CATAPRES-TTS-2
Clinical safety rating: caution
Comprehensive clinical and safety monograph for CATAPRES-TTS-2 (CATAPRES-TTS-2).
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.
| Metabolism | Approximately 50% of clonidine is metabolized in the liver via cytochrome P450 (CYP) enzymes, primarily CYP2D6; the remainder is excreted unchanged in the urine. |
| Excretion | Renal: ~65% as unchanged drug; biliary/fecal: ~20% as metabolites; about 15% eliminated as metabolites in urine. |
| Half-life | Terminal elimination half-life: 12–16 hours (up to 48 hours following transdermal administration due to continued absorption from the skin depot). |
| Protein binding | 20–40% bound to plasma albumin. |
| Volume of Distribution | 2.1 L/kg (moderate distribution into tissues, including brain and kidneys). |
| Bioavailability | Transdermal: approximately 60% of the drug released from the patch is absorbed systemically (compared to immediate-release oral bioavailability of 75–95%). |
| Onset of Action | Transdermal: 2–3 days after initial application (therapeutic antihypertensive effect). |
| Duration of Action | Transdermal: 7 days (when patch is worn continuously, steady-state plasma levels maintained; effect persists for up to 8 hours after removal due to skin depot). |
Transdermal patch delivering 0.2 mg/day clonidine applied every 7 days to hairless area of upper arm or chest.
| Dosage form | SYSTEM |
| Renal impairment | CrCl 10-30 mL/min: reduce dose by 25-50%; CrCl <10 mL/min: reduce dose by 50-75%. |
| Liver impairment | Severe hepatic impairment (Child-Pugh C): reduce dose by 50%. |
| Pediatric use | Not recommended for use in pediatric patients; safety and efficacy not established. |
| Geriatric use | Initiate at lowest dose (0.1 mg/day patch) due to increased sensitivity and risk of hypotension; titrate slowly based on BP response. |
| 1st trimester | Consult provider |
| 2nd trimester | Consult provider |
| 3rd trimester | Consult provider |
Clinical note
Comprehensive clinical and safety monograph for CATAPRES-TTS-2 (CATAPRES-TTS-2).
| Breastfeeding | 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. |
| Teratogenic Risk | 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. |
■ FDA Black Box Warning
No FDA black box warning.
| Serious Effects |
["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)"]
| Precautions | ["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"] |
| Food/Dietary | Avoid alcohol and grapefruit juice; may increase drug effects. |
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| Fetal Monitoring | Monitor maternal blood pressure, heart rate, and signs of orthostatic hypotension. Fetal monitoring (nonstress test, biophysical profile) in third trimester if maternal hypotension occurs. Assess for signs of neonatal withdrawal if clonidine continued until delivery. Consider monitoring of fetal growth if prolonged use in pregnancy. |
| Fertility Effects | Clonidine has not been associated with impaired fertility in humans. Animal studies have shown no effect on fertility. However, use in pregnancy may be required for management of chronic hypertension, but alternative agents with more safety data are preferred. |
| Clinical Pearls | 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. |
| Patient Advice | 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. |