Drugs online research references
J Hypertens. 1985 Feb;3(1):47-53.
Acute and chronic effects of the converting enzyme inhibitors enalapril and lisinopril on reflex control of heart rate in normotensive man.
Ajayi AA, Campbell BC, Howie CA, Reid JL.
The effects of enalapril maleate and its lysine analogue, lisinopril, on reflex control of heart rate after acute and chronic administration were examined in 10 normotensive males. Both drugs reduced blood pressure without change in heart rate after acute dosing and after seven days. Both drugs impaired the vagally mediated early cardiac acceleration associated with lying down (standing to lying test). A similar effect was observed following edrophonium. After lisinopril bradycardia induced by facial immersion (diving reflex) was significantly attenuated. Edrophonium similarly attenuated the bradycardia. Both these reflexes are parasympathetically mediated. Neither drug altered heart rate or blood pressure changes following Valsalva's manoeuvre and the cold pressor test. Plasma noradrenaline was unchanged. Absence of reflex tachycardia with blood pressure reduction by converting enzyme inhibitors may be related to increased parasympathetic activity either centrally or peripherally without impairment of baroreflexes or sympathetic function.
online pharmacy ref source: www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=2987341&dopt=Abstract
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Int J Clin Pharmacol Res. 1985;5(6):419-27.
Pharmacodynamics and population pharmacokinetics of enalapril and lisinopril.
Ajayi AA, Campbell BC, Kelman AW, Howie C, Meredith PA, Reid JL.
The di-acid metabolite of enalapril, enalaprilat, and its lysine analogue lisinopril are potent inhibitors of angiotensin converting enzyme (ACE); they do not contain sulphydryl groups. Both drugs can be assayed by high pressure liquid chromatography and by radioimmunoassay and plasma ACE inhibition remains stable under normal storage conditions. It is therefore possible to study their pharmacokinetics as well as their pharmacodynamic effects in man. Enalaprilat and lisinopril as well as ACE activity have been measured in blood taken during the course of two studies of the effects of these drugs on blood pressure and autonomic responsiveness. A population pharmacokinetic analysis approach applied to a few concentration-time data points in each of a relatively large number of subjects provided average population parameter estimates of the absorption rate constant, volume of distribution and clearance which correspond closely with the limited published data based on conventional pharmacokinetic approaches. It also provided estimates of pharmacodynamic parameters and the concentration of the drug required to produce a 50% ACE inhibition. Population drug concentration data obtained in the course of early clinical evaluations of new drugs may provide a rational basis for dosage regimens with improved efficacy and, in particular, reduced concentration-related toxic effects.
online pharmacy ref source: www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=3005181&dopt=Abstract
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Endocrinol Jpn. 1985 Dec;32(6):803-9.
An improved method for measuring angiotensin I converting enzyme activity using a highly sensitive angiotensin II radioimmunoassay.
Hidaka H, Sawada S, Sato R, Oka H.
A highly sensitive assay for angiotensin I converting enzyme has been developed by using angiotensin I as a substrate. Angiotensin II generated in the reaction mixture was measured by a newly developed specific radioimmunoassay. To protect against angiotensin II destruction, bestatin, an inhibitor of renin, was also used to inhibit plasma renin activity. The reaction was stopped by adding EDTA and MK-521, inhibitors of angiotensin I converting enzyme. The specificity of the antiserum used for the angiotensin II radioimmunoassay was very high. The cross reactivity with angiotensin I was less than 0.5% and none of the proteolytic enzyme inhibitors crossreacted in the assay. The inhibitory effect of pepstatin on plasma renin activity was very high (more than 80%) under the standard assay conditions employed. Serum angiotensinase activity was completely inhibited by the addition of bestatin. An excellent correlation was obtained between this new method and the spectrophotometric method using a synthetic substrate, Hip-His-Leu. The generation of as little as 12 pM of Angiotensin II can be detected. Such low concentration have not been measurable with the usual spectrophotometric method. This new method will facilitate clinical and experimental studies on this unique enzyme, since very low levels of activity can be determined by this highly sensitive radioimmunoassay for angiotensin II.
online pharmacy ref source: www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=3009165&dopt=Abstract
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