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-TTS-1
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.
Alpha-2 adrenergic agonist that reduces sympathetic outflow from the CNS, leading to decreased peripheral vascular resistance and 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 (FDA-approved),Off-label: attention deficit hyperactivity disorder (ADHD), opioid withdrawal, menopausal hot flashes, migraine prophylaxis, anxiety disorders
Transdermal patch delivering 0.2 mg/day clonidine applied every 7 days to hairless area of upper arm or chest.
Clonidine transdermal system 0.1 mg/24 hours applied to intact skin on upper arm or chest once every 7 days. Titrate based on response, maximum 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).
12-16 hours; may be prolonged in renal impairment (up to 40 hours).
Approximately 50% of clonidine is metabolized in the liver via cytochrome P450 (CYP) enzymes, primarily CYP2D6; the remainder is excreted unchanged in the urine.
Hepatic metabolism via CYP2D6 and other pathways; approximately 50% metabolized in the liver, with the remainder excreted unchanged in urine.
Renal: ~65% as unchanged drug; biliary/fecal: ~20% as metabolites; about 15% eliminated as metabolites in urine.
Renal: 40-60% unchanged; biliary/fecal: ~20% as metabolites; remainder metabolized.
20–40% bound to plasma albumin.
20-40% bound to albumin.
2.1 L/kg (moderate distribution into tissues, including brain and kidneys).
2.1-4.0 L/kg; indicates extensive tissue distribution.
Transdermal: approximately 60% of the drug released from the patch is absorbed systemically (compared to immediate-release oral bioavailability of 75–95%).
Transdermal: ~60% compared to oral; oral: ~100% but extensive first-pass.
Cr Cl 10-30 m L/min: reduce dose by 25-50%; Cr Cl <10 m L/min: reduce dose by 50-75%.
For GFR 10-50 m L/min: reduce dose by 50% and monitor. For GFR <10 m L/min: reduce dose by 75%. Not recommended in dialysis patients due to poor efficacy.
Severe hepatic impairment (Child-Pugh C): reduce dose by 50%.
No specific Child-Pugh based guidelines. Use with caution in severe hepatic impairment due to increased risk of hypotension and bradycardia.
Not recommended for use in pediatric patients; safety and efficacy not established.
Not recommended for children <12 years. For adolescents >12 years, apply 0.1 mg/24 hours patch weekly; adjust based on response.
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 (0.1 mg/24 hours) due to increased sensitivity to hypotensive effects. Monitor for orthostatic hypotension and CNS effects.
No FDA black box warning.
None
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 on abrupt discontinuation (especially with high doses),Use with caution in patients with cerebrovascular disease, renal impairment, or history of depression,May require dose adjustment in renal impairment,Risk of hypotension, bradycardia, and sedation
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)
Known hypersensitivity to clonidine or any component of the transdermal system,Concurrent use with other alpha-2 agonists (e.g., tizanidine) may cause additive effects
Avoid alcohol and grapefruit juice; may increase drug effects.
Avoid excessive alcohol consumption, as it may potentiate the hypotensive and sedative effects of clonidine. Limit or avoid grapefruit juice, as it can alter drug metabolism. No specific food restrictions; maintain a balanced diet low in sodium to help control blood pressure. Caffeine may counteract the antihypertensive effect; advise moderate consumption.
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.
First trimester: No evidence of increased risk of major malformations from human data; animal studies show no teratogenicity at clinically relevant doses. Second and third trimesters: Exposure associated with reduced placental perfusion and fetal growth restriction; neonatal withdrawal syndrome including hyperirritability, tremors, and respiratory depression reported with third trimester use.
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 a milk-to-plasma ratio of approximately 1.5; limited data, but risk of infant hypotension and sedation; use only if benefit outweighs risk; monitor infant for bradycardia, somnolence, and feeding difficulties.
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.
No standard dose adjustment recommended for pregnancy; pharmacokinetic changes (increased volume of distribution, enhanced renal clearance) may require dose titration based on clinical response; avoid abrupt discontinuation to prevent 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.
Clonidine transdermal (Catapres-TTS-1) is indicated for hypertension. Apply to a hairless, intact area of skin on the upper arm or torso, rotating sites to minimize irritation. Avoid abrupt discontinuation to prevent rebound hypertension. Onset of therapeutic effect is delayed 2-3 days after initial application; consider overlapping oral therapy during titration. The patch may be less effective in patients with extensive sweating or during fever.
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.
Apply the patch to a clean, dry, hairless area of skin, such as the upper arm or chest. Rotate application sites with each new patch to avoid skin irritation.,Replace the patch every 7 days to maintain consistent blood pressure control. Do not cut the patch or apply over cuts, scars, or irritated skin.,Do not stop using this medication abruptly, as this can cause a dangerous rise in blood pressure (rebound hypertension). Follow your doctor's instructions for discontinuing therapy.,If the patch falls off, apply a new one to a different skin site. If you forget to change the patch, do so as soon as you remember and adjust your schedule accordingly.,Avoid alcohol, as it may increase the sedative effects of this medication. Limit or avoid consuming grapefruit juice, as it may affect how the drug works.,Monitor your blood pressure regularly and report any persistent dizziness, dry mouth, or skin rash at the patch site to your healthcare provider.,Keep the patch away from heat sources (such as heating pads, saunas, or direct sunlight) as heat can increase the release of the medication and cause overdose symptoms.
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-TTS-1, 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-TTS-1 is a Central Alpha-Agonist that works by Alpha-2 adrenergic agonist that reduces sympathetic outflow from the CNS, leading to decreased peripheral vascular resistance and blood pressure.. They differ in pharmacokinetic profiles, FDA-approved indications, and side effect profiles.
Potency comparisons between CATAPRES-TTS-2 and CATAPRES-TTS-1 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-TTS-1 is: Clonidine transdermal system 0.1 mg/24 hours applied to intact skin on upper arm or chest once every 7 days. Titrate based on response, maximum 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-TTS-1 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-TTS-1 is classified as Category C. First trimester: No evidence of increased risk of major malformations from human data; animal studies show no teratogenicity at clinically relevant doses. Second and third trimeste. Always consult a maternal-fetal medicine specialist before taking either drug during pregnancy or lactation.