THERAPEUTICS

Brands

• Duraclon (injection)
• Catapres
• Catapres-TTS (Clonidine Transdermal Therapeutic System)
• Clorpres
• see index for additional brand names

Generic?

• Yes (not for transdermal)

Class

• Antihypertensive; centrally acting alpha 2 agonist hypotensive agent

Commonly Prescribed For

• (bold for FDA approved)
• Hypertension
• Attention deficit hyperactivity disorder (ADHD)
• Tourette’s syndrome
• Substance withdrawal, including opiates and alcohol
• Anxiety disorders, including Posttraumatic stress disorder (PTSD) and social anxiety disorder
• Clozapine-induced hypersalivation
• Menopausal flushing
• Severe pain in cancer patients that is not adequately relieved by opioid analgesics alone (combination with opiates)

How The Drug Works

• For hypertension, stimulates alpha 2 adrenergic receptors in the brain stem, reducing sympathetic outflow from the CNS and decreasing peripheral resistance, renal vascular resistance, heart rate, and blood pressure
• An imidazoline, so also interacts at imidazoline receptors
• For CNS uses, presumably has central actions on either pre- or postsynaptic alpha 2 receptors, and/or actions at imidazoline receptors may cause behavioral changes in numerous conditions (unknown and speculative)

How Long Until It Works

• Blood pressure may be lowered 30–60 minutes after first dose; greatest reduction seen after 2–4 hours
• May take several weeks to control blood pressure adequately
• For CNS uses, can take a few weeks to see therapeutic benefits

If It Works

• For hypertension, continue treatment indefinitely and check blood pressure regularly
• For CNS uses, continue to monitor continuing benefits as well as blood pressure

If It Doesn’t Work (for CNS indications)

• Since clonidine is a second-line and experimental treatment for CNS disorders, many patients may not respond
• Consider adjusting dose or switching to another agent with better evidence for CNS efficacy

Best Augmenting Combos for Partial Response or Treatment-Resistance

• Best to attempt another monotherapy prior to augmenting for CNS uses
• Chlorthalidone, thiazide-type diuretics, and furosemide for hypertension
• Possibly combination with stimulants (with caution as benefits of combination poorly documented and there are some reports of serious adverse events)
• Combinations for CNS uses should be for the expert, while monitoring the patient closely, and when other treatment options have failed

Tests

• Blood pressure should be checked regularly during treatment