenzaprine tapering recommended over 2 to 3 weeks to help prevent withdrawal symptoms 1.
- Patients experiencing withdrawal-related hypertension may require temporary antihypertensive medication, with alpha-2 agonists like clonidine being particularly effective as they help counteract the sympathetic overactivity driving the blood pressure elevation.
Clinical Implications
- It is essential to monitor patients closely during the tapering process and adjust the tapering schedule as needed to minimize the risk of withdrawal-related complications.
- Healthcare providers should be aware of the potential for systolic hypertension during muscle relaxant withdrawal and take proactive steps to prevent and manage it, prioritizing the patient's morbidity, mortality, and quality of life.
From the Research
Mechanism of Systolic Hypertension due to Withdrawal from Muscle Relaxants
- The withdrawal of certain muscle relaxants, such as baclofen, can lead to a syndrome that includes hypertension, among other symptoms 2.
- This syndrome is thought to be caused by the sudden removal of the drug's inhibitory effects on the nervous system, leading to an increase in sympathetic activity 3.
- The increase in sympathetic activity can cause an increase in blood pressure, heart rate, and other symptoms such as hyperthermia, seizures, and altered mental status 2.
Rebound Hypertension
- Rebound hypertension is a well-documented phenomenon that can occur when certain antihypertensive drugs, such as clonidine, are abruptly withdrawn 4, 5, 3.
- This phenomenon is characterized by a sudden and significant increase in blood pressure, often accompanied by other symptoms such as headache, tremor, and flushing 4.
- The mechanism of rebound hypertension is thought to be related to the sudden removal of the drug's inhibitory effects on the sympathetic nervous system, leading to an increase in sympathetic activity and a subsequent increase in blood pressure 3.
Sympathetic Overactivity
- Sympathetic overactivity is a key component of the withdrawal syndrome and rebound hypertension associated with certain muscle relaxants and antihypertensive drugs 4, 5, 3.
- This overactivity can lead to an increase in blood pressure, heart rate, and other symptoms, and can be potentially dangerous if not recognized and treated promptly 3.
- The use of adrenergic beta-receptor blocking drugs may alleviate some of the symptoms of sympathetic overactivity, but may not prevent the rise in blood pressure 3.