Linked Life Data

6130864

Source:http://linkedlifedata.com/resource/pubmed/id/6130864

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
3
pubmed:dateCreated
1983-4-15
pubmed:abstractText
The hypotensive effect of short-term labetalol, the alpha- and beta-adrenoceptor blocker, is greater in subjects in the orthostatic position, possibly because of the alpha-adrenoceptor blockade. During prolonged use the orthostatic blood pressure fall disappears. To verify whether or not this is due to reduction in alpha-blocking activity, phenylephrine-induced increase in blood pressure was studied in six subjects with mild essential hypertension before and after 3 and 6 days and 1 and 6 mo of continuous treatment with 200 mg labetalol three times a day by mouth. At the same intervals, isoproterenol-induced tachycardia was followed to assess beta-blockade. After 3 days on labetalol, the log dose-response curve of phenylephrine-induced increase in blood pressure shifted to the right and the dose of agonist required to elicit a 20% increase in systolic pressure was 1.7 times that before treatment. There was a progressive decline in the dose of agonist that induced the same increase in pressure so that after 6 mo of continuous labetalol it was the same as control. In contrast, the amount of isoproterenol needed to induce a 20% increase in heart rate was two to three times that before labetalol and did not change throughout 6 mo of therapy. These data indicate a decline in the alpha-adrenoceptor-blocking effect of oral labetalol without concomitant change in the degree of beta-adrenoceptor blockade. This might account for the disappearance of orthostatic hypotension early in the course of treatment and for some decrease in the antihypertensive efficacy of labetalol.
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
AIM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Mar
pubmed:issn
0009-9236
pubmed:author
pubmed:issnType
Print
pubmed:volume
33
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
278-82
pubmed:dateRevised
2004-11-17
pubmed:meshHeading
pubmed:year
1983
pubmed:articleTitle
Alpha-adrenoceptor blockade by labetalol during long-term dosing.
pubmed:publicationType
Journal Article