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Patients should be instructed not to discontinue therapy without consulting their physician. Sudden cessation of clonidine treatment has, in some cases, resulted in symptoms such as nervousness, agitation, headache, and tremor accompanied or followed by a rapid rise in blood pressure and elevated catecholamine concentrations in the plasma. The likelihood of such reactions to discontinuation of clonidine therapy appears to be greater after administration of higher doses or continuation of concomitant beta-blocker treatment and special caution is therefore advised in these situations. Rare instances of hypertensive encephalopathy, cerebrovascular accidents and death have been reported after clonidine withdrawal. When discontinuing therapy with CATAPRES tablets, the physician should reduce the dose gradually over 2 to 4 days to avoid withdrawal symptomatology.
An excessive rise in blood pressure following discontinuation of CATAPRES tablets therapy can be reversed by administration of oral clonidine hydrochloride or by intravenous phentolamine. If therapy is to be discontinued in patients receiving a beta-blocker and clonidine concurrently, the beta-blocker should be withdrawn several days before the gradual discontinuation of CATAPRES tablets.
Because children commonly have gastrointestinal illnesses that lead to vomiting, they may be particularly susceptible to hypertensive episodes resulting from abrupt inability to take medication.
In patients who have developed localized contact sensitization to Catapres-TTS® (clonidine), continuation of Catapres-TTS or substitution of oral clonidine hydrochloride therapy may be associated with the development of a generalized skin rash.
The sympatholytic action of clonidine may worsen sinus node dysfunction and atrioventricular (AV) block, especially in patients taking other sympatholytic drugs. There are post-marketing reports of patients with conduction abnormalities and/or taking other sympatholytic drugs who developed severe bradycardia requiring IV atropine, IV isoproterenol and temporary cardiac pacing while taking clonidine.
In hypertension caused by pheochromocytoma, no therapeutic effect of CATAPRES tablets can be expected.
Administration of Catapres® (clonidine hydrochloride, USP) tablets should be continued to within 4 hours of surgery and resumed as soon as possible thereafter. Blood pressure should be carefully monitored during surgery and additional measures to control blood pressure should be available if required.
Carcinogenesis, Mutagenesis, Impairment Of Fertility
Chronic dietary administration of clonidine was not carcinogenic to rats (132 weeks) or mice (78 weeks) dosed, respectively, at up to 46 or 70 times the maximum recommended daily human dose as mg/kg (9 or 6 times the MRDHD on a mg/m² basis). There was no evidence of genotoxicity in the Ames test for mutagenicity or mouse micronucleus test for clastogenicity.
Fertility of male or female rats was unaffected by clonidine doses as high as 150 μg/kg (approximately 3 times MRDHD). In a separate experiment, fertility of female rats appeared to be affected at dose levels of 500 to 2000 μg/kg (10 to 40 times the oral MRDHD on a mg/kg basis; 2 to 8 times the MRDHD on a mg/m² basis).
Pregnancy Category C
Reproduction studies performed in rabbits at doses up to approximately 3 times the oral maximum recommended daily human dose (MRDHD) of Catapres® (clonidine hydrochloride, USP) tablets produced no evidence of a teratogenic or embryotoxic potential in rabbits. In rats, however, doses as low as 1/3 the oral MRDHD (1/15 the MRDHD on a mg/m² basis) of clonidine were associated with increased resorptions in a study in which dams were treated continuously from 2 months prior to mating. Increased resorptions were not associated with treatment at the same time or at higher dose levels (up to 3 times the oral MRDHD) when the dams were treated on gestation days 6 to 15. Increases in resorption were observed at much higher dose levels (40 times the oral MRDHD on a mg/kg basis; 4 to 8 times the MRDHD on a mg/m² basis) in mice and rats treated on gestation days 1 to 14 (lowest dose employed in the study was 500 μg/kg).
No adequate, well-controlled studies have been conducted in pregnant women. Clonidine crosses the placental barrier (see CLINICAL PHARMACOLOGY, Pharmacokinetics). Because animal reproduction studies are not always predictive of human response, this drug should be used during pregnancy only if clearly needed.
As clonidine hydrochloride is excreted in human milk, caution should be exercised when CATAPRES tablets are administered to a nursing woman.
Safety and effectiveness in pediatric patients have not been established in adequate and wellcontrolled trials (see WARNINGS, Withdrawal).
Last reviewed on RxList: 8/19/2015
This monograph has been modified to include the generic and brand name in many instances.
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