CATAPRES-TTS-1
Clinical safety rating: caution
Comprehensive clinical and safety monograph for CATAPRES-TTS-1 (CATAPRES-TTS-1).
Alpha-2 adrenergic agonist that reduces sympathetic outflow from the CNS, leading to decreased peripheral vascular resistance and blood pressure.
| Metabolism | Hepatic metabolism via CYP2D6 and other pathways; approximately 50% metabolized in the liver, with the remainder excreted unchanged in urine. |
| Excretion | Renal: 40-60% unchanged; biliary/fecal: ~20% as metabolites; remainder metabolized. |
| Half-life | 12-16 hours; may be prolonged in renal impairment (up to 40 hours). |
| Protein binding | 20-40% bound to albumin. |
| Volume of Distribution | 2.1-4.0 L/kg; indicates extensive tissue distribution. |
| Bioavailability | Transdermal: ~60% compared to oral; oral: ~100% but extensive first-pass. |
| Onset of Action | Transdermal: 2-3 days steady-state; initial effect within 24-48 hours. |
| Duration of Action | Patch worn 7 days; antihypertensive effect persists for 2-3 days after removal. |
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.
| Dosage form | SYSTEM |
| Renal impairment | For GFR 10-50 mL/min: reduce dose by 50% and monitor. For GFR <10 mL/min: reduce dose by 75%. Not recommended in dialysis patients due to poor efficacy. |
| Liver impairment | No specific Child-Pugh based guidelines. Use with caution in severe hepatic impairment due to increased risk of hypotension and bradycardia. |
| Pediatric use | Not recommended for children <12 years. For adolescents >12 years, apply 0.1 mg/24 hours patch weekly; adjust based on response. |
| Geriatric use | Start with lowest dose (0.1 mg/24 hours) due to increased sensitivity to hypotensive effects. Monitor for orthostatic hypotension and CNS effects. |
| 1st trimester | Consult provider |
| 2nd trimester | Consult provider |
| 3rd trimester | Consult provider |
Clinical note
Comprehensive clinical and safety monograph for CATAPRES-TTS-1 (CATAPRES-TTS-1).
| Breastfeeding | 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. |
| Teratogenic Risk | 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. |
■ FDA Black Box Warning
None
| Serious Effects |
["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"]
| Precautions | ["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"] |
| Food/Dietary | 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. |
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| Fetal Monitoring | Maternal: Monitor blood pressure, heart rate, sedation, and symptoms of dry mouth; renal function and electrolytes if prolonged use. Fetal/neonatal: Serial ultrasound for fetal growth and amniotic fluid index; neonatal monitoring for signs of withdrawal (jitteriness, tachycardia, poor feeding) for 48-72 hours post-delivery. |
| Fertility Effects | In males, clonidine may cause decreased libido or impotence; in females, oligomenorrhea or amenorrhea reported; no definitive effect on fertility in humans; animal studies show no impairment of fertility at therapeutic doses. |
| Clinical Pearls | 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. |
| Patient Advice | 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. |