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Query: UMLS:C0020538 (hypertension)
 170,190 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Clonidine (Catapres) administered intramuscularly in a dose of 150 microng produced a satisfactory reduction in blood pressure in 13 of 16 hypertensive patients. Its effect occurred within five minutes, was maximal at 75 minutes and persisted for five hours. In six patients who received two doses (150 microng and 300 microng), the response was shown to be dose-related. No serious side effects were noted. Intramuscular administration of clonidine thus appears to be safe and effective. It has a place in the management of uncontrolled hypertension when a rapid reduction in blood pressure is undesirable and in the maintenance of blood pressure control when oral therapy cannot be tolerated.
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PMID:The use of clonidine by intramuscular injection in the treatment of hypertension. 26 67

Clonidine hydrochloride is a new antihypertensive agent with a primary site of action in the central nervous system. When administered with a diuretic, it is effective for long-term therapy and may be particularly useful in patients with moderately severe hypertension. Clonidine is comparable to methyldopa in efficacy but may cause side-effects more frequently. The only potentially serious adverse reaction that has been reported is a rebound increase in blood pressure that may occur following rapid withdrawal.
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PMID:Evaluation of clonidine hydrochloride (Catapres). A new antihypertensive agent. 117 48

Sixteen of 22 elderly male patients (aged 60-74 years) who had previously taken only hydrochlorothiazide 50 mg completed a study evaluating the safety, efficacy, and tolerability of 12-20 weeks of transdermal clonidine (Catapres TTS) as monotherapy for mild hypertension. Thirteen of the sixteen patients (81%) responded to transdermal clonidine which was begun after 28 days of placebo. Five patients discontinued transdermal clonidine therapy because of intolerable skin irritation, and one because of daytime fatigue. Clonidine caused none of the metabolic effects we observed with hydrochlorothiazide: no change in serum potassium, uric acid, cholesterol, or triglyceride. Eleven of the 22 patients (50%) who began the study experienced a skin reaction under the transdermal clonidine patch. The incidence of dry mouth and fatigue in patients using transdermal clonidine was dose-related and similar to reports of dry mouth and fatigue in patients taking oral clonidine tablets. Rebound hypertension occurred in one patient upon withdrawal of transdermal clonidine. There was no effect of transdermal clonidine or hydrochlorothiazide on cognitive function or emotional state tested with three questionnaires. Overall, transdermal clonidine, in various doses, was as effective as hydrochlorothiazide in elderly male hypertensive patients. The effectiveness of both was inversely proportional to the level of untreated blood pressure. The high incidence of skin reactions limited prolonged use of transdermal clonidine in our patients.
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PMID:Transdermal clonidine compared with hydrochlorothiazide as monotherapy in elderly hypertensive males. 271 69

The effectiveness and safety of transdermally administered clonidine hydrochloride was assessed in 16 patients with type-II diabetes mellitus. This group of patients was chosen because of the frequent occurrence of hypertension in diabetic patients and potential problems with transdermal absorption of medication because of small vessel disease. A skin patch containing clonidine hydrochloride (Catapres TTS) was applied at weekly intervals after an appropriate placebo lead-in period. Satisfactory response to therapy was seen in 15 of the 16 patients. One patient developed a generalized skin rash and was withdrawn from the study. Correlation between change in diastolic blood pressure and plasma clonidine levels was noted. Of note was the absence of the usual side effects (drowsiness, dry mouth, etc.) seen with oral clonidine administration. This study thus highlights the success of transdermal clonidine therapy in controlling blood pressure in the mild hypertensive patient with diabetes mellitus.
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PMID:The use of transcutaneous clonidine hydrochloride in the patient with diabetes mellitus and mild hypertension. 383

The pharmacology of central alpha-adrenoceptor-stimulating agents is discussed, with particular reference to clonidine (Catapres; Boehringer Ingelheim) and guanfacine (Estulic; Sandoz), and their haemodynamic effects are compared and contrasted. The main differences between the effects of clonidine and guanfacine on hypertension are: guanfacine activates presynaptic alpha-adrenoceptors 10 times more selectively than clonidine; guanfacine has an alpha 2/alpha 1-selectivity ration 25 times higher than clonidine; clonidine decreases cardiac output and guanfacine decreases peripheral resistance, clonidine has no effect on stroke volume but guanfacine increases it; and when the clonidine withdrawal syndrome in the spontaneously hypertensive rat is compared with cessation of guanfacine treatment at an equipotent antihypertensive dose, the withdrawal syndrome after guanfacine appears later and is much less severe. Guanfacine may be preferable to clonidine as a central alpha-adrenoceptor stimulant in the treatment of hypertension.
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PMID:Clonidine and guanfacine--comparison of their effects on haemodynamics in hypertension. 388 93

A prospective, double-blind, randomized controlled trial was carried out, comparing alpha-methyldopa and clonidine hydrochloride in 100 pregnant women with hypertension. There was no difference in hypotensive effect or reported maternal side effects with either agent. There was one neonatal loss in each group (98% survival). Neither drug caused clinically significant hypotension nor rebound hypertension in the neonates. Clonidine hydrochloride, like methyldopa, appears to be a safe antihypertensive agent in pregnancy.
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PMID:Clonidine hydrochloride--a safe and effective antihypertensive agent in pregnancy. 390 81

