Contraindications of Clonidine
Clonidine is contraindicated in patients with known hypersensitivity to the medication. 1
Primary Contraindications
- Hypersensitivity: Patients with known allergic reactions to clonidine should not receive this medication 1
- Severe bradycardia: Clonidine should be avoided in patients with pre-existing severe bradycardia as it may worsen the condition 2
- Severe conduction disorders: Patients with second or third-degree heart block should avoid clonidine 3
- Concurrent beta-blocker therapy: Combination can increase risk of severe bradycardia 3
Relative Contraindications and Cautions
Cardiovascular Conditions
- Sinus node dysfunction: Patients with clinical sinus node dysfunction are at increased risk for severe bradycardia 2
- Recent myocardial infarction: Caution is advised due to potential hemodynamic effects 4
- Severe orthostatic hypotension: Paradoxically, clonidine may raise blood pressure in patients with severe idiopathic orthostatic hypotension 5
Renal Impairment
- Renal insufficiency: Patients with renal dysfunction are at higher risk for severe bradycardia due to decreased drug clearance 2
- Monitoring required: Dose adjustment may be necessary in patients with impaired renal function 4
Neurological Considerations
- Risk of increased intracranial pressure: Clonidine should be used with caution in patients with cerebrovascular disease 3
- Sedation effects: May impair cognitive function, particularly in elderly patients 4
Other Precautions
- Abrupt discontinuation: Never stop clonidine suddenly as this may cause rebound hypertension, which can be severe and potentially life-threatening 3, 6
- Concomitant medications: Use with caution in patients taking other sympatholytic agents as this increases risk of bradycardia 2
- Pregnancy: Limited safety data available; use only when benefits outweigh risks 4
Special Populations
Elderly
- Increased sensitivity: Elderly patients may be more sensitive to the hypotensive and sedative effects of clonidine 4
- Start low: Lower initial dosing is recommended in elderly patients 4
Pediatric Use
- Limited data: Safety and efficacy in children under 12 years should be carefully evaluated 3
- Monitoring: Close monitoring of heart rate and blood pressure is essential in pediatric patients 3
Clinical Pearls
- Withdrawal management: When discontinuing clonidine, gradual tapering over 2-4 days is recommended to prevent rebound hypertension 3
- Monitoring: Regular assessment of heart rate, blood pressure, and renal function is advised, particularly during initiation and dose adjustments 2
- Drug interactions: Be aware of potential interactions with CNS depressants, which may enhance sedative effects 4
Hypertensive Emergency Considerations
- Clonidine is particularly useful in hypertensive emergencies induced by catecholamine excess (pheochromocytoma, interactions between monoamine oxidase inhibitors and other drugs or food, cocaine toxicity, amphetamine overdose) 3, 6
- Oral clonidine can be effective for hypertensive urgencies when properly monitored 6