Drugs online research references
shimane-med.ac.jp
1. Low doses of sublingual nifedipine are still used for the treatment of hypertensive crises, although recent studies have raised concerns that sublingual nifedipine may cause serious dose-dependent adverse effects. The present study was performed to test the safety of low-dose sublingual nifedipine administered to elderly hypertensive patients. 2. Systemic blood pressure measurements and electrocardiographic (ECG) examinations were performed before and 45-60 min after a 5 mg dose of sublingual nifedipine in 93 consecutive hypertensive patients, 65 years of age or older, who were without coronary artery disease. In 33 patients, the effects of nifedipine on myocardial lactate metabolism were studied during cardiac catheterization. 3. In all patients, following nifedipine administration, blood pressure (BP) decreased significantly, while heart rate (HR) increased, and symptoms associated with elevated BP disappeared. However, changes consistent with myocardial ischaemia appeared on the ECG in six of 55 patients with left ventricular hypertrophy (LVH) and in one of 38 patients without LVH, although only two of these seven patients experienced angina-like precordial tightness. Sublingual nifedipine decreased myocardial lactate extraction from 52 +/- 13 to 38 +/- 19% in 20 patients with LVH (P = 0.02), but myocardial lactate extraction remained stable in 13 patients without LVH (49 +/- 7 to 50 +/- 5%; NS). The change in lactate extraction was significantly correlated with the percentage change in diastolic arterial pressure (r = 0.77, P < 0.001). 4. These results suggest that sublingual nifedipine, even at the low dose of 5 mg, may cause myocardial ischaemia in some elderly patients with LVH that is associated with a marked reduction in coronary perfusion pressure.
online pharmacy ref source: www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=10386229&dopt=Abstract
J Neurosci. 1988 Feb;8(2):463-71.
Characterization of the electrically evoked release of substance P from dorsal root ganglion neurons: methods and dihydropyridine sensitivity.
Holz GG 4th, Dunlap K, Kream RM.
Department of Physiology, Tufts University School of Medicine, Boston, Massachusetts 02111.
The mechanism by which dihydropyridines (DHPs) modulate the electrically evoked or KCI-induced release of substance P (SP) from embryonic chick dorsal root ganglion (DRG) neurons was investigated in the present study. The release of SP, as measured by radioimmunoassay (RIA), was characterized in terms of its dependence on extracellular calcium ion, its stimulus-response relationship, its sensitivity to the calcium-channel blocker omega conus toxin (omega-CgTx), and its modulation by the DHPs Bay K 8644 and nifedipine. Here it is reported that omega-CgTx (1 microM) blocked the electrically evoked release of SP. In contrast, the calcium-channel agonist Bay K 8644 (5 microM) facilitated the release of SP (by 45%), whereas the calcium-channel antagonist nifedipine (5 microM) was without effect. When the release of SP was triggered by depolarization of cultures with 60 mM KCI, the actions of the DHPs became much more pronounced. Under these conditions, Bay K 8644 facilitated (by 115%), whereas nifedipine inhibited (by 58%), peptide secretion. Voltage-clamp analysis of DRG cell calcium currents demonstrated that these actions of omega-CgTx, Bay K 8644, and nifedipine are explicable in terms of their effects on the slowly inactivating (L-type) calcium current. On the basis of these findings, it is suggested that the SP release mechanism exhibits DHP sensitivity due to the involvement of L-type calcium channels in the neurosecretory process. This model predicts that the voltage and time-dependent antagonist actions of nifedipine are sufficient to explain its failure to inhibit the electrically evoked release of SP.
online pharmacy ref source: www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=2448433&dopt=Abstract
Rom J Physiol. 1997 Jan-Dec;34(1-4):115-25.
Effect of nifedipine on electrical activity of the brain in rat.
Fulga IG, Stroescu V.
Department of Pharmacology, Faculty of Medicine, Carol Davila University of Medicine, Bucharest, Romania.
Effect of calcium channel blocker nifedipine on the electrical activity of the brain in anaesthetized rats was studied. The electoencephalographic signals were registered on a computer as series of data and thereafter they were decomposed by Fourier analysis in very narrow fields of frequency. The electrical activity of the brain of the control rats was asymmetrical, with a more important activity in the left brain hemisphere, particularly between 20-30 Hz when the electrical activity of the brain was globally more important. The nifedipine increased the electrical activity of the brain between 0.5-4 Hz and 20-30 Hz in a dose-dependent manner. The drug also increased the interhemispheric asymmetry. Some possible explanations of these effects are analyzed.
online pharmacy ref source: www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=9653815&dopt=Abstract
Herbs and Pharmaceuticals Online ||
Hair Million herbal formula for hair loss and hair growth ||
Wellstreet online pharmacy for click-order prescription medications ||
Altace Online Pharmacy ||
Rx Drugs USA, Prescription Drugs Online Pharmacy ||
Insurance plans and information ||
Insurance policies for all purposes ||
Antibiotics and prescription medications online literature ||