- Last edited on February 23, 2021
Clonidine
Primer
Clonidine is an alpha 2-adrenergic agonist used in the treatment of attention-deficit/hyperactivity disorder (ADHD).
Pharmacokinetics
See also article: Introduction to Pharmacology
Pharmacokinetics of Clonidine
Absorption | Clonidine is rapidly absorbed, with 100% bioavailability when given by mouth (Tmax = 3 to 5 hours) |
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Distribution | Clonidine is highly lipid soluble and distributes throughout the body. Clonidine is primarily to bound to albumin. |
Metabolism | 50% hepatically, but does not seem to interact with other drugs via CYP450 system |
Elimination | 50% is excreted unchanged by the kidneys |
Half-life | 5 to 13 hours |
Cytochrome P450 Metabolism
See also article: Cytochrome (CYP) P450 Metabolism
Clonidine: Cytochrome P450 Metabolism
Substrate of (Metabolized by) | |
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Induces | |
Inhibits |
Pharmacodynamics
Mechanism of Action
- Clonidine binds to all three alpha 2-adrenergic receptor subtypes (2A, 2B, 2C) and other receptors (a1- and beta- adrenergic, histamine, imidazoline)
Toxicity
Indications
- Symptomatic management of alcohol withdrawal symptoms
Dosing
Dosing for Clonidine
Starting | ADHD: 0.025 mg BID or 0.05 mg daily |
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Titration | ADHD: Increase every 3-7 days by 0.05 mg/day |
Maximum | ADHD: Maximum 0.4 mg (children) |
Taper | Slowly taper dose over several weeks to avoid withdrawal symptoms and rebound hypertension |
Notes |
- Multiple daily doses is recommended in the treatment of ADHD (QID dosing is often ideal, but TID or even BID dosing may do – especially if adherence is a concern).
- More frequent dosing is preferred because of clonidine's short half-life, and because a greater number of smaller doses may be less sedating than a smaller number of bigger doses.
Formulations
- Clonidine comes in oral and transdermal patches
Monitoring
Contraindications
Absolute
Relative
Drug-Drug Interactions
Side Effects
Adverse Events
Clinical Pearls
Special Populations
Geriatric
See main article: Geriatric Pharmacology
Pediatric
See main article: Pediatric Pharmacology
Obstetric and Fetal
See main article: Obstetric and Fetal Pharmacology
Medically Ill
See main article: Psychotropic Dosing in the Medically Ill