Clonidine (Catapres, Catapresan), guanfacine (Estulic), and methyldopa (Aldomet) are the prototypes of centrally acting antihypertensive drugs. Clonidine and guanfacine are lipophilic drugs that readily penetrate into the brain, where they stimulate alpha-adrenergic receptors in the pontomedullary region. The stimulation of these central alpha-adrenergic receptors has been shown to activate an inhibiting neuron, which causes a reduction of peripheral sympathetic tone and a subsequent fall in arterial blood pressure and heart rate. Both a centrally initiated reduction of vagus reflex activity and the activation of presynaptic alpha 2-adrenergic blocking agents in the heart may contribute to the bradycardia. Studies indicate that methyldopa also penetrates into the brain, where it is converted into alpha-methylnorepinephrine. This amine may stimulate the same central alpha-adrenergic receptors as those activated by clonidine, which will result in a hypotensive effect. Possibly, alpha-methyldopamine might also play a role. Accordingly, the modes of action of clonidine and alpha-methyldopa probably are very similar at a basic level. The central adrenergic receptors probably are located postsynaptically. Their receptor demand corresponds more closely to that of the alpha 2-subtype. Central alpha 1-adrenergic receptors might possibly play a part in the modulation of vagally induced baroreflex bradycardia. A discussion on the pharmacological basis of the side effects of the centrally acting antihypertensives has been limited to those adverse reactions that are somehow related to alpha-adrenergic receptors. Sedation, a common side effect, appears to be mediated by central alpha 2-adrenergic receptors, at least in animal models.(ABSTRACT TRUNCATED AT 250 WORDS)
Hypertension
PMID:The hypotensive activity and side effects of methyldopa, clonidine, and guanfacine. 609 46

This article describes in vitro and in vivo performance of two transdermal drug delivery systems. Transderm -Nitro delivers nitroglycerin for the treatment and prevention of angina for 24 hours following a single application. In a three-way crossover study comparing Transderm -Nitro with two other transdermal nitroglycerin products, mean plasma levels of drug were similar 0.5 and 6 hours after application; however, with Transderm -Nitro the area under the plasma concentration curve was highest and the coefficient of variation was least. A transdermal therapeutic system for delivering clonidine ( Catapres -TTS) is used for the treatment of hypertension. In a two-way crossover study comparing Catapres -TTS and oral Catapres , plasma levels of clonidine with use of the transdermal system reached a steady-state value in 2 to 3 days and remained steady for the duration of the wearing period; plasma levels with oral Catapres , however, fluctuated markedly. The ratio of maximum to minimum plasma levels during a dosing interval was 2 for oral Catapres and approximately 1 for Catapres -TTS. The potential use of intact skin as a route of entry for controlled delivery of drugs to the systemic circulation is promising.
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PMID:Pharmacokinetics of nitroglycerin and clonidine delivered by the transdermal route. 642 8

Clonidine hydrochloride (CH) is an antihypertensive drug with complex pharmacologic activity including central and peripheral alpha-adrenergic stimulation and CNS depression. We reviewed the records of 5 children admitted to our Pediatric Intensive Care Unit following accidental ingestion of CH. All patients presented with lethargy or stupor, beginning 20-60 minutes after ingestion. Respiratory depression or apnea occurred in 4, requiring endotracheal intubation in 2 and mechanical ventilation in 1. All 5 developed mild to moderate hypertension, and 3 developed asymptomatic bradycardia. The dose of CH ingested was estimated to be 0.2-0.4 mg in 4 out of 5 patients. Treatment consisted of efforts to prevent absorption of CH from the GI tract and supportive care. All signs of CH toxicity resolved within 6-14 hours. Four patients were transferred from ICU within 24 hours and discharged home the following day. One patient developed post-extubation stridor and atelectasis. Significant toxicity occurred even though the amount of CH ingested was relatively small in at least 4 or 5 patients. Transient hypertension occurred early in the hospital course of all patients and resolved without treatment. Hypotension and symptomatic bradycardia were not observed. Apnea was the most serious abnormality observed. All patients recovered without significant morbidity.
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PMID:Hypertension associated with clonidine ingestion. 652 27

Twenty-four patients with severe hypertension (diastolic blood pressure (DBP) greater than 14.7 kPa (110 mmHg] were allocated at random to one of two treatment groups. All were given clonidine hydrochloride; twelve by intramuscular injection (Group 1), and 12 by intravenous injection (Group 2). The two routes were equally effective; diastolic blood pressure was reduced to less than 13.3 kPa (100 mmHg) in 11 patients in Group 1 and 10 patients in Group 2. The response in both groups was smooth, with no episodes of severe hypotension. Two patients in each group showed an initial transient pressor response. Clonidine hydrochloride, administered either intravenously or intramuscularly, is an effective treatment for severe hypertension but patients should be observed closely during the first hour after injection.
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PMID:Comparison of intramuscularly and intravenously administered clonidine in the treatment of severe hypertension. 667 85


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