From the Guidelines
Clonidine is generally reserved as a last-line treatment for hypertension due to its significant CNS adverse effects, especially in older adults, and should be used with caution 1.
Key Points
- Clonidine works by stimulating alpha-2 adrenergic receptors in the brain, reducing sympathetic outflow and thereby decreasing blood pressure, heart rate, and anxiety.
- The typical starting dose for hypertension is 0.1 mg twice daily, which can be gradually increased to 0.2-0.6 mg per day divided into 2-3 doses 1.
- Clonidine is available in immediate-release tablets, extended-release tablets, and transdermal patches, with common side effects including drowsiness, dry mouth, dizziness, constipation, and sedation.
- Patients should not abruptly stop taking clonidine, as this can cause dangerous rebound hypertension; dosage should be tapered gradually under medical supervision 1.
Important Considerations
- Clonidine may interact with other blood pressure medications, CNS depressants, and certain antidepressants, so patients should inform their healthcare provider about all medications they're taking.
- The medication is generally not recommended as a first-line agent due to its side effect profile and the availability of other treatments with more favorable risk-benefit ratios 1.
Dosage and Administration
Special Populations
- Older adults: Use with caution due to increased risk of CNS adverse effects 1.
- Patients with renal impairment: Use with caution, as clonidine may worsen renal function 1.
From the FDA Drug Label
Clonidine hydrochloride tablets, USP are indicated in the treatment of hypertension. Clonidine hydrochloride tablets, USP may be employed alone or concomitantly with other antihypertensive agents. Clonidine hydrochloride, USP is a centrally acting alpha-agonist hypotensive agent available as tablets for oral administration in three dosage strengths: 0.1 mg, 0.2 mg and 0.3 mg.
Key Points:
- Clonidine is used to treat hypertension.
- It can be used alone or with other antihypertensive agents.
- Clonidine is a centrally acting alpha-agonist hypotensive agent.
- It is available in oral tablet form in three dosage strengths: 0.1 mg, 0.2 mg, and 0.3 mg 2, 2.
From the Research
Overview of Clonidine
- Clonidine is a synthetic imidazole derivative with both central and peripheral alpha-adrenergic agonist actions 3
- It is used as an antihypertensive medication, as well as for the treatment of attention-deficit/hyperactivity disorder (ADHD) 3, 4
- Clonidine can be compounded as a liquid formula for patients who are unable to take pills, but this can add to the risk of dosing errors 4
Mechanism of Action and Effects
- Clonidine acts as a central alpha-2 agonist, causing sedation, bradycardia, and hypotension in overdose 4
- It can also cause paradoxical hypertension, particularly in the early stages of overdose 3
- The primary clinical syndrome involves prominent neurological and cardiovascular effects, with the most commonly reported features being depressed sensorium, bradycardia, and hypotension 3
Clinical Uses and Efficacy
- Clonidine has been used for several years to treat hypertension, and has also been used "off label" for opioid and anesthetic sparing effects, anxiolysis and sedation, and drug withdrawal 5
- It has been shown to reduce the risk of procedure-related cardiac events in patients with overt or underlying cardiac disease 5
- Clonidine has also been used in the prevention of migraine headaches, with low dosages (75 to 150 mug daily) being effective in about 30%-50% of patients 6
Comparison with Other Medications
- Clonidine has been compared to guanfacine as an antihypertensive agent, with both drugs showing similar efficacy and side-effects 7
- Guanfacine and clonidine have similar optimal daily doses, with guanfacine being 3-4 mg and clonidine being 0.3-0.45 mg 7
- The most common side-effects of both drugs are tiredness and dryness of the mouth 7