Drugs online research references
J Cardiovasc Electrophysiol. 1996 Sep;7(9):802-8.
Changes in plasma epinephrine concentration and in heart rate during head-up tilt testing in patients with neurocardiogenic syncope: correlation with successful therapy with beta-receptor antagonists.
Klingenheben T, Kalusche D, Li YG, Schopperl M, Hohnloser SH.
Department of Internal Medicine, J.W. Goethe-University, Frankfurt, Germany.
INTRODUCTION: Tilt table testing is widely used in the management of patients with neurocardiogenic syncope. However, the exact pathophysiologic mechanism of this disorder is still under debate. Likewise, therapy of these patients continues to represent a challenge in many cases. Therefore, the present study aimed to gain further insight into the pathophysiology of this syndrome and to examine easily accessible clinical parameters that can improve therapy selection. METHODS AND RESULTS: In 16 patients with neurocardiogenic syncope, changes in endogenous catecholamine concentrations were determined during repeated tilt table testing before and during treatment with metoprolol. Tachycardia preceded syncope in 8 of 10 responders compared to only 1 of 6 nonresponders (P < 0.05). In responders, the relative increase in epinephrine levels averaged 197% +/- 51% during drug-free tilting and 75% +/- 33% during repeated testing while on beta-blocker therapy (P < 0.05). In nonresponders, there was a smaller relative increase in epinephrine averaging 137% +/- 35% at baseline tilt. During repeated tilt testing, a similar increase was observed in these patients with recurrent syncope (156% +/- 104%; P = NS compared to baseline). CONCLUSION: In patients with neurocardiogenic syncope who show both an increase in epinephrine concentration during tilt test and sinus tachycardia prior to the onset of symptoms, beta-blocker treatment is very effective. These findings confirm the major role of sympathetic activation as a trigger of syncope. Particularly, heart rate changes at the onset of syncope may allow early identification of patients responding to antiadrenergic therapy.
online pharmacy ref source: www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=8884509&dopt=Abstract
Clin Pharmacol Ther. 1982 Jun;31(6):685-90.
Effect of low-dose epinephrine infusion on hemodynamics after selective and nonselective beta-blockade in hypertension.
Houben H, Thien T, van 't Laar A.
We studied hemodynamic effects of low doses of epinephrine in five hypertensive patients receiving long-term treatment with propranolol and metoprolol. Epinephrine was infused at graded rates of 0.5, 1.0, 2.0, and 4.0 micrograms/min. During propranolol treatment epinephrine induced a marked pressor effect at all rates. There was a considerable rise in systolic as well as in diastolic blood pressure and heart rate fell. During metoprolol treatment there was only a slight rise in blood pressure and heart rate rose. Forearm blood flow was decreased by epinephrine during propranolol. Calculated forearm vascular resistance showed opposite effects. We conclude that infusion of small doses of epinephrine results in a marked difference in reaction in propranolol- and metoprolol-treated patients and that this may have relevance in the choice of beta blocker to be used in the treatment of hypertension.
online pharmacy ref source: www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=6122527&dopt=Abstract
Anesth Analg. 1991 Oct;73(4):449-54.
Halothane increases epinephrine threshold for the development of slow responses in isolated canine trabeculae.
Oshita S, Oka H, Hiraoka I, Takeshita H.
Department of Anesthesiology, Yamaguchi University Hospital, Japan.
We studied halothane/epinephrine interaction in isolated canine trabeculae using the doses of epinephrine necessary to produce slow responses (epinephrine threshold for the development of slow responses, ETSR) as an indicator. The preparations were depolarized in Tyrode's solution containing 26 mmol/L of KCl, then epinephrine concentrations in the solution were increased in a stepwise manner. Halothane (1%) had no significant effect, whereas 2% and 4% halothane significantly increased the ETSR. alpha 1-Blockade with either 4, 8, or 16 ng/mL of prazosin or 20, 40, or 80 ng/mL of droperidol did not alter the ETSR, whereas beta 1-adrenergic blockade with 8, 17, or 34 ng/mL of metoprolol significantly increased the ETSR. The same trend was observed when either 8 ng/mL of prazosin or 17 ng/mL of metoprolol was given in combination with 2% halothane. Verapamil (5, 10, or 20 ng/mL) increased the ETSR in a dose-dependent manner. These results indicate that halothane decreases rather than increases the sensitivity of slow calcium channels to epinephrine and that any increase above the baseline ETSR after halothane administration cannot be ascribed to halothane/adrenoceptor interaction but rather to calcium entry-blocking effects of halothane. As slow responses are induced by the activation of slow calcium channels, our findings are consistent with known data that halothane can interfere with slow calcium channel conductance.
online pharmacy ref source: www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=1654755&dopt=Abstract
online pharmacies ||
Hair Million herbal formula for hair loss and hair growth ||
Amoxicillin ||
Tramadol ||
Paxil ||
Rx Drugs USA, Prescription Drugs Online Pharmacy ||
Zithromax ||
online pharmacy ||
Antibiotics and prescription medications online literature ||
Antibiotics