Cardiac retention of [11C]HED in genotyped long QT patients: a potential amplifier role for severity of the disease.
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Although mutations in cardiac sodium and potassium channel genes are associated with congenital long QT syndrome (LQTS), a "modifier" role of the sympathetic nervous system was proposed to explain the distinct severity of the disease. We evaluated cardiac sympathetic innervation using [11C]hydroxyephedrine ([11C]HED) and positron emission tomography (PET) in genotyped LQTS patients. H215O and [11C]HED PET studies were performed in 11 patients (5 symptomatic) and 8 controls. Perfusion and [11C]HED images were depicted as 36-sector polar maps. Sectorial values of perfusion (H2O%), absolute (HEDRet) and relative retention (HED%Ret) of [11C]HED, and the ratio of HED%Ret to H2O% (HED%Ret/H2O%) were calculated. Normal databases were obtained from controls. Sectorial values below 2SD database values were defined as "outside sectors." Controls and patients showed similar sectorial perfusion. Sectorial HEDRet did not differ between groups, but means of HED%Ret were lower in three sectors for patients (P < 0.05). Three sectors from 3 controls had HED%Ret below 2SD, whereas 36 sectors in 9 patients were outside sectors (P < 0.01). In patients, average HED%Ret/H2O% was lower in 9 sectors (P < 0.05 vs. controls); 2 outside sectors were found in controls, but 43 outside sectors were found in patients (P < 0.01), 77% of them in the 5 symptomatic patients. Heterogeneous [11C]HED retention was localized in the septal, anterior, and lateral walls. Most LQTS patients showed a localized and decreased pattern of [11C]HED retention. The larger number of heterogeneous sectors in symptomatic patients suggests that sympathetic function could play an amplifier role for severity of the disease. (+info)
Stroke associated with sympathomimetics contained in over-the-counter cough and cold drugs.
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BACKGROUND AND PURPOSE: Phenylpropanolamine (PPA) and pseudoephedrine are sympathomimetics contained in over-the-counter cold preparations. A case-control study linked PPA use with hemorrhagic stroke in women. Twenty-two patients with stroke associated with use of these drugs are described. METHODS: In a consecutive stroke registry since 1988, 22 patients had stroke associated with over-the-counter sympathomimetics. Sympathomimetic dosage and type, time interval until stroke onset, and neuroimaging findings are described. RESULTS: Ten male and 12 female patients were included. Intracerebral hemorrhage occurred in 17 patients, subarachnoid hemorrhage in 4, and ischemic stroke in 1. Stroke was associated with PPA use in 16 patients (dose 75 to 675 mg), with pseudoephedrine in 4 (dose 60 to 300 mg), and with others administered by the nasal route in 2 (oxymetazoline and phenylephrine). Stroke occurred after a single dose in 17 patients and after daily use during several days in 5. The interval between drug exposure and clinical onset varied from 30 minutes to 24 hours. Stroke occurred after recommended doses of PPA (50 to 75 mg) in 32% and pseudoephedrine (60 mg) in 50% of patients. Eight patients had acute hypertension at stroke onset. Cerebral angiography was normal in 8 cases and showed diffuse vasospasm or beading in 10 patients. CONCLUSIONS: Stroke related to over-the-counter sympathomimetics was associated with acute hypertension and/or vasospasm or angiitis mechanisms, most related to the use of PPA; however, stroke also occurred with the use of other sympathomimetics, particularly pseudoephedrine. Although stroke complications occurred when doses were used that were higher than recommended doses, apparently there is also a stroke risk when these agents are taken properly. (+info)
HPLC determination of (+)-pseudoephedrine and (-)-ephedrine in Japanese herbal medicines containing Ephedra herb using solid-phase extraction.
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We developed a rapid and simple HPLC method combined with solid-phase extraction (SPE) for quantitative analysis of (+)-pseudoephedrine (PEP) and (-)-ephedrine (EP) in Japanese herbal (Kampo) medicines such as Kakkon-to, Sho-seiryu-to, Goshaku-san and Bofu-tsusho-san. SPE was performed on TOYOPAK IC-SP M containing propylsulfonic groups. Determination of PEP and EP was carried out using ion-pair reversed-phase HPLC with sodium dodecyl sulfate. N-Benzyldiethylamine was used as an internal standard. The analytical procedure was validated with regard to specificity, linearity, accuracy, and precision. These data suggest that the analytical method developed in this study is useful for quantitative analysis of PEP and EP in various formulations of Kampo medicine containing Ephedra herb. (+info)
Pseudoephedrine: effects on milk production in women and estimation of infant exposure via breastmilk.
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AIMS: To assess the effects of pseudoephedrine on breast blood flow, temperature and milk production, and to estimate the likely infant dose during breastfeeding. METHODS: Eight lactating women (mean age 35 years and weight 69 kg) participated in a single-blind randomized crossover study of 60 mg pseudoephedrine hydrochloride vs placebo. Breast blood flow and surface temperature were measured from 0 to 4 h following the dose, and change in plasma prolactin was measured as the difference between predose and 1 h postdose concentrations. Milk production was measured for 24 h following placebo and pseudoephedrine. Infant dose of pseudoephedrine for a 60-mg dose administered four times daily to the mother was quantified as the product of average steady-state drug concentration in milk and an estimated milk production rate of 0.15 l x kg(-1) x day(-1) and expressed relative to the maternal weight-adjusted dose. RESULTS: There were no physiologically significant changes in breast blood flow or temperature between the placebo and pseudoephedrine periods. The mean change in plasma prolactin was slightly (13.5%), but not significantly lower (t = 1.245, P = 0.253) after pseudoephedrine (1775 mU x l(-1)) compared with placebo (2014 mU x l(-1)). However, the mean milk volume was reduced by 24% from 784 ml x day(-1) in the placebo period to 623 ml x day(-1) in the pseudoephedrine period (difference between means 161 ml x day(-1) (95% CI: 63, 259 ml x day(-1)); t = 3.9, P = 0.006). Assuming maternal intake of 60 mg pseudoephedrine hydrochloride four times daily, the estimated infant dose of pseudoephedrine was 4.3% (95% CI, 3.2, 5.4%) of the weight-adjusted maternal dose. CONCLUSIONS: A single dose of pseudoephedrine significantly reduced milk production. This effect was not attributable to changes in blood flow, but depression of prolactin secretion may be a contributing factor. At the maximum recommended pseudoephedrine doses, the calculated infant dose delivered via milk was < 10% of the maternal dose, and is unlikely to affect the infant adversely. The ability of pseudoephedrine to suppress lactation suggests a novel use for the drug. (+info)
In vitro characterization of ephedrine-related stereoisomers at biogenic amine transporters and the receptorome reveals selective actions as norepinephrine transporter substrates.
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Ephedrine is a long-studied stimulant available both as a prescription and over-the-counter medication, as well as an ingredient in widely marketed herbal preparations, and is also used as a precursor for the illicit synthesis of methamphetamine. Ephedrine is related to phenylpropanolamine, a decongestant removed from the market place due to concerns that its use increased the risk of hemorrhagic stroke. Standard pharmacology texts emphasize that ephedrine is both a direct and indirect adrenergic agonist, activating adrenergic receptors both by direct agonist activity as well as by releasing norepinephrine via a carrier-mediated exchange mechanism. Chemically, ephedrine possesses two chiral centers. In the present study, we characterized the stereoisomers of ephedrine and the closely related compounds pseudoephedrine, norephedrine, pseudonorephedrine (cathine), methcathinone, and cathinone at biogenic amine transporters and a large battery of cloned human receptors (e.g., "receptorome"). The most potent actions of ephedrine-type compounds were as substrates of the norepinephrine transporter (EC50 values of about 50 nM) followed by substrate activity at the dopamine transporter. Screening the receptorome demonstrated weak affinity at alpha2-adrenergic and 5-hydroxytryptamine7 receptors (Ki values 1-10 microM) and no significant activity at beta-adrenergic or alpha1-adrenergic receptors. Viewed collectively, these data indicate that the pharmacological effects of ephedrine-like phenylpropanolamines are likely mediated by norepinephrine release, and although sharing mechanistic similarities with, they differ in important respects from those of the phenylpropanonamines methcathinone and cathinone and the phenyisopropylamines methamphetamine and amphetamine. (+info)
Efficient synthesis of B-alkylated oxazaborolidines derived from ephedrine and norephedrine.
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[reaction: see text] Representative B-butyl- and B-methyl-1,3,2-oxazaborolidines derived from ephedrine and norephedrine were prepared in good yield and excellent purity by one-pot treatment of B-H oxazaborolidines with the corresponding organolithium reagent and subsequent hydrolysis of the cyclic borohydride intermediate with anhydrous ammonium chloride. (+info)
Influence of thymoxamine on changes in pupil diameter and accommodation produced by homatropine and ephedrine.
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Local instillation of thymoxamine eye drops (0-1%) completely reversed the mydriasis produced by ephedrine (5%) but not that produced by ephedrine (5%) together with homatropine (0-5%). Small but significant changes in accomodation were found with ephedrine and with thymoxamine, as well as the larger expected changes with homatropine. (+info)
Pharmacology of thermogenic drugs.
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Thermogenic combinations of ephedrine with caffeine and newer selective beta 3-agonists are being assessed for the treatment of obesity. The actions of beta-agonists may be multifaceted, with acute stimulation of thermogenic mechanisms in various tissues. During chronic treatment recruitment of brown fat may occur and hypertrophy of skeletal muscle may occur and simultaneously increase lean body tissue and reduce fat mass by stimulation of lipolysis and energy expenditure. The weight-reducing effect of an ephedrine-caffeine combination was superior to placebo treatment during 24 wk of energy restriction in obese women, whereas caffeine and ephedrine separately had no effect. In a second study it was found that ephedrine-caffeine compared with placebo preserved fat-free mass and enhanced fat loss, which could be accounted for both by anorexia (75%) and by increased thermogenesis (25%). The ephedrine-caffeine compound seems useful for the treatment of obesity and may serve as reference in the clinical assessment of new beta-agonists. (+info)