CATAPRES
Clinical safety rating: caution
Comprehensive clinical and safety monograph for CATAPRES (CATAPRES).
Selective alpha-2 adrenergic agonist that reduces sympathetic outflow from the central nervous system, resulting in decreased peripheral vascular resistance and lowered blood pressure.
| Metabolism | Extensively metabolized in the liver via cytochrome P450 enzymes, primarily CYP2D6, with about 50% undergoing first-pass metabolism. |
| Excretion | Renal: ~65% (40-50% unchanged; 20-25% as metabolites). Biliary/fecal: ~35% (conjugated metabolites). |
| Half-life | 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. |
| Protein binding | 20-40% bound to albumin and alpha-1-acid glycoprotein (AAG). |
| Volume of Distribution | Vd: 2.1-4.0 L/kg. Distribution widely into tissues including CNS; high Vd reflects extensive extravascular distribution. |
| Bioavailability | Oral: 75-95% (immediate release). Transdermal: ~60% relative to oral (dose-adjusted). |
| Onset of Action | Oral: 30-60 minutes. Transdermal: 2-3 days after initial application (therapeutic levels reached at 48-72 hours). |
| Duration of Action | Duration: 8-12 hours after single oral dose. Transdermal patch provides steady-state over 7 days once equilibrium achieved. |
| Action Class | Alpha 2-adrenoceptors agonist (Central sympatholytics) |
| Brand Substitutes | Arkapres 150 Tablet, Nefropres C 150mcg Tablet, Albamine 150mcg Tablet |
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.
| Dosage form | TABLET |
| Renal impairment | CrCl 10-30 mL/min: reduce dose by 50% or extend interval. CrCl <10 mL/min: administer 25-50% of usual dose. Not significantly removed by hemodialysis. |
| Liver impairment | Child-Pugh Class B or C: reduce dose by 50% and monitor for hypotension; titrate slowly due to reduced clearance. |
| Pediatric use | Oral: Initial 5-10 mcg/kg/day divided every 8-12 hours; titrate to 15-25 mcg/kg/day; maximum 0.9 mg/day. |
| Geriatric use | Start with lowest dose (0.05 mg twice daily) due to increased sensitivity; avoid abrupt discontinuation; monitor for orthostatic hypotension and CNS depression. |
| 1st trimester | Consult provider |
| 2nd trimester | Consult provider |
| 3rd trimester | Consult provider |
Clinical note
Comprehensive clinical and safety monograph for CATAPRES (CATAPRES).
| Breastfeeding | 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. |
| Teratogenic Risk | 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. |
■ FDA Black Box Warning
No FDA black box warning.
| Serious Effects |
["Hypersensitivity to clonidine","Concurrent use with monoamine oxidase inhibitors (MAOIs)","Severe bradycardia or sick sinus syndrome without pacemaker"]
| Precautions | ["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"] |
| Food/Dietary | Avoid excessive alcohol consumption as it may potentiate the hypotensive effects and increase sedation. |
| Clinical Pearls |
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| Fetal Monitoring | Monitor maternal blood pressure regularly. Monitor fetal heart rate and uterine activity with continuous electronic fetal monitoring during labor. Assess neonatal vital signs and neurological status after delivery for signs of clonidine withdrawal or toxicity. |
| Fertility Effects | Clonidine may decrease libido in men and women due to central alpha-2 agonism. Reversible erectile dysfunction and ejaculatory failure reported. No direct evidence of impaired fertility in humans; animal studies show no adverse effects on fertility. |
| 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. |
| Patient Advice | 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. |