Head-to-head clinical analysis & difference comparison: details on mechanism of action, dosing, half-life, interactions, and maternal-fetal safety.
CATAPRES vs CATAPRES-TTS-3
Clinician-reviewed, head-to-head comparison of mechanism, dosing, pharmacokinetics, and safety profiles.
Last clinically reviewed: July 2026 · OpiCalc Medical Review Team
Selective alpha-2 adrenergic agonist that reduces sympathetic outflow from the central nervous system, resulting in decreased peripheral vascular resistance and lowered blood pressure.
Clonidine is an alpha-2 adrenergic agonist that reduces sympathetic outflow from the central nervous system, resulting in decreased peripheral vascular resistance, decreased heart rate, and lowered blood pressure.
Hypertension,Attention deficit hyperactivity disorder (ADHD) - off-label,Anxiety - off-label,Opioid withdrawal - off-label,Migraine prophylaxis - off-label
Hypertension (first-line treatment),Off-label: Attention deficit hyperactivity disorder (ADHD), management of opioid withdrawal, menopausal flushing, diabetic diarrhea, migraine prophylaxis
Oral: 0.1 mg twice daily initially, titrate to 0.2-0.6 mg/day in divided doses; maximum 2.4 mg/day. Transdermal: 0.1 mg/24 hours patch applied every 7 days, titrate to 0.2-0.3 mg/24 hours.
Transdermal patch: 0.3 mg/day applied once every 7 days; initial dose 0.1 mg/day, titrate weekly by 0.1 mg/day increments to desired response.
Terminal elimination half-life: 12-16 hours in normal renal function; prolonged to 48-96 hours in severe renal impairment. Use with caution in CKD.
Terminal elimination half-life is 12-16 hours after oral administration; with transdermal delivery, the effective half-life is prolonged to 20-40 hours due to continued absorption from the skin depot. In renal impairment, half-life may extend to 40 hours or longer.
Extensively metabolized in the liver via cytochrome P450 enzymes, primarily CYP2D6, with about 50% undergoing first-pass metabolism.
Clonidine is extensively metabolized in the liver by cytochrome P450 enzymes (CYP2D6) to inactive metabolites; approximately 50% excreted unchanged in urine.
Renal: ~65% (40-50% unchanged; 20-25% as metabolites). Biliary/fecal: ~35% (conjugated metabolites).
Approximately 40-60% of the absorbed dose is excreted unchanged in urine. About 20-30% is eliminated as metabolites via bile and feces. Renal clearance accounts for 50-60% of total clearance.
20-40% bound to albumin and alpha-1-acid glycoprotein (AAG).
Approximately 30-40% bound to albumin and alpha1-acid glycoprotein.
Vd: 2.1-4.0 L/kg. Distribution widely into tissues including CNS; high Vd reflects extensive extravascular distribution.
2.9-4.5 L/kg, indicating extensive distribution into tissues including the central nervous system.
Oral: 75-95% (immediate release). Transdermal: ~60% relative to oral (dose-adjusted).
Transdermal system: Comparable to oral, approximately 50-80% of the dose reaches systemic circulation, with reduced peak-trough fluctuations. Oral: 70-80% (first-pass metabolism reduces bioavailability to ~40% in some individuals).
Cr Cl 10-30 m L/min: reduce dose by 50% or extend interval. Cr Cl <10 m L/min: administer 25-50% of usual dose. Not significantly removed by hemodialysis.
For GFR 10-50 m L/min: reduce initial dose to 0.1 mg/day; for GFR <10 m L/min: use 0.1 mg/day and adjust cautiously, dosing interval may be extended to every 14 days; not dialyzable.
Child-Pugh Class B or C: reduce dose by 50% and monitor for hypotension; titrate slowly due to reduced clearance.
No specific Child-Pugh based recommendations; use with caution in severe hepatic impairment due to possible accumulation; monitor for hypotension and bradycardia.
Oral: Initial 5-10 mcg/kg/day divided every 8-12 hours; titrate to 15-25 mcg/kg/day; maximum 0.9 mg/day.
Safety and efficacy not established; use not recommended in pediatric patients.
Start with lowest dose (0.05 mg twice daily) due to increased sensitivity; avoid abrupt discontinuation; monitor for orthostatic hypotension and CNS depression.
Initiate at 0.1 mg/day; titrate slowly due to increased sensitivity and risk of hypotension; monitor for dizziness, syncope, and renal function declines.
No FDA black box warning.
None
Rebound hypertension upon abrupt discontinuation,Sedation and dizziness,Bradycardia and heart block,Dry mouth and constipation,Use with caution in renal impairment,May mask signs of hypoglycemia
Rebound hypertension upon abrupt discontinuation (dose tapering required),CNS depression (sedation, dizziness),Bradycardia and heart block (use caution with conduction abnormalities),Orthostatic hypotension,Renal impairment (dose adjustment needed),Contraindicated in patients with severe bradycardia or sick sinus syndrome
Hypersensitivity to clonidine,Concurrent use with monoamine oxidase inhibitors (MAOIs),Severe bradycardia or sick sinus syndrome without pacemaker
Hypersensitivity to clonidine or any component of the patch,History of severe bradycardia or sick sinus syndrome
Avoid excessive alcohol consumption as it may potentiate the hypotensive effects and increase sedation.
No specific food interactions. Limit alcohol intake as it may potentiate hypotensive and sedative effects.
Clonidine (CATAPRES) crosses the placenta. First trimester: No clear evidence of major congenital malformations; limited data. Second and third trimesters: May cause decreased fetal heart rate variability and transient neonatal hypertension, bradycardia, and jitteriness. Risk for rebound maternal hypertension if discontinued abruptly.
First trimester: No evidence of major congenital malformations in human studies; avoid use unless benefit outweighs risk. Second and third trimesters: Associated with decreased placental perfusion and fetal growth restriction; may cause fetal bradycardia, hypotension, and hypoxia. Discontinue or reduce dose if fetal distress occurs.
Clonidine is excreted into breast milk with M/P ratio approximately 1.4-2.0. Relative infant dose is about 2-4% of maternal weight-adjusted dose. Caution in premature infants or those with renal impairment; monitor for sedation, hypotension, and apnea. Breastfeeding is generally considered compatible but weigh risks vs benefits.
Clonidine is excreted into breast milk; M/P ratio approximately 1.5:1. Limited data on infant effects; potential for infant hypotension, bradycardia, and sedation. Use with caution and monitor infant for adverse effects.
Increased plasma volume and renal clearance during pregnancy may reduce clonidine serum levels; monitor blood pressure and consider dose adjustment (increase if needed) to maintain normotension. Avoid abrupt discontinuation due to risk of rebound hypertension.
Increased plasma volume and renal clearance in pregnancy may require dose adjustment; empirical dose reduction in third trimester is not recommended; titrate to achieve optimal blood pressure control while avoiding maternal hypotension and fetal compromise.
Abrupt discontinuation can cause rebound hypertension. Monitor heart rate and blood pressure closely in patients with renal impairment. Can cause orthostatic hypotension, especially when combined with diuretics. Use with caution in patients with bradycardia or heart block. Transdermal patch may cause contact dermatitis; rotate sites. IV clonidine can be used for hypertensive emergencies.
Catapres-TTS-3 (clonidine transdermal system) delivers 0.3 mg/day. Apply to hairless, intact skin on upper arm or torso. Rotate site weekly to minimize local irritation. Do not cut or trim patch. If patch falls off, replace with new patch. Onset of action delayed ~2-3 days after first application; oral clonidine may be needed initially. Contraindicated in patients with history of hypersensitivity to clonidine. Use cautiously in severe coronary insufficiency, recent MI, cerebrovascular disease, or chronic renal failure. Rebound hypertension may occur if patch is removed abruptly; taper over 2-4 days if discontinuing. May cause dry mouth, drowsiness, dizziness, constipation, and orthostatic hypotension.
Do not stop taking this medication abruptly as it may cause a rapid increase in blood pressure.,Avoid driving or operating heavy machinery until you know how this medication affects you, as it may cause dizziness or drowsiness.,If you are using the patch, apply it to a hairless area of skin on the upper arm or chest and rotate sites to avoid skin irritation.,Rise slowly from sitting or lying down to prevent dizziness from low blood pressure.,Avoid alcohol as it can increase the side effects of this medication.
Apply patch once every 7 days to a clean, dry, hairless area of skin on the upper arm or torso.,Do not cut or trim the patch; use a new patch if it falls off.,Rotate application site weekly to prevent skin irritation.,Avoid applying patch to irritated or scarred skin.,Do not stop using the patch without talking to your doctor; abruptly stopping can cause a dangerous rise in blood pressure.,If you have surgery, inform your surgeon you are using this patch.,Side effects may include dry mouth, drowsiness, dizziness, and constipation. Avoid driving or hazardous activities until you know how the patch affects you.,Alcohol can increase drowsiness and dizziness; limit alcohol consumption.
No interactions on record
No interactions on record
Explore head-to-head clinical comparisons of other medications in the same therapeutic classes.
Common clinical questions about CATAPRES vs CATAPRES-TTS-3, answered by our medical review team.
CATAPRES is a Central Alpha-Agonist that works by Selective alpha-2 adrenergic agonist that reduces sympathetic outflow from the central nervous system, resulting in decreased peripheral vascular resistance and lowered blood pressure.. CATAPRES-TTS-3 is a Central Alpha-Agonist that works by Clonidine is an alpha-2 adrenergic agonist that reduces sympathetic outflow from the central nervous system, resulting in decreased peripheral vascular resistance, decreased heart rate, and lowered blood pressure.. They differ in pharmacokinetic profiles, FDA-approved indications, and side effect profiles.
Potency comparisons between CATAPRES and CATAPRES-TTS-3 depend on the specific clinical indication. These are both Central Alpha-Agonist agents and are not directly interchangeable by dose. A physician or clinical pharmacist should guide any therapeutic switching decisions.
The standard adult dose of CATAPRES is: Oral: 0.1 mg twice daily initially, titrate to 0.2-0.6 mg/day in divided doses; maximum 2.4 mg/day. Transdermal: 0.1 mg/24 hours patch applied every 7 days, titrate to 0.2-0.3 mg/24 hours.. The standard adult dose of CATAPRES-TTS-3 is: Transdermal patch: 0.3 mg/day applied once every 7 days; initial dose 0.1 mg/day, titrate weekly by 0.1 mg/day increments to desired response.. Dosing should always be individualized based on indication, renal and hepatic function, age, and other patient factors.
No direct drug-drug interaction has been formally documented between CATAPRES and CATAPRES-TTS-3 in current clinical databases. However, individual patient risk factors including other medications, organ function, and comorbidities should always be evaluated by a qualified healthcare provider.
The maternal-fetal safety profiles differ. CATAPRES is classified as Category C. Clonidine (CATAPRES) crosses the placenta. First trimester: No clear evidence of major congenital malformations; limited data. Second and third trimesters: May cause decreased feta. CATAPRES-TTS-3 is classified as Category C. First trimester: No evidence of major congenital malformations in human studies; avoid use unless benefit outweighs risk. Second and third trimesters: Associated with decreased pla. Always consult a maternal-fetal medicine specialist before taking either drug during pregnancy or lactation.