Drugs online research references
Life Sci. 1992;50(2):127-35.
Binding characteristics of naftopidil and alpha 1-adrenoceptor antagonists to prostatic alpha-adrenoceptors in benign prostatic hypertrophy.
Yamada S, Suzuki M, Kato Y, Kimura R, Mori R, Matsumoto K, Maruyama M, Kawabe K.
Department of Biopharmacy, School of Pharmaceutical Sciences, University of Shizuoka, Japan.
Binding properties of naftopidil and alpha 1-adrenoceptor antagonists to alpha-adrenoceptors in prostates from benign prostatic hypertrophy (BPH) were characterized by radioreceptor assays using [3H]prazosin and [3H]rauwolscine. Specific binding of [3H]prazosin and [3H]rauwolscine in human prostatic membranes was saturable and of high affinity, and it showed a pharmacological specificity which characterized alpha 1 and alpha 2-adrenoceptors, respectively. Naftopidil and several alpha 1 antagonists competed for prostatic [3H]prazosin binding in order: R-(-)-YM-12617 greater than prazosin greater than bunazosin greater than terazosin greater than naftopidil greater than urapidil, and the inhibitory effect (Ki = 11.6 nM) of naftopidil was 10 to 45 times less potent than quinazoline derivatives such as prazosin, bunazosin and terazosin. The potencies of these antagonists in competing for [3H]prazosin binding sites in human prostates correlated well with their pharmacological potencies (pA2). Scatchard analysis indicated that the decrease of prostatic [3H]prazosin binding by naftopidil was due to a marked increase in the Kd value without a change in the Bmax value. The inhibition of prostatic [3H]prazosin binding by naftopidil was reversible. Naftopidil also inhibited prostatic [3H]rauwolscine binding (Ki = 70.0 nM). Thus, it is suggested that naftopidil antagonizes alpha 1-adrenoceptors in human prostates in a competitive and reversible manner.
online pharmacy ref source: www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=1370569&dopt=Abstract
Prostate. 1992;20(2):89-95.
The relative efficacy of terazosin versus terazosin and flutamide for the treatment of symptomatic BPH.
Lepor H, Machi G.
Department of Urology, Medical College of Wisconsin, Milwaukee 53226.
Pharmacotherapy for the treatment of BPH is currently being targeted to relax prostate smooth muscle (alpha blockade) and decrease prostate volume (androgen suppression). The objective of the present study was to determine the relative efficacy of terazosin vs. terazosin and flutamide (combination therapy) for the treatment of symptomatic BPH. Twenty-nine males with symptomatic BPH were enrolled into this 6-month open label study. The entry criteria included peak urinary flow rate between 4-15 ml/sec, a total Boyarsky symptom score greater than 7, and postvoid residual less than 300 ml. The daily dosage of terazosin was titrated to 5 mg over a 2-week interval. A 750 mg daily dosage of flutamide was added following 1 month of terazosin monotherapy. The dosages were lowered if significant adverse events developed. Efficacy assessments were performed at 1 month (terazosin alone), 6 months (combination therapy), or at the time of early withdrawal from the study. The efficacy of combination therapy was evaluable in 24 patients receiving combination therapy. At one month, the mean peak urinary flow rate and mean total Boyarsky symptom score improved 38% and 56% relative to baseline, respectively. The present study confirmed the previously observed efficacy and safety of terazosin for BPH. The addition of flutamide did not result in statistically significant improvements in the peak urinary flow rate or total Boyarsky symptom score. The adverse events related to flutamide resulted in 16 dose reductions and 14 premature withdrawals. The role of combination therapy will require a randomized placebo controlled study sufficiently powerful to identify clinically and statistically significant improvements in objective outcome parameters relative to the monotherapies.
online pharmacy ref source: www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=1372430&dopt=Abstract
Nippon Hinyokika Gakkai Zasshi. 1992 Mar;83(3):334-7.
[Comparison of selective alpha-1 blockades for alpha-receptors in human hypertrophied prostatic adenomas]
[Article in Japanese]
Morita T, Kondo S.
Department of Urology, Tokyo Medical and Dental University School of Medicine.
The adrenergic alpha-1 and -2 adrenoceptors in six human hypertrophied prostatic adenomas were measured in the saturation experiment using 3H-prazosin and 3H-yohimbine. Not only alpha-1 adrenoceptons, but also alpha-2 adrenoceptors were found to exist in large amounts in prostatic adenomas. In the inhibition experiment selective alpha-1 antagonists inhibited the 3H-prozosin or 3H-yohimbine bindings to adenomas. The potency of alpha-1 antagonists in the order prazosin greater than bunazosin greater than alfuzosin greater than urapidil greater than terazosin and that of alpha-2 antagonists is urapidil greater than alfuzosin greater than terazosin greater than bunazosin greater than prazosin. These data suggest that urapidil, alfuzosin and terazosin may affect the human hypertrophied prostatic adenoma like phenoxybenzamine, nonselective alpha-1 antagonist, which was used for benign prostatic hypertrophy.
online pharmacy ref source: www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=1373456&dopt=Abstract
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