1. Introduction
Clonidine is a centrally acting alpha-2 adrenergic agonist used to manage hypertension, attention deficit hyperactivity disorder (ADHD), and certain withdrawal syndromes. By stimulating alpha-2 adrenergic receptors in the brain, it reduces sympathetic outflow, lowering blood pressure and calming hyperactivity.
2. Indications
- Approved Indications:
- Hypertension (primary or adjunctive therapy).
- Attention deficit hyperactivity disorder (ADHD), especially for hyperactivity and impulsivity.
- Severe pain (as part of epidural analgesia).
- Off-Label Uses:
- Withdrawal syndromes (e.g., opioids, nicotine, or alcohol).
- Hot flashes in menopausal women.
- Tourette syndrome.
3. Dosage
- For Hypertension:
- Initial dose: 0.1 mg orally twice daily.
- Maintenance dose: 0.2–0.6 mg/day in divided doses.
- Maximum dose: 2.4 mg/day.
- For ADHD (Children ≥6 years):
- Initial dose: 0.1 mg at bedtime.
- Increase by 0.1 mg/day weekly, given in 2–4 divided doses.
- Maximum dose: 0.4 mg/day.
- For Opioid Withdrawal:
- 0.1–0.2 mg orally every 6–8 hours as needed (maximum: 1.2 mg/day).
4. Administration
- Take orally with or without food.
- For transdermal patches, apply to a hairless area on the upper outer arm or chest; replace every 7 days.
- Do not abruptly discontinue to avoid rebound hypertension.
5. Forms Available
- Tablets: 0.1 mg, 0.2 mg, 0.3 mg.
- Extended-release tablets: 0.1 mg.
- Transdermal patch: 0.1 mg/24 hours, 0.2 mg/24 hours, 0.3 mg/24 hours.
- Injectable (epidural): 100 mcg/mL.
6. Side Effects
6.1. Common Side Effects
- Drowsiness.
- Dry mouth.
- Dizziness.
- Fatigue.
6.2. Less Common Side Effects
- Constipation.
- Decreased libido.
- Bradycardia.
6.3. Rare but Serious Side Effects
- Severe hypotension.
- Rebound hypertension (on abrupt discontinuation).
- Depression.
7. Warnings
- Avoid abrupt withdrawal to prevent rebound hypertension or hypertensive crisis.
- Use cautiously in patients with severe coronary artery disease or cerebrovascular disease.
- Avoid use in patients with severe bradycardia or advanced atrioventricular block.
8. Precautions
- Use with caution in elderly patients, as they are more susceptible to sedation, hypotension, and bradycardia.
- Monitor patients with a history of depression or mental health conditions for worsening symptoms.
- Avoid alcohol or other sedatives during therapy.
9. Interactions
- Drug-Drug Interactions:
- Beta-blockers: Increased risk of bradycardia and hypotension.
- CNS depressants (e.g., benzodiazepines, opioids): Enhanced sedative effects.
- Antidepressants: May reduce the efficacy of clonidine.
- Drug-Food Interactions:
- No significant interactions, but alcohol should be avoided.
10. Monitoring Parameters
- Blood pressure and heart rate regularly, especially during dose adjustments.
- Watch for signs of sedation or CNS depression.
- Monitor for rebound hypertension upon discontinuation.
11. Use in Children
- Approved for ADHD in children aged 6 years and older.
- Monitor closely for sedation, hypotension, and behavioural changes.
12. Use in Pregnancy
- Category C: Use only if the benefits outweigh the risks.
- May cause foetal bradycardia or hypotension; monitor carefully if used.
13. Use in Elderly
- Use with caution due to increased sensitivity to side effects, especially hypotension and sedation. Start at the lowest effective dose and monitor closely.
14. Use in Kidney Disease
- Use cautiously in patients with severe renal impairment.
- Dose adjustments may be required as clonidine is excreted renally.
15. Use in Liver Disease
- No specific dose adjustments required, but monitor for side effects as metabolism may be affected.
16. Patient Counselling Points
- Take clonidine exactly as prescribed. Do not skip or abruptly stop doses to avoid rebound hypertension.
- Transdermal patches should be replaced weekly and applied to a clean, dry, hairless area.
- Inform patients about the risk of drowsiness and advise against driving or operating heavy machinery if affected.
- Avoid alcohol and other sedatives during treatment.
- Seek medical attention for symptoms such as chest pain, palpitations, or severe dizziness.
17. Table of Brand Names, Manufacturers, and Prices
Brand Name | Manufacturer | Price (USD) |
---|---|---|
Catapres | Boehringer Ingelheim | $15–25 (30 tablets, 0.2 mg) |
Kapvay | Shionogi | $30–50 (30 ER tablets, 0.1 mg) |
Generic Options | Various | $10–20 (30 tablets, 0.2 mg) |
18. FAQs (15 Questions)
- What is clonidine used for?
It is used to treat hypertension, ADHD, and withdrawal symptoms. - How does clonidine work?
It activates alpha-2 adrenergic receptors in the brain, reducing sympathetic outflow and lowering blood pressure. - Can clonidine cause drowsiness?
Yes, drowsiness is a common side effect. - Can clonidine be stopped suddenly?
No, abrupt discontinuation can lead to rebound hypertension. - Is clonidine safe during pregnancy?
It is not typically recommended unless the benefits outweigh the risks. - Can children use clonidine?
Yes, it is approved for ADHD in children aged 6 years and older. - What are the common side effects of clonidine?
Drowsiness, dry mouth, dizziness, and fatigue. - How is clonidine taken?
It can be taken orally, applied as a transdermal patch, or administered epidurally for pain management. - Does clonidine interact with other medications?
Yes, it interacts with beta-blockers, CNS depressants, and antidepressants. - How long does clonidine take to work?
Blood pressure reduction usually occurs within 30–60 minutes, with peak effects in 2–4 hours. - Can clonidine cause low blood pressure?
Yes, hypotension is a common side effect. - What should I do if I miss a dose of clonidine?
Take it as soon as you remember, but skip it if it’s close to the next dose. Do not double the dose. - How should clonidine patches be stored?
Store patches at room temperature, away from heat and moisture. - Can clonidine be used for anxiety?
It is sometimes used off-label for anxiety, but this is not an approved indication. - Can clonidine be taken with alcohol?
No, alcohol should be avoided due to the risk of enhanced sedation and hypotension.