Head-to-head clinical analysis & difference comparison: details on mechanism of action, dosing, half-life, interactions, and maternal-fetal safety.
CATAPRES-TTS-2 vs CATAPRES
Clinician-reviewed, head-to-head comparison of mechanism, dosing, pharmacokinetics, and safety profiles.
Last clinically reviewed: July 2026 · OpiCalc Medical Review Team
Clonidine is a centrally acting alpha-2 adrenergic agonist that stimulates alpha-2 adrenergic receptors in the brainstem, activating inhibitory neurons and reducing sympathetic outflow from the central nervous system, resulting in decreased peripheral vascular resistance, heart rate, and blood pressure.
Selective alpha-2 adrenergic agonist that reduces sympathetic outflow from the central nervous system, resulting in decreased peripheral vascular resistance and lowered blood pressure.
Hypertension (alone or in combination with other antihypertensive agents),Off-label: Attention deficit hyperactivity disorder (ADHD), menopausal hot flashes, opioid withdrawal, migraine prophylaxis, Tourette syndrome
Hypertension,Attention deficit hyperactivity disorder (ADHD) - off-label,Anxiety - off-label,Opioid withdrawal - off-label,Migraine prophylaxis - off-label
Transdermal patch delivering 0.2 mg/day clonidine applied every 7 days to hairless area of upper arm or chest.
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.
Terminal elimination half-life: 12–16 hours (up to 48 hours following transdermal administration due to continued absorption from the skin depot).
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.
Approximately 50% of clonidine is metabolized in the liver via cytochrome P450 (CYP) enzymes, primarily CYP2D6; the remainder is excreted unchanged in the urine.
Extensively metabolized in the liver via cytochrome P450 enzymes, primarily CYP2D6, with about 50% undergoing first-pass metabolism.
Renal: ~65% as unchanged drug; biliary/fecal: ~20% as metabolites; about 15% eliminated as metabolites in urine.
Renal: ~65% (40-50% unchanged; 20-25% as metabolites). Biliary/fecal: ~35% (conjugated metabolites).
20–40% bound to plasma albumin.
20-40% bound to albumin and alpha-1-acid glycoprotein (AAG).
2.1 L/kg (moderate distribution into tissues, including brain and kidneys).
Vd: 2.1-4.0 L/kg. Distribution widely into tissues including CNS; high Vd reflects extensive extravascular distribution.
Transdermal: approximately 60% of the drug released from the patch is absorbed systemically (compared to immediate-release oral bioavailability of 75–95%).
Oral: 75-95% (immediate release). Transdermal: ~60% relative to oral (dose-adjusted).
Cr Cl 10-30 m L/min: reduce dose by 25-50%; Cr Cl <10 m L/min: reduce dose by 50-75%.
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.
Severe hepatic impairment (Child-Pugh C): reduce dose by 50%.
Child-Pugh Class B or C: reduce dose by 50% and monitor for hypotension; titrate slowly due to reduced clearance.
Not recommended for use in pediatric patients; safety and efficacy not established.
Oral: Initial 5-10 mcg/kg/day divided every 8-12 hours; titrate to 15-25 mcg/kg/day; maximum 0.9 mg/day.
Initiate at lowest dose (0.1 mg/day patch) due to increased sensitivity and risk of hypotension; titrate slowly based on BP response.
Start with lowest dose (0.05 mg twice daily) due to increased sensitivity; avoid abrupt discontinuation; monitor for orthostatic hypotension and CNS depression.
No FDA black box warning.
No FDA black box warning.
Rebound hypertension upon abrupt discontinuation (particularly at high doses or with beta-blocker combination),CNS depression (drowsiness, sedation),Bradycardia and heart block,Dry mouth, constipation, and orthostatic hypotension,Impaired renal function (dose adjustment required),Rash and contact dermatitis from transdermal patch
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
Hypersensitivity to clonidine or any component of the patch,In patients with active bradycardia or sick sinus syndrome (without pacemaker),Concomitant use with other centrally acting alpha-2 agonists (e.g., methyldopa)
Hypersensitivity to clonidine,Concurrent use with monoamine oxidase inhibitors (MAOIs),Severe bradycardia or sick sinus syndrome without pacemaker
Avoid alcohol and grapefruit juice; may increase drug effects.
Avoid excessive alcohol consumption as it may potentiate the hypotensive effects and increase sedation.
Clonidine (Catapres-TTS-2) is classified as FDA Pregnancy Category C. Animal studies have shown fetal harm at high doses. Human data are limited; however, use during pregnancy, especially in the first trimester, should be avoided unless clearly needed. A small increased risk of congenital malformations, particularly oral clefts, has been suggested in some retrospective studies, but not confirmed. Third-trimester use may cause maternal hypotension and reduced placental perfusion. Neonatal withdrawal (hypertension, irritability, tremor) may occur if used near term.
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.
Clonidine is excreted into human breast milk with a milk-to-plasma ratio of approximately 1.5. Concentrations in milk are similar to maternal plasma levels. Use during breastfeeding is not recommended due to potential adverse effects in the infant, including hypotension, bradycardia, and sedation. If used, monitor infant for these effects.
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.
No specific dose adjustments are recommended for clonidine during pregnancy. However, increased plasma volume and enhanced renal clearance in pregnancy may reduce drug concentrations, potentially requiring dose titration to achieve blood pressure control. Close monitoring is warranted. The transdermal system (Catapres-TTS) may have variable absorption during pregnancy; consider switching to oral formulation if efficacy is compromised.
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.
Catapres-TTS-2 is a transdermal clonidine patch delivering 0.2 mg/day. Apply to hairless, intact skin on upper arm or chest; replace every 7 days. Avoid abrupt discontinuation to prevent rebound hypertension. Monitor for local skin reactions, bradycardia, and orthostatic hypotension. May cause dry mouth and drowsiness.
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.
Apply patch to clean, dry, hairless skin on upper arm or chest; do not cut or trim patch.,Replace patch every 7 days; remove old patch before applying new one at a different site.,Do not stop using patch suddenly; may cause dangerous rise in blood pressure.,May cause dry mouth, drowsiness, or dizziness; avoid driving if affected.,If patch falls off, apply a new one; if it becomes loose, cover with adhesive bandage.,Keep patches away from children and pets; used patches still contain active drug.
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.
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-TTS-2 vs CATAPRES, answered by our medical review team.
CATAPRES-TTS-2 is a Central Alpha-Agonist that works by Clonidine is a centrally acting alpha-2 adrenergic agonist that stimulates alpha-2 adrenergic receptors in the brainstem, activating inhibitory neurons and reducing sympathetic outflow from the central nervous system, resulting in decreased peripheral vascular resistance, heart rate, and blood pressure.. 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.. They differ in pharmacokinetic profiles, FDA-approved indications, and side effect profiles.
Potency comparisons between CATAPRES-TTS-2 and CATAPRES 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-TTS-2 is: Transdermal patch delivering 0.2 mg/day clonidine applied every 7 days to hairless area of upper arm or chest.. 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.. 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-TTS-2 and CATAPRES 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-TTS-2 is classified as Category C. Clonidine (Catapres-TTS-2) is classified as FDA Pregnancy Category C. Animal studies have shown fetal harm at high doses. Human data are limited; however, use during pregnancy, esp. 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. Always consult a maternal-fetal medicine specialist before taking either drug during pregnancy or lactation